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Critical period for yield determination is essential for crop management. Research on soybean has focused on grain number sensitivity to stress, while the impact of weight per grain remains underexplored. Redefine soybean yield determination by accounting for grain number and weight per grain. Three field experiments that imposed shading treatments at different growth stages. Crop development, yield, and yield components were monitored. Critical period for yield determination extended from R4 to R7 stages, with peak sensitivity around R5.5. Grain number sensitivity lasted from R3 to R6, while weight per grain sensitivity occurred from R5 to R7. Compensation between yield components up to R4 occurred. Source-sink ratio accounted for most of the variation in weight per grain, which showed no significant deviation from this relationship across all treatments. Critical period for soybean yield determination was identified, emphasizing the need to consider both grain number and weight per grain. Early compensation between yield components indicated a source limitation state in non-stressed crops. Additionally, no evidence of a sink limitation on yield within the range of stresses imposed was found. The critical period for soybean yield encompassed R4 to R7, with differential sensitivity to stress between grain number and weight per grain. Sink limitation did not directly cause yield reduction under the conditions studied. Yield optimization should focus on addressing source limitation during those growth stages. Provided valuable insights on soybean management, modeling and breeding. Orientate the focus on enhancing source capacity during critical stages. • The most critical period for yield determination extended from the R4 to the R7 stages. • The most critical period for grain number determination extended from the R3 to the R6 stages. • The most critical period for weight per grain determination extended from the R5 to the R7 stages. • Yield for non-stressed crops was limited by the source during the grain filling period. • Grain number was associated with, but not the cause of, yield depression due to stress. [ABSTRACT FROM AUTHOR]

Potato belongs to the category of the staple food playing an important role in global food security and nutrition. Because potato plants have a shallow root system and stop nitrogen uptake early in the growing season (between 20 and 60 days after emergence), potato fields are more prone to leaching of nitrate to lower soil layers and the groundwater than deep rooting crops, thus posing a higher risk for polluting the environment with nitrate. On the other hand, lowering fertilizer dosages could result in yield loss and reduced tuber quality. To balance the risk of yield and quality loss against the risk of nitrate leaching, the fertilization dose should be adapted to the local production potential, which can vary considerably within a field. However, there is no consensus on how to adapt the fertilization to this variability. Therefore, the objective of this study was to assess various N fertilization scenarios and their effect on the concentration of residual nitrate, total potato yield and tuber quality. Five potato fields located in Flanders with historical spatial variation in crop productivity were selected as potential candidates for implementing site-specific nitrogen management practice. The fields were divided into management zones based on variation visible in soil maps, maps of electrical conductivity, maps of vegetation indices and soil samples. Nitrogen was applied in three different dosages, including the conventional dose, and two reduced fertilization levels. Based on time series of vegetation indices, cumulative vegetation indices and pair-wise correlations between the vegetation index values obtained from Sentinel-2 satellite imagery (FAPAR, NDVI, FCOVER, LAI) only two fields of five showed temporal stability of the spatial management zones, while in three other fields the zone performance shifted depending on the weather conditions during the growing season. In the fields with stable zones, the lowest N fertilization levels in the areas with lower productivity potential resulted in a reduction of the concentration of leachable nitrates while total yield and potato tuber quality (dry matter and nitrogen content) did not change. For this type of fields with temporally stable zones, it was concluded to recommend reducing the nitrogen dosage in the zones with a lower productivity potential and high mineralization levels to limit nitrate leaching. In the fields where better performing zones change their location in wet and dry years, significant differences between treatments in the total potato yield, dry matter and nitrogen content in the tuber were also often detected. However, application of a low nitrogen dose during the first fertilization in one of the zones in such fields is not recommended as it is not yet known how the zones will behave the coming season, leading to a risk for underfertilization of these zones. Therefore, conventional fertilization remains the recommended practice in case the production potential of the zones depends on the weather during the growing season and is not yet known at the moment of fertilization. However, fertilizer fractions applied later during the growing season may be adapted to the crop development and actual weather conditions. [Display omitted] • In fields with temporally stable zones reduction of N dose lowers the post-harvest soil nitrate. • Lowering N dose in zones with lower productivity potential did not affect potato yield or quality. • In fields with temporally unstable management zones uniform base fertilization is recommended. • Cumulative vegetation indices from past seasons allow to detect the stability of management zones. [ABSTRACT FROM AUTHOR]

Effective nutrient management is critical for crop growth and development. However, using nitrogen-based fertilizers in agriculture raises substantial concerns about environmental pollution. The optimal timing for applying nitrogen to maximize floret fertility and production efficiency in wheat remains undetermined. This study investigated the optimal timing for N fertilizer application to enhance floret fertility and production efficiency in eastern Afghanistan's commonly cultivated Chonte#1 wheat variety. A total of four experimental sets were conducted at Nangarhar University Faculty of Agriculture and Bihsood district during the 2019–2022 growing seasons. The first-year experiment consisted of two treatments: (1) control (no fertilizer) and (2) fertilized. The second and third-year experiments comprised four treatments, including (1) control (no fertilizer added), (2) basal dressing at the tillering stage (BDTS), (3) BDTS+light top-dressing (LD), and (4) BDTS+heavy top-dressing (HD) applied two weeks before spike emergence. The results indicated that the application of N topdressing had a significant (P<0.05) effect on the SPAD value and floret fertility percentage. In contrast, SPAD values showed a positive relationship with floret fertility rate and yield components but negatively correlated with unfilled grain per spike. The use of BDTS+LD treatment significantly increased spike length, spike weight, number of spikelets per spike, and filled grain per spike compared to the control. The number of unfilled grains ranged from 6.4 % to 51.9 % between the control and N application. The 1000-grain weight, number of spikes per m–2, and floret number per m–2 were also significantly higher in the N top-dressed groups. In the first experiment, fertilized treatment showed a 28.3 % increase in yield per m–2. Meanwhile, in the second experiment, the yield range varied among the treatment groups compared to the control group, ranging from 30.7 % to 66.8 %. The application of N two weeks before spike emergence in wheat significantly improved floret fertility and production efficiency and led to the increment of final yield. The findings suggest that prior spike emergence nitrogen fertilizer application is crucial for maximizing floret fertility and yield, offering a potential strategy for farmers to enhance production efficiency. • Comparing floret fertility under various nitrogen application regimes. • A high SPAD value caused an increment in the floret fertility rate. • Nitrogen top-dressing improved the floret production efficiency in wheat. • Nitrogen topdressing resulted in a reduction in the number of unfilled grains. [ABSTRACT FROM AUTHOR]

Poor fertilizer management and intensive tillage have increased production costs, lowered productivity, and significantly depleted soil nutrients. Although nutrient management options (NMOs) within crop establishment options (CEOs) based maize production system (MPS) is seldom explored, CEOs is increasingly advocated to tackle problems with soil health, food security, and climate change. Developing and implementing effective NMOs is needed for improving system sustainability, profitability, and productivity. We evaluated the effects of CEOs and NMOs on nutrient acquisition, profitability, and maize productivity in the Northwestern Indo-Gangetic Plains (IGPs) of India during 2018–2019. In this study, four CEOs treatment [(i) conventional tillage without residue {CT–R}, (ii) conventional tillage with residue {CT+R}, (iii) permanent raised bed without residue {PRB–R}, and (iv) permanent raised bed with residue {PRB+R}], were kept in the main plot and three NMOs [(i) soil test-based recommendation {STBR}, (ii) nutrient expert-based recommendation {NE}, and (iii) NE with GreenSeeker {NE+GS} were tested in subplots. The results showed that the crop growth metrics, including plant height, dry matter accumulation, leaf area index, and crop growth rate, were significantly greater at PRB+R comparing to treatments. Additionally, PRB+R resulted in the shortest time to 50 % and 75 % silking, indicating enhanced crop development. NMOs significantly improved crop growth parameters. The NE+GS treatment recorded higher plant height (145.8–149.2 cm and 222.3–224.8 cm), dry matter accumulation (195.5–198.4 g/m² and 408.4–412.0 g/m²), leaf area index (2.45–2.48 and 3.24–3.30), and crop growth rate (6.50 and 7.10 g/m²/day). PRB+R showed the shortest silking times (60.5 and 62.2 days). PRB+R also attained the maximum maize yield (6.23 and 6.26 t/ha), by a 17.82 % and 17.57 % increase over CT–R in 2018 and 2019. The NE+GS treatment resulted in the highest maize productivity, with additional yield gains over NE alone and STBR. The lowest cultivation cost ($513.87/ha and $513.97 /ha), highest net return ($1028.91/ha and $1083.60/ha), and best benefit-cost ratio (2.00 and 2.11) were observed with PRB–R, while gross returns ($1573.78/ha and $1630.42/ha) had highest in PRB+R. The NE+GS option achieved higher gross returns ($1544.73/ha and $1599.37/ha), net returns ($918.29/ha and $977.30/ha), and benefit-cost ratios (1.47 and 1.57) with lower cultivation costs ($626.43/ha and $622.06/ha) compared to NE and STBR. The PRB+R and NE+GS combination had found highest nutrient uptake (N, P, K) in grain and straw, highlighting their effectiveness in nutrient management. Overall, our findings recommend adopting PRB+R and NE+GS to optimize maize production system productivity and profitability, ensuring agricultural sustainability and resilience to adverse climatic conditions in Northwest India. [Display omitted] • PRB+R and NE+GS optimize maize yields and nutrient uptake in NW India. • PRB+R boosts maize yield by 17.8 %, enhancing resilience to climate stress. • NE+GS increases maize productivity, profitability, and nutrient efficiency. • PRB+R and NE+GS enhance maize growth, yield, and profitability in NW India. [ABSTRACT FROM AUTHOR]

Hybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood. We quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production. Two field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance. On individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect. Our results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production. • Stem density affected stem branching and yield formation in hybrid potato. • Higher stem density decreased branching and shifted branch distribution aboveground and belowground. • Stem density affected branching more in true-seed-grown plants than in seedling-tuber-grown plants. • Propagule type showed greater impact on crop performance than stem density. [ABSTRACT FROM AUTHOR]

Ultra-narrow row (UNR) cotton, a production system with rows spaced less than 40 cm apart, has been proposed as a system for earlier maturity without substantial yield loss. However, trials in the U.S.A. and Australia have found maturity benefits difficult to achieve consistently. Studies undertaken in high input cotton systems that compared UNR to conventionally (1 m) spaced cotton found yield differences but failed to demonstrate differences in crop maturity. This paper examines crop development and fruiting dynamics of the two systems in more detail to understand why there were no differences in maturity. Results showed that lack of difference in maturity between the row spacings was not influenced by differences in the time to reach crop development stages nor by lower fruit retention of early bolls in the UNR plants. Node production and fruiting site production on a per plant basis were significantly slower in the UNR plants from early in the growing season. Slower node and fruiting site production delayed maturity in the UNR plants as they set fewer fruit within the same period of time compared to plants grown in conventional spaced rows. The number of fruiting sites produced per plant was highly dependent on the amount of dry matter per plant. Fruiting site production was reduced in the UNR crop because each plant produced less total dry matter, and hence plant development was slower. To further help understand the reasons for outcomes generated in these studies, and how UNR could possibly mature earlier without impacting yield, a conceptual modelling framework was developed to integrate seasonal patterns in fruiting site production, retention, and boll growth. A key component of this framework is translating from a per plant basis to an area basis. The analysis showed that for individual UNR plants to mature earlier and maintain yield on an area basis, early node production and fruiting site production must proceed at a similar rate to conventionally spaced crops. In this scenario 90 % of final yield would be present 14 days earlier in the UNR crop compared to conventionally spaced crops. To realise any benefits of potential earlier maturity further research is needed to explore genetic or management interventions that might avoid the early competitive stress response that slows node development in UNR. • UNR cotton had higher yield than conventionally spaced cotton, but no significant difference in maturity. • UNR crops had slower node/site production and lower fruit retention. • Slower site production was dependent on dry matter production, also affecting boll size. • For UNR cotton to mature earlier and sustain yield, it requires faster early node and fruiting site production.. [ABSTRACT FROM AUTHOR]

Future productivity increases of lentil in the face of changing climates and their expansion into areas traditionally considered marginal for commercial production will require greater tolerance to a range of abiotic constraints, particularly in relation to edaphic conditions. Variation in root system architecture presents a possible means of addressing these constraints. Whilst considerable attention has been paid in the past to above-ground traits; little attention has been given to how root traits can improve adaptation to new environments and productivity. This study aimed to characterise the diversity in root traits present in the Australian lentil germplasm and how breeding may have impacted these traits. The study examined 36 genotypes of lentil registered over the past 27 years in Australia. The experiments were carried out under glasshouse conditions in 2021 and in the field in 2020 and 2021. Results showed a significant variation in both shoot and root traits. Late maturing genotypes accumulated more root biomass, which was associated with a negative impact on yield, harvest index and 100 grain weight. Root traits that varied substantially among genotypes included root biomass, length, depth, surface area, root: shoot ratio and diameter below 60 cm. Geneotypes were catergoised into two major root forms based on root length distribution, 'Shallow' and 'Deep'. Assessment of genotypes registered since the inception of the breeding program showed an indirect selection for smaller roots with early maturity and increasing yield. Lentil varieties released for broadacre cropping in Australia have been selected for shoot architecture and yield, which has inadvertently resulted in variation in root architecture. Thus, these variations and plasticity in root architectural responses can be directly targeted for the future development of climate-ready crops. • Lentil breeding has produced genotypes with early maturity and greater yields. • Breeding for better shoot and yield traits has indirectly selected smaller roots. • Genotypes differed significantly in both shoot and root traits. • Late maturing genotypes accumulated more shoot and root biomass. • Root biomass had a negative impact on yield traits under optimum conditions. [ABSTRACT FROM AUTHOR]

High temperatures can substantially reduce the yield of rain-fed wheat at any stage of crop development. They can result in poor establishment, poor floral fertility, inopportune flowering time, or inadequate grain filling. They can inflict damage through sudden heat shock, such as leaf scorching or pollen sterility, or by chronic effects of sustained above-optimal or average temperatures. There are good immediate prospects to protect the crop’s canopy from heat damage during reproductive phases by breeding for the specific morphological traits of erect and glaucous flag leaves, combined with the ability of the leaves to roll in hot and dry conditions. These traits are present in current cultivars, but their frequencies are low and their combination is rare. There is a good opportunity to increase their frequency and to pyramid them in the next generation of cultivars to help cope with rising temperatures. The interactions between heat and drought can greatly reduce yield. There are synergistic interactions between breeding and agronomic management (G*M) that can substantially increase yield in hot and dry conditions. Early sowing is beneficial and can be facilitated by water in the subsoil, but it requires new cultivars with appropriate developmental patterns and long coleoptiles that enable deep sowing. Suitable management can defer the use of this water for use during grain filling, when its availability may help mitigate potential heat damage. There is good evidence that in recent decades farmers have experienced increases in both seasonal average temperatures and extreme heat events. This trend is likely to continue. Synergistic breeding and agronomic possibilities have good prospects to substantially reduce heat damage within the trade-offs involved in farming systems. Further, recent advances in the understanding of the meteorological patterns and underlying climate drivers of heat events are leading to forecasts of the likelihood of heat events at a multi week and seasonal timescale. These forecasts, as they improve, have the potential to refine the Genetic * Environment * Management (G*E*M) choices for wheat farmers. [ABSTRACT FROM AUTHOR]

In West Africa Sudano-Sahelian zone, sorghum sensitivity to photoperiod is a major trait for flowering adjustment toward the end of the rainy season. This trait ensures that conditions for crop development are optimal. Improving the understanding of the genetic control of flowering time in sorghum is thus an important step toward breeding climate resilient varieties for meeting the challenge of climate smart agriculture. In the wake of green revolution, most sorghum breeders eliminated photoperiod sensitivity to develop early maturing varieties. The evidence is now that simultaneous improvement of production, yield stability and grain quality requires the development of photoperiod-sensitive varieties. A segregating sorghum population derived from a cross between two photoperiod sensitive elite parents was evaluated in three different locations and five environments. CERES crop model was applied to decompose the flowering time of each genotype into basic vegetative phase, critical photoperiod and photoperiod sensitivity. Phenology and model derived variables were used for genetic analysis. The three model parameters were controlled by specific genomic regions. A major QTL affecting critical photoperiod was identified, whereas only independent minor QTLs were found for basic vegetative phase and photoperiod sensitivity. Candidate gene analysis in the major QTL region allowed us to propose a candidate gene ( ELF3 ) involved in the circadian clock as a key regulator of flowering time in photoperiod-sensitive sorghum. Our findings provide critical information supporting the development of photoperiod-sensitive genotypes specifically adapted to climate variability encountered in Sudano-Sahelian zone. [ABSTRACT FROM AUTHOR]

Lodging has been identified as one of the factors responsible for the lack of improvement in farm yields of oilseed rape. Despite this, no studies have attempted to quantify the cost of lodging at regional or national scales. The objectives of this study were to better understand the impact of timing and angle of lodging on seed yield and oil content of modern oilseed rape varieties, test whether a model predicting lodging-induced yield losses for wheat is appropriate for oilseed rape and quantify the extent of lodging in UK oilseed rape crops using an aerial photograph survey, estimating the consequential effects of lodging on the value of the crop at a national scale. Artificial lodging experiments showed that the crop developmental stage at which lodging occurred and the angle of lodging had a significant impact on yield, with lodging to 90° during flowering reducing yield by 46% and lodging to 45° during flowering reducing yield by approximately 20%. Variable, but usually smaller amounts of yield were lost when lodging occurred during seed filling. Reductions in oil content of the seed were greatest when lodging occurred to 90° at early flowering. Yield losses were mainly related to reductions in seeds/m 2 . A model for predicting lodging-induced yield losses in winter wheat was tested for its suitability in predicting the effect of different angles of lodging at different growth stages on yield in oilseed rape against the experimental datasets. This wheat model was based on existing models of canopy photosynthesis and respiration to account for lodging induced changes to the canopy and the impact on light capture and rates of photosynthesis and respiration. This was shown to provide a reasonable prediction of yield losses from lodging during flowering, which indicated that reductions in photosynthesis was the primary cause of yield loss. The model was less effective at predicting yield losses from lodging during seed filling and additional work is required to explore whether the model needs further development to be appropriate for sink limited crops such as oilseed rape. In 2012 and 2014, approximately 35% and 27% of oilseed rape fields surveyed in the UK contained some lodging respectively. It is estimated that lodging to 90° during early flowering could cost the UK oilseed rape industry£120 million per year and lodging to 45° during mid seed fill could cost £47 million per year. [ABSTRACT FROM AUTHOR]

Reliable, rapid and timely assessments of forage crop biomass are crucial for managing feed supply and animal husbandry. While process-based models are regularly promulgated in modeling crop and pasture growth and development, the reliability and functionality of such models in simulating alfalfa (Medicago sativa L.) growth remains limited. The purpose of this study was to address deficits associated with simulation of long-term growth dynamics in perennial alfalfa; to assess potential alfalfa yield across the Loess Plateau and dissect key abiotic factors constraining alfalfa yields. We undertook an extensive review of the literature to collate and analyze existing alfalfa biomass data across the entire Loess Plateau in China. We then developed an alfalfa multi-year growth curve using a Gauss-amplitude function; when enacted this algorithm reliably reproduced the rise, peaks and declines in biomass with crop development. To assess the performance of our new function as part of an integrated system, we incorporated a multi-year growth curve into the DeNitrification-DeComposition (DNDC) model to assess longitudinal yields under rain-fed and irrigation conditions. Our adapted model reproduced aboveground trends in biomass more accurately than the original model. The regional simulation results show that alfalfa yield was less than 8000 kg ha–1 in most areas with an annual precipitation lower than 500 mm under rain-fed condition, while the alfalfa yield in most areas was above 8000 kg ha–1 under irrigation condition. Compared with rain-fed alfalfa, there is an increased 69% of yield after irrigation in irrigated areas of the Loess Plateau. The rain-fed alfalfa yield was severely constrained by drought when the aridity index fell below 0.31. Our new model development paves the way for additional refinement of alfalfa crops in process-based models, and provides opportunities for adoption of alfalfa crops in new regions by adjusting the parameters in the Gauss-amplitude function. [Display omitted] • We use a Gauss-amplitude model to elicit growth dynamics of alfalfa. • The adapted model significantly improved simulation performance of DNDC. • Rainfed alfalfa yields were severely constrained when aridity index reached 0.31. • Irrigation improved alfalfa yields over irrigated areas of Loess Plateau by 69%. [ABSTRACT FROM AUTHOR]

Prairie strips, or plantings of diverse perennial vegetation integrated into cropland, can have disproportionate ecological benefits compared to the amount of land they occupy. These benefits include improved water quality, reduced soil loss, reduced nutrient loss, and increased abundance and diversity of wildlife. However, the impacts of prairie strips on the adjacent cropland soil and crop health are unknown. We assessed the effect of long-term prairie strips on plant-available nutrients in adjacent soils (from 0.1 to 9 m distance from prairie strips), gravimetric soil moisture, soybean (Glycine max (L.) Merr.) and maize (Zea mays L.) leaf greenness (via soil plant analysis development or SPAD), and yield. Our results show strong effects of prairie strips on plant-available nutrients and early crop health in adjacent soils but little effect on soybean and maize grain yields. The prairie strip effects were strongly determined by crop (maize vs. soybean) but also likely climate. Prairie strips reduced soil moisture by 6% in adjacent cropland soils (<1 m) during a wet year, decreased salt-extractable nitrate by 23%, and increased Mehlich-III phosphorus and potassium by 63% and 24%, respectively, upslope compared to downslope from the prairie strip. Prairie strips had a marginal benefit to soybean SPAD but decreased maize SPAD by 7% within 1 m of the prairie strip. While prairie strips can significantly affect soils under adjacent cropland, they have little effect on crop yield. • We investigated the impact of prairie strips on adjacent soil properties and crops. • Prairie strips had no effect on adjacent soil's pH, CEC, or SOM. • Prairie strips had strong influence on plant-available nutrients up to 3 m away. • Prairie strips had slight effect on crop development but minimal effect on yield. [ABSTRACT FROM AUTHOR]

A field trial to investigate the effects of plant growth promoting bacteria (PGPB) Paenibacillus yonginensis (DCY84 T ) and/or SiO 2 seed coating on rice growth ( Oryza sativa L.) was carried out on reclaimed tidal land in Taean County in South Korea. The field test was performed twice between May–October 2014 and May–October 2015, in a randomized complete block (RCB) design with three replications. Treatments consisted of: Mock, DCY84 T -treated seeds, SiO 2 -coated seeds and DCY84 T -SiO 2 -treated seeds and each treatment area covered approximately 300 m 2 . During the early developmental period of rice seedlings, the SiO 2 coating without DCY84 T led to the most favorable 30 DAS rice seedling parameters. Moreover, the combination of DCY84 T and SiO 2 treatments resulted in 2-fold greater fresh and dry weights of 60 DAS rice seedlings compared to Mock seedlings. DCY84 T and SiO 2 , both individually and together, produced a greater grain yield and a greater total yield; specifically, DCY84 T and SiO 2 treatments yielded a 73% and 70% increase in mass compared to Mock plants, respectively. Rice treated with both DCY84 T and SiO 2 treatment contained the highest amount of Al, Fe, Ca and Mg, which were 54%, 169%, 42% and 67% higher than the Mock rice, respectively. Remarkably, DCY84 T treatment had the most phosphate [P], potassium [K] and total nitrogen [T–N]. DCY84 T and/or SiO 2 treatment highly increased the whole kernel percentage. Thus, lower its broken kernel percentage to 9.60–24.58%. The protein content of the grain with both treatments was 7.2%, which was greater than that of the Mock grain (6.0%). The content of chlorophyll a, b and carotinoid in the rice leaves which were treated with silica and DCY84 has increased more than the mock without treatment. After harvest, the GABA content of brown rice was increased to 1.9-fold (2014), 1.5 fold (2015) compared to mock grain, respectively. Overall, DCY84 T treatment and SiO 2 coating can be useful methods for promoting growth of rice under conditions of saline stress. Results from other laboratory trials and greenhouse experiments are also provided. [ABSTRACT FROM AUTHOR]

In the extensive rice–wheat system of north-west (NW) India, harvesting is by large combines and the rice residues are normally burnt after harvest, followed by irrigation and intensive tillage prior to sowing wheat. While in-field retention of crop residues can play an important role in replenishing soil quality and reducing environmental pollution from stubble burning, until recently, there has been no suitable technology for seeding wheat in rice residues. To address this need, a series of machines (‘Happy Seeders’) was developed over the past 10 years, culminating in the development of version 2 of the 9-row Turbo Happy Seeder (v.2). The 9-row Turbo Happy Seeder(v.2) has a weight of 506 kg and can be operated by a 33.6 kW tractor at a work rate of 0.3 ha h −1 . Numerous on-farm trials show that yield of wheat sown into rice residues with the 9-row Turbo Happy Seeder is similar to or higher than yield with straw burning and conventional tillage prior to sowing, while providing many benefits to the farmer. These include greatly reduced fuel consumption and cost of crop establishment, and the ability to sow as soon as desired after harvest, ensuring the possibility of sowing at the optimum time and reducing the need for irrigation. However, adoption has been low to date, despite a 50% price subsidy. Constraints to adoption include the low window of operation of the machine (25 days per year), the low machine capacity compared with conventional seed drills, the inability to operate in wet straw, and the lack of straw spreaders on combine harvesters. Removal of subsidies for diesel and electricity (for pumping groundwater) and implementation of the policy banning in-field straw burning would help to accelerate adoption of technology for direct drilling wheat into rice residues. [ABSTRACT FROM AUTHOR]

Pigeonpea ( Cajanus cajan (L.) Millsp.) is an important crop in Asia, Africa, Latin America and Caribbean. Despite pigeonpea's global importance there is a dearth of crop simulation models available for studying pigeonpea growth. The objectives of this study were to adapt the CSM-CROPGRO model for simulating pigeonpea growth and development through parameter modification and to illustrate the use of a sequential parameter estimation technique using a dataset from Gainesville, FL in 1984 and a dataset from India in 2003. The sequential approach to parameter estimation using a hybrid Metropolis–Hastings–Gibbs algorithm worked well at estimating physiologically plausible values for parameters with good correspondence to measured data. Reasonable results were obtained despite the use of approximations for measurement errors for the Gainesville dataset, which contained only treatment means. This study demonstrated that CROPGRO can be used to simulate the growth and development of pigeonpea. However, further testing of CROPGRO with more extensive pigeonpea datasets should be undertaken to confirm the accuracy of the parameter estimates developed from this study. Further theoretical and practical research into the parameter estimation approach is needed. [ABSTRACT FROM AUTHOR]

There is debate over determining the appropriate model complexity to simulate crop development, growth, and yield. An approach that is sometimes suggested is to compare the performance of models using common datasets for ability to reproduce specific sets of observations. However, this narrow-focused approach overlooks the critical heuristic aspects in using models to explore and understand the behavior of cropping systems at the process level. We argue that the key criteria of model evaluation are both transparency and overall robustness. While model robustness (often mislabeled as “validation”) is sometimes presented at some level, model transparency has normally been ignored in model comparison studies. The objective of this paper is to examine the transparency and robustness of four wheat ( Triticum aestivum L.) models that are markedly different in detail: CropSyst and SSM as simpler models and APSIM and DSSAT as more complex models. Data for development, growth and yield of the crop were collected from a wide range of environmental and growth conditions in the Grogan region of Iran. Models parameterization was done according to the guidelines for each model and then model testing and comparison were performed using different datasets. The two simpler models were found to be more robust than the complex models; across all the evaluated crop variables, the coefficient of variation in yield prediction was lower for SSM (8.2%) and CropSyst (14.3%) than APSIM (15.0%) and DSSAT (18.5%). Transparency of the models was mainly gauged by the number of input parameters needed by the models. Simulations using APSIM (292 parameters) and DSSAT (211 parameters) required the definition of about fourfold more parameters than CropSyst (50 parameters) and SSM (55 parameters). The simulation results showed no significant relationship between model performance and parameter number; the lack of transparency sacrificed in complexity was not rewarded by increased robustness in the output. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle (UAV) remote sensing and machine learning have emerged as a practical approach with ultra-high temporal and spatial resolutions to overcome the limitations of ground-based sampling for continuous crop monitoring. However, little is known on the suitability of distinct sensing indices for different crop management and distinct crop development phases. In this study, we assessed the potential of the UAV-based modeling to monitor field-scale crop growth under different water and nutrient supply considering distinct phenological phases of maize. UAV multispectral observations were deployed over two long-term experimental sites in three growing seasons. Calibration and validation of the random forest model took place at the Nutrient Balance Experimental Site (NBES) and the Water Nitrogen Crop Relation Site (WNCR), respectively. Leaf area index, leaf chlorophyll concentration, and aboveground dry matter were measured at the jointing, heading, and grain filling phases of maize in 2018–2020. Our results revealed that the suitability of sensing indicators differed at distinct maize phenological phases. Overall, red edge, red edge reflectance ratio, and chlorophyll index green are the most appropriate UAV indicators for estimating maize growth variables. The random forest model developed and calibrated at NBES with nutrient supply detected the signal of nitrogen × irrigation interactions at the other experimental site (WNCR) in different development phases and years very well, suggesting that random forest models developed by UAV images of same spatial and spectral attributes could be transferred across sites with the same cultivar while different irrigation and fertilizer management. We conclude that the selected number of UAV detected indicators processed with a random forest model could be used for robustly estimating environment × management (fertilizer and irrigation) interactions on maize growth variables. • Red edge and chlorophyll index green best estimate maize growth across distinct nutrient and water management. • The suitability of UAV-based indicators depends on crop development phase. • Random forest models developed at nutrient experiment can detect distinct water and nutrient effects using similar cultivars. [ABSTRACT FROM AUTHOR]

Abstract: Chickpea (Cicer arietinum L.) yield is unstable and low in major producer countries. A robust crop model can assist in evaluation of possible genetic improvements and cultural management practices to improve yield. The objectives of this study were to develop and test a chickpea simulation model that could be used across a wide range of environments. This model simulates phenological development, leaf development and senescence, mass partitioning, plant nitrogen balance, yield formation and soil water balance. Responses of crop processes to environmental factors of solar radiation, photoperiod, temperature, nitrogen and water availability, and genotype differences were included in the model. The model uses a daily time step and readily available weather and soil information. The model was tested using independent data from a wide range of growth and environmental conditions. In most cases, simulated grain yield were similar to observed yield (ranging from 20 to 379gm−2) with a root mean square root of 26gm−2 (15% of average measured yield). It was concluded that the model generality, i.e., constant parameters for genotypes across locations, and applicability to a wide range of environmental conditions factors made this model especially useful. [Copyright &y& Elsevier]

Abstract: Crop management plays an important role in the transition from a deepwater rice to a flooded rice production system but information about optimum management strategies are currently lacking. The goal of this study was to determine the effect of planting date and variety on flooded rice production in the deepwater area of Thailand. Two experiments were conducted at the Bang Taen His Majesty Private Development Project in 2009 and 2010 to represent conditions prior to flooding (early rainy season) and after flooding (dry season). The early rainy season crop covered the period from May to October 2009, while the dry season crop covered the period from November 2009 to April 2010. The experimental design was a split plot with four main plots and three sub plots replicated four times. The treatments for the main plot were various planting dates, while the treatments for the sub plots were rice varieties. The dates of the critical developmental phases of rice were recorded and biomass was sampled during the growing period. The collected data were statistically analyzed using ANOVA and treatment means were compared to identify the appropriate plating date and the best variety for the area. The highest average yield was obtained for variety PSL2 across transplanting dates from June 19 to July 23, with an average yield of 3898kgha−1. The dry season crop showed that both biomass and yield were affected by the interaction between planting date and variety. The highest yield was obtained for variety PTT1 transplanted on November 9. The research showed that the variety PSL2 is the most suitable variety for early rainy season production with a transplanting date ranging from June 19 to July 23, while the variety PTT1 planted on November 9 was the best management practice for the dry season crop. However, a high yielding flooded rice variety that has a short growth duration is still needed for this area. [Copyright &y& Elsevier]

Abstract: Simple plant-based diagnostic tools can be used to determine crop P status. Our objectives were to establish the relationships between P and N concentrations of the uppermost collared leaf (PL and NL) of spring wheat (Triticum aestivum L.) and maize (Zea mays L.) during the growing season and, in particular, to determine the critical leaf P concentrations required to diagnose P deficiencies. Various N applications were evaluated over six site-years for wheat and eight site-years for maize (2004–2006) with adequate soil P for growth. Phosphorus and N concentrations of the uppermost collared leaf were determined weekly and the relationships between leaf N and P concentrations were established using only the sampling dates from the stem elongation stage for wheat and from the V8 stage of development for maize. Leaf P concentration generally decreased with decreasing N fertilization. Relationships between PL and NL concentrations (mgg−1 DM) using all site-years and sampling dates were described by significant linear–plateau functions in both maize (PL =0.82+0.089NL if NL ≤32.1 and PL =3.7 if NL >32.1; R 2 =0.41; P <0.001) and wheat (PL =0.02+0.106NL if NL ≤33.2 and PL =3.5 if NL >33.2; R 2 =0.42; P <0.001). Variation among sampling dates in the relationships were noted. By restricting the sampling dates [413–496 growing degree days (5°C basis) in wheat (i.e., stem elongation) and 1494–1579 crop heat units in maize (i.e., silking), relationships for wheat (PL =0.29+0.073NL, R 2 =0.66; P <0.001) and maize (PL =1.04+0.084NL, R 2 =0.66; P <0.001) were improved. In maize, expressing P and N concentrations on a leaf area basis (PLA and NLA) at silking further improved the relationship (PLA =0.002+0.101NLA, R 2 =0.80; P <0.001). Predictive models of critical P concentration as a function of N concentration in the uppermost collared leaf of wheat and maize were established which could be used for diagnostic purposes. [Copyright &y& Elsevier]

Abstract: Crop growth and development as well as yield are the result of the efficiency of the chosen agricultural management system within the boundaries of the agro-ecological environment. End-of-season yield results do not permit the evaluation of within-season management interactions with the production environment and do not allow for full understanding of the management practice applied. Crop growth and development were measured during the 2004, 2006 and 2008 crop cycles with an optical handheld NDVI sensor for all plots of the different management treatments of a long-term (since 1991) sustainability trial in the highlands of Mexico. Cropping systems varying in (1) tillage (conventional vs. zero tillage); (2) residue management (retention vs. removal); (3) rotation (monocropping vs. a maize [Zea mays L.]/wheat [Triticum aestivum L.] rotation) were compared. The NDVI-handheld sensor was evaluated as a tool to monitor crop growth and development and was found to be an excellent tool for this purpose. There was a strong relation between NDVI and biomass accumulation of maize and wheat. The measurement with the handheld sensor was non-destructive and fast so that a representative plot area could be measured easily and time-efficiently. Zero tillage induced different crop growth dynamics over time compared to conventional tillage. Zero tillage with residue retention is characterized by a slower initial crop growth, compensated for by an increased growth in the later stages, positively influencing final grain yield. Also crop rotation influenced early crop growth, with lower NDVI values for crops sown after wheat than crops after maize. Zero tillage with residue removal had low NDVI values throughout the growing season. Zero tillage with retention of crop residues results in time efficient use of resources, as opposed to conventional tillage, regardless of residue management, and zero tillage with residue removal. The results indicated that different tillage, rotation and residue management practices influence crop growth and development. It is important to monitor and understand crop growth under different management systems to select the right varieties and adjust timing and practice of input supply (fertilizer, irrigation etc.) in a holistic way in each cropping system. [Copyright &y& Elsevier]

Abstract: The growth of microorganisms during maturation is influenced by several factors including temperature, moisture content and water activity (a w). In order to better understand the conditions in which microorganisms develop during kernel development, the evolution of the grain moisture content and water activity (a w) in a commercial hybrid (Pioneer PR34N43) has been recorded during maturation and the relationships between moisture content, a w and temperature have been analysed. In 2007, maize grain samples were collected in two fields during grain maturation at 60–17% (±1%) of grain moisture (wet basis). The samples were analysed for a w at 15, 25, and 40°C and the moisture content was determined. The results have shown that the moisture content drops linearly during maturation, while a w is constant (a w =1.000) until about 36–38% of grain moisture, and only after this moisture level, does it start to decrease. This would seem to indicate that: (i) the water that is initially lost is all surface or loosely held water and a w does not actually start dropping until late on the maturation phase, and that, (ii) consequently the conditions remain favourable to microbial growth and development until the last grain maturation phases. The measurements conducted at the three temperatures indicate that the effect of temperature only starts to be evident at a grain moisture content of about 30%: after this level, the higher the temperature, the higher the water activity at the same moisture content. Moreover, the lower the moisture content, the more the temperature influence a w. [ABSTRACT FROM AUTHOR]

Abstract: Sorghum (Sorghum bicolor (L.) Moench) is the staple crop of Burkina Faso in West Africa where guinea race landraces are grown in low-input cropping systems. National and international breeding programs have had little success in disseminating modern varieties based on high yield potential caudatum or kafir race breeding materials, mostly introduced from other countries. It has been argued that the breeding objectives were not sufficiently oriented towards the farmers’ needs and preferences, and that they did not target the prevailing growing conditions of Burkina Faso. The objectives of the present article are (i) to identify and examine farmers’ selection criteria for sorghum varieties in the Centre-West of Burkina Faso, (ii) to compare these criteria with the breeder''s agronomic observations and standard practices, and (iii) to show how the criteria of both farmers and breeders can be effectively integrated into the early stages of a pedigree breeding program. These objectives take into consideration gender differentiation, consistency of selection criteria and the interrelationship of measured quantitative traits, as well as the impact of these traits and criteria on the final selection. The present paper is based on a pedigree breeding program that was carried out over three years (2001–2003) in two villages of Burkina Faso. Options for integrating farmers’ selection expertise with that of the breeders’ were examined. Participatory selection was initiated with 53 F3/F4 progenies in field trials managed by farmers using rating and voting exercises. The breeders measured and analysed the agronomic data while the farmers evaluated a large number of progenies by means of their three most important selection criteria and a general appreciation. Farmers’ initial choices remained consistent in the selection exercises (voting) performed in subsequent years. The farmers’ methods for defining traits turned out to be more multivariate than the breeders’ formal understanding of these same traits. This was especially so for the criteria of grain quality, earliness, and productivity for which the farmers’ definition encompasses factors such as flour yield and stability across environments. However, rating results between farmer groups were variable. A disagreement between female and male ratings was especially found for the grain quality traits. The results clearly show that farmers can effectively select for traits on the basis of progeny and single plants while pursuing specific agronomic aims such as adaption. Subsequent yield improvement schemes will thus be more efficient in terms of selection intensity related to grain yield. The study is showing the way for breeders to adjust their selection criteria to suit the basic needs of small-scale farmer in semi-arid regions of sub-Saharan Africa. [Copyright &y& Elsevier]

Abstract: Extending the phase of stem elongation (SE) has been proposed as a tool to further improve yield potential in small-grain cereals. The genetic control of pre-heading phases may also contribute to a better understanding of phenological traits conferring adaptability. Given that an optimized total time to heading is one of the most important traits in a breeding program, a prerequisite for lengthening SE would be that this and the previous phase (leaf and spikelet initiation, LS) should be under different genetic control. We studied the genetic control of these two pre-heading sub-phases (from sowing to the onset of stem elongation, LS, and from then to heading, SE) in terms of Quantitative Trait Loci (QTL) in a barley double-haploid population derived from the cross Henni×Meltan, both two-rowed spring North European barley cultivars. DH lines (118) and their parents were studied in four field trials in North-Eastern Spain. Genetic control of a number of traits related to leaf appearance and tillering dynamics, which could be important for an early crop canopy structure, were also studied. LS and SE are, at least partially, under a different genetic control in the Henni×Meltan population, mainly due to a QTL on chromosome 2HS. The QTLs responsible for a different control of LS and SE did not seem to correspond with any major gene reported in the literature. Moreover shortening LS, so as to lengthen SE without modifying heading date, would not necessarily imply a negative drawback on traits that could be important for early vigour, such as phyllochron and the onset of tillering. [ABSTRACT FROM AUTHOR]

Abstract: Cereal–legume intercrops are a promising way to combine high productivity and several ecological benefits in temperate agro-ecosystems. However, the proportion of each species in the mixture at harvest is highly variable. The aim of this study was to test whether the timing of small application of N fertilizer is an effective way of influencing the dynamic interactions between species during crop growth and affecting the percentage of each species in the biomass of the mixture without greatly disturbing N2 fixation. The influence of timing of nitrogen fertilization in pea–wheat intercrops was studied as regards (i) the dynamics of crop growth, (ii) nitrogen acquisition of each species, (iii) the inhibition and recovery of symbiotic N2 fixation (SNF) after N application and (iv) final performance (yield, % of wheat, grain protein content). This was assessed in winter pea–wheat (Pisum sativum L.–Triticum aestivum L.) intercrops in 2007 and 2008 at two locations in France. Whatever the stage of application, N fertilizer tended to increase wheat growth and to decrease pea growth. N fertilization (applied once at different dates from tillering to the end of stem elongation) delayed the decrease in the contribution of wheat to total biomass and maintained the competitive ability of wheat over pea for longer than in unfertilized intercrops. N acquisition dynamics and N sharing between the two species were modified by N fertilization and its timing. Crop conditions at the time of N application (growth and phenology of each species, and their proportions in the intercrop biomass) greatly influenced intercrop response to N fertilization. Partitioning between species of soil and fertilizer N was correlated with the proportion of wheat in the total intercrop biomass observed at the date of N application. Short-term inhibition of nitrates on SNF was shown during the few days after N application, whatever its date. SNF recovery after N applications was observed only until pea flowering, but was prematurely stopped by N fertilization after this stage. The effect of N fertilization on the amount of fixed N2 at harvest was correlated with pea biomass. N fertilization affects N2 fixation mainly by affecting crop growth rather than %Ndfa in pea–wheat intercrops. In conclusion, N fertilization could be used as a tool to enhance the contribution of wheat in the intercrop biomass but may reduce the amount of fixed N2 in the intercrop by decreasing pea biomass. [Copyright &y& Elsevier]

Abstract: Varying the spatial distribution of applied nitrogen (N) fertilizer to match demand in crops has been shown to increase profits in Australia. Better matching the timing of N inputs to plant requirements has been shown to improve nitrogen use efficiency and crop yields and could reduce nitrous oxide emissions from broad acre grains. Farmers in the wheat production area of south eastern Australia are increasingly splitting N application with the second timing applied at stem elongation (Zadoks 30). Spectral indices have shown the ability to detect crop canopy N status but a robust method using a consistent calibration that functions across seasons has been lacking. One spectral index, the canopy chlorophyll content index (CCCI) designed to detect canopy N using three wavebands along the “red edge” of the spectrum was combined with the canopy nitrogen index (CNI), which was developed to normalize for crop biomass and correct for the N dilution effect of crop canopies. The CCCI–CNI index approach was applied to a 3-year study to develop a single calibration derived from a wheat crop sown in research plots near Horsham, Victoria, Australia. The index was able to predict canopy N (gm−2) from Zadoks 14–37 with an r 2 of 0.97 and RMSE of 0.65gNm−2 when dry weight biomass by area was also considered. We suggest that measures of N estimated from remote methods use N per unit area as the metric and that reference directly to canopy %N is not an appropriate method for estimating plant concentration without first accounting for the N dilution effect. This approach provides a link to crop development rather than creating a purely numerical relationship. The sole biophysical input, biomass, is challenging to quantify robustly via spectral methods. Combining remote sensing with crop modelling could provide a robust method for estimating biomass and therefore a method to estimate canopy N remotely. Future research will explore this and the use of active and passive sensor technologies for use in precision farming for targeted N management. [Copyright &y& Elsevier]

Abstract: Growing cotton during the dry (winter) season avoids many insect pests endemic in the wet season (summer) and could permit the reintroduction of cotton to the semi-arid tropics in Australia. This research addressed the questions: (1) what yield is possible given the lower mid-season radiation and temperature of the dry season, (2) the prediction and management of crop development using a range of sowing months to assess whether cotton can be grown and picked within the dry season. Over three seasons two Gossypium hirsutum L. (upland) cultivars and one Gossypium barbadense L. cultivar were sown from March, to June at the Ord River (15.5°S) in Western Australia. For the upland cultivars, lint yields of 1900–2300kg/ha for March and April sowings were at the high end of Australian and International benchmarks. High lint yields were linearly correlated with a greater proportion of bolls that were located on outer sites on fruiting branches than for high yielding crops in temperate climates (∼30°lat.). The change in boll position increased the length of the growing season which was also linearly correlated with yield. Future research needs to confirm if low minimum temperatures early in flowering caused the change in boll position and to measure the impact of extreme temperature seasons on yield and time to maturity. The lint yield of the G. barbadense cultivar was highest at a March sowing, at least 87% of the upland cultivars, which is comparable with temperate climates. The frequency of temperatures >35°C and <11°C affected time to squaring, requiring modification of existing development models derived in temperate climates. It was concluded sowing during March to April should achieve the dual objectives of high yields and avoidance of rain at maturity. The wide temperature range observed in these experiments improved the prediction of boll period from mean temperature; this function should be applicable outside the semi-arid tropics. [Copyright &y& Elsevier]

Abstract: Stem lodging is a risk to sunflower production in Argentina, and may contribute to fixing the upper limit to commercially viable crop population density, since yield is known to increase up to densities higher than those currently used. Reputedly, crops are particularly susceptible to stem lodging during grain filling and at harvest maturity, but the temporal and spatial unpredictability of lodging events under field conditions has hampered systematic research on this issue. In this study we used mechanical lodging to examine the relationships between stem failure moment of force and stem structure in plants of two sunflower hybrids of contrasting susceptibility to stem lodging grown at each of three crop population densities (5.6 plantsm−2, 10 plantsm−2 and 16 plantsm−2). Measurements were performed at mid- and near-end of grain filling and at harvest maturity in crops grown in three separate seasons at two locations. Stem failure moment of force at all three developmental stages was significantly (p <0.05) greater in the lodging-resistant hybrid than in the lodging-susceptible hybrid used in these experiments at 5.6 plantsm−2, and fell with increasing crop population density and between 90% grain filling and harvest maturity in both hybrids. At harvest maturity differences in stem failure moment of force between hybrids were significant (p <0.05) at all three crop population densities. Stem flexural rigidity (ability of the stem to resist bending) and stem deformation (horizontal displacement from the vertical of the stem immediately prior to breakage) exhibited responses to hybrid, crop population density and developmental stage that were broadly consistent with those of stem failure moment of force. Stem diameter at the breakage point fell with crop population density, but there was little difference between hybrids except at the harvest maturity, when the susceptible hybrid at the two highest crop population densities had smaller diameters than the resistant hybrid. Measured at the breakage point, the thickness of the epidermis plus cortex tissues (i.e., the effective thickness of the stem wall) which surround the friable stem pith fell with crop population density and between end of grain filling and harvest maturity in both hybrids. Differences in effective thickness of the stem wall between hybrids were small and often not significant, but there was a tendency for the susceptible hybrid to exhibit greater thickness of the effective stem wall, particularly at the two higher population densities. Stem failure moment of force was linearly related to thickness of the effective stem wall in both hybrids, the slope of the relationship being significantly greater for the resistant hybrid. We conclude that, within limits, the thickness of the effective stem wall may prove to be useful as a guide to genotype susceptibility to stem lodging in breeding programs and may offer a simple approach to modelling susceptibility. This work has also served to highlight the need to investigate the origins (presumably related to stem anatomy and/or cell wall properties) of the genotypic effects on the stem failure moment of force/the effective stem wall relationship. Finally, the demonstration of the existence of genotype differences in tolerance to stem lodging should encourage the execution of a broader survey aimed at identifying sources of tolerance to stem lodging at high crop population densities in sunflower. [Copyright &y& Elsevier]

Abstract: We present a simple generic framework to quantify source–sink relationships during grain filling, by using a determinate growth function which has a unique property, namely being able of explicitly describing the time for the end of a growth process. This model framework was applied to analyze these relationships in plants of six wheat (Triticum aestivum L.) genotypes grown in pots in climate-controlled greenhouses under two temperature regimes (day/night: 20/15 and 25/20°C). The function accurately described the sigmoid pattern of grain growth (sink activity), as its modified form did for the reversed sigmoid shape of flag-leaf area (source capacity), during grain filling. The six genotypes differed significantly in grain number as well as in grain yield, ranging from 54 to 81 grains and from 2.67 to 4.52g DM per culm, respectively, when grown at 20/15°C. Biomass and grain yield were significantly reduced by a rise of 5°C. Grain nitrogen contents raised from 2.1 to 2.6% as a consequence of less carbon accumulation resulting in lower grain weights at the high temperature. On average, a rise of 5°C in temperature reduced the duration of grain growth by 12 days (>30%), and increased the growth rate from 1.32 to 1.67mggrain−1 d−1 (20%). Genotypic differences in grain-filling duration were also larger than in rate of grain growth. The genetic variation in the flag-leaf area duration (a proxy for the capacity for intercepting radiation and photosynthesis) was positively associated with sink size. Model analysis showed that whether or not the timing for the cessation of grain filling and for the end of post-anthesis source activity was synchronized depended on temperature. The quantitative approach yielded parameters that characterize genotypic differences of post-anthesis source and sink capacity in responding to environmental variables. [Copyright &y& Elsevier]

Abstract: The stem elongation phase seems critical in yield potential determination in barley (Hordeum vulgare L.). Extending its duration, without modifying total time to anthesis, has been proposed as a promising breeding tool. A prerequisite for its use is that the duration of phases before and after jointing (that including leaf and spikelet initiation, LS, and that of stem elongation, SE) should be under different genetic control. In addition, little is known about the implications of changes in the duration of LS and SE upon other developmental traits which could affect other aspects of yield generation, such as phyllochron and tillering. Thus, the objectives of the present work were to study the genetic variability in LS and SE, in traits related to leaf appearance and tillering, as well as their relationships, in a double-haploid (DH) population derived from the cross Henni×Meltan. DH lines and both parents were studied in four field trials. Despite the similarity in development between parents, there was significant genetic variability in duration of both LS and SE (i.e. considerable transgressive segregation was observed), with no major genetic correlations found between them. Although some significant genetic correlations were found between duration of phases and leaf appearance and tillering traits, it has been shown that modifying the duration of LS does not necessarily imply concomitant changes in traits that could be important for an early expansion of the crop canopy (i.e. phyllochron, onset and rate of tillering). [Copyright &y& Elsevier]

Crop models are essential tools for analysing the effects of climate variability, change on crop growth and development and the potential impact of adaptation strategies. Despite their increasing usage, crop model estimations have implicit uncertainties which are difficult to classify and quantify. Failure to address these uncertainties may result in poor advice to policymakers and stakeholders for the development of adaptation strategies. Since the 1990s, the number of crop model uncertainty assessments that consider different sources of model uncertainty (model structure, model parameters and model inputs such as climate, soil, and crop management practices) has increased significantly. We present the outcomes of a systematic review focused on uncertainty assessments of crop model outputs (mainly grain yield) and crop model uncertainty decomposition. We reviewed 277 articles from 1991 to 2019 which included studies conducted in 82 countries (460 locations) across all continents. 57% of the articles have been published between 2015 and 2019. 52% of the studies focus on input uncertainty assessments with climate change projections as the most frequently considered source of input uncertainty. Only 28% and 20% of the studies, respectively, dealt with uncertainties related to model parameters and model structure. The latter was mainly quantified using multi-model ensembles. Over half the studies were carried out in European and Asian countries, 34% and 23%, respectively. Most articles estimated model uncertainty focusing on the grain yield of major cereal crops (wheat > maize > rice) using the Decision Support System for Agrotechnology Transfer (DSSAT) model. Sensitivity analysis was the most used technique to quantify the contribution of different sources of uncertainty although the range of approaches for uncertainty quantification was wide. There is a need for standard procedures to estimate crop model uncertainty and evaluate estimates. We discuss the challenges of quantifying the components of uncertainty within crop models and identify research needs to better understand sources of uncertainty and thus improve the accuracy of crop models. [Display omitted] • We conducted a systematic review focused on crop model uncertainty decomposition. • Input uncertainty was the most frequently considered source of uncertainty. • Over half of the uncertainty studies were carried out in Europe and Asia. • Most uncertainty studies focused on grain yield of wheat and maize using DSSAT. • There is a need for standard procedures to estimate crop model uncertainty. [ABSTRACT FROM AUTHOR]

Abstract: Chinese wheat (Triticum aestivum) production has developed rapidly during the last 57 years, largely due to improved crop management technologies and new varieties. The history of wheat planting technologies in China was reviewed, and the physiological mechanisms that allow wheat to attain high yield under these planting systems were analyzed. The use of leaf number and stage of development to indicate the optimum timing for applications of fertilizers and irrigation water, and uniform seeding at reduced seeding rates to control lodging contributed significantly to the substantial progress in wheat productivity. However, flood irrigation and tillage-based practices also resulted in serious problems, including a decline in soil fertility and quality, environmental pollution, and inefficient use of water resources. The major future challenges facing wheat production are to improve water and nutrient use efficiency. Conservation agriculture-based resource conservation technologies such as zero or reduced tillage, flat or raised bed-planting systems, and rational management of crop residues to eliminate burning in the field are among the strategies we strongly recommend for improving agricultural environments and stabilizing/increasing wheat production in China. [Copyright &y& Elsevier]

Abstract: Water yam (Dioscorea alata L.) is one of the most popular tuber crops in the tropics. Although it is well known that photoperiod greatly affects yam development, little information is available on the effect of temperature on different developmental phases, and there has been no attempt to model the effect of both environmental factors. The aim of this study was to assess the combined effect of photoperiod and temperature on the development of two early maturing varieties of yam with similar growth pattern. For this we used a model proposed for potatoes grown under tropical conditions. Experimental information was obtained from 15 field experiments carried out in Guadeloupe (French West Indies) covering a wide range of planting dates. Two yam phases were analyzed: from emergence (EM) to tuber initiation (TI), and from TI to harvest (HA). The EM–HA period varied from 3 to 6 months, with the longer cycles corresponding to early planting dates (e.g. April). On average, EM–TI represented one-third of the EM–HA period, and was mainly affected by photoperiod and to a lesser extent by temperature. Both factors also affected the duration of TI–HA but their effects were less noticeable. The observed mean temperature during TI–HA was near the estimated optimum and its effect was less than that of photoperiod. The variation of the phase duration was higher for EM–TI (CV 45%) than for TI–HA (8%), which was satisfactorily explained by the model. For EM–TI there was a positive interaction between both environmental factors which, together with the greater influence of climatic conditions, resulted in much variability in its duration. For TI–HA, a small influence of environmental factors, coupled with a compensatory effect between environmental factors, resulted in a relatively smaller variation in the duration of this phase. The model estimated satisfactorily the dates and the duration of each phase. The root mean square error (RMSE) was 7.4 d which corresponded to 13% and 7% of the observed mean duration of EM–TI and TI–HA, respectively. Our results showed that small changes in photoperiod and temperature, which are very usual in the tropics, have a big effect on the tested yam varieties. We also showed that the model applied in this study can be a useful tool to predict yam development for management purposes as well as for the modeling of yam growth. [Copyright &y& Elsevier]

Abstract: The black earths of Central Europe are an important soils for crop production but sustainability of crop production on such soils has not been examined. In the present paper, yield of winter wheat over 50 years of FYM, N, P and K fertilizer application (12 treatments altogether) was analyzed in the Ivanovice Crop Rotation Experiment (ICRE), established in 1955 on a degraded black earth soil (chernozem). The ICRE is located in a warm (8.4°C mean annual temperature) and moderately dry (556mm mean annual precipitation) sugar beet cropping area. Summarizing 50 years’ results, variety had the largest effect on grain yield followed by the effect of mineral fertilizers, the preceding crop and farmyard manure application. The highest increase in grain yields was recorded after the introduction of short-straw varieties. High year-to-year variability in grain yields was recorded and some fluctuations were consistent with oscillations in the whole Czech Republic. Despite the high fertility of black earth soils in the locality, the mean grain yield in the ICRE was lower than the mean annual yield in the Czech Republic in five cases out of 50 years. The effect of fertilizer treatment on the grain yield was not significant in the first decade (the mean grain yields ranged from 3.4 to 3.8tha−1), but was significant in the fifth decade of the experiment (the mean grain yields ranged from 4.2 in control to 6.6tha−1 in N121P89K102 treatment, respectively). Calculated by linear regression, the annual yield increased by 45.9–89.6kg of grain per ha. The mean yield per 1kg of applied Nha−1 increased by 18.7kg of grain in the fifth decade of the experiment. In unfertilized soil, the concentration of plant-available P, K and Mg was still optimal for winter wheat production even after 50 years without any fertilizer input. The black earth soils in the locality clearly demonstrates a high and long-term stable natural fertility. The results from the ICRE stress the necessity for long-term research in grain yield analysis. [Copyright &y& Elsevier]

Abstract: Solanum sisymbriifolium (Lam.), a plant that was introduced as a trap crop for potato cyst nematodes, shows strong temperature limitation of its growth. Previous research indicated that the crop needs to accumulate at least 700gm−2 dry matter to achieve sufficient nematode control. In that context, three functionally different geographical zones can be distinguished: (i) a zone with insufficient growth, independent of sowing time, (ii) a zone with potentially sufficient growth if the crop is allowed to grow for the whole growing season, and (iii) a zone with sufficient growth early or late in the growing season, opening the option to combine cultivation of the trap crop with another crop in the same year. The aim of the current research was to delimit these zones for western and central Europe, by developing a model enabling simulation of the potential growth of S. sisymbriifolium in 64 locations between Scandinavia and Spain and between the UK and Hungary. A LINTUL type crop growth model for potential growth was adapted to S. sisymbriifolium. Adaptations regarded particularly the relative growth rate of the leaf area, the specific leaf area, and the radiation use efficiency, that were made temperature dependent using experimental data. Furthermore, the leaf death rates were modelled as limited by light availability in the canopy. The model was calibrated with field data from an experiment in 2002, and validated on field experiments in 2001, 2003 and 2004, resulting in a root mean square error (RMSE) of 118.1gm−2 crop dry matter and a mean deviation (MD) of −15.9gm−2 for the validation data. Simulations were done for the 64 sites, using weather data from 1996 to 1999, and the studied area was divided in the three zones (i, ii and iii) as described above. In all regions the crop could reach the required minimum size, although barely so in Scandinavia and the north of the United Kingdom. Zone (ii) included the south of the United Kingdom and Sweden, The Netherlands, Germany, Belgium and the north of France. Zone (iii) included the rest of France, Spain, Portugal, Italy, and Hungary; here temperature and radiation suffice for the crop to reach its required minimum size in only part of the growing season, leaving space for an other (main) crop in the same season, at least in the absence of water limitations. [Copyright &y& Elsevier]

Abstract: Nitrogen (N) fertilisation boosts the grain yield of wheat through its influence on yield components, phenology and leaf traits. Both crop growth and senescence are dependent on N supply, as are the number of kernels set per unit area and per ear, and the mean kernel size. A two-season trial of four semi-dwarf durum wheat cultivars, grown at two levels of N, was used to illustrate the effects of N on canopy temperature, leaf resistance and flag leaf senescence pattern under irrigated conditions in a Mediterranean climate, and to explore the consequences of these effects on the crop phenology, its yield and its yield components. The well-fertilised crop developed a larger leaf area index at anthesis and a lower leaf resistance, thus generating a lower canopy temperature and delayed anthesis. Its grain fill duration was shorter, in spite of its lower canopy temperature, presumably because the increased N availability resulted in the development of a stronger sink (more kernels per unit area and per ear), which was associated with earlier senescence, thereby shortening the duration of grain fill, and led to reduced kernel weight. [Copyright &y& Elsevier]

Abstract: Spike grain number, a major component in the yield of wheat, is suspected of being determined by the sudden death of most of the initiated floret primordia, which occurs at around booting. By counting twice weekly the number of floret primordia in the middle and top spikelets, the onset time for the death of floret primordia (T d) was assessed in six genotypes of differing earliness and fertility subjected to three treatments that were applied during stem elongation. The variation in T d was positively correlated with overall earliness, as well as with spike fertility. Ovary development and enlargement were quantified in eight specified positions within the spikes, but T d could not be assigned to a developmental stage attained by any ovary. Development and enlargement were very strongly correlated with each other throughout the floret lifetime, yet with significant effects of genotype, treatment and position within spikes. In each position within a spike, the proportion of florets that set a grain correlated to the initial delay of development as compared to the most advanced floret (r 2 =0.64), but this correlation was severely biased by genotype and the floret position effect. Better correlations were obtained with either the development or width of each ovary at T d, thus highlighting the role of the preceding phase. The best prediction (r 2 =0.93) was obtained from the ratio of ovary width to that of the most advanced floret at T d. The importance of this width ratio emphasized the role of partitioning in grain set: only florets able to divert nutrients survived after T d and eventually set a grain. This relationship was no longer biased by floret position, while some remaining variability due to genotype suggested potential for plant breeding: width ratios at T d were generally related to the growth duration of various primordia, as well as to their relative growth rate. [Copyright &y& Elsevier]

• Twenty-three models estimated carbon fluxes in croplands and grasslands worldwide. • Vegetation data were needed as a minimum data requirement for model calibration. • C flux simulation improved with a multi-model approach (multi-model median). Croplands and grasslands are agricultural systems that contribute to land–atmosphere exchanges of carbon (C). We evaluated and compared gross primary production (GPP), ecosystem respiration (RECO), net ecosystem exchange (NEE) of CO 2 , and two derived outputs - C use efficiency (CUE=-NEE/GPP) and C emission intensity (Int C = -NEE/Offtake [grazed or harvested biomass]). The outputs came from 23 models (11 crop-specific, eight grassland-specific, and four models covering both systems) at three cropping sites over several rotations with spring and winter cereals, soybean and rapeseed in Canada, France and India, and two temperate permanent grasslands in France and the United Kingdom. The models were run independently over multi-year simulation periods in five stages (S), either blind with no calibration and initialization data (S1), using historical management and climate for initialization (S2), calibrated against plant data (S3), plant and soil data together (S4), or with the addition of C and N fluxes (S5). Here, we provide a framework to address methodological uncertainties and contextualize results. Most of the models overestimated or underestimated the C fluxes observed during the growing seasons (or the whole years for grasslands), with substantial differences between models. For each simulated variable, changes in the multi-model median (MMM) from S1 to S5 was used as a descriptor of the ensemble performance. Overall, the greatest improvements (MMM approaching the mean of observations) were achieved at S3 or higher calibration stages. For instance, grassland GPP MMM was equal to 1632 g C m−2 yr-1 (S5) while the observed mean was equal to 1763 m-2 yr-1 (average for two sites). Nash-Sutcliffe modelling efficiency coefficients indicated that MMM outperformed individual models in 92.3 % of cases. Our study suggests a cautious use of large-scale, multi-model ensembles to estimate C fluxes in agricultural sites if some site-specific plant and soil observations are available for model calibration. The further development of crop/grassland ensemble modelling will hinge upon the interpretation of results in light of the way models represent the processes underlying C fluxes in complex agricultural systems (grassland and crop rotations including fallow periods). [ABSTRACT FROM AUTHOR]

Improving grain yield and adaptation is achieved by synchronising crop phenology with the environment. Phenology research is complex and encounters analytical challenges in characterising genotype x environment (GxE) interactions. This paper presents a simple approach that helps to explain the environmental drivers of phenology. Photoperiod and temperature are major environmental cues for expression of crop developmental genes, and sensitivity to photoperiod is thought to be the major cause of maturity differences among Australian spring barley varieties. However, temperature and photoperiod show similar seasonal trends and strong autocorrelation makes it difficult to distinguish their relative importance in crop development. Partial Least Squares regression (PLS) was developed to handle large data sets with many correlated explanatory variables and only one dependent variable. Across 35 environments encompassing a wide range of temperature and photoperiod regimes in southern Australia, a PLS model described more than 90 % of the phenotypic variation in time to anthesis of three adapted barley cultivars. The PLS outputs defined the critical periods when photoperiod and temperature were most influential, and revealed that temperature effects are of equal or greater importance than photoperiod in determining anthesis date, which is a new finding for genotypes adapted to Australian environments. Insight into the previously elusive differential responses to changes in daily average, maximum, and minimum temperatures will assist in developing flowering models for growers that are more accurate, and assist breeders in the genetic dissection of phenology for target environments. [ABSTRACT FROM AUTHOR]

• Repeatable genetic variation in canopy architecture was found in two multi-parent wheat populations. • Lines with an erectophile canopy yielded 24% more grain than planophile lines. • Greater yield was largely due to an increase in above-ground biomass and grain number. • QTL analyses showed canopy architecture to be a complex trait yet QTL were repeatable in a dryland and an irrigated environment. In wheat (Triticum aestivum L.) canopy architecture influences light penetration into the canopy and radiation use efficiency particularly during the period between stem elongation and anthesis which is the critical time for the determination of yield. Despite large differences in canopy architecture among spring wheat genotypes, ranging from erectophile to planophile upper leaves, there is little prior evidence to suggest that selection for canopy architecture influences yield. In this study we evaluated the variation for canopy architecture in a 4-way MAGIC population (n=∼ 1000 lines) developed from 4 Australian commercial spring wheats and an 8-way MAGIC population (n=∼ 300 lines) developed from 3 Australian and 5 northern hemisphere commercial wheats. The 4-way population was grown at both an irrigated and a dryland site in southern New South Wales whereas the 8-way population was grown at the irrigated site. We also measured grain yield, plant height and crop development stage at the irrigated site. Using a smaller subset of lines which we grouped into either erectophile or planophile we studied how canopy architecture influences grain yield and associated yield traits (above-ground biomass (AGBM), harvest index, yield components, flowering time and height). The grain yield in the latter experiments varied from 5 to 6 t ha−1. Averaged over two years and two sowing dates in each year lines that were erectophile yielded 13% more than the planophile lines and most of this yield advantage was associated with a higher AGBM (11%). Erectophile lines had 24% more grains per unit area but a 9% lower grain weight. Erectophile lines flowered 2 days later than planophile lines and they were 7 cm shorter. Lodging, although rare in these studies, was more evident in the planophile lines. In both MAGIC populations the most erectophile lines yielded 24% more grain than the most planophile lines. Mapping was conducted on the 1000 lines from the 4-way MAGIC population grown at the irrigated and the dryland site. It showed that genetic control of canopy architecture was complex but QTL were generally repeatable at both sites. Significant QTL were identified on most chromosomes. G x E was low for canopy architecture as the scores were repeatable across years (r2 = 0.85). This trait opens the way to improve wheat yields via increasing crop biomass which in the past has been largely intractable in breeding programs. [ABSTRACT FROM AUTHOR]

• An international G by E sugarcane growth analysis dataset was collected. • E and GxE variation were present in final dry biomass and stalk yields. • G differences found for germination, canopy development and photosynthesis parameters. • Data analysis reveals strengths and weaknesses in process model concepts. • Solar radiation, in addition to temperature, influences onset of stalk growth. Crop improvement aims to produce high yielding genotypes for target environments. Crop models simulate yield formation as the outcome of a series of low-level processes, driven by environmental (E) variables and regulated by genetic (G) traits. There is potential for crop models to aid sugarcane breeding, by identifying desirable genetic traits for target environments. The objective of this study was to evaluate existing concepts of G and E control of plant processes for explaining crop development, growth and yield, using an international growth analysis dataset. Crop development, growth and yield were monitored in the plant and 1st ratoon crops for seven cultivars (N41, R570, CP88-1762, HoCP96-540, Q183, ZN7 and NCo376) grown under well-watered conditions at La Mare (Reunion Island, France), Pongola (South Africa (RSA), Chiredzi (Zimbabwe), and Belle Glade (Florida, USA). Weather data were collected and environmental conditions characterized for each experiment. Derived process-level phenotypic parameters, based on concepts from four sugarcane growth simulation models (DSSAT-Canegro, Mosicas, APSIM-Sugar and Canesim), were calculated from observations and used to (1) evaluate current understanding of E drivers of sugarcane growth and development processes, and (2) identify and quantify G control at a process level. Final yields showed significant E and GxE variation; dry above-ground biomass and stalk yields were highest in La Mare and lowest in Pongola. Cultivar rankings in stalk dry mass for the common cultivars (N41, R570, CP88-1762) varied significantly between Es. Significant E variation in phenotypic parameters describing germination, tillering and timing of the onset of stalk growth (OSG) revealed shortcomings in the underlying simulation concepts. Significant G variation was found for germination rate, leaf appearance rate and canopy development rate per unit thermal time (TT), and maximum radiation use efficiency, indicating strong G control of the associated underlying processes. Solar radiation was found to influence tillering rate per unit TT, and TT to OSG, challenging the current theory of TT as the sole driver of these processes. By explaining more of the E variation, more stable and accurate G-specific model parameters can be defined and evaluated. This is anticipated to lead to less GxE confounding of modelled processes, and hence crop models that are better-equipped for supporting sugarcane crop improvement. [ABSTRACT FROM AUTHOR]

• Winter grain legumes had a higher soil coverage than spring-sown grain legumes up to mid-May. • Autumn-sowing resulted in earlier flowering and a longer duration of development stages. • Grain and residue yields of autumn-sown faba bean and pea were higher than that of the corresponding spring types. Shifting from spring-sowing to autumn-sowing of crops might be a way to address expected changes in agro-climatic conditions in Central European cropping systems. Therefore, a two-year field experiment was conducted under Pannonian climate conditions in eastern Austria for assessing development, soil coverage and yields of winter faba bean and winter pea in comparison to spring faba bean and spring pea and winter wheat and winter oat. Both winters were mild and both winter grain legumes showed a high winter survival. Winter grain legumes had lower soil coverage in autumn than winter wheat but higher soil coverage than spring-sown grain legumes up to mid-May. Autumn-sowing resulted in earlier flowering, a longer duration of developmental stages and higher grain and residue yields than spring-sown grain legumes. Winter pea had higher grain yield than winter faba bean. Autumn-sowing of both faba bean and pea can be recommended in Central European growing conditions. [ABSTRACT FROM AUTHOR]

• Three major environmental types summarized the variability of drought patterns. • Moderate pre-flowering and low drought stresses were the most frequent ENVT. • Heat stress around flowering occurs independently of drought ENVT. • Heat stress (>33 °C) was frequent (20–50%) only at lower latitudes. • Our characterization is relevant for defining breeding and management strategies. Argentinean current sorghum management is similar across the entire temperate region, and no environmental characterization is assisting breeding and management decisions. Crop growth and development simulation models are a valuable tool for generating this characterization. Our study calibrated and validated APSIM-sorghum for our genetics and production environments, and used it to characterize the main water and heat stress patterns at our temperate central region. The calibration and validation provided accurate phenology, biomass, and yield estimations. Long-term weather records (44–61 years per site) and soil data were used to simulate the seasonal drought patterns at seven representative sites across the region. Clustering analysis identified three major drought environmental types (ENVT): (i) a pre-flowering drought stress, showing large occurrence frequency (39%), (ii) a low terminal drought stress, showing similar frequency (38%), and (iii) a grain-filling drought stress, showing lower frequency (23%). The most frequent ENVT at individual sites agrees with the spatial distribution of annual rainfall. However, most sites evidenced variable frequency of all ENVT. Flowering heat stress (>33 °C) showed an intermediate occurrence frequency (20–50%) only at lower latitudes, and was independent of drought ENVT. Defined ENVT helped explain observed genotype x environment (GxE) interactions for yield in an independent data set, showing they have practical implications for optimizing breeding and management strategies across the region of interest. Grouping sites of similar frequency can help to handle the spatial variability when defining these strategies, but dealing with seasonal variability will be challenging in the context of no predominant ENVT. [ABSTRACT FROM AUTHOR]