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Quantifying historic increases in water-limited potential yield (PY w ) achieved through breeding provides insight into associated changes in physiology and can assist with future cultivar improvement. We compared PY w of bread wheat cultivars popular in southern New South Wales released between 1901 and 2014. In both 2015 and 2016, cultivars were sown at multiple sowing dates to allow comparisons to be made at a consistent optimal flowering date (early October), and thus control for the large differences in life cycle duration. Seasonal conditions were close to average in 2015 and extremely favorable in 2016. In both, grain yield increased across the historic period studied at 26 kg/ha per annum, regardless of whether a common sowing date or flowering date was used. Yield gain was not linear, and there was a period of rapid yield increase during the middle of the 20th century, that culminated with the release of semi-dwarf cultivars. Yield gain was relatively slower from the 1980s until the present day, possibly due to selection for grain quality traits (grain size) at the expense of grain number. Historic yield increases were not associated with earlier flowering, but with an interplay between greater grain number/m 2 and greater grain weight which was the result of increased partitioning of assimilates to spikes, and greater number of grains per unit spike weight (fruiting efficiency). Greater partitioning to the spike in modern cultivars was associated with reduced dry matter (DM) production prior to flowering. Modern cultivars have a less stable flowering time across sowing dates, and shorter life cycle, but improved partitioning in modern cultivars appeared decoupled from shorter developmental phases prior to flowering. The performance of the novel vernalisation sensitive cultivar Longsword showed that future yield gain may be achieved through the combination of early sowing and slow development, increased DM production and superior partitioning to grain. [ABSTRACT FROM AUTHOR]

[Objectives] Wheatear spikelet number and grain number directly reflect the yield of wheat,which are two very important parameters in the research of wheat phenotype. This measuring accuracy about the number of spikelet is very low at present,which can not meet the actual needs of breeding and estimating yield. The literature on measuring grain number has not yet appeared.[Methods] In order to measure these two parameters quickly,a parabolic segmentation method based on image processing technique for wheatear spikelet was presented in this paper,and the synchronously counting spikelet number and grain number were realized by using the wheatear front view image. Firstly,image preprocessing algorithm was used in order to obtain adjusted binary image of wheatear. Then the pixels were summed according to rows of binary image,and the curve of the row pixels sum was plotted. Then the smoothing curve was obtained by using smoothing filtering algorithm and the peaks and troughs of the smoothing curve were obtained by using extracting extremum. The stalk of the wheat was separated by setting a pixels threshold depending on the width difference between the stalk and the ear head. The number of peaks at the ear head in the smoothing curve indicated the number of spikelet. Then the abscissa values of the peaks and troughs were obtained,which represented the ordinal number Y of rows in binary image. A set of intersection points between the rows ordinal number Y and the boundary of the wheatear in binary image could be obtained. Then the midpoint coordinate of the wheatear boundary was obtained at the trough. And the maximum and minimum point coordinates of the wheatear boundary were obtained at the peak. Then three position points of fitting the parabolic curve for spikelet were ascertained according to the coordinate of peaks and troughs of the smoothing curve at the binary image. Finally,each spikelet in wheatear was segmented using the fitted parabolic curve. The area of each spikelet was extracted. Meanwhile,the grain number of each spikelet was counted manually. So then the relation between the area of each spikelet and the grain number was obtained by using threshold method.[Results]The wheatear images of three wheat varieties were identified to validate the spikelet number and grain number of each wheatear. The experiment results manifested that the average zero error rate of the spikelet number for three wheat varieties was 68.16%,the average absolute error of three wheat varieties of the spikelet number was 0.46,and the average relative error of the spikelet number for three wheat varieties was 2.99% by using aforementioned method to identify the spikelet number at wheatear. The recognition accuracy and the average zero error rate of the spikelet number were greatly improved by compared with the existing literature. And using aforementioned method to identify the grain number at wheatear,the average absolute error of grain number for three wheat varieties was 2.11,and the average relative error of grain number for three wheat varieties was 5.62%.The average measurable time for three wheat varieties was 7.99 s for a wheatear.[Conclusions] The automatically image counting wheat grain number and spikelet number for a wheatear with faster and higher precision can be realized. [ABSTRACT FROM AUTHOR]

Availability of nitrogen and water are major constraints for crop yield, and their interactions are manyfold. Yield gap analysis in rainfed systems commonly uses water-limited yield potential (Y w ) as a benchmark; benchmarking against nitrogen-limited yield potential (Y N ) is less common. The aim of this study was to benchmark wheat yield against Y N in winter-rainfall regions of Australia. We established experiments, and sampled both farmers’ fields and National Variety Trials spanning wide ranges of soils, management practices, and water supply (seasonal rainfall + irrigation) from 153 to 759 mm in South Australia, and from 178 to 428 mm in Western Australia. We measured yield, quantified crop nitrogen nutrition index (NNI) at stem elongation, anthesis or both, derived boundary functions relating Y N and NNI, calculated yield gaps as the difference between Y N and actual yield, and explored the associations between yield gaps and environmental, crop and agronomic factors. In South Australia, NNI at anthesis ranged from 0.45 to 1.45 and yield from 0.9 to 8.9 t ha −1 ; in Western Australia NNI at stem elongation ranged from 0.27 to 1.16 and yield from 1.0 to 7.1 t ha −1 . Bi-linear boundary functions were fitted with a linear Y N – NNI phase up to a NNIx threshold (0.95 ± 0.134 in South Australia, 0.87 ± 0.145 in Western Australia), and a plateau reflecting yield potential (7.8 ± 0.38 t ha −1 in South Australia, 6.5 ± 0.52 t ha −1 in Western Australia). Similar bi-linear boundaries, with congruent NNIx (≈0.9), were found for grain number and shoot biomass at maturity. In South Australia, water supply explained 54% of the yield gap, which declined linearly from about 6 t ha −1 to zero with increasing water availability. Further, the yield gap correlated negatively with carbon isotope discrimination at anthesis, a direct measure of crop water status. In Western Australia, the direct association between yield gap and rainfall was weak, but there was an indirect agronomic link, where low seeding rate in low rainfall environments contributed to low biomass at stem elongation, which in turn explained a large part of the yield gap. In two out of five National Variety Trials, where the aim is comparing the yield of current and emerging varieties, crops were nitrogen deficient. This is a potential source of bias as some varieties were above and others below the NNIx threshold of nitrogen sufficiency. Supply of nitrogen in varietal comparisons needs attention. The approach advanced in this paper can be applied to benchmark yield against crop nitrogen status and identify causes of yield gaps, and for in-season quantification of crop nitrogen status to assist fertiliser decisions directly, or indirectly as a reference for spectral indices. [ABSTRACT FROM AUTHOR]

Rice includes 93 nitrate and peptide transporters family (NPF) members that facilitate the soil uptake and internal reallocation of nitrogen for growth and development. This study demonstrated that OsNPF7.7 had two splicing variants, and altered expression of each variant could regulate shoot branching and nitrogen utilization efficiency (NUtE) in rice. The expression of both variants was down-regulated in the buds by increased nitrogen level in the Japonica rice variety ZH11. The expression level of long-variant OsNPF7.7-1 was higher in panicles at reproductive stage, however, the expression level of short-variant OsNPF7.7-2 was higher in buds and leaves at vegetative stage compared to each other in ZH11. OsNPF7.7-1 was localized in the plasma membrane, whereas OsNPF7.7-2 was localized in the vacuole membrane. Furthermore, the results indicated that the expression level of each variant for OsNPF7.7 determined axillary bud outgrowth, and then influenced the rice tiller number. Overexpression of OsNPF7.7-1 could promote nitrate influx and concentration in root, whereas overexpression of OsNPF7.7-2 could improve ammonium influx and concentration in root. RNAi and osnpf7.7 lines of OsNPF7.7 showed an increased amount of amino acids in leaf sheaths, but a decreased amount in leaf blades, which affected nitrogen allocation and plant growth. The elevated expression of each variant for OsNPF7.7 in ZH11 enhanced NUtE using certain fertilization regimes under paddy field conditions. Moreover, overexpression of each variant for OsNPF7.7 in KY131 increased significantly the filled grain number per plant. Thus, increased each variant of OsNPF7.7 has the potential to improve grain yield and NUtE in rice. [ABSTRACT FROM AUTHOR]

Genetic improvements have significantly contributed to wheat production. Five wheat cultivars--widely grown in north China in the 1950s, 1990s, or 2010s--were grown in field experiments conducted in the 2014-2015 and 2015-2016 growing seasons. This study evaluated the genetic progress in wheat grain yield and its related traits in north China and explored how breeding and selection have influenced grain numbers and weights within spikelets in the past 60 years. The results showed that the significant increases in grain yield in the past 60 years were mainly due to increases in grain number per spike and grain weight, while spike number per m2 has not changed significantly. Improvements in thousand grain weight (TGW) from the 1950s to 2010s have occurred at four grain positions (G1 to G4). The relative contribution of G4 to TGW increased over time, but was much less than the contributions of G1, G2, and G3. Indeed, the average grain weight at G4 was much less than that of 1000 grains. The increase in grain number per spike since the 1950s was mainly due to an increase in grain number at G1, G2 and G3, with the relative contribution of grain position to grain number being G1 > G2 > G3 > G4. Dwarfing genes increased grain number per spike and grain number at G3 and G4, but not TGW. In future, yields could be boosted by enhancing grain weight at G4 and grain number at G3 and G4, while maintaining those at G1 and G2. [ABSTRACT FROM AUTHOR]

Tropospheric ozone is known to adversely affect crops and other vegetation. Most studies have focussed on the effects of elevated ozone levels vs. present ambient. We investigated the effect of present ambient surface ozone (O 3 ) concentrations vs. preindustrial on a range of agronomically important response variables in field-grown wheat, using results from 33 experiments (representing 9 countries, 3 continents, 17 cultivars plus one set of 4 cultivars) having both charcoal filtered (CF) and non-filtered (NF) air treatments. Average filtration efficiency was 62%, reducing the O 3 concentration from 35.6 ± 10.6 SD ppb in NF to 13.7 ± 8.8 SD ppb in CF. Average CF concentrations were in the range of levels believed to represent pre-industrial conditions, while NF concentrations were 7% lower than in the ambient air at plant height on the experimental sites. NF had significant (p < 0.05) negative effects compared to CF on grain yield (− 8.4%), grain mass (− 3.7%), harvest index (− 2.4%), total above-ground biomass (− 5.4%), starch concentration (− 3.0%), starch yield (− 10.9%), and protein yield (− 6.2%). No significant effect was found for grain number and protein concentration. There was a significant relationship between the effect of filtration on grain yield and the difference in O 3 concentration between NF and CF treatments. The average yield loss per ppb O 3 removed was 0.38% and did not systematically vary with year of experiment (ranging from 1982 to 2010) or with the average O 3 level in the experiments. Although there are many differences among the field experiments included in this meta-analysis (e.g. genotype, degree of O 3 pollution of the site and year, nutrient and soil condition, filtration efficiency), our study clearly shows that there is a consistent and significant effect of present ambient O 3 exposure on a range of important response variables in wheat, the most strongly affected being starch yield. [ABSTRACT FROM AUTHOR]

There is a lack of studies that have investigated grain yield, its components and photosynthesis in late stages of wheat growth, giving us insufficient understanding of how these factors interact to contribute to yield during this period. As a result, three field experiments were carried out examining 20 winter wheat genotypes of diverse origins under irrigated, terminal drought and dryland conditions in the southern Idaho. Our objective was to evaluate the interaction between post-anthesis physiological traits, especially leaf-level photosynthetic capacity, senescence and yield components on grain yield in different moisture regimes. Genotype differences were found in leaf-level photosynthesis and senescence, canopy temperature depression, grain yield and yield components in each water regime. Grain yield was closely associated with traits related to grain numbers. In all three moisture regimes, positive correlations were observed between grain yield and photosynthesis that were dependent on the timing or physiological growth stage of the photosynthetic measurement: highly significant correlations were found in the mid- and late grain filling stages, but no correlations at anthesis. Consistent with these findings, flag leaf senescence at the late grain filling stage was negatively correlated with grain yield and photosynthetic rate (under terminal drought and dryland conditions). These findings provided evidence that grain yield was sink-limited until the final stages of growth, at which time sustained photosynthesis and delayed senescence were critical in filling grain. Because the trends were consistent in moisture sufficient and deficient conditions, the results suggest that late-season photosynthesis and delayed leaf senescence are driven by the size of the reproductive carbon sink, which was largely governed by factors affecting grain numbers. [ABSTRACT FROM AUTHOR]

Grain yield in wheat is generally considered to be sink-limited during grain filling. But is this limitation inherent to the crop species or a consequence of the breeding process? A way to ascertain this is by using genetic materials not subject to selection. Grain yield could be analyzed as the product between: (i) grain number per unit area, (ii) the potential grain weight (i.e. weight per grain obtained without source limitation); and (iii) the degree of sink limitation (DSL). The product of the first two components defines the crop sink capacity (SICA), and the DSL could be assessed as the quotient between weight per grain and its potential weight. Such an analysis was carried out in a RIL population derived from the cross between Baguette 10 and Klein Chajá (Argentinean cultivars with contrasting grain number). Three field experiments were conducted at Balcarce, Argentina during the 2013, 2014 and 2015 crop seasons, under non-limiting conditions; 146 recombinant inbred lines (RILs), the parental cultivars and other commercial cultivars were evaluated. At maturity, grain yield and grain weight were determined. The potential grain weight was obtained by thinning rows at the beginning of grain filling. Grain number m −2 was calculated as grain yield/grain weight. Grain yield was highly associated with SICA; the slope of the relationship between grain yield and SICA was lower than the expected 1:1 ratio above ∼8 tons ha −1 , indicating that the source for grain filling becomes a limiting factor when SICA increases, particularly in the RILs. This suggests that much of the sink limitation observed in modern wheat cultivars may be the result of genetic improvement. [ABSTRACT FROM AUTHOR]

Barley is one of the most relevant crops worldwide and an essential component of agriculture in Europe in general, and in the Mediterranean region in particular. As cropping areas will hardly rise in the future, yield must be improved to enhance global crop production. Naturally, understanding how yield is affected by environmental and genetic factors in two- and six-rowed barley can help us to develop more efficient management and breeding strategies to increase current yield gains. We aimed to determine the relative importance of genetic and environmental factors on numerical and physiological components of GN for two- and six-rowed barley types. To generate a large and unbiased database, we compiled data of yield and its numerical and physiological components from crop-based experiments (i.e., excluding controlled-conditions experiments and/or approaches using isolated plants) reported in figures and tables in every single paper having the word "barley" in the title published over 25 years in four rigorous and prestigious international journals: Field Crop Research, European Journal of Agronomy, Crop Science and Crop and Pasture Science (formerly Australian Journal of Agricultural Research) between January 1996 and December 2021, both inclusive. Spike number (SN) was the most relevant numerical component explaining GN regardless of the source of variation. Regarding physiological components, it seemed that when the driving force was environmental factors, spike dry weight at flowering (SDW F) was more relevant than fruiting efficiency (FE); whilst when the differences were due to genotypic factors, clearly the FE was the component mostly responsible for the changes in GN. When the analysis was restricted to two- and six-rowed barley types, GN improvements were mainly explained by changes in SN for both two- and six-rowed barley types. However, when the physiological components were considered, the responsiveness of GN was more related to SDW F than to FE in two-rowed genotypes, while the opposite was true for the six-rowed type. In barley, SN always explained the responses of GN better than grain number per spike (GNS), regardless the source of variation and the type of barley. Respect to the physiological components, environmental factors affected GN mainly through affecting SDW F , while genotypic factors affected GN through affecting FE. SDW F and FE were more relevant for explaining changes in GN two- and six-rowed barleys, respectively. Breeders and agronomists can be aware that it will be more likely to achieve significant gains in yield through focusing more on SN than on GNS regardless of the barley type, whilst regarding the physiological components it would be more relevant to focus on SDW F in two-rowed barley, and on FE in six-rowed barley. • We quantified grain number components depending on source of variation in barley. • Spike number (SN) explaining grain number regardless of the source of variation. • Spike dry weight (SDW F) was the most relevant component for environment factor. • Fruiting efficiency was more relevant for genotypic factor. • Grain number was more related to SDW F in two-rowed, while FE in six-rowed type. [ABSTRACT FROM AUTHOR]

Nitrogen use efficiency is important for the development of sustainable agriculture. Plants have different transporters to facilitate nitrogen uptake and internal distribution. This study demonstrates that the peptide transporter OsNPF7.3 enhances nitrogen allocation and increases grain yield in rice. OsNPF7.3 is a member of the nitrate transporter 1/peptide transporter family (NPF) and is localized in the vacuolar membrane. Its expression is higher in the lateral roots and stems. Its transcripts concentrate in the vascular bundle and significantly regulated by organic nitrogen sources. The RNAi lines of OsNPF7.3 affect plant growth and cause amino acids to accumulate in leaf sheaths and decrease in the leaf blades. At later stages of reproductive growth, nitrogen degradation accelerates in the leaves of plants over-expressing OsNPF7.3 and the nitrogen is translocated to grains. The tiller numbers, panicles per plant, filled grain numbers per panicle, and grain nitrogen content of the OsNPF7.3 over-expressing plant were more than that of wide type. The elevated gene expression in OsNPF7.3 could enhance nitrogen utilization efficiency in rice paddy.

Grains number is one of the most important agronomic traits in the determination of rice productivity. To explore the underlying genetic basis of grain number in rice, quantitative trait locus (QTL) analysis was performed using three recombinant inbred line populations derived from indica rice crosses of Teqing/IRBB lines, Zhenshan 97/Milyang 46, and Xieqingzao/Milyang 46, respectively. A total of 58 QTLs distributed on all 12 rice chromosomes were identified, including 22 for number of grains per panicle (NGP), 17 for number of spikelets per panicle, and 19 for spikelet fertility. The individual QTL counted for 1.5 to 22.1% of phenotypic variation. Among them, 15 QTLs shared by two or three populations and eight QTLs showed large effects with R2 larger than 10%. Furthermore, three QTLs with minor effects for NGP, qNGP5.5, qNGP9.1, and qNGP12.1, were detected and validated by eliminating the segregation of major-effect QTL using four residual heterozygote-derived populations. These results not only enrich our understanding of the mechanism of grain number, but also provide a foundation for cloning and selecting candidate for marker-assisted selection breeding in rice.

Elevated carbon dioxide (eCO2) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO2 concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO2 concentration. Grain yield increased by 26% under eCO2 (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO2 concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456–600 ppm compared to 601–750 ppm. Yield response to eCO2 was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO2 yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO2, was of large importance for crop modelling and assessments of future food production under rising CO2.

Background: Rice is a major source of food, particularly for the growing Asian population; hence, the utilization of genes for enhancing its yield potential is important for ensuring food security. Earlier, we have mapped a major quantitative trait loci (QTL) for the grain number per panicle, qGN4.1, using biparental recombinant inbred line (RIL) populations involving a new plant type Indica rice genotype Pusa 1266. Later, three independent studies have confirmed the presence of a major QTL for spikelet number by three different names ( SPIKE, GPS and LSCHL4) in the same chromosomal region, and have implicated the overexpression of Nal1 gene as the causal factor for high spikelet number. However, the effect of qGN4.1 in different rice genetic backgrounds and expression levels of the underlying candidate genes is not known. Results: Here, we report the effect of qGN4.1 QTL in the genetic backgrounds of 12 different high-yielding mega varieties of rice, introgressed by marker assisted-backcross breeding (MABB) using two QTL positive markers for foreground selection and two QTL negative flanking markers for recombinant selection together with phenotypic selection for the recovery of recipient parent genetic background. Analysis of the performance of BCF plants showed a significant increase in the average number of well-filled grains per panicle in all the backgrounds, ranging from 21.6 in CSR 30- GN4.1 to 147.6 in Samba Mahsuri- GN4.1. Furthermore, qGN4.1 caused a significant increase in flag leaf width and panicle branching in most backgrounds. We identified BCF qGN4.1 near-isogenic lines (NILs) with 92.0-98.0% similarity to the respective recipient parent by background analysis using a 50 K rice SNP genotyping chip. Three of the NILs, namely Pusa Basmati 1121- GN4.1, Samba Mahsuri -GN4.1 and Swarna -GN4.1, showed a significant yield superiority to their recipient parents. Analysis of differential gene expression revealed that high grain number in these QTL-NILs was unlikely due to the overexpression of Nal1 gene (LOC_Os04g52479). Instead, another tightly linked gene (LOC_Os04g52590) coding for a protein kinase domain-containing protein was consistently overexpressed in the high grain number NILs. Conclusion: We have successfully introgressed the qGN4.1 QTL for high grain number per panicle into 12 different mega varieties of rice using marker-assisted backcross breeding. The advanced near-isogenic lines are promising for the development of even higher yielding versions of these high-yielding mega varieties of rice. [ABSTRACT FROM AUTHOR]

Most crop models have been developed with crops growing under full sunlight conditions and they commonly use daily cumulated global radiation as part of the climatic input data. This approach neglects the spatio-temporal dimension of the light reduction experienced by the crop in agroforestry systems. In this study, we evaluate the ability of the crop model STICS to predict winter wheat ( Triticum aestivum L.) growth and yield under three distinct light conditions using field observations from a two year artificial shade experiment. The shade structure induced a continuous shade (CS) treatment characterized by a reduction of the proportion of light during the entire day and a periodic shade (PS) treatment defined by an intermittent shade varying on the plot throughout the day. These two shade conditions were compared to a no shade treatment (NS) receiving 100% of the available light. The model accurately predicted the timing of the grain maturity stage under the PS treatment by reducing the daily global radiation only. A correct prediction of this growth stage in the CS treatment required a decrease of the daily maximum air temperature in addition to the reduction of global radiation. Overall, the model accurately reproduces the total aboveground dry matter dynamics under the CS and NS treatments, but did not simulate the reduction observed under the PS treatment correctly. Three parameters ( nbjgrain , cgrain and cgrain vo ) involved in the determination of the number of grains have been calibrated with the NS treatment data and were then used to predict the crop behavior under the shaded treatments. Using this adjusted parameter set, the STICS model gave a good prediction of the grain number under all treatments. Nevertheless, the simulation of final grain yield under the shade treatments was not satisfactory yet, presumably due to an overestimation of the reallocation of the biomass between shoots and grains. Improving the prediction of these reallocation processes is challenging and critical to improve the simulation of crop behavior under fluctuating light environments such as encountered in agroforestry systems. [ABSTRACT FROM AUTHOR]

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Grain weight (GW) is an important component of grain yield and quality of sunflower and the improvement of this trait has been proposed as an aim for breeding of this crop. There is strong evidence suggesting the pre-flowering period as key to determining GW in different crops; however, the key traits and mechanisms controlling GW during this phase are still largely unknown in sunflower. This study conducted a detailed survey of how the pre-flowering period determines grain growth dynamics by assessing the early developmental process during the growth of reproductive organs and the sensitivity of GW, grain number (GN) and grain oil concentration to different source–sink manipulations immediately before flowering. Two experiments were carried out under field conditions in two growing seasons. In Exp. 1 two sunflower oilseed hybrids contrasting in GW (Alybro and SG) were sown at the Experimental Station of the Universidad Austral de Chile in Valdivia (39°47′S, 73°14′W), Chile. In Exp. 2, the same hybrids plus a confectionery genotype (RHA) were evaluated in the Experimental Station where two source–sink treatments were performed: a control (without manipulation) and a shading treatment starting 16 days previous to anthesis, i.e. during the R2-R5 period. Crop development, average and individual GW, GN and oil concentration of grains were assessed at harvest. Also, flower and grain traits and their dynamics were measured from early reproductive stage (ovary at R3) to harvest in different grain positions from the capitulum (e.g., fresh and dry weight and dimensions of grains, pericarp and embryo and grain oil concentration). GW was significantly affected by genotype and shading treatments imposed at pre-anthesis, but no statistical effect of the lower source–sink ratio was found on GN. Contrary to GW, grain oil of oilseed genotypes was highly conservative under the source–sink reduction in our study. Positive associations were found between final GW and: ovary weight at R3, at anthesis (R5), ovary growth rate, grain dimensions and water content. Final GW also showed a linear association with ovary growth rate. This study is the first to evaluate the ovary weight from the early development stage and the ovary growth rate during the pre-anthesis period in sunflower and the effect of source reduction at pre-anthesis on grain oil concentration, supporting the importance of the maternal tissues on the setting of potential and actual GW in sunflower. [ABSTRACT FROM AUTHOR]

Background: Rice plays an extremely important role in food safety because it feeds more than half of the world's population. Rice grain yield depends on biomass and the harvest index. An important strategy to break through the rice grain yield ceiling is to increase the biological yield. Therefore, genes associated with organ size are important targets for rice breeding. Results: We characterized a rice mutant gns4 ( grain number and size on chromosome 4) with reduced organ size, fewer grains per panicle, and smaller grains compared with those of WT. Map-based cloning indicated that the GNS4 gene, encoding a cytochrome P450 protein, is a novel allele of DWARF11 ( D11). A single nucleotide polymorphism (deletion) in the promoter region of GNS4 reduced its expression level in the mutant, leading to reduced grain number and smaller grains. Morphological and cellular analyses suggested that GNS4 positively regulates grain size by promoting cell elongation. Overexpression of GNS4 significantly increased organ size, 1000-grain weight, and panicle size, and subsequently enhanced grain yields in both the Nipponbare and Wuyunjing7 (a high-yielding cultivar) backgrounds. These results suggest that GNS4 is key target gene with possible applications in rice yield breeding. Conclusion: GNS4 was identified as a positive regulator of grain number and grain size in rice. Increasing the expression level of this gene in a high-yielding rice variety enhanced grain yield. GNS4 can be targeted in breeding programs to increase yields. [ABSTRACT FROM AUTHOR]

The ratio of spike to stem measured at anthesis (spike:stem ratio) could be considered as a promising trait in physiological studies and breeding programs of wheat. This study was performed to investigate the genotypic variations for spike:stem ratio among Iranian wheat cultivars, and to study the possible associations between this trait and the phenological and agronomical characteristics. Eighty-one wheat cultivars released between 1930 and 2006 were examined in 2010-2011 with normal sowing conditions and in 2013-2014 with late sowing conditions. Considerable variations were found for spike:stem ratio among wheat cultivars. Spike:stem ratio was, on average, 0.60 and 0.97 in 2010-2011 and 2013-2014 growing seasons, respectively. Linear regression analysis of spike:stem ratio against the year of cultivar release indicated that this trait significantly increased from old to modern cultivars. Improvements in spike:stem ratio were 0.002 and 0.005 per year during 2010-2011 and 2013-2014, respectively. Generally, spike:stem ratio correlated negatively with thermal time (TT) from sowing to anthesis. No clear relationship was found between spike:stem ratio and TT from jointing to anthesis. Spike:stem ratio correlated positively and significantly with grain number obtained either from square meter or from main stem spike. [ABSTRACT FROM AUTHOR]

Background: Both grain size and grain number are significant for rice yield. In the past decade, a number of genes related to grain size and grain number have been documented, however, the regulatory mechanisms underlying them remains ambiguous. Results: We identified a rice small grain ( sg2) mutant in an EMS mutant library generated from an indica variety, Shuhui498. Using the MutMap gene mapping strategy, we identified two linkage regions on chromosome 7 and 8, respectively, consistent with the segregation ratios in the F population. We focused on the linkage region on chromosome 8, and named this locus as 08sg2. One of three SNPs identified in the linkage region was located in an exon of OsBAK1, leading to a nonsynonymous mutation in the kinase domain. The plant harboring the mutant version 08sg2 locus exhibited a decreased grain size, grain number and plant height. Cytological analysis indicated that 08SG2 regulated spikelet hull development by affecting cell proliferation. The grain size and number of knockout mutants of OsBAK1 in the japonica background were significantly decreased, but less so than in 08sg2, supporting the idea that the SNP in OsBAK1 was responsible for the 08sg2 phenotype, but that 08SG2/OsBAK1 function differently in indica and japonica backgrounds. 08sg2 was insensitive to 24-epiBL, and the expression of BR-related genes was obviously altered in 08sg2. The proportionally decreased grain length when 08sg2 and GS3 were combined indicate that 08SG2 and GS3 regulate grain length independently. Conclusions: Our work shows that 08SG2/OsBAK1 is important for rice yield in both indica and japonica backgrounds, by regulating grain size and grain number, and the function of 08SG2/OsBAK1 is obviously affected by genetic background. The amino acid substituted in 08sg2 is highly conserved among different species, supporting the idea that it is important for the molecular function of 08SG2/OsBAK1. Together, our work is helpful for fully understanding the function of 08SG2/OsBAK1. [ABSTRACT FROM AUTHOR]

Quinoa high nutritive value increases interest worldwide, especially as a crop that could potentially feature in different cropping systems, however, climate change, particularly rising temperatures, challenges this and other crop species. Currently, only limited knowledge exists regarding the grain yield and other key traits response to higher temperatures of this crop, especially to increased night temperatures. In this context, the main objective of this study was to evaluate the effect of increased night temperature on quinoa yield, grain number, individual grain weight and processes involved in crop growth under the environmental conditions (control treatment) and night thermal increase at two phases: flowering (T1) and grain filling (T2) in southern Chile. A commercial genotype, Regalona, and a quinoa accession (Cod. BO5, N°191, grain bank from Semillas Baer, hereby referred to as Accession) were used, due to their adaptability to Southern Chilean conditions and contrasting grain yield potential, grain weight and size of plants. Temperature was increased ≈4°C above the ambient from 8 pm until 9 am the next morning. Control treatments reached a high grain yield (600 and 397 g m-2, i.e., Regalona and Accession). Temperature increase reduced grain yield by 31% under T1 treatment and 12% when under T2 in Regalona and 23 and 26% in Accession, respectively. Aboveground biomass was negatively affected by the thermal treatments and a positive linear association was found between grain yield and aboveground biomass across treatments. By contrast, the harvest index was unaffected either by genotype, or by thermal treatments. Grain number was significantly affected between treatments and this key trait was linearly associated with grain yield. On the other hand, grain weight showed a narrow range of variation across treatments. Additionally, leaf area index was not affected, but significant differences were found in SPAD values at the end of T1 treatment, compared to control. Little change was found in the harvest index, individual grain weight, grain protein content or water soluble carbohydrates in response to the increased night temperature in this crop. [ABSTRACT FROM AUTHOR]

The impact of different allelic combinations of VERNALIZATION1 (VRN1) and PHOTOPERIOD1 (PPD1) on the development of reproductive structures, spike dry weight (SDW) and its links to the duration of stem elongation (SE) and yield components was assessed using Near Isogenic Lines (NILs) of the cultivar Sunstate for both genes. Emphasis was on observations on the main shoot and tillers, linking to plant and canopy level in Steinfort at al. (2016). Experiments under controlled and irrigated field conditions relevant to the northern wheat growing region of Australia were designed. In vernalised plants, the number of fertile florets in the main shoot spike was positively related to the number of fertile spikelets, the duration of SE, the SDW at anthesis and the sum of the radiation intercepted during SE, while no associations were found under non vernalised and slow vernalising field conditions. Vernalised plants also produced more grains in the average tiller spike, compared to non vernalised plants, particularly under short days. Both main shoot and tiller grain number per spike contributed to the higher grain number per plant observed in vernalised plants in Steinfort et al. (2016), as spike number was similar. In the field, higher yield of lines with spring alleles of VRN1 was underpinned by longer spikes, with fewer spikelets but more fertile florets per spikelet in the main shoot spike, and more grains per tiller. When non vernalised, winter lines had an apex that grew slower, shorter spikes and higher spikelet density compared to the other genotypes. The utilisation of sensitivity to VRN1 or PPD1 to increase the duration of the SE and the number of fertile florets and grains is a more complex process than originally proposed. [ABSTRACT FROM AUTHOR]

The use of physiological traits for indirect selection may help to increase wheat yield potential. Fruiting efficiency (FE, grain number per unit of spike dry weight at anthesis −SDWa-) may be an alternative to increase grain number per unit area (GN), but the possible cross-over genotype (G) × environment (E) interaction and trade-off with SDWa and grain weight (GW) may limit its usefulness. The present paper aimed to determine (i) the degree of G × E interaction of FE at plot, main stem and tiller levels, (ii) the relationship between GN and FE, and (iii) the possible trade-off between FE and (a) SDWa, and (b) GW. Three FE contrasting genotypes (B11 and B19 – high FE, and B2002 – low FE) were grown under different Nitrogen (N) availability at sowing [(i) low – Ni: ca. 50 kg N ha −1 ; (ii) middle −130 kg N ha −1 and (iii) high −200 kg N ha −1 ). Two other treatments were applied within the 200N: (iv) late sowing, i.e. delaying sowing 30 days in relation to optimum date (200N + LS) and (v) shading the canopy during stem elongation (200N + SH). The FE showed G × E interaction (year × genotype and genotype × treatment) but it only explained 13.4% of its variation. The environment (year) had similar impact than the genotype, explaining both ca. 38% of FE variation (19% each). The FE of tiller spikes was higher than that of main stem spikes, but the difference among cultivars was maintained. Thus, canopies of the same genotype with different proportion of main stem and tiller spikes may present different FE value at plot level. Nevertheless, a high correlation (r = 0.82, p < 0.0001) and a close 1:1 relationship was observed between FE at plot level and FE in main stems, for all treatments and cultivars, suggesting that sampling the main stem spikes represents the FE at plot level in dense canopies. A G × E cross-over interaction was observed when the sowing was delayed one month (200N + LS) from the optimum date because B19 reached anthesis later than B2002, exploring higher heat stress index (°Ch > 27 °C) around anthesis, which reduced FE. The correlation of GN with FE was high and significant (r = 0.74, p < 0.00001) for all treatments and for a wide range of SDWa values (from 90 to 188 g m −2 ). The B19, selected as a high FE genotype, showed higher GN than B2002 (selected as a low FE genotype) under all treatments, while B11 (also of high FE) showed similar or higher GN than B2002, depending on treatment. Thus, despite the G × E interaction, the genotypes with higher FE had more GN under a wide range of environments. Nevertheless, the SDWa and GW were negatively correlated with FE (for SDWa r = −0.73 p < 0.005, without considering 200N + SH; and for GW r = −0.48 p < 0.01 for all treatments or r = −0.75 p < 0.08 for genotypes only). Then, special attention should be given to SDWa and GW when selecting for higher FE in a breeding program. [ABSTRACT FROM AUTHOR]

Genetic variation in the VERNALIZATION1 ( VRN1 ) and PHOTOPERIOD1 ( PPD1 ) genes, which control the vernalisation and photoperiod response, underpin wheat adaptation to different environments. Near isogenic lines were used to investigate the role of allelic combinations of VRN1 and PPD-D1, including new alleles for VRN1-A1, on the length of developmental phases, dynamics of leaf and tiller appearance and yield components in complementary irrigated field trials relevant to low latitude wheat growing areas and controlled conditions. Allelic differences in VRN1 had a stronger effect on the duration of the vegetative phase, while photoperiod sensitivity at PPD-D1 lengthened the stem elongation phase (SE) by up to 23%. If a phase was lengthened, flowering was delayed. The level of response to daylength during stem elongation (SE) introduced by photoperiod sensitive alleles was dependent on the VRN1 composition and vernalisation status. A longer SE under short days was achieved by PPD1 sensitive genotypes when one VRN1 spring allele was present and plants were vernalised. The duration of SE was weakly related to spike dry weight m −2 at DC65 in the field but did not translate into higher grain number m −2 . In the field, lines with two to three VRN1 spring alleles had shortest development phases, including SE, close flowering dates, sampled similar temperature environments at different stages, and achieved high yields. Yield advantage was explained by higher biomass, harvest index, grain number m −2 and thousand kernel weight. Genotypes with three winter VRN1 alleles were comparatively disadvantaged, with a longer vegetative phase placing SE under higher temperatures. Allelic differences in both genes caused large variation in leaf and tiller number generation but also in tiller mortality and individual leaf size, lessening the impact on leaf area. Changes in plant morphology and yield components that did not seem mediated via the influence of development genes on the duration of different stages and their impact on resource capture deserve further investigation. [ABSTRACT FROM AUTHOR]

Grain number is an important factor in determining grain production of rice (Oryza sativa L.). The molecular genetic basis for grain number is complex. Discovering new genes involved in regulating rice grain number increases our knowledge regarding its molecular mechanisms and aids breeding programs. Here, we identified GRAINS NUMBER 2 (GN2), a novel gene that is responsible for rice grain number, from "Yuanjiang" common wild rice (O. rufipogon Griff.). Transgenic plants overexpressing GN2 showed less grain number, reduced plant height, and later heading date than control plants. Interestingly, GN2 arose through the insertion of a 1094-bp sequence from LOC_Os02g45150 into the third exon of LOC_Os02g56630, and the inserted sequence recruited its nearby sequence to generate the chimeric GN2. The gene structure and expression pattern of GN2 were distinct from those of LOC_Os02g45150 and LOC_Os02g56630. Sequence analysis showed that GN2 may be generated in the natural population of Yuanjiang common wild rice. In this study, we identified a novel functional chimeric gene and also provided information regarding the molecular mechanisms regulating rice grain number. [ABSTRACT FROM AUTHOR]

The genetic heritage of wheat (Triticum spp.) crops has been shaped by millions of years of predomestication natural selection, often driven by competition among individuals. However, genetic improvements in yield potential are thought to involve selection towards reduced competitiveness, thus enhancing adaptation to the crop environment. We investigated potential trade-offs between individual plant fitness and community performance using a population of introgression lines carrying chromosome segments of wild emmer (nondomesticated) in the background of an elite durum cultivar. We focused on light as a primary factor affecting plant-plant interactions and assessed morphological and biomass phenotypes of single plants grown in mixtures under sunlight and a simulated canopy shade, and the relevance of these phenotypes for the monoculture community in the field. We found that responses to canopy shade resemble responses to high density and contribute to both the individual and the community. Stepwise regressions suggested that grain number per spike and its persistence under shade are essential attributes of productive communities, advocating their use as a breeding target during early-generation selection. Overall, multiple phenotypes attained under shade could better explain community performance. Our novel, applicable, high-throughput set-up provides new prospects for studying and selecting single-plant phenotypes in a canopy-like environment., (© 2022 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.)

Background: Large-scale genotype-phenotype association studies of crop germplasm are important for identifying alleles associated with favorable traits. The limited number of single-nucleotide polymorphisms (SNPs) in most wheat genome-wide association studies (GWASs) restricts their power to detect marker-trait associations. Additionally, only a few genes regulating grain number per spikelet have been reported due to sensitivity of this trait to variable environments., Results: We perform a large-scale GWAS using approximately 40 million filtered SNPs for 27 spike morphology traits. We detect 132,086 significant marker-trait associations and the associated SNP markers are located within 590 associated peaks. We detect additional and stronger peaks by dividing spike morphology into sub-traits relative to GWAS results of spike morphology traits. We propose that the genetic dissection of spike morphology is a powerful strategy to detect signals for grain yield traits in wheat. The GWAS results reveal that TaSPL17 positively controls grain size and number by regulating spikelet and floret meristem development, which in turn leads to enhanced grain yield per plant. The haplotypes at TaSPL17 indicate geographical differentiation, domestication effects, and breeding selection., Conclusion: Our study provides valuable resources for genetic improvement of spike morphology and a fast-forward genetic solution for candidate gene detection and cloning in wheat., (© 2023. BioMed Central Ltd., part of Springer Nature.)

The cytochrome P450 (CYP450) gene family plays a critical role in plant growth and developmental processes, nutrition, and detoxification of xenobiotics in plants. In the present research, a comprehensive set of 105 OsCYP71 family genes was pinpointed within the genome of indica rice. These genes were categorized into twelve distinct subfamilies, where members within the same subgroup exhibited comparable gene structures and conserved motifs. In addition, 105 OsCYP71 genes were distributed across 11 chromosomes, and 36 pairs of OsCYP71 involved in gene duplication events. Within the promoter region of OsCYP71 , there exists an extensive array of cis-elements that are associated with light responsiveness, hormonal regulation, and stress-related signaling. Further, transcriptome profiling revealed that a majority of the genes exhibited responsiveness to hormones and were activated across diverse tissues and developmental stages in rice. The OsCYP71P6 gene is involved in insect resistance, senescence, and yield-related traits in rice. Hence, understanding the association between OsCYP71P6 genetic variants and yield-related traits in rice varieties could provide novel insights for rice improvement. Through the utilization of linear regression models, a total of eight promoters were identified, and a specific gene variant (Ser33Leu) within OsCYP71P6 was found to be linked to spikelet fertility. Additionally, different alleles of the OsCYP71P6 gene identified through in/dels polymorphism in 131 rice varieties were validated for their allelic effects on yield-related traits. Furthermore, the single-plant yield, spikelet number, panicle length, panicle weight, and unfilled grain per panicle for the OsCYP71P6- 1 promoter insertion variant were found to contribute 20.19%, 13.65%, 5.637%, 8.79%, and 36.86% more than the deletion variant, respectively. These findings establish a robust groundwork for delving deeper into the functions of OsCYP71 -family genes across a range of biological processes. Moreover, these findings provide evidence that allelic variation in the promoter and amino acid substitution of Ser33Leu in the OsCYP71P6 gene could potentially impact traits related to rice yield. Therefore, the identified promoter variants in the OsCYP71P6 gene could be harnessed to amplify rice yields.

Background: Grain count is crucial to wheat yield composition and estimating yield parameters. However, traditional manual counting methods are time-consuming and labor-intensive. This study developed an advanced deep learning technique for the segmentation counting model of wheat grains. This model has been rigorously tested on three distinct wheat varieties: 'Bainong 307', 'Xinmai 26', and 'Jimai 336', and it has achieved unprecedented predictive counting accuracy., Method: The images of wheat ears were taken with a smartphone at the late stage of wheat grain filling. We used image processing technology to preprocess and normalize the images to 480*480 pixels. A CBAM-HRNet wheat grain segmentation counting deep learning model based on the Convolutional Block Attention Module (CBAM) was constructed by combining deep learning, migration learning, and attention mechanism. Image processing algorithms and wheat grain texture features were used to build a grain counting and predictive counting model for wheat grains., Results: The CBAM-HRNet model using the CBAM was the best for wheat grain segmentation. Its segmentation accuracy of 92.04%, the mean Intersection over Union (mIoU) of 85.21%, the category mean pixel accuracy (mPA) of 91.16%, and the recall rate of 91.16% demonstrate superior robustness compared to other models such as HRNet, PSPNet, DeeplabV3+ , and U-Net. Method I for spike count, which calculates twice the number of grains on one side of the spike to determine the total number of grains, demonstrates a coefficient of determination R 2 of 0.85, a mean absolute error (MAE) of 1.53, and a mean relative error (MRE) of 2.91. In contrast, Method II for spike count involves summing the number of grains on both sides to determine the total number of grains, demonstrating a coefficient of determination R 2 of 0.92, an MAE) of 1.15, and an MRE) of 2.09%., Conclusions: Image segmentation algorithm of the CBAM-HRNet wheat spike grain is a powerful solution that uses the CBAM to segment wheat spike grains and obtain richer semantic information. This model can effectively address the challenges of small target image segmentation and under-fitting problems in training. Additionally, the spike grain counting model can quickly and accurately predict the grain count of wheat, providing algorithmic support for efficient and intelligent wheat yield estimation., (© 2023. The Author(s).)

The effects of irrigation regimes (full irrigation and water-withholding at anthesis) and post-anthesis nitrogen supplies (LN: 0, MN: 20 and HN: 40 kg N/ha) on grain yield and its components in winter wheat were studied, with attention to biomass gain by assimilation and its loss by respiration. Fully-irrigated wheat responded to N fertilization with increased grain number (GN) and decreased grain weight (GW) and achieved similar grain yields (5.2 to 5.5 t/ha) at different N supplies. However, drought-stressed wheat responded to N with higher GN without significant changes in GW, and achieved higher grain yields (2.7 vs. 3.3 t/ha) with HN compared to LN. Net assimilation rates during grain filling (NARg) increased with increasing post-anthesis N fertilization for drought-stressed wheat (NARg: 3.8 and 4.5 g/m/day for LN and HN). Apparent whole-plant respiration (RA) was not influenced by increased post-anthesis N fertilizer. Thus, in drought-stressed wheat, the total biomass and straw yield at maturity were increased by increasing N supply. These results suggest that high N supply at anthesis satisfied the grains' increased demand for N by increasing post-floral assimilation, and the surplus assimilates not only compensated for the low-N-induced biomass loss by respiration but may also have increased the

To understand the mechanisms causing yield limitations in defoliated plants subjected to water deficiency, the experiments were laid out as a randomized complete block design with split-plot arrangement. Soil-water regimes consisted of moderate irrigation until physiological maturity (W1) or short severe water stress periods (W2) at V8 stage of ontogenesis, and tasseling which allotted to the main plots. Defoliation times (V8 and tasseling) and intensities (cutting of one or two thirds of leaf blade) combinations and one control level (five Source restriction treatments) were allotted to subplots. Early defoliation caused reduction in grain yield at W1 and W2 by 19.2 and 14.8%, respectively. On the other hand, water deficiency reduced grain per ear by 23.9% and increased individual grain weight by 37.0% (plasticity of sink capacity). These results show that under water deficiency, grain yield limitation was mostly due to a reduction in dry matter allocation to grains (sink capacity) than a result of lower dry matter production (source strength). Findings suggest that in non-irrigated corn, breeders must direct their selection program to increase grain set and decrease surplus leaves.