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Higher-yield and superior-quality rice are the major goals in rice breeding and nitrogen management. Genetic modification combined with optimal nitrogen (N) fertilization is expected to realize it. Modification in transaldolase (TAL) expression alters both the number and pattern of vascular bundles in rice plants, but its interactions with N rate remains unknown. We employed three representative lines with different expression levels of TAL in the same genetic background (Wuyunjing 7, WT), and analyzed their responses in dry matter accumulation (DMA), carbohydrate transport, grain filling, yield, yield components, and grain quality under a wide range of N rate. Increased expression of TAL (OE) promoted rice yield by producing more spikelets per panicle and higher 1000-grain weight, while decreased expression of TAL lowered the seed setting rate and grain weight significantly. Under a fixed N rate, when TAL expression was altered, the direct path coefficients of the seed setting rate and 1000-grain weight to the yield were higher than other yield components, especially at a high N rate. Decreased expression of TAL (RNAi) significantly reduced the starch and non-structural carbohydrates (NSC) contents in the stems, but enhanced the soluble sugar retention, whereas increased expression of TAL enhanced the translocation of NSC. The grain weight at maturity and mean grain-filling rate (mg d−1) increased significantly along with the TAL expression, but their differences among RNAi, WT and OE narrowed at higher N rate. Decreased expression of TAL enhanced the apparent amylose content (ACC) and protein (PC), reduced the starch granule size, and caused a loose starch arrangement and elevated chalkiness, as a consequence, significantly reduced the peak viscosity, hot viscosity, final viscosity, and taste value in a N rate dependent manner. The taste values of OE and WT were similar and the highest value was attained under a moderate N rate. TAL expression plays an important role in the regulation of assimilate supply, grain filling, yield formation, and grain quality. Increased expression of TAL alleviates competition effect among the yield components and enhances the yield potential, especially under moderate to high N rate. Higher TAL expression combined with a moderate N rate improves ECQ. TAL expression and N rate interacts to regulate yield components and quality. This finding provides meaningful knowledge to administering N rate and genetically modifying TAL expression in a rice variety. • Altered TAL gene expression impacts seed setting and grain weight dependent on N-rate. • High TAL level improves grain filling and final weight via more assimilate supply. • Higher TAL under mild N rate improves taste value by amylose and protein contents. [ABSTRACT FROM AUTHOR]

Identification and purification of the landrace Chittimuthyalu using stability and molecular heterozygosity can be useful for rice diversity. The present study reports the characterization of 12 genotypic variants of Chittimuthyalu in terms of (i) variation and correlation among agromorphological, grain quality and nutrient traits, viz., Zn and Fe; (ii) stability across years; and (iii) characterization and heterozygosity. A total of twelve genotypic variants were identified based on field-level agromorphological observations in the Chittimuthyalu landrace. For identification of a stable genotypic variant for grain Zn, genotype by environment (G × E) interaction was analyzed across three years using additive main effects and multiplicative interaction (AMMI) model and genotype main effects plus G × E (GGE) model for multienvironment data analysis along with principal component analysis (PCA). Correspondingly, twenty-five high polymorphism information content (PIC) RM markers were used for the identification of molecular heterozygosity in landrace. Stepwise regression analysis of phenotype revealed the interdependence of zinc in polished rice (ZPR), iron in polished rice (IPR), and single plant yield (SPY) and the positive association of grain Zn with IPR and SPY. Based on GGE and AMMI analyses of the variants, MCM3 was found to be stable across the environments for ZPR. Out of 46% polymorphic RM markers, seven markers (RM10149, RM13347, RM21749, RM13263, RM10361, RM12276 and RM474) were heterozygous. Heterozygous alleles were observed in eight variants (MCM2, MCM3, MCM5, MCM6 MCM7, MCM8, MCM10 and MCM12). The polymorphic information content (PIC) of the markers ranged from 0.58 to 0.88, with an average of 0.64. The percentage of the most common allele frequencies ranged from 4.2 to 95.8 across the markers. RM13347 showed nine marker trait associations with P ≤ 0.05 and R2 ranging from 2.3% to 14.3% with a mean of 7.74%. The present study has revealed the inherent heterogeneity in landraces in terms of their agromorphological, yield-related and nutritional quality traits. A promising genetic stock (MCM3) was identified as a donor for high grain ZPR and was registered as genetic stock. The identified genetic stock is being shared with breeders in the breeding programme and farmers for the multiplication of high grain Zn rice. ● The research has highlighted the heterogeneity in the landraces grown by farmers. ● In a single landrace "Chittimuthyalu", 12 genotypic variants were identified. ● Molecular characterization has shown the variability by heterozygous alleles. ● The purification of landraces before deployment in rice breeding is underscored. [ABSTRACT FROM AUTHOR]

Cotton has a complex branching pattern including sympodial and vegetative branching. Traditionally managed cotton mainly depends on sympodial branching for formation of yield-contributing fruit. Whether seedcotton yield based solely on vegetative branching is comparable with that based solely on sympodial or both types of branching is unclear. The study determined how terminal removal at first square to avoid formation of sympodial branches (SBs) regulated vegetative branching and yield under different plant densities. A two-year split-plot design field experiment had main plots with plant density (4.5 and 9.0 plants m−2) and subplots with plant pruning mode. Pruning modes were terminal removal at first square (TRS) to avoid formation of sympodial branches but retain only vegetative branches (VBs), removal of VBs (RVB) to retain only SBs, and no pruning (CK), with both branch types remaining intact. Canopy photosynthesis, dry matter accumulation and partitioning, and seedcotton yield and yield components were examined. At low plant density (4.5 plants m−2), compared with other pruning modes, TRS increased seedcotton yield and biological yield but did not affect harvest index. At high plant density (9.0 plants m−2), compared with other pruning modes, TRS decreased seedcotton yield and harvest index, although biological yield increased. The yield increase with TRS at low plant density was attributed to the increase in biological yield, which was due to significantly higher canopy photosynthesis with TRS than with other pruning modes. At high plant density, photosynthesis with TRS was higher than that with no pruning at peak boll-setting and boll-opening stages and higher than that with RVB from peak squaring to boll-opening. Compared with other pruning modes, TRS increased dry matter partitioning to vegetative organs but decreased partitioning to reproductive organs. Pearson correlation analysis revealed a significant positive correlation between canopy apparent photosynthesis and biological yield, biomass partitioning, and harvest index, irrespective of plant pruning and plant density. Plant pruning and plant density interacted to affect seedcotton yield. With TRS, cotton yield at low plant density was higher than that with other pruning modes, which was attributed to an increase in biological yield associated with an increase in canopy photosynthesis. At high plant density, the yield decrease with TRS was attributed to low harvest index associated with reduced reproductive partitioning. Cotton cultivation relying solely on vegetative branching can be an alternative to obtain moderate yields and economic benefits under conditions of low plant density. • Plant pruning and density affected cotton branching and yield formation. • Terminal removal at first square led to the highest seed cotton yield at low plant density. • Terminal removal at first square increased yield by promoting canopy photosynthesis. [ABSTRACT FROM AUTHOR]

Uneven crop stands result from natural variation in emergence time that is related to soil moisture and temperature, and variation of within-row plant-to-plant distance caused during planting operations. Understanding the effect of the spatial and temporal variation of plant emergence on crop yield can help farmers make improved management decisions about planting. The objectives of this work were to i) compare the timing of maize plant emergence across and within sub-field yield stability zones, ii) evaluate the impact of delayed emergence on crop yield and yield components by yield stability zone, and iii) compare the effect of spatial and temporal variability of plant emergence on crop yield and yield components. Ten experiments were conducted in farmers' maize fields in Springport (Michigan, US), Portland (Michigan, US), and Parana (Entre Rios, Argentina). Several years of yield monitored data for each field were used to delimitate yield stability zones (YSZ). Individual plant emergence was recorded daily, across yield stability zones. Emerged plants were tagged and the distance between plants within the row was recorded and used to calculate plant growing space (cm2 plant−1), and to classify them within plant stand as uniform, double or skips. Tagged plants were hand harvested to analyze the individual plant yield, number and weight of grains, and total crop yield. Individual plant emergence time ranged from 3 to 31 days after planting (DAP). The variation in timing of plant emergence had a greater impact than the variation of within-row plant spacing on crop yield and yield components. In general, the impact was larger in stable low yield areas. On average, plant yield was reduced by 7 %, grain number by 6 %, and final crop yield by 8.5 % per day of emergence delay after planting. The greater variation in the days of emergence delay when compared to within-row plant spacing variation can be related to the small overall spatial variability within the rows. Plant emergence temporal variability had a higher impact than within-row plant spatial variability on crop yield and its components. The decrease in maize yield caused by the delay in emergence was not statistically related to yield stability zones. However, a trend of a more negative impact of delayed emergence in the low yield stability zones was observed. Understanding factors affecting the spatial and temporal plant emergence patterns of crops can help farmers optimize their planting operation and may help them with decisions on using more precise and tailored inputs (such as seed rate and nitrogen fertilizer) on different sub-field yield stability zones. Incorporating emergence data and information into crop models will also help improve yield simulation results. [Display omitted] • Plant emergence was quantified in yield stability zones across multiple farmers' fields. • Plant yield was reduced by 8.5 % per day of emergence delay after planting. • Temporal variation in crop emergence had higher impact than spatial variation on crop yield. • Delayed in emergence lead to lower kernel number. [ABSTRACT FROM AUTHOR]

Selenium (Se) is an essential microelement for humans and a beneficial element for plants. Increasing grain yield and Se content simultaneously in crop is of great significance. In the present study, we hypothesize that the delay in the application of appropriate concentrations of Se contributes to increased grain yield and Se content. A two-year field experiment was conducted to investigate the effects of three concentrations of selenite (0, 5, or 20 g ha−1) sprayed at two stages (initial or peak flowering stage) on the yield, yield components, agronomic traits, photosynthetic characteristics, dry matter, and Se accumulation and distribution of common buckwheat plants. Results indicated that low concentration of Se promoted leaf photosynthesis more than higher concentration. The grain dry matter weight and Se content increased linearly with increasing Se application concentration. Delayed growth stages resulted in 2.65 and 1.66 times higher grain Se content in plants sprayed with low and high Se concentrations, respectively. Both Se application rate and spray time contributed significantly to grain yield. The grain produced under low-concentration spraying of Se at the IFS was safe for human consumption. In the present study, we suggest that foliar application of Se at 5 g ha−1 at the IFS is the most efficient way to improve grain Se accumulation and yield in common buckwheat. Future research may focus on quantifying the species of Se and localizing the Se element distribution in grains. [Display omitted] • Low Se rate (5 g ha−1) promoted the growth and grain yield of common buckwheat. • The delay of spraying stage increased the Se content in common buckwheat grain. • The interaction of Se rates and spraying stage significantly affected grain yield. • Se content in common buckwheat grain correlated positively with Se application rates. [ABSTRACT FROM AUTHOR]

With the increasing global food and oil security problems, improvement in rapeseed (Brassica napus L.) yield become urgent. Moreover, previous studies rarely used the semi-dwarf and compact plant type of rapeseed to improve yield potential. Herein, we aimed to investigate the effects of different nitrogen application rates and plant density on root growth and yield-related traits using three genotypes with different plant types to clarify various regulatory mechanisms using semi-dwarf and compact plant type mutants to achieve high yield. Split-split-plot experiments with three nitrogen application rates (N1: N2: N3, 120: 240: 360 kg ha−1) and three plant densities (D1: D2: D3, 15 × 104: 45 × 104: 75 × 104 plants·ha−1) were conducted during the three growing seasons (2019–2022) using semi-dwarf mutant HS5 sca , and HS5 (wild type) as well as their F 1 hybrid HS5 +/sca. With decreasing nitrogen application rate (N3 to N2), the expression level of IAA signal response genes BnaA07. GH3 and BnaA03. IAA13 was decreased in root, while increased in shoot at the early-flowering stage. Moreover, IAA content was decreased in roots and aboveground parts, whereas soluble sugar content of root bleeding sap was increased and volume of root bleeding sap was decreased in three genotypes at early-flowering stage. Additionally, nitrogen accumulation per plant and yield per plant was decreased, while population nitrogen accumulation and population yield were increased with decreasing nitrogen application rate in three studied genotypes. On the other side, with increasing plant density, the expression of BnaA07. GH3 and BnaA03. IAA13 genes were first increased and then decreased in root tissues. In addition, root surface area, the total volume of root bleeding sap, and nitrogen accumulation were decreased, which decreased dry matter and yield per plant. However, total root area, population nitrogen accumulation, and population yield in the three genotypes were increased, and yield was the highest at D2. The population yield of HS5 sca , HS5 +/sca , and HS5 achieved the largest increase of 26.0%, 10.3%, and 9.5% under N2D2 in 2019, 6.9%, 8.4%, and 4.7% under N3D2 in 2020, respectively, as compared to N3D1. Moreover, the morphological indices of HS5 +/sca were greater than other genotypes, with the highest population yield. Appropriate nitrogen application rate with plant density optimized the root architecture and aboveground type of HS5 +/sca that improved auxin level through affecting the downstream auxin-related genes, as well as improved dry matter accumulation and distribution, which increased yield potential. Compared with the two parents, F 1 genotype HS5 +/sca was suitable for nitrogen fertilizer (240 kg ha−1) and plant density (45–75 × 104 plants ha−1). + /sca heterozygous genotypes might promote root growth under low nitrogen application rate and high plant density. A strong root system is an important guarantee of high yield; thus, this heterozygous site could use to introduce excellent hybrids in rapeseed production to further improve root traits and optimize cultivation factors to increase seed yield. • Various plant architecture rapeseeds responded differently to nitrogen and density. • HS5 +/sca was suitable for reducing nitrogen rate and increasing plant density. • BnaA3. IAA7 mutation caused more lateral roots and root biomass in HS5 +/sca. • Auxin level and its signaling genes expression affected root-crown growth. [ABSTRACT FROM AUTHOR]

Water shortage has become one of the major threats to global food security. To meet the challenge of increasing food demand and water scarcity, water-saving and drought-resistant rice (WDR) is increasingly cultivated in China. However, there are few comprehensive studies on the effect of WDR on grain yields as well as CH 4 and N 2 O emissions in the literature. A three-year field experiment was conducted with one common rice (CR) and three WDR varieties in a rainfed paddy field in Southwest China. The results showed that in the WDR treatments, both CH 4 emissions and the global warming potential of CH 4 and N 2 O emissions decreased by 6.2–15% on average. Seasonal CH 4 emission was positively correlated with the mean tiller number but negatively correlated with the harvest index. Moreover, WDR increased the mean grain yield by 18–23% compared to CR, and especially in 2017, an increase within the range of 31–61% was observed when precipitation was low. The increasing grain yield was mainly due to the rise in the percentage of filled grains, and as a result, the greenhouse gas emission intensity was higher by 12–83% in CR than in WDR, while the lowest value was observed in one of the WDR varieties (Hanyou 73). Here, we report for the first time that planting water-saving and drought-resistance rice, especially the Hanyou 73 variety, under rainfed conditions would increase plant grain yield and decrease greenhouse gas emission intensity in regions with water shortage in Southwest China. ● Both CH 4 emissions and GWP were 6.2–15% lower in WDR than in CR. ● Seasonal CH 4 emission was positively correlated with the mean tiller number. ● Seasonal CH 4 emission was negatively correlated with the harvest index. ● WDR increased mean yield by 18–23% due to increase in percentage of filled grains. ● The greenhouse gas emission intensity was higher by 12–83% in CR than in WDR. [ABSTRACT FROM AUTHOR]

Highlights • The yield potential and yield stability of sorghum hybrids can be used to inform crop designs. • The APSIM model was able to reproduce genotype × environment interactions observed in field trials. • We identified physiological traits that potentially modify yield stability. • A skilful climate forecast would allow crop designs to be matched to expected seasonal conditions. Abstract Reducing yield gaps in dryland cropping depends on our capacity to identify combinations of genetics (G) and management (M) (i.e. crop designs, G × M) that best suit site and seasonal conditions (the environment, E). We combined empirical and modelling approaches to characterise and explain the yield stability and yield potential of commercial sorghum hybrids when grown under a range of agronomic managements and environments yielding between 3 and 12 t ha−1. The empirical data includes two seasons (2014-15 and 2015–2016) of on-farm and on-research station trials conducted across six sites in Queensland, Australia. Agronomic management treatments included plant density, row configuration, level of irrigation and fertiliser inputs, and time of sowing. Six hybrids contrasting in maturity and tillering type were characterised relative to the industry standard MR-Buster in terms of yield potential, yield stability (b i), and an expected utility index that combines both indices. A medium-late maturity and high tillering hybrid (MR-Scorpio), had the highest utility rank and showed high b i values due to high tiller productivity. A variety of significant row spacing and configuration, and plant density effects on yield were observed, but these were inconsistent across sites and seasons. A long-term simulation experiment across contrasting environments was used to identify hybrid traits and managements capable of modifying yield stability. Combined with the empirical data, the simulations suggest hybrids showing high biomass production and multiple productive tillers can increase the response of yield to the productivity of the environment, whereas reducing the thermal time to floral initiation may increase the stability of yields across environments. Expected changes in hybrid rank due to such G × E interactions, along with the complex effects of management on yield, increase the need to match crop design to specific sites and seasons. The value of targeted crop design depends on the diversity of traits among commercial hybrids and the availability of a skilful seasonal climate forecast to allow farmers to match hybrids and management to prevailing and expected seasonal conditions. [ABSTRACT FROM AUTHOR]

Lodging is a major adversity which limits maize grain yields and quality, especially under dense population. The present study was conducted to determine the efficacy of mepiquat chloride, a potential anti-gibberellic plant growth retardant on plant height, the physical strength of stem, lignin content and its relationship with lodging resistant in maize crop. Maize seeds were dressed with mepiquat chloride at the rate of 0 (MC0), 2.0 (MC1), 2.5 (MC2), and 3.0 (MC3) g kg −1 during 2015–2016. Our results showed that mepiquat chloride treatments enhanced the culm physical strength, as revealed by enhanced rind puncture strength and stalk bending strength, increased dry weight per cm, stem diameter, and lignin accumulation resulting in strong lodging resistance. A significant and negative correlation was detected between stalk bending and rind puncture strength with lodging rate. Moreover, the lodging rate, plant height, internodes length and gravity center height were significantly reduced following a dose-response trend, and MC2 and MC3 treatments resulted in relatively shorter plants, compared to control treatment. In addition, the grain yield, lignin contents and activities of lignin-related enzymes were enhanced by mepiquat chloride, and the MC2 (2.5 g kg −1 ) treatment showed the best effect of all treatments. The correlation analysis revealed that lignin accumulation was negatively and significantly correlated with lodging rate of the maize crop. Our results imply that plant height obviously, as well as the culm physical strength and lignin are closely associated with the lodging resistance in maize, and the decreased plant height, enhanced culm morphological characteristics and lignin content could strengthen the resistance of crops to lodging. [ABSTRACT FROM AUTHOR]

During the past few years, several studies have compared the performance of crop simulation models to assess the uncertainties in model-based climate change impact assessments and other modelling studies. Many of these studies have concentrated on cereal crops, while fewer model comparisons have been conducted for grasses. We compared the predictions for timothy grass ( Phleum pratense L.) yields for first and second cuts along with the dynamics of above-ground biomass for the grass simulation models BASGRA and CATIMO, and the soil-crop model STICS. The models were calibrated and evaluated using field data from seven sites across Northern Europe and Canada with different climates, soil conditions and management practices. Altogether the models were compared using data on timothy grass from 33 combinations of sites, cultivars and management regimes. Model performances with two calibration approaches, cultivar-specific and generic calibrations, were compared. All the models studied estimated the dynamics of above-ground biomass and the leaf area index satisfactorily, but tended to underestimate the first cut yield. Cultivar-specific calibration resulted in more accurate first cut yield predictions than the generic calibration achieving root mean square errors approximately one third lower for the cultivar-specific calibration. For the second cut, the difference between the calibration methods was small. The results indicate that detailed soil process descriptions improved the overall model performance and the model responses to management, such as nitrogen applications. The results also suggest that taking the genetic variability into account between cultivars of timothy grass also improves the yield estimates. Calibrations using both spring and summer growth data simultaneously revealed that processes determining the growth in these two periods require further attention in model development. [ABSTRACT FROM AUTHOR]

Understanding the effect of genetic factors controlling flowering time is essential to fine-tune phenological development and to maximize yield. Thirty-four spring durum wheat genotypes classified in five allelic combinations for Ppd-A1/Ppd-B1 loci were grown for two years at three contrasting latitudes: Mexico-North, Spain-South and Spain-North. In all them, a delay in flowering date due to the presence of photoperiod sensitivity alleles Ppd-A1b and Ppd-B1b resulted in lower yields. The number of days to flowering, determined by an increasing number of photoperiod sensitivity alleles, accounted in all sites for more than 80% of the variation in the contribution of translocation of pre-flowering assimilates to grain yield. In Mexico and Spain-North late-flowering resulted in decreased harvest index as influenced by high temperatures during grain filling. In Mexico, where grain filling occurred under high temperatures and solar radiation, translocation of pre-flowering assimilates accounted from 55 to 63% of yield, independently of the flowering date of the genotype. In Spain-North, where water was available during grain filling, current photosynthesis was the main contributor to yield (57–73%), with independence of the allelic combination at Ppd loci. In Spain-South, the relative contribution of photosynthesis and translocation depended on the allelic composition at Ppd loci, with translocation increasing by 24% in the latest-flowering genotypes compared with the earliest ones. In all sites the limiting factor for attaining high yields was the capacity of the plant canopy to photosynthesize after anthesis. This study suggests that the expression of genes Ppd-A1 and Ppd-B1 regulating the response to photoperiod modulates the physiological strategy adopted by durum wheat to fill its grains, underlining the importance of phenology fitting in maximizing grain yield. [ABSTRACT FROM AUTHOR]

The effects of supplemental nitrogen (N) on soybean [ Glycine max (L.) Merr.] seed yield have been the focus of much research over the past four decades. However, most experiments were region-specific and focused on the effect of a single N-related management choice, thus resulting in a limited inference space. Here, we composited data from individual experiments conducted across the US that examined the effect of N fertilization on soybean yield. The combined database included 207 environments (experiment × year combinations) for a total of 5991 N-treated soybean yields. We used hierarchical modeling and conditional inference tree analysis on the combined dataset to establish the relationship and contribution of several N management choices on soybean yield. The N treatment variables were: N-application (single or split), N-method (soil incorporated, foliar, etc. ), N-timing (pre-plant, at a reproductive stage, etc. ), and N-rate (from a 0 N control to as much as 560 kg ha −1 ). Of the total yield variability, 68% was associated with the effect of environment, whereas only a small fraction of that variability (< 1%) was attributable to each N variable. Averaged over all experiments, a single N application and the split N application were 60 and 110 kg ha −1 greater yielding than the zero N control treatment, respectively. A split N application with more than one method ( e.g., soil incorporated and foliar) resulted in 120 kg ha −1 greater yield than zero N plots. Split N application between planting and reproductive stages (Rn) resulted in greater yield than zero N and single application during a Rn; however, the effect was not significantly different than N application at other growth stages. Increasing the N rate increased the environment average soybean yield; however, 93% of the environment-specific N-rate responses were not significant which suggested a minimal effect of N across the examined region. A large yield variability was observed among environments within the same N rates, which was attributed to growing environment differences ( e.g ., in-season weather conditions, soil type etc. ) and non-N related management ( e.g ., irrigation). Conditional inference tree analysis identified N-timing and N-rate to be conditional to irrigation, and to seeding rates >420,000 seeds ha −1 , indicating that N management decisions should take into account major, non-N related management practices. Overall, the analysis revealed that N management decisions had a measurable, but small, effect on soybean yield. Given the growing pressure for increasing food production, it is imperative to further examine all soybean N decisions (application method, timing, and rate) in environment- and cropping system-specific randomized trials in important agricultural regions. [ABSTRACT FROM AUTHOR]

Wheat ( Triticum aestivum L.) and rice ( Oryza sativa L.), which belong to the Poaceae family, are starch-grain crops, but wheat is adapted to cooler temperature conditions than rice. In this study, the difference between the two contrasting crops in grain-filling adaptability in response to temperature was investigated. Two spring wheat cultivars were grown in the Mediterranean-type environments of Western Australia and Southeast Turkey, and four temperate-zone rice cultivars were grown in several locations in Japan under irrigated conditions. Portions of the crops were enclosed under a plastic canopy to elevate the temperature after anthesis. Average temperatures during grain filling ranged from 14 to 24 °C for wheat and from 23 to 29 °C for rice. Grain yield varied from 280 to 599 g m −2 in wheat and 354 to 736 g m −2 in rice. When plant density was halved at flowering to estimate the potential grain-filling rate under an increased supply of assimilates, the grain-filling percentages [%F, observed grain weight (G)/potential grain weight (PG)] of both crops were represented by similar logistic curves of cumulative temperatures during the grain filling period. These results suggest that grain-filling responses to temperature scarcely differ between spring wheat and temperate-zone rice. G was estimated for the spring wheat and temperate-zone rice cultivars under different temperatures after anthesis using an assimilate-limited grain-potentiality model consisting of the following parameters: rate of whole-plant weight increase (ΔW/Δ t ), rate of potential grain dry weight increase (ΔPG/Δ t ) based on rate of%F (%F/Δ t ) and PG, and the amount of stem reserves (SP). The observed data showed that the decrease in ΔW/Δ t with an increase in temperature in wheat was greater than in rice. According to the model, G started to decrease at lower temperatures in wheat than in rice, and this decrease was accelerated by lower amounts of SP. Therefore, the difference in the optimal temperatures for G during grain filling between the two crops was suggested to mainly result from the sensitivity of assimilation to high temperatures. [ABSTRACT FROM AUTHOR]

Climate changes in temperature, solar radiation, and precipitation potentially interrupt progressive improvement in crop yield. Genetic and agronomic strategies to adapt climate changes were proposed in previous studies, but were rarely evaluated. In this study, meteorological data from 1954 to 2014 at one representative station in the North China Plain (NCP), model simulation of Hybrid-Maize, and a field experiment were combined together to detect climate change impacts on maize yield and to assess the adaptive effects of cultivars. Three maize cultivars with contrasting lengths of growing period were grown at three specific plant densities. Cultivar with a long growing period (LG) was grown at 67500 (optimal density), 82500, and 97500 plant ha −1 , medium-growing (MG) cultivar at 82500 (optimal), 97500, and 112500 plant ha −1 , and short-growing (SG) cultivar at 97500 (optimal), 112500, and 124500 plant ha −1 . During the past six decades, temperature increased and solar radiation decreased significantly in the total, vegetative, and reproductive growing periods of maize in the NCP with a slight decline in precipitation. These climate changes significantly reduced yield at a rate of 30.8, 31.3, and 25.0 kg ha −1 yr −1 , respectively, for SG, MG, and LG maize cultivars. Decline in growing degree days (GDD) use efficiency of LG cultivar with changing climate was one-fold slower than that of SG and MG cultivars. MG maize cultivar was estimated to produce the highest grain yield in NCP owing to its relatively long growing period and high tolerance of plant density. LG maize cultivar has a larger potential to adapt changing climate, but has a larger difficulty in improving yield because of lower tolerance of high plant density. Improvement of plant architecture in space and in time is expected to resolve the conflict between adapting climate changes and tolerating high plant density in maize. [ABSTRACT FROM AUTHOR]

This study was done with an objective to attempt to pool together in wheat, the three most important traits (spot blotch resistance, high yield and earliness) for warm humid Eastern Gangetic plains (EGP) of South Asia. A Recombinant Inbred Line (RIL) population, developed from two contrasting parents (YS#58 × YS#24) for spot blotch resistance, was tested in seven environments falling under three locations of EGP. Most of the components of variation for three traits were highly significant for each environment as well as in pooled analysis. In general, phenotypic correlation for Area Under Disease Progress Curve (AUDPC) among centers was high and positive. Out of 214 genotypes (211 RILs along with their parents YS#24, YS#58 and Sonalika, check for spot blotch susceptibility and earliness) tested, 15 RILs showed better resistance than the resistant parent. Measured over seven environments, six lines were significantly superior to best check for spot blotch resistance while two for grain yield, four for earliness and two for 1000-grain weight. However, only one line (#94) was found significantly superior for all four traits compared to the best check. Genotype × Environment (G × E) interaction was significant but Genotype × Year (G × Y) was non-significant which indicated the importance of locations for spot blotch. To support this fact, lines superior in one location did not perform well in the other. For resistance, line #174 performed most consistently over 7 environments. Although there was negative correlation between AUDPC and days to heading, low AUDPC was observed in two early maturing RILs (#94 and #1). The study demonstrated that through appropriate crossing and evaluation, it is possible to pool together spot blotch resistance in to high yield back ground of wheat with early maturity. [ABSTRACT FROM AUTHOR]

Field morpho-physiological characterization of barley is essential for selecting salt-tolerant genotypes and for predicting yield reduction. A field experiment was conducted for two consecutive growing seasons (2012-13 and 2013-14) in Kairouan (semi arid, Central Tunisia) and in Medenine (arid, South-East Tunisia), where 4 widely grown varieties, 23 local landraces originated from saline and non-saline agro-ecosystems, and 13 genotypes from the Near East North Africa (NENA) region, were tested. In each location, saline groundwater and drinking water were used. Grain yield, plant ion content (Na + , K + and Ca 2+ ), flag leaf chlorophyll content index (CCI), relative water content (RWC), specific leaf area (LA) and plant earliness at heading (E60) were measured for each genotype. Grain yield reduction ratio (YRR) was calculated for all genotypes to estimate their tolerance to salinity. [ABSTRACT FROM AUTHOR]

Italian ryegrass ( Lolium multiflorum L.) seed crops are often routinely fertilized with a predetermined amount of nitrogen (N) fertilizer in spring. However, nitrate leaching and increasing N fertilizer prices require rationalized fertilizer applications without compromises in seed yield. The objectives of this study were (1) to determine the seed yield response to N fertilization, and (2) to evaluate if NDVI values can reliably predict the N status in Italian ryegrass seed crops. During eight years, field trials were conducted with two cultivars ‘Melclips’ and ‘Melquatro’, and seven N strategies applied after the forage cut as single or split application: 0, 60, 60 + 30, 90, 90 + 30, 120 and 150 kg N ha −1 . NDVI values were obtained with a ‘GreenSeeker’ optical sensor. Maximum seed yield was attained at 141 kg N ha −1 total available N (92 kg N ha −1 fertilized). Higher fertilizations only increased NNI values but not seed yield. Split-application strategies were equal to single-applications in terms of seed yield, which indicates that remedial fertilizations at the two-three node stage are effective. NNI values at all growth stages predicted seed yield adequately: maximum seed yield was attained at NNI values of 0.86 in the 2–3 node stage, 0.72 at the beginning of heading, and 0.59 at full ear emergence. NDVI values were correlated with NNI values, but were also heavily influenced by trial year. Therefore, is it impossible to establish NDVI thresholds to decide on remedial N fertilization. [ABSTRACT FROM AUTHOR]

High temperatures across the Australian sorghum belt can reduce sorghum yields, but genotypic differences in heat tolerance could mitigate these yield losses. The objectives of this study were to quantify occurrences of high temperatures around anthesis of sorghum, determine their yield impacts, and assess the potential for management and genetics to minimise any adverse effects. Long term weather records for six locations across the Australian sorghum belt were used to quantify the probability of high temperature occurrence. These records were then used in a simulation study with the APSIM-sorghum model. The model was adapted to capture high temperature effects on grain yield for five hypothetical genotypes that differed in temperature threshold for effects on seed set and in tolerance to temperatures above that threshold. Results showed that the most common incidence of heat stress around anthesis was the occurrence of individual days with maximum temperatures between 36–38° C. Because these temperatures were near the threshold limiting seed set in tolerant genotypes, an increased temperature threshold generally minimised adverse yield effects. However, 1–5 ° C predicted temperature increases in coming decades will justify additional selection for increased tolerance above the threshold. Manipulation of sowing dates did not reduce risks of heat stress around anthesis, unless sowing was extremely late. Hence, genetic improvement provides the best prospect to mitigate heat stress effects on grain yield. [ABSTRACT FROM AUTHOR]

Heat stress is a major constrain to sustain rice production and grain quality. Rising atmospheric [CO 2 ] is predicted to increase photosynthesis resulting in higher biomass and yield. Conversely, both elevated (e[CO 2 ]) and heat stress (HT) are documented to deteriorate grain quality traits in rice. However, interactive effect of e[CO 2 ] + HT on rice grain yield, quality traits and particularly mineral composition under natural field condition in tropical environments are limited. Independent field experiments were conducted to assess the potential impact of e[CO 2 ] alone and in combination with HT on grain yield, quality traits and mineral composition of two rice cultivars Nerica-L-44 (heat tolerant) and Indian basmati rice variety Pusa 1121, using field based open top chamber (OTC) facility. Elevated [CO 2 ] significantly influenced grain quality traits by increasing chalkiness (69–83%), amylose content (18–37%), decreasing protein content by 4% and altering grain mineral nutrient composition across the cultivars. Proportion of chalky grains was further increased in Nerica-L-44 and Pusa 1121 under e[CO 2 ] + HT interaction. Correlation analysis revealed negative relationship of grain minerals with chalkiness and amylose content. In summary, independent exposure of rice to e[CO 2 ] reduced grain quality and e[CO 2 ] + HT further increased the negative effects on grain nutrient and quality. [ABSTRACT FROM AUTHOR]

Cropped area under no-till (NT) is increasing worldwide, but the extent to which breeding for yield is selecting for adaptation to NT is unclear. In addition, the consequences of selection for yield and that of tillage system on senescence patterns are not known. This study compared yield and senescence patterns of fourteen Australian wheat varieties released between 1958 and 2011, under no-till with stubble retention, and under conventional tillage (CT) without stubble. Grain yield increased at a rate of 21 kg ha −1 year −1 irrespective of tillage system, which implied that selection for yield did not improve wheat adaptation to no-till. Selection for yield changed the pattern of canopy senescence, whereby modern varieties had lower peak normalised difference vegetative index (NDVI), higher NDVI at maturity, a faster rate of senescence, and greener leaves, compared with older counterparts. [ABSTRACT FROM AUTHOR]

Understanding the mechanism underlying high grain yield and high nitrogen use efficiency (NUE) is very crucial for the development of optimal crop management practices. However, whether and how the canopy eco-physiological characteristics contribute to crop NUE and how they are regulated by crop management practices are unclear. In this study, two high yielding ‘super’ rice cultivars, Yongyou 2640 and Wuyunjing 24, were grown in the field, and integrated management practices of N rates, planting densities, water management, tillage depth, and organic fertilizer application, were used during the growing season. Results showed that the internal NUE (grain yield/N uptake of plants) is highest in the N blank treatment (0 kg N ha −1 ), and it decreased as the N rate increases. However, at comparable N rates, both rice grain yield and NUE could be improved simultaneously by crop management practices. Canopy N and light profile parameters, i.e. the extinction coefficient for N ( K N ) and for light ( K L ), and their ratio ( K N / K L ), contributed to yield and NUE. Crop management practices improved canopy eco-physiological characteristics (lower K L , higher K N and K N / K L ) to coordinate the distribution of light and N within the canopy to maximize canopy photosynthesis, and resulted in higher yield and NUE. The physiological mechanisms could be that the increased root activities by management practices contributed to cytokinin synthesis and accumulation in the flag leaves which regulated N partitioning and translocation. The results indicate that canopy eco-physiological traits, especially K N / K L ratio is a good indicator of N use efficiency. K N / K L is closely correlated with crop yield and NUE, and can be optimized by crop management practices. [ABSTRACT FROM AUTHOR]

Smallholder farmers frequently suffer limited resources and cannot afford to buy improved seeds every season resulting in poor crop establishment. Strategies are needed to reduce costs of crop establishment while maintaining or improving productivity. The objective of this study was to assess the viability of ratooning pigeonpea in maize ( Zea mays L.)—pigeonpea ( Cajanus cajan (L.) Millsp.) intercropping over four cropping seasons (2012–2015) at Ilonga Research Institute, eastern Tanzania. Two major factors were considered: cropping system (intercropping vs. sole cropping) and tillage (conventional tillage vs. no-tillage), while ratooning (cutting pigeonpea at 30 cm and 60 cm above ground) was a minor factor. Total grain yields of all intercropped maize and pigeonpea were significantly higher than those of maize and legume in the corresponding sole crop treatments showing a high complementarity between maize and pigeonpea crops. All the intercrop treatments had LER values greater than 1, even in situations where component crop yields were small. Results suggested that a ratooning height of 30 cm allowed large maize yields whereas a height of 60 cm allowed larger pigeonpea yields, and the choice of ratooning height might depend on the farmer’s objective per season. The tillage system had no significant effect on crop yield. The hypothesis that ratooning pigeonpea is an effective cost reduction strategy that maintains or increases productivity in maize-pigeonpea intercropping was supported. When ratooning was practiced in the intercrops, the seed cost reduction of 23% per season was recorded. Ratooning in sole pigeonpea entailed a larger seed cost reduction from TZS40, 000.00 to TZS13, 333.00 (1US$ = TZS2, 000.00) per season representing a reduction of 67%. The cost reduction due to ratooning was significant as generally less than 10% of the smallholder farmers are able to purchase significant quantities of seed. The prevailing cropping systems and general farmers’ resource endowment in eastern Tanzania coupled with the fragmented seed systems especially for legumes provide a greater scope for the wide scale practice of ratooning pigeonpea in maize-pigeonpea intercropping, reducing seed costs while maintaining productivity. [ABSTRACT FROM AUTHOR]

The seed emergence and yield of rainfed rapeseed ( Brassica napus L.) are commonly limited by soil water availability during the growing season. The return of straw to the field helps maintain soil moisture status, but can cause long hypocotyls of seedlings and result in yield reduction. Using the swede rape hybrid Huayouza 62 as material, the effects of sowing depth and soil compaction on seedling growth and yield under conditions of straw return to the field were investigated. The bulk density and water content for the soil layers of 0–10 and 10–20 cm significantly increased and total porosity decreased under the compaction of shallow (2 cm) and deep sowing (3 cm), and the effect was greater for the 0–10 cm layer. Without soil compaction, the seedling emergence rate was substantially improved with increased sowing depth, but was dramatically decreased in the case of compacted soil. The soil compaction significantly elevated the seedling emergence rate with shallow sowing, and increases were 15.57 and 17.08% for 2013–2014 and 2014–2015, respectively; however, with deep sowing, compaction had no significant effect. The variation in seedling density was consistent with that of the seedling emergence rate. Compared to shallow sowing, deep sowing induced a thinner rapeseed stem, but soil compaction had an opposite effect. Increasing the sowing depth or soil compaction improved the overall yield by elevating the root/shoot ratio of seedlings and lodging resistance, effectively eliminating weed infestation. Significant interactions were found between sowing depth and soil compaction in yield and siliques. Shallow sowing with soil compaction had a positive effect on growth and development, and dramatically increased seedling density and siliques, leading to improved yield. [ABSTRACT FROM AUTHOR]

A liquid silicon fertilizer [Si(OH) 4 ] was root sprayed at various concentrations during the seedling stage (T1) and early bud stage (T2) using the rapeseed varieties ( Brassica napus L.) Huayouza 62 and Fengyou 520. The lodging- and yield-related index, silique shatter were evaluated. Our results indicated that the lodging resistance, silique shatter resistance, and yield all increased significantly in the two rapeseed varieties after the application of silicon fertilizer in both stages. The seed number per silique was reduced after silicon application, but the silique number per plant and 1000-grain weight were increased, especially the silique number on the branches, thereby improving the overall yield, where the most obvious effect on the yield increase occurred at the T2 stage with 0.96 mM silicon. At the T1 and T2 stages, the higher concentration of silicon fertilizer increased the root diameter, as well as the stem SiO 2 content and breaking strength, but reduced the plant height and lodging index. There were also increases in the expression levels of the key genes related to stem lignin biosynthesis (phenylalanine ammonia lyase ( PAL ) and 4-coumarate: CoA ligases), the lignin content, thereby increasing the resistance to lodging. At stages T1 and T2, the higher concentration of silicon fertilizer increased the expression of the PAL , which induced the accumulation of lignin. There was a significant correlation between the silique dry weight and silique shatter index. The silique SiO 2 content and dry weight also increased, thereby improving the shatter resistance. Considering the yield and mechanical harvesting properties, the results of the present study show that the optimum effect of the liquid silicon fertilizer on both rapeseed varieties occurred during the early bud stage (bolting height of 8–12 cm) with a monosilicic acid content was 0.96 mM. [ABSTRACT FROM AUTHOR]

Intercropping tends to have a higher productivity than traditional sole crops, mainly due to complementary resource use in time and space among different species. Intercropping may become more important in a world that needs to produce 60–70% more food by 2050 with limited land and other agricultural resources. To assess the role of intercropping in agricultural systems and its contribution to future food security, an intercrop model is needed for growth and yield predictions of intercrops under different growing conditions. Strip intercropping is a prevalent intercropping system, but the existing intercrop models are generally built for full mixtures and are less suitable for strip intercrops. Here we describe a simple intercrop model which is developed based on a sole crop model using the radiation use efficiency (RUE) concept and a strip intercrop light partitioning module. The model allows simulating the growth and yield of each intercropped species in relay-strip intercropping under potential growing conditions (only competition for light; other resources are assumed to be non-limiting), and the intercrop could vary in species combination, planting configuration, sowing densities and sowing dates. The daily inputs of the model are temperature and radiation, and crop-specific parameters are required to simulate crop leaf area index (LAI), biomass and final yield. Data collected during two years (2013 and 2014) field experiments were used to calibrate and test the model. The experiments consisted of two sole crop treatments (sole wheat, SW and sole maize, SM) and three intercrop treatments (replacement intercrop, 6:2WM and add-row intercrops, 8:2WM and 6:3WM). The experiments were conducted in Wageningen, the Netherlands. Data of sole crops (SW and SM) and replacement intercrop (6:2WM) treatment were used to calibrate the model, and data of add-row intercrops (8:2WM and 6:3WM) were used to test the model. Bayesian analysis was applied to calibrate RUE of wheat and maize in sole crops and intercrop. This calibration procedure resulted in posterior distributions of RUE for sole crops and intercrop, on the basis of which distributions of biomass and land equivalent ratio (LER) were simulated. Biomass accumulation and yield of each species were simulated adequately but LAI was slightly overestimated compared to observations. The intercrop model allows simulating the contribution of border row effects to the productivity of intercrops. It combines a simple structure with easy calibration and enables growth and yield simulations for a wide range of relay-strip intercrops. The model thus can be of value in exploratory land use studies to assess the role of intercropping. [ABSTRACT FROM AUTHOR]

Planting density management can regulate cotton (Gossypium hirsutum L.) biomass accumulation and seed cotton yield formation, which are associated with water consumption. However, it is unclear whether modifying the planting density affects the water use in different soil layers and thus regulates the plant growth and yield formation of cotton. In a two-year field experiment in 2020–2021, cotton was grown at various plant densities (1.5, 3.3, 5.1, 6.9, 8.7, and 10.5 plants m−2), and the spatial profile of water consumption, plant height, the leaf area index (LAI), biomass accumulation, and seed cotton yield were evaluated. The results showed that increase in planting density leads to more water consumption in the middle and lower soil layers (40–80 and 80–120 cm), and improved water use efficiency (WUE) in each soil layer (0–40, 40–80, 80–120 and 0–120 cm). The difference in plant height was attributed to cumulative total water consumption (0–120 cm), and the variation in LAI was due to planting density and cumulative total water consumption. More aboveground biomass at higher planting density was mainly attributed to more water consumption of the middle and lower soil layers (40–80 and 80–120 cm). Additionally, excessively high planting density may lead to the premature senescence of root systems, as the correlation between the water consumption at 40–100 cm and belowground biomass was weaker under high planting density. Moreover, the WUE at 0–40 cm was proportional to the boll distribution on the lower part (1st-6th fruiting branches) of the plant and boll number per unit area, was inversely proportional to boll weight and harvest index (HI), and had parabolic relationship with seed cotton yield (y = −426.83 +244.50–3.48x2). Taken together, our data focused on the effects of water use in various soil layers induced by planting density on cotton growth and yield formation; moreover, these findings fill knowledge gaps within cotton science and provide a feasible direction for determining reasonable water management practices on the North Plain China. • Monitoring soil moisture with high spatiotemporal resolution. • Increasing planting density is expected to promote the water utilization in deep soil layers. • It is more likely that the increase of water use efficiency (WUE) of the 0–40 cm soil layer is at the expense of yield. [ABSTRACT FROM AUTHOR]

Decreases in grain yield and milling quality in the ratoon crop due to crushing damage to stubbles from mechanical harvesting of the main crop constrain the further extension of mechanized rice ratooning technology. Skip-row planting (SP), where the track zone is left untransplanted in the main crop to provide traffic paths for harvest machines, might be effective to alleviate these constraints by avoiding the crushing damage. However, it is remains unclear if border effects could compensate for the yield loss due to decreased planting density from SP in both the main and ratoon crops, and if SP could improve the milling quality of the ratoon crop. To address these questions, a SP pattern with 33.3% decrease in planting density was compared to conventional planting (CP) pattern in field experiments on mechanized ratoon rice in 2018 and 2019. Compared with CP, the grain yield of the main and ratoon crops in SP was reduced by 4.8% and increased by 4.6%, respectively. The large decrease in planting density from SP did not affect grain yield substantially because of the border effects on grain yield in the rows next to traffic paths in both crops. Panicle number, spikelet number panicle−1, and total dry weight were responsible for the border effects on grain yield in the main crop, whereas panicle number and total dry weight were responsible for the border effects on grain yield in the ratoon crop. Milling quality of the ratoon crop was improved by SP, and the improvement in head rice rate was 2.5–7.0% compared with CP. Our results suggest that SP is effective for improving milling quality of the ratoon crop in mechanized rice ratooning system by avoiding the crushing damage, while maintaining high grain yield of the two crops due to the border effects. • Skip-row planting did not affect grain yield substantially in mechanized rice ratooning system due to border effects. • Panicle number, spikelet number panicle−1, and total dry weight were responsible for border effect in main crop. • Panicle number and total dry weight were responsible for border effect in ratoon crop. • Skip-row planting improved the milling quality of ratoon crop by avoiding the crushing damage. [ABSTRACT FROM AUTHOR]

Coordination between source and sink is vital for the final maize grain yield planted under high density. To clarify the source and sink characteristics of high yield potential (22.5 Mg ha-1), a four-year field experiment was conducted at Qitai Farm in Xinjiang, China. At silking, the maximum leaf area indexes were 5.8, 7.5, and 6.2 for cultivars of high yield level-1 (H1), high yield level-2 (H2), and high yield level-3 (H3) with yield increase of H1 < H2 < H3, which were 2.2, 4.6, and 3.9 at maturity, respectively. The H3 biomass was significantly higher than those of H1 and H2 during post-silking, and the H2 and H3 total kernel numbers were significantly higher than H1's, although H2 had a significantly higher harvest ear number. While H3's kernel size was not the largest of the three levels, H3 had a significantly higher thousand kernel weight. The grain filling analysis showed that H1 and H3 had shorter lag period durations (D1) than H2, and H3 had a longer maturation drying period duration (D3) than the other groups did. However, H1 and H3 had significantly higher grain filling rates than H2 in the lag period (D1), and H3's was the lowest in the maturation drying period (D3). Also, H3's maximum grain filling rate was significantly higher than H2's, and H3 had significantly higher biomass/kernel number and kernel weight/leaf area ratios than H1 and H2 did. Based on our findings, three high yield levels were classified into three source-sink types: (1) H1: small source and weak productivity, small sink and short maturation drying period duration (D3); (2) H2: large source but weak productivity, large sink but slow grain filling start, and low maximum grain filling rate; (3) H3: small source but strong productivity, large sink, fast grain filling start, long maturation drying period duration (D3), and high maximum grain filling rate. We achieved an actual high yield of 22.4 Mg ha-1 for H3, which was also the highest yield in China. Therefore, hybrids with H3-type source and sink characteristics should be selected in the future for high-yield cultivation under dense planting. • Maize yield level of more than 22.5 Mg ha-1 has small source and strong biomass productivity under high density. • Large sink with more population kernel number and higher thousand kernel weight are vital for high yield maize. • Fast grain filling start, higher maximum grain filling rate and longer maturation drying period duration are essential. [ABSTRACT FROM AUTHOR]

Light interception (LI) by the canopy is an important environmental factor that determines dry matter production and crop development. Using a geostatistical sampling-based method, we studied the spatial distribution of LI at different points, in different layers and profiles and in the entire cotton canopy. The results showed that the LI decreased with increasing height. During early development, the horizontal changes in LI were large for a given vertical point. However, the horizontal changes in LI were smaller during later development. Profile maps of the LI for the six plant densities showed that different LIs occurred during the early growth stage. In addition, the linear regressions between the total accumulated LIs of the different layers and the cottonseed yield revealed that the LI in the bottom layer and in the middle of two cotton rows significantly contributed to the cottonseed yield. Thus, a higher economic yield could be obtained by improving the micro-environment in these two layers. [ABSTRACT FROM AUTHOR]

Early generation selection (EGS) aims to accelerate genetic yield gain by applying selection pressure for desirable traits at early generations within breeding programmes. This study was designed to evaluate single plant yield (SPY), harvest index (HI; SPY divided by aboveground biomass) and estimated fruiting efficiency (FE m ; kernels per unit chaff weight) as EGS traits in predominantly F3 populations of winter wheat. Lines were sown as single plants and in plots of pooled family seed in northwest Victoria, Australia in 2018. From the single plant populations, 21–23 lines were selected for each EGS trait and 52 lines were selected at random to estimate true population mean; 25 lines were selected visually from pooled plots. Selected lines were sown in partially replicated plots in 2019. Lines selected for HI yielded 24% more than lines selected at random and 22% more than lines selected visually; selections made for SPY and FE m yielded the equivalent of HI selections, but not significantly higher than the random or visual treatments. In 2020, the 7 highest-yielding lines from the HI, random and visual selection treatments were sown in replicated plots. There was no significant difference in yield between treatments. Nevertheless, EGS for HI successfully culled low yielding lines, and enriched populations with high yielding lines prior to plot-level yield testing. Advancements in high-throughput phenotyping are required before widespread adoption but are anticipated in the near future. [ABSTRACT FROM AUTHOR]

Winter oilseed rape (WOSR) is an important oil and protein crop in Europe, used in biofuel production and as protein source in livestock farming. In contrast to cereals, WOSR seed yields are still increasing in most countries but yield stability was not improved during the last decades. In our study, we analyzed the effects of weather conditions during different growth stages on maximum seed yield, maximum oil yield, number of seeds per m 2 and 1000-seed weight to get further information on yield formation processes. Field trials performed at 34 environments (site × year combinations) representing different soil characteristics and climate regions in Germany were used for the analysis. About 40% of seed yield variability could be explained by weather conditions during specific growth phases. The most important phenological phases thereby were: onset of pods and seeds (BBCH 50–65) and seed development (BBCH 71–79). During onset of pods and seeds, yield was significantly influenced by temperature, radiation and drought stress. Assimilate availability during this phase determines the number of seeds per m 2 (sink size). After flowering, only temperature significantly affected WOSR yield. Temperature is the major parameter determining the duration of growth stages. Lower temperature elongates the time of assimilate production and translocation to the seeds. During this growth stage, seed weight is determined. In our data sets, low sink size was not yield limiting due to compensatory effects between the yield components number of seeds per m 2 and 1000-seed weight. Yield response pattern suggests that WOSR yield is predominantly source-limited, especially during the late reproductive phase. [ABSTRACT FROM AUTHOR]

Banana-bean intercropping systems are common in the bimodal rainfall areas of the East African Highlands and are characterized by low banana productivity. In these systems, the soil is tilled manually twice a year before bean planting with potentially damaging effects to the shallow banana root system. No-tillage with mulching (NT + M) may constitute an interesting alternative to conventional manual tillage (CMT) to avoid such root damage and improve banana productivity. The objectives of this study were therefore (i) to assess tillage-induced damage to the banana rooting system and its subsequent recovery, and (ii) to evaluate the impact of three NT + M systems vs. CMT on banana root distribution and banana bunch weight. At two sites in the D.R. Congo, the cord root length density (RLD) and fresh weight (FW) were monitored monthly in the top 0.2 m of the soil over a 5 to 6-month period following manual tillage, and compared with NT + M plots. Immediately after tillage and on average over the two sites, cord RLD and FW in the top 0.1 m of the soil were reduced on average to 15% and 16%, respectively, of the levels observed under NT + M. At 0.3 m from the rhizome, cord roots needed 2–4 months to recover to a level similar to the one observed prior to tillage. On average over the two sites, direct root damage by tillage caused the loss of 47% and 63% of the RLD and FW observed in NT + M plots, respectively. The remaining rooting deficit (38% of RLD and 21% of FW) was hypothesized to originate from differences in root growth conditions unrelated to immediate mechanical root damage. There was no evidence that the mechanical damage of roots by tillage affected banana growth in the short term. The medium-term effect of CMT and NT + M treatments was evaluated at three sites (two in D.R. Congo and one in Rwanda) 30 months after banana planting. At two sites out of three, root density profiles indicated lower rooting densities in the top 0.1 m of the soil in CMT plots compared with NT + M plots. Banana bunch weight was consistently lower in CMT plots compared with NT + M plots. Compared with NT + M, CMT appears to affect banana rooting and bunch weight in the medium term under the pedo-climatic conditions of the East African Highlands. No-tillage with mulching may constitute an alternative to manual tillage to enhance the sustainability of these systems but its impact on the whole intercropping system's productivity must be verified. [ABSTRACT FROM AUTHOR]

Improving sucrose yield is one of the main objectives of sugarcane breeding. Splitting this complex trait into yield components should make this task easier, as each component may be influenced in its own way by environmental factors and by genetic background. Abiotic conditions experienced by sugarcane across its cropping areas differ in many respects; among them, water availability and photo-thermal conditions particularly affect sucrose yield formation. In this study, sucrose yield was divided into seven component traits and studied in a panel of 155 sugarcane accessions phenotyped at two sites under contrasting photo-thermal conditions: one in low altitude and the other in higher altitude. The accessions were hybrids developed during the last century and representing the worldwide cultivated genetic diversity. The proportion of Saccharum spontaneum genome in the genome of each accession was estimated by analyzing the genetic structure of the panel associated with two outgroups formed by 19 S. spontaneum and 29 S. officinarum accessions genotyped with 419 DArT markers and using a Bayesian clustering method implemented in STRUCTURE software. A K = 2 number of clusters clearly separated S. spontaneum from S. officinarum , while the estimated proportions of the S. spontaneum genome in the genome of hybrid accessions ranged from 0.5 to 0. Multivariate mixed model of log transformed yield components was adjusted to estimate each component's contribution to sucrose yield genetic variance, taking into account interrelationships among components. Each component's contribution to sucrose yield variance was site-dependent. On the low altitude site with high photo-thermal conditions, stalk section was the main contributor to yield variance, while on the high altitude site with low photo-thermal conditions, stalk height was the main contributor. A linear regression showed that the estimated proportion of S. spontaneum genome in the hybrids’ genome had significant effects on sucrose yield and its components. These effects also varied with the site: under low altitude conditions, the estimated proportion of S. spontaneum genome in the hybrid's genome exerted a significant negative effect on sucrose yield, whereas no significant effect was found under high altitude conditions. These results suggest that both efforts toward introgression and selection on yield components for sugarcane breeding purposes should depend on the targeted cropping environment. [ABSTRACT FROM AUTHOR]

Soil moisture stress due to drought results in low storage root yield of sweetpotato. Eighty-four sweetpotato clones were evaluated at Kenya Agricultural Research Institute (KARI), Kiboko and Thika between May 2011 and September 2012 for drought tolerance. A split plot design with drought stress and no drought stress conditions as whole plots, and clones as subplots, arranged in a 14 × 6 alpha lattice design with two replicates repeated in two seasons was used. Approximately 30 cm long vine cuttings of each clone were planted 10 cm deep on 25 cm high beds, in single rows of 6 hills spaced at 30 × 90 cm. The field study was also validated in screenhouse box experiments at KARI-Muguga. Data on growth and yield characteristics were recorded and analysed using SAS 9.2 edition. Across sites, data indicated that genotype, environment, and their interaction significantly differed for fresh storage root weight (FSR) (kg plant −1 ), total fresh biomass weight (FB) (kg plant −1 ), marketable fresh storage root weight (MFSR) (kg plant −1 ), harvest index (HI) and chlorophyll content (CC) (8.47%) at ( P ≤ 0.05). Comparing data from both environments, drought stress caused a reduction of FSR (59.3%), FB (72.1%), MFSR (75.5%), NSR (25.6%), but seemed to increase percent root dry matter (%RDM) (−0.29%), and HI (−26.6%). Clones 194555.7, Unawazambane06-01, 189150.1, Tanzania, Chingova, W119, 441725, and Xiadla-xa-kau, had ≥75 days to permanent wilting point (DPWP), drought stress index (DSI) <1 and high FSR yield under drought stress and no drought stress conditions. These clones may be used in a drought tolerance breeding programme. Clones that had low DSI values, also had low FSR yield difference under drought and no drought environment, indicating they were drought tolerant, but had less DPWP. However, high yielding clones under no drought, also had relatively high yield difference between drought and no drought environments, and high DSI values, which implied less drought tolerance. Thus, DPWP demonstrates high discriminative power to identify clones with both drought tolerance and improved yielding ability, especially in root crops such as sweetpotato, which occasionally produce pencil roots instead of edible storage roots even under adequate moisture conditions. [ABSTRACT FROM AUTHOR]

Triangle planting geometry (TPG) is a new rice arrangement mode, whereby plants form a “dense intra-hill, sparse inter-hill” group structure. This allows them to have more spatial options, thus avoiding excessive infra-hill competition when compared to conventional row configurations. However, there is limited information on how TPG might affect rice production, especially for newly-bred varieties featuring a heavy panicle size (5 g panicle −1 ). This study was conducted to evaluate grain yield performance and yield component changes of heavy panicle varieties under TPG. Moreover, to identify any promising agronomy traits and population structural features that might explain the difference in yield performance as well as to probe whether the high-yielding performance of TPG is reproducible in other circumstances. In 2012, Eryou498 (a heavy panicle variety) was grown under four planting geometries (PGs) in two fields that had similar soil fertility, but that were conducted with either conventional tillage or zero-tillage systems. In 2013, two heavy panicle varieties and two medium panicle varieties (2–5 g panicle −1 ) were grown under three PGs in two ecological regions. Grain yield and effective panicles were significantly affected by both variety and PG. A significant interaction of PG and variety was seen on grain yield, but the high-yielding performance of TPG was consistent with all varieties. Sufficient total spikelets were the basis of achieving a high grain yield. Effective panicles predominantly attributed to total spikelets across all four experiments. Robust spikelets were crucial when grain yield was at a high level. Heavy panicle varieties and TPG showed some similar high-yielding traits. These included rapid crop growth rate (CGR) during the two weeks before full heading, plenty non-structural carbohydrate (NSC) accumulated at full heading, mass NSC output in two weeks after full heading, and high radiation use efficiency (RUE). Rice under TPG presented a more compact top three leaves as well as more stretched lower leaves when compared to other PGs. Overall, all leaves of heavy panicle varieties were more stretched than those found in medium ones. Heavy panicle varieties accumulated more nitrogen (N) in leaves from elongation to 30 days after full heading while PG showed no significant effect on leaf N concentration during the late grain-filling period. These results suggest that the high-yielding performance of TPG is reproducible in other circumstances. The combination of TPG and heavy panicle varieties is advantageous, allowing for a more efficient canopy structure for heavy panicle varieties and a more robust photosynthetic ability at late grain-filling period under TPG. [ABSTRACT FROM AUTHOR]

In West Africa, upland rice ( Oryza spp.) is mainly grown in low-input systems by resource-poor farmers. Weeds are one of the major constraints to rice production. Ideal rice varieties are high-yielding with strong weed-suppressive ability (WSA). WSA is the ability to suppress weed growth and reduce weed seed production and is determined by assessing weed biomass under weedy conditions. Development of such varieties requires simple screening protocols based on highly heritable traits, which can be evaluated in small plots under weed-free conditions. Then, in later stages of the breeding program, selected breeding lines could be evaluated with substitute weeds instead of natural weeds, as natural weed growth is heterogeneous. To develop such a protocol, I evaluated agronomic traits of 10 diverse rice varieties grown in plots with different numbers of rows (unbordered 1-row and 2-row, and self-bordered 4-row, in which the middle 2-rows were sampled) without weed competition and evaluated weed biomass of these varieties under competition with rice and cowpea as substitute weeds. I then examined whether agronomic traits in unbordered plots can predict yield and weed biomass in self-bordered plots. Broad-sense heritabilities of agronomic traits measured in weed-free conditions and weed biomass under weedy conditions were estimated. Among agronomic traits in unbordered plots, yield was positively correlated with yield in self-bordered plots ( r = 0.88 and 0.96 in 1-row and 2-row plots, respectively, P < 0.01). Weed biomass estimated in competition with two rice varieties was more heritable than weed biomass in competition with cowpea. In 1-row plots, growth vigor at 63 days after sowing (DAS), total aboveground biomass at harvest, and yield were related to weed biomass in competition with cowpea and rice variety Aus 257. Growth vigor at 42 and 63 DAS was a reliable estimator for total aboveground biomass and number of panicles at harvest, as well as integrated information on height and number of stems (height multiplied by number of stems). I suggest that growth vigor at 42–63 DAS in unbordered, 1-row plots appears to be a useful selection criterion for developing high-yielding varieties with superior WSA, and WSA of selected varieties can be validated using rice varieties as substitute weeds. Future research is needed to validate this protocol with breeding populations, a wide range of genetic materials, and other important weed species in West Africa before it can be implemented in breeding programs. [ABSTRACT FROM AUTHOR]

Eight dry-land winter wheat cultivars ( Triticum aestivum L.), representative of those widely cultivated from the 1940s to the 2010s in Shaanxi Province of China, were grown in plots that could be sheltered from rain. The plots were subjected to irrigation and drought treatments to identify the agronomic and photosynthetic traits associated with yield progress. Plant height at maturity decreased from 140.7 cm to 79.5 cm from the earliest to the most recent studied cultivar. The yield increased significantly with an annual genetic gain of 0.48% and was consistently and positively associated with the grain weight and harvest index. Modern cultivars were more sensitive to drought stress, and no obvious increase in harvest index was found to indicate possible limitations on further yield increase after the 1980s. The mean tilt angle was similar among all of the cultivars. A trend over time towards a high photosynthetic rate of flag leaf and leaf area index at the heading stage was observed. Both trends were significantly related to a yield increase. The post-anthesis photosynthetic traits showed no trend with cultivar replacement or obvious stable relationship with yield. A future challenge for wheat breeding in this region is to increase the genetic gain in grain yield under water deficits, likely through increases in the grain weight and harvest index as well as an improvement of the photosynthetic rate before and after anthesis. [ABSTRACT FROM AUTHOR]

Phenotyping of drought resistance traits in rice is challenging at the field level due to the spatial variability of soil characteristics linked to soil water content. Apparent soil electrical conductivity (EC a ) mapping may therefore be useful for characterizing spatial variability and improving phenotyping efforts in drought screening trials. EC a mapping was conducted over two seasons in lowland rice drought phenotyping trials. EC a was positively correlated with clay content and soil depth, and negatively correlated with volumetric soil water content during periods of moderate to severe drought. In addition, EC a was negatively correlated with indicators of plant performance including canopy temperature, normalized difference vegetation index, biomass, plant height, and grain yield. The results suggest that clay content and topsoil depth were the primary factors influencing the timing and severity of the drought response during the dry down of the field. Overall, the results illustrate the usefulness of EC a mapping for the spatio-temporal characterization of soil heterogeneity that influences plant performance under drought in lowland rice fields. EC a mapping can be useful for optimizing experimental plot layouts to ensure their uniformity and to improve validity of drought phenotyping and breeding trials. [ABSTRACT FROM AUTHOR]

Little progress has been made in determining the combining ability and gene action controlling early storage root yield (SRY) and disease resistance traits in the Ugandan cassava germplasm. Such information is important in the selection of parents and breeding strategies for an effective breeding programme. The objective of this study was to estimate the general combining ability (GCA) of nine cassava parents and their specific combining ability (SCA) for early SRY and disease resistance traits, as well as to determine the gene action controlling these traits. Thirty-six full-sib cassava families were generated from a 9 × 9 half-diallel mating design and were evaluated in two distinct environments in Uganda using a 3 × 12 row by column design. Family, GCA and SCA effects and their interactions with environments were significantly different for most traits, indicating, respectively significant differences in the mean performances of the families, additive and non-additive gene action in the expression of the traits, and the non-additive influence of the environments. The relative importance of additive and non-additive gene action varied between traits, indicating the need for specific breeding strategies for each trait. Parents with desirable GCA effects for most traits were developed from cassava introductions from South America, highlighting their importance and possibility of widening genetic variability of African cassava germplasm. The GCA effects for the parents did not always correlate with their per se performance, implying that selection of parents based on their per se performance may not necessarily lead to development of superior hybrids. [ABSTRACT FROM AUTHOR]

Sunflower ( Helianthus annuus L.) production in South Africa depends on natural rainfall which is variable and unpredictable, hence the need to develop drought tolerant sunflower genotypes to stabilise production under random stress environments. An exploratory research study was undertaken to determine the effectiveness of using moisture stress selection environments and three secondary traits, head diameter (HD), stem diameter (SD) and stay green canopy (SG) in developing drought tolerant sunflower cultivars with high oil yield (OY) in the presence of drought stress. A total of 84 testcross hybrids (TCHs) developed by crossing two testers to 42 female cytoplasmic male sterile (CMS) inbred lines were evaluated in nine environments for oil yield and other agronomic traits. The environments were classified as random drought stress environments (RSE), managed drought stress environments (MSE) and non-stress environments (NSE). Type A and type B genetic correlations based on broad sense heritability ( H 2 ) and narrow sense heritability ( h 2 ), respectively were estimated to quantify indirect selection efficiency. Type A genetic correlations indicated that SG had the potential to be used as a secondary trait to indirectly improve OY. The indirect selection efficiency (ISE) for OY via SG using genetic correlation based on H 2 were 0.79, 0.82 and 0.78 in the RSE, MSE and NSE, respectively and genetic correlation based on h 2 were 0.67, 0.98, and 0.93 in the RSE, MSE and NSE, respectively. In both cases, selection in the MSE had the highest ISE. Estimates of indirect selection based on type B genetic correlation indicated that indirect selection for OY in the MSE and NSE for the RSE was as effective as direct selection for OY in the RSE based on the additive genetic correlations of 0.96 obtained in both selection environments. Overall, the results from this exploratory study should inform the development of breeding strategies to improve the drought tolerance of sunflower cultivars grown in South Africa and associated environments. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rainfall×potassium interactions determine banana yields in rain-fed systems. [•] Potassium mitigates early growth drought impact on banana dry matter production. [•] Drought stress induces no phenotypic dry matter allocation plasticity in bananas. [•] Potassium deficiency induces phenotypic dry matter allocation plasticity in bananas. [ABSTRACT FROM AUTHOR]

Highlights: [•] The scheduling of supplemental irrigation (SI) affected wheat yield components. [•] Irrigating after anthesis increased photosynthesis without excessive transpiration. [•] An appropriate delay in SI delayed leaf senescence and increased grain yield. [•] Excess irrigation or drought during late grain-filling reduced water use efficiency. [ABSTRACT FROM AUTHOR]

Highlights: [•] We evaluated 28 newly developed high yielding early maturing CIMMYT wheat lines and 2 checks in South Asia and Mexico. [•] We identified early maturing lines with higher grain yield and stable performance across locations in South Asia. [•] Early maturity provides a better adaptation under terminal and continual high temperature stress common in South Asia. [•] Canopy temperature and leaf chlorophyll content were identified as promising traits that may contribute to adaptation. [ABSTRACT FROM AUTHOR]

Highlights: [•] We assess WUE of dryland wheat in the Loess Plateau through analyzing the published data over more than 20 years. [•] The maximum yield and WUE were achieved under RM and RMS and the minimum under NT/RT. [•] The yield–evapotranspiration relationship indicated that present yields are limited by environmental (e.g. seasonal distribution of rainfall) and management factors. [•] The range of WUE is very large for the same or various practices, and thus offers tremendous opportunities for maintaining or increasing WUE. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nutrient concentration and biomass yield varied among accessions. [•] The variations were related to the origin geographic factors. [•] The significant genetic variation conferred the possibility for Miscanthus breeding. [ABSTRACT FROM AUTHOR]

• Lowland and aerobic rice cultivars differed in canopy structure, nitrogen and light profiles. • Differences in leaf angle were responsible for the variation in canopy light profile. • The better nitrogen vs light profiles in the aerobic cultivar contributed to its lower reduction in biomass under stress. • The relative nitrogen vs light profile is an important trait for rice under water deficit. In the wake of declining water availability for agricultural use that will severely disturb the cultivation of irrigated lowland rice (Oryza sativa), aerobic genotypes have been developed allowing rice to grow under drier conditions. However, canopy physiological and morphological characteristics associated with adaptation of aerobic rice to water-limited conditions have so far been understudied. Canopy architectural characters, light and nitrogen distribution parameters (i.e. the extinction coefficient for light, K L ; and for nitrogen, K N ; and their ratio K N : K L), plant growth and yield were examined in irrigated-lowland (cv. IR64) vs aerobic (cv. Apo) rice genotypes grown under three water regimes. Compared with cv. IR64, cv. Apo allocated less nitrogen to strongly shaded leaves, allowing the vertical nitrogen distribution to better acclimate to light distribution within the canopy. The K N : K L ratio increased with increasing water deficit, and cv. Apo (up to 49 % increase) had a higher increase than cv. IR64 (up to 24 % increase). This was attributed to the maintenance of erect leaves at the upper part of the canopy, allocation of less leaf area and less nitrogen to the shaded leaves under water deficit in cv. Apo. The observed differential response in the K N : K L ratio partly explained the difference in biomass gain and yield in response to water deficit between the two rice cultivars. We concluded that favourable above-ground architecture and canopy nitrogen profile relative to the light profile contributed greatly to the better performance of cv. Apo than cv. IR64 under dry conditions. [ABSTRACT FROM AUTHOR]

• We examine inter- and intra-plot heterogeneity of productivity in maize plots. • We find high inter- and intra-plot variabilities in plant population and yield. • Intra-plot heterogeneity overrides inter-plot heterogeneity in smallholder maize. • The magnitude and distribution of yield estimation errors are method-dependent. • More intensively managed plots show lower intra-plot heterogeneity and lower yield. Intra-plot heterogeneity in yield is often observed in smallholder farming systems, although its implications for yield measurement remain under-investigated. Using a unique dataset on smallholder maize production in Ethiopia, we quantify the magnitude of inter- and intra-plot heterogeneity, describe the relationship between intra-plot heterogeneity and maize productivity, and document the implications of intra-field heterogeneity on the accuracy of alternative yield estimation protocols. Our data include five common yield estimation protocols, as well as full plot harvests of 230 smallholder maize fields. We surveyed agronomic decisions, biophysical variables, and accessibility characteristics of the surveyed fields. We quantify intra-plot heterogeneity using the coefficient of variation (CV) of stand density, cob weight, and maize grain yield. A generalized linear mixed model is used to explore the relationship between these variables and the method- and heterogeneity-dependence of yield estimation accuracy. We find inter-plot CV values ranging from 32 to 56 %, 22 to 73 % and 39 to 49 % in population density, cob weight and grain yield, respectively. Intra-plot heterogeneity constituted most of this variation, with across-method mean CV values of 41 %, 82 % and 63 %, respectively, of the total variability in population density, cob weight and grain yield. A rise in intra-plot heterogeneity of 0.5 % to 0.8 % is associated with a significant increase in yield estimation error under alternative yield estimation protocols. Regression analysis shows that interactions in agronomic decisions, input intensity and plot accessibility factors dictate intra-plot heterogeneity and method accuracy in smallholder systems. Intra-plot heterogeneity is larger than inter-plot heterogeneity in the current study area. Our analysis shows that the effect of intra-plot heterogeneity on yield estimation accuracies is method-dependent and yield estimation methods that fail to capture true intra-plot heterogeneity are more error-prone. Results of such estimations should be considered with caution when used as the basis of decision-making. [ABSTRACT FROM AUTHOR]

• Red clover seedling density (CSD) is a good predictor of forage production in mixtures with chicory and prairie grass. • Forage prediction models based on CSD depend on environmental yield potential. • Count time as early as 3 weeks after sowing was similar to late counts to predict biomass. Biomass predictive models can be useful tools to design management strategies for mixed pastures of red clover (Trifolium pratense) with either grasses or herbs in intensive grazing systems. This paper proposes mixed regression models to predict the annual yield of two mixtures based on red clover seedling density (CSD) and environmental effects (low, intermediate, high-yield environments). Two mixtures of red clover with either chicory (Cichorium intybus) or prairie grass (Bromus catharticus) were sown in Uruguay in a multi-environment experiment with six sowing rates to generate varying levels of species seedling densities. The CSD was recorded at 3, 7 and 12 weeks after sowing (WS). Yield prediction models in the initial establishment year (Y1) and second-year (Y2) were fitted with CSD at the three count times. CSD increased proportionally to the sowing rates in all environments. The CSD, even at 3 WS, provided a good prediction of expected annual yield (error mean <15 %). The fitted models estimated the probability of exceeding the threshold of 10,000 kg DM ha−1 annual yield based on CSD observed at 3 WS in all three environments. There is a high probability of harvesting more than the threshold, even when the CSD at 3 WS is higher than 50 seedlings m-2 in the high-yield environment. Forage prediction models based on CSD, fitted for environments of different yield potential, will contribute to improved management of mixed pastures in intensive grazing systems. [ABSTRACT FROM AUTHOR]

Conceptual representation of the response of absolute heterosis plasticity to traits plasticities for both genotypic groups. Both plasticities are expressed as the response (i.e. , slope) to the environment (i.e. , environmental index). ASI: anthesis-silking interval, BIO PM : aboveground biomass at physiological maturity, EGR CP : apical ear growth rate during the critical period, KNP: kernel number per plant, KW: individual kernel weight, PGR CP : plant growth rate during the critical period, PGY: plant grain yield, Pr: prolificacy. • A balanced environmental index is a robust tool for phenotypic plasticity analysis. • The response to the environmental index was linear, bilinear or null depending on the trait. • A tight association exists between phenotypic and absolute heterosis plasticities. • The positive trend in mentioned association is driven by hybrids. • The relative benefit of exploiting heterosis for grain yield is not environment-dependent. Maize grain yield is determined by genotype (G), environment (E) and G × E interaction effects that influence the expression of traits along the crop cycle. Inbreds and hybrids may differ in their responses to fluctuations in environmental conditions, determining changes in heterosis levels across environments and consequently the target environment for their evaluation. The objectives of this work were (i) to compare traits related to grain yield, aboveground biomass production and its partitioning in two contrasting genotypic groups (inbreds and hybrids) and (ii) to analyze their performance across environments for the assessment of their phenotypic plasticity as well as environmental effects on the expression of heterosis. We built a balanced environmental index based on normalized plant grain yield (BEI NPGY) from 14 contrasting environments using a 6-inbred complete diallel mating design and analyzed the response of the 12 evaluated traits to this index for each genotypic group. This approach allowed us to (i) differentiate among traits with simple linear (grain yield, total biomass, kernel numbers, the anthesis-silking interval and plant reproductive efficiency), bilinear (harvest index, individual kernel weight, prolificacy and apical ear reproductive efficiency) or no response (ear and plant growth rates around flowering as well as their relationship) in phenotypic plasticity of each group to the BEI NPGY , and (ii) group traits depending upon their absolute heterosis response (i.e., heterosis plasticity) to the BEI NPGY , which varied in sign (positive, null or negative) depending upon the trait. There was a clear and positive relationship between absolute heterosis plasticity and traits plasticities, which was mainly driven by hybrids. Genotypic groups differed in the association patterns of traits values per se as well as of their phenotypic plasticities, indicative of the different genetic bases that determine them. The fact that percent heterosis for grain yield and other relevant secondary traits did not vary across environments, whereas heritability is expected to decrease under stressful conditions, may contribute to guide future breeding efforts aiming to develop superior hybrids with successful performance, particularly in future challenging environmental scenarios. [ABSTRACT FROM AUTHOR]

• Seedling root traits can be translated to root traits, plant performance and yield of field grown plants under drought. • Seminal root number in maize seedlings directly predicted crown root number in field-grown maize. • Negative correlations among lateral root traits revealed the optimization of the root system along root developmental stages. • Root emergence angle and hull area are two novel root traits that could be used to indirectly predict maize yield under drought. Variation of root traits is associated with soil resource acquisition under abiotic stresses. However, plant breeding programs targeting beneficial root traits are hampered by lacking appropriate phenotyping tools. The availability of high-throughput root phenotyping technologies for seedlings as well as for mature plants grown in the field enabled us to investigate trait translation from the lab to the field. Here we used the established phenotyping techniques Rhizoslides , Shovelomics , and the image-based root phenotyping software, Digital Imaging of Root Traits (DIRT) to phenotype root traits of thirty seedlings and mature maize donor lines from the Drought Tolerance Maize for Africa (DTMA) project. The experiments were carried out in a controlled-environment and a field trial under well-watered and drought conditions. We found significant correlation between seedlings seminal and crown root number in the field (r = 0.68). Primary root branching of seedlings was negatively correlated with crown root branching of field-grown plants (r=-0.54). Our study showed indirect translation of traits between primary root length (r = 0.29) and primary root branching (r = 0.20) with plant performance in the field under drought. Our results suggest that root traits of maize seedlings are predictive for mature maize root traits and plant performance in the field. Our findings suggest that using open tools for high-throughput root phenotyping to screen in maize seedling could be beneficial for breeding programs and paves a cost-efficient way for plant improvement and breeding programs in developing countries. [ABSTRACT FROM AUTHOR]