Genetic Gain In Yield Research Articles

Genetic gain in yield of Australian faba bean since 1980 and associated shifts in the phenotype: Growth, partitioning, phenology, and resistance to lodging and disease

ContextFeeding a growing human population with limited arable land requires greater crop yield that is, in turn, driven by improved agronomy, better varieties, and their synergy. Here we focus on faba bean, Vicia faba L., an under-researched grain legume for which on-farm yield in Australia has increased at 0.8 % y−1 since 1990. ObjectiveWe aimed to quantify genetic gain in seed yield of Australian faba bean varieties released since 1980, and to identify associated shifts in physiological and agronomic traits. MethodsWe combined three studies: the complete historical collection of Australian faba bean varieties was grown in 1) a vintage experiment of three field trials; and 2) a pot experiment inoculated with old and new strains of Ascochyta fabae. Since most varieties were grown in a national network of trials, we 3) estimated genetic gain in seed yield and individual seed weight in 129 environments. ResultsIn the vintage experiment, genetic gain in seed yield varied from 0.4 % y−1 to almost zero; low rates of genetic gain were also apparent in the national network of trials. Biomass, harvest index, and crop growth rate in the critical period had low rates of genetic change, and there were strong trade-offs between yield components and in their responses to selection. Breeding increased seed size at 0.5 % y−1. Visual lodging scores decreased at 4.9 % y−1. There was breakdown in resistance to Ascochyta blight, but it was restored in new varieties. ConclusionsAustralian faba bean breeding contributed to on-farm yield and profitability through improved agronomic traits and seed quality. Low genetic gain in yield can be partially attributed to physiological trade-offs between traits, economic trade-offs between multiple breeding targets, and genotype-by-environment interaction. ImplicationUnder-researched crops require greater investment to match the genetic gain in yield of major crops.

Advancements in Genetic Enhancement: CRISPR/Cas-Mediated Genome Editing in Leguminous Crops

Legumes play a crucial role in human nutrition and sustainable agriculture due to their high protein content and health-promoting phytochemicals. To accelerate genetic gain in yield, stress resilience, and nutritional quality, extensive efforts are underway. Recent advancements in genomic resources have paved the way for the application of cutting-edge breeding technologies like genomic selection and genome editing in legume crops. This review focuses on the latest advancements in CRISPR/Cas9-based gene editing technology, specifically tailored for improving traits in legume crops. While successful gene-editing methods have been established for crops like soybean, cowpea, and chickpea, challenges remain, particularly in overcoming the recalcitrance of certain legumes to gene transfer and regeneration in vitro. Strategies to enhance transformation and regeneration rates through modifications in culture methods and DNA delivery are discussed. Despite the potential benefits of gene editing in legume breeding, regulatory barriers pose significant challenges. A comparison of regulatory environments in different regions sheds light on the importance of favourable regulations and public acceptance for realizing CRISPR's potential in enhancing global food security. Additionally, leguminous crops are vital for their nutritional properties, nitrogen-fixing abilities, and contribution to sustainable agriculture. Traditional breeding methods focused on increasing yield, while recent advancements in genome editing techniques, notably CRISPR-Cas technology, have revolutionized the improvement of agronomic traits in legumes. This chapter provides insights into the application of genome editing tools for enhancing traits such as stress tolerance, yield, and seed content in grain legumes. Furthermore, it discusses the challenges and prospects associated with enhancing grain legumes using molecular breeding techniques. Genome editing has been successfully employed in diverse legumes, including model species like Medicago and widely cultivated crops such as soybean and chickpea, offering exciting opportunities for enhancing agronomic characteristics.

Assessment of Efficiency of Breeding Methods in Accelerating Genetic Gain in Rice

The pedigree, bulk, and single-seed descent-based rapid generation advance methods are commonly practiced breeding methods in rice. But the efficiency of these breeding methods in enhancing genetic gain has not been investigated yet. In this study, we compared the pedigree and bulk method-derived breeding lines of five crosses with RGA-derived lines. The RGA method was found to be almost two times more efficient in capturing high-yielding lines with a high breeding value and thus accelerated genetic gain much more than the bulk and pedigree methods. The RGA method is not only more efficient but also significantly cheaper (~24%) compared to pedigree methods. The cost per kilogram of genetic gain in yield for the RGA lines is almost 3 times lower than the bulk method and 4.5 times lower than the pedigree method, and it can be achieved in half the time required for line development with either the bulk or pedigree method.

Insights into progress of wheat breeding in arid and infertile areas of China in the last 14 years

Contextor problem: Wheat (Triticum aestivum L.) is a major cereal crop driving food security, but its production is hampered by drought and low soil fertility, which are worsening due to climate change. Understanding genetic gain and its closely related traits of wheat varieties in arid areas will provide a meaningful reference for optimizing breeding strategies. ObjectivesThis study aims to evaluate the genetic yield gain of wheat breeding materials based on robust data from National Wheat Regional Trials in arid and infertile areas of China over the past 14 years, and screened agronomic traits that contributed to grain yield (GY) increase. MethodsThe trials were conducted at 17 sites in five provinces with Jinmai 47 as the check variety. The temporal variation trends of GY were assessed by regression analysis using the GY of Jinmai 47 as the covariate. The analysis of Pearson's correlation, path coefficient, and principal component were performed to investigate the association between GY and agronomic traits. ResultsAverage GY of advanced lines (ALs) and certified varieties (CVs) were 4377.3 kg ha−1 and 4647.7 kg ha−1, respectively and the breeding-driven yield gains of ALs and CVs were estimated as 28.2 kg ha−1 year−1 and 17.8 kg ha−1 year−1, accounting for 36.1% and 28.3% of the total observed yield gain, respectively. The effective spike number (ESN) and plant height (PH) are important causal traits leading to yield differences among ALs, and have pyramiding effect on GY. Remarkably, modern breeding practices have conducted positive selection for ESN and negative selection for PH. The yield stability of ALs exhibited an increasing trend, implying that genetic variations favorable for yield potential and adaptability could be pyramided by breeding. Moreover, Jinmai 47 has maintained its advantage in terms of yield stability, ranking in the top three of all ALs in nine years of trials. ConclusionsIn arid and infertile areas of China during 2007–2020, approximately one-third of wheat yield gains rely on genetic yield potential improvement, and ESN and PH were the key traits confer yield gap among ALs. Jinmai 47 is an excellent germplasm resource with high and stable yield that may provide essential gene pool for wheat improvement. Implications or signifcanceThis study reveals the current wheat breeding situation in terms of yield and agronomic traits in the arid and infertile areas of China, and provides valuable information for the development and deployment of new-generation wheat varieties.

Genetic Variability for Micronutrient Content and Tuber Yield Traits among Biofortified Potato (Solanum tuberosum L.) Clones in Ethiopia.

Malnutrition is one of the global issues of public health concern, and iron and zinc deficiencies are at the top of the list. Iron deficiency affects more than 2 billion people in the world and is a major cause of anemia. Potato has the potential to be an important source of iron and zinc. This study assessed the nature and magnitude of genetic variability in Fe and Zn concentrations, tuber yield, and quality traits among biofortified tetraploid potato clones and their relationships through correlation and path analysis. A total of 45 potato genotypes, including the variety Gudanie, were grown in field trials in a 9 × 5 alpha lattice design with three replications. Significant differences in mineral, tuber quality, and yield traits were observed among the genotypes, and high broad-sense heritability was obtained for most traits, suggesting that progress through breeding can be achieved. However, negative correlations and direct effects on most of the traits with Fe and Zn contents are found both at genotypic and phenotypic levels. Therefore, attaining simultaneous genetic gain for yield and enhanced Fe and Zn concentrations will be challenging. Cluster analysis assembled them into five groups. Cluster II contained the most prominent genotypes, having better mean values compared to all other genotypes for micronutrient traits, viz., Fe (23.80 mg kg-1) and Zn (17.07 mg kg-1). The results of this study confirm the presence of sufficient genetic variation for iron and zinc mineral concentration and the possibility to make significant progress through breeding.

Genomic versus phenotypic selection to improve corn borer resistance and grain yield in maize.

The study of yield and resistance/tolerance to pest are related traits fundamental for maize breeding programs. Genomic selection (GS), which uses all marker information to calculate genomic breeding values, is presented as an emerging alternative to phenotypic and marker-assisted selections for improving complex traits controlled by many genes with small effects. Therefore, although phenotypic selection (PS) has been effective for increasing resistance and yield under high infestation with maize stem borers, higher genetic gains are expected to be obtained through GS based on the complex architecture of both traits. Our objective was to test whether GS is more effective than PS for improving resistance and/or tolerance to maize stem borers and grain yield. For this, we compared different selection programs based on phenotype and genotypic value for a single trait, resistance or yield, and for both traits together. We obtained that GS achieved the highest genetic gain for yield, meanwhile phenotypic selection for yield was the program that achieved the highest reduction of tunnel length, but was ineffective for increasing yield. However, phenotypic or genomic selection for increased resistance may be more effective in improving both traits together; although the gains per cycle would be small for both traits.

Retrospective study in U.S. commercial sorghum breeding: II. Physiological changes associated to yield gain

AbstractUnderstanding physiological changes in response to long‐term selection for yield can inform breeding decisions and hasten genetic gain. The objective of this study was to characterize changes over time in yield‐relevant physiological traits for hybrids with different years of release for grain sorghum (Sorghum bicolor L. Moench). Field trials were conducted during the 2018 and 2019 seasons in 8 site‐years across the states of Kansas and Texas including 20 commercially available grain sorghum hybrids released by Pioneer between 1963 and 2017. Detailed yield‐related physiological traits were determined in 2 site‐years including grain yield and its components, grain filling, plant biomass, panicle length, and water‐soluble carbohydrates (WSC) during the reproductive period. Consistent with estimates using historical yield data, sorghum yield improvement was 27 kg ha−1 yr−1. For the 2 site‐years with detailed yield‐related physiological traits, no changes in final grain weight, grain‐filling duration, and rate over time were documented. In contrast, grain number increased at a rate of 100 grains m−2 yr−1. Modern hybrids had larger panicle size and showed greater accumulation of WSC during vegetative period (as measured at the start of flowering) and greater remobilization of WSC during the reproductive period (after flowering) to grain, thus, maintaining grain size on the increased grain number per unit area and harvest index. These findings suggest that WSC dynamics play a critical role on past genetic yield gain in sorghum and its potential for future improvements should be considered.

Identification of Disease Resistance Parents and Genome-Wide Association Mapping of Resistance in Spring Wheat.

The likelihood of success in developing modern cultivars depend on multiple factors, including the identification of suitable parents to initiate new crosses, and characterizations of genomic regions associated with target traits. The objectives of the present study were to (a) determine the best economic weights of four major wheat diseases (leaf spot, common bunt, leaf rust, and stripe rust) and grain yield for multi-trait restrictive linear phenotypic selection index (RLPSI), (b) select the top 10% cultivars and lines (hereafter referred as genotypes) with better resistance to combinations of the four diseases and acceptable grain yield as potential parents, and (c) map genomic regions associated with resistance to each disease using genome-wide association study (GWAS). A diversity panel of 196 spring wheat genotypes was evaluated for their reaction to stripe rust at eight environments, leaf rust at four environments, leaf spot at three environments, common bunt at two environments, and grain yield at five environments. The panel was genotyped with the Wheat 90K SNP array and a few KASP SNPs of which we used 23,342 markers for statistical analyses. The RLPSI analysis performed by restricting the expected genetic gain for yield displayed significant (p < 0.05) differences among the 3125 economic weights. Using the best four economic weights, a subset of 22 of the 196 genotypes were selected as potential parents with resistance to the four diseases and acceptable grain yield. GWAS identified 37 genomic regions, which included 12 for common bunt, 13 for leaf rust, 5 for stripe rust, and 7 for leaf spot. Each genomic region explained from 6.6 to 16.9% and together accounted for 39.4% of the stripe rust, 49.1% of the leaf spot, 94.0% of the leaf rust, and 97.9% of the common bunt phenotypic variance combined across all environments. Results from this study provide valuable information for wheat breeders selecting parental combinations for new crosses to develop improved germplasm with enhanced resistance to the four diseases as well as the physical positions of genomic regions that confer resistance, which facilitates direct comparisons for independent mapping studies in the future.

Assessment of Genetic Variability, Heritability and Genetic Gain for Yield and Quality Traits in Onion (Allium cepa L.)

The experiments were undertaken at ‘C’ Block Farm of Bidhan Chandra Krishi Viswavidyalaya, Kalyani, Nadia, West Bengal, India during 2017–18 and 2018–19 to study the genetic variability, heritability and genetic gain of 23 onion genotypes. Twenty open-pollinated varieties, two hybrid varieties were taken under consideration with one variety taken as standard check. Characters like number of leaves at 30 DAT and 90 DAT, neck thickness, number of scales per bulb, bolters, average weight of 10 bulbs, vitamin C content, dry matter, TSS, phenol content, severity of purple blotch disease, total yield and marketable yield expressed high heritability along with high genetic gain. These traits were least influenced by environmental effect, so, additive genetic effect might be the influential factor for expression of such traits. Traits with such high heritability values gives clear indication that the variability observed was mainly under genetic control and offers ample scope and opportunities to conduct selection based on phenotypic performances for improvement in future onion breeding programme. For traits with moderate heritability viz., double bolters, pyruvic acid, total sugar, storage loss, selection would be less effective in these traits but can still be taken up. Characters plant height at 90 DAT and unmarketable yield, which expressed low heritability are governed by non-additive genes and therefore, hybridization between diverse parents will be the best strategy for their improvement.

A strong negative trade-off between seed number and 100-seed weight stalls genetic yield gains in northern Japanese soybean cultivars in comparison with Midwestern US cultivars

US soybean yields have steadily increased, largely due to genetic factors. In contrast, Japanese yields remain low, partly due to a lack of genetic yield gain, but the yield potential and associated traits in Japanese cultivars have not been fully evaluated. The objectives of the present study were to estimate genetic gains in soybean yield and agronomic traits in Japan, and to determine whether Japanese cultivars are inferior to US cultivars in yield and agronomic traits; if so, which traits should be improved? We conducted a 4-year field trial to compare yield and agronomic traits of cultivars released between 1953 and 2014 in northern Japan and the Midwestern US. Japanese cultivars had lower yield. New US cultivars showed genetic yield gain of 9.86 kg ha –1 year –1 , with the highest contributions from seed number. The increased seed number decreased 100-seed weight, but the increased seed number outweighed that effect, resulting in consistent yield gain. Increased node number contributed most to the increased seed number. Old and new Japanese cultivars showed no significant yield difference. Their yield did not increase over time because 100-seed weight increased but seed number decreased (i.e., there was a strong trade-off). Only 100-seed weight increased in new Japanese cultivars, as this trait is important to Japanese breeders; it determines the processing quality for tofu and the esthetic quality for nimame (boiled beans). We could not confirm a genetic yield gain, but variations in 100-seed weight and seed number contributed similarly to yield in Japanese cultivars. Japanese breeders also focused on improving seed number, but it has been difficult to achieve high yield by simultaneously improving 100-seed weight and seed number. Innovation will be needed to resolve the trade-off between these factors. • Soybean cultivars in northern Japan had lower yield than in the Midwestern US. • Increased seed number contributed strongly to yield gain in recent US cultivars. • There was no evidence of genetic yield gain by recent breeding in Japan. • Recent breeding in Japan increased 100-seed weight but decreased seed number.

Genetic yield gain between 1942 and 2013 and associated changes in phenology, yield components and root traits of Australian barley

Background and AimsBarley breeding has increased yield over the last century, but the associated changes in the phenotype are largely unknown. Our aim was to quantify the rate of genetic gain in a collection of Australian barley cultivars representing seven decades of breeding, and the associated changes in the phenotype.MethodsThirteen barley cultivars were grown in the field at Roseworthy and Mintaro, South Australia, to evaluate shifts in phenology, yield, and its components. A subset of five cultivars was grown under controlled conditions to probe for changes in root traits and nutrient uptake.ResultsGrain yield increased at 16.0 ± 5.3 kg ha−1 yr−1 or 0.43 ± 0.15% yr−1 at Roseworthy, where average yield was 3.1 t ha−1. There was no relation between yield and year of registration at Mintaro, where severe, extended frost disrupted reproduction. Changes in phenology with year of registration were not apparent. The main drivers of yield gain were grain number per m2 and harvest index, with a minor contribution of shoot biomass. Root length density, specific root length, root extension rate, and nutrient uptake per cm of root length increased with year of registration.ConclusionsThe rate of genetic gain of Australian barley aligned with rates reported for other breeding programs worldwide and compared to 21.0 ± 2.3 kg ha−1 yr−1 for actual yield in Australian farms between 1961 and 2019. Changes in the growth and functionality of the root system highlight the indirect effects of selective pressure for yield and agronomic adaptation.

Indirect early generation selection for yield in winter wheat

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

Selection for yield shifted the proportion of oil and protein in favor of low-energy seed fractions in soybean

Owing to the high contents of oil and protein, soybean [Glycine max L. (Merr.)] seeds are energy-rich. Genetic improvement of soybean yield is linked to the dilution in seed protein; changes in low-energy compounds such as carbohydrates have received less attention. We tested the hypothesis that selection for yield in soybean has shifted seed composition in favor of low-energy compounds. We characterized the dynamics of three seed fractions (protein, oil, and residual) during seed filling in seven commercial soybean varieties released between 1980 and 2013 in a two-year field experiment. Genetic gain in yield was linked with reduced seed energy cost: seed protein concentration decreased by 0.06% yr−1, oil remained stable, and the residual fraction increased by 0.09% yr−1. Seed accumulation of the residual fraction revealed a shorter lag phase and a longer effective filling period for the modern relative to the older soybean varieties. Seed energetic requirement significantly decreased − 0.06% yr−1. Resource availability per seed during the seed-filling period was not limiting across all tested varieties. Further research is warranted on the biochemical nature of the residual fraction, and on the implications of seed composition for future breeding, soybean meal and end uses.

Integrated Crop Management Practices Improve Grain Yield and Resource Use Efficiency of Super Hybrid Rice.

Super hybrid rice genotypes have transformed the rate of genetic yield gain primarily due to intersubspecific heterosis, although the physiological basis underpinning this yield transformation has not been well quantified. We assessed the radiation use efficiency (RUE) and nitrogen use efficiency (NUE) of novel hybrid rice genotypes under four management practices representative of rice cropping systems in China. Y-liangyou 900 (YLY900), a new super hybrid rice widely adopted in China, was examined in field experiments conducted in Jingzhou and Suizhou, Hubei Province, China, from 2017 to 2020. Four management practices were conducted: nil fertilizer (CK), conventional farmer practice (FP), optimized cultivation with reduced nitrogen (OPT–N), and optimized cultivation with increased nitrogen (OPT+N). Yield differences across the treatment regimens were significant (p < 0.05). Grain yield of OPT+N in Jingzhou and Suizhou were 11 and 12 t ha–1, which was 14 and 27% greater than yields obtained under OPT–N and FP, respectively. Relative to OPT–N and FP, OPT+N had greater panicle numbers (9 and 18%), spikelets per panicle (7 and 12%), spikelets per unit area (17 and 32%), and total dry weight (9 and 19%). The average RUE of OPT+N was 2.7 g MJ–1, which was 5 and 9% greater than that of OPT–N and FP, respectively, due to higher intercepted photosynthetically active radiation (IPAR). The agronomic efficiency of applied N (AEN) of OPT+N was 17 kg grain kg–1 N, which was 9 and 68% higher than that of OPT–N and FP. These results show that close correlations exist between yield and both the panicles number (R2 = 0.91) and spikelets per panicle (R2 = 0.83) in OPT+N. We conclude that grain yields of OPT+N were associated with greater IPAR, RUE, and total dry matter. We suggest that integrated cropping systems management practices are conducive to higher grain yield and resource use efficiency through expansion of sink potential in super hybrid rice production.

Plant breeding increases spring wheat yield potential in Afghanistan

AbstractWheat (Triticum aestivum L.) is an essential food security crop in Afghanistan. To determine the contribution of wheat breeding to increasing productivity, we analyzed data obtained from 192 trials conducted over 11 locations from 2002–2003 to 2015–2016. Using this data, we estimated annual genetic gains for grain yield, days to heading and plant height over the 14‐yr period. We used best linear unbiased estimates to measure genetic gains across CIMMYT Elite Spring Wheat Yield Trials per se and for the top 5 and top 10% performing genotypes relative to checks. Mean realized genetic gain for grain yield was 115 kg ha–1 yr−1, whereas the top 10 genotypes achieved annual yield gains of 123 kg ha–1. The continually replaced local checks also contributed an annual genetic gain for yield of 107 kg ha–1. The associated adaptive traits days to heading and plant height varied in their response over time with the top 10 yielding genotypes having a 1.82 d annual reduction in heading date while plant height increased by 0.77 cm yr−1 for the same set of genotypes. Results show that continual breeding improvements confer yield gains, contributing to increasing Afghan wheat productivity. This has wider relevance for demonstrating the value of continued investment in public sector plant breeding supporting wheat production and food security in Central Asia.

Genetic Improvement of Post-Heading Root Morphology and Physiology Facilitating Yield Increase of japonica Inbred Rice

Since genetic improvement greatly promoted an increased yield japonica inbred rice in east China after the 1990s, better root characteristics were certainly expected. In 2018 and 2019, nine japonica inbred rice released in the 1990s, 2000s, and 2010s were investigated to evaluate the changes in root morpho-physiology and identify root traits that contributed to the positive yield trends during the genetic process. The 2010’s rice had 8.0 and 4.3% higher grain yield than the 1990’s and the 2000’s rice, respectively (p &lt; 0.05). Genetic yield gain was mainly attributed to the increased spikelets per panicle. Compared with the 1990’s and the 2000’s rice, the 2010’s rice had higher shoot biomass at heading and maturity (p &lt; 0.05), as well as root biomass (p &lt; 0.05), especially for root biomass of 15–30 cm soil depth. Leaf area index (LAI), soil-plant analysis development (SPAD) values, and leaf photosynthetic rate at middle grain-filling period (MGP) and late grain-filling period (LGP) were all increased. The 2010’s rice had consistently higher root length and volume, root oxidation activity, and root bleeding rate at MGP and LGP than the 1990’s and the 2000’s rice (p &lt; 0.05). Positive correlations were detected between root length and volume, root oxidation activity, and root bleeding rate at MGP, LGP, and SPAD values, leaf photosynthetic rate at MGP and LGP, and higher shoot biomass accumulation after heading and grain yield (p &lt; 0.05 or p &lt; 0.01). The present study implied that genetic improvement optimized post-heading root morphology and physiology, which maintained shoot stay-green and facilitated biomass accumulation and yield increase in japonica inbred rice during the genetic process since the 1990s.

Reduced Nitrogen Rate with Increased Planting Density Facilitated Grain Yield and Nitrogen Use Efficiency in Modern Conventional Japonica Rice

The past three decades have seen a pronounced development of conventional japonica rice from the 1990s, although little information is available on changes regarding grain yield and nutrient use efficiency during this process. Nine conventional japonica rice released during the 1990s, 2000s, and 2010s were grown under a reduced nitrogen rate, with increased planting density (RNID) and local cultivation practice (LCP) in 2017 and 2018. The rice from the 2010s had 3.6–5.5% and 7.0–10.1% higher (p &lt; 0.05) grain yield than the 2000s and the 1990s, respectively, under RNID and LCP. The harvest index contributed more to genetic yield gain from the 1990s to the 2000s; whereas from the 2000s to 2010s, yield increase contributed through shoot biomass. Genetic improvement increased total nitrogen (N), phosphorus (P), and potassium (K) accumulation, and their use efficiencies. The rice from the 2010s showed a similar grain yield, whereas the 1990s and 2000s’ rice exhibited a lower (p &lt; 0.05) grain yield under RNID relative to LCP. RNID increased N, P, and K use efficiencies, particularly the N use efficiency for the grain yield (NUEg) of the 2010s’ rice, compared with LCP. For three varietal types, RNID increased the panicles per m2, the filled-grain percentage, and the grain weight (p &lt; 0.05) while decreasing spikelets per panicle of the 2010s’ rice. Compared with LCP, RNID reduced non-structural carbohydrate (NSC) content and shoot biomass, at heading and maturity, while increasing the remobilization of NSC and the harvest index, especially for the 2010s’ rice. Our results suggested the impressive progressive increase in grain yield and nutrient use efficiency of conventional japonica rice since the 1990s in east China. RNID could facilitate grain yield and NUEg for modern conventional japonica rice.

Genetic Gain in Yield and Associated Changes in Agronomic Traits in Wheat Cultivars Developed Between 1900 and 2016 for Irrigated Ecosystems of Northwestern Plain Zone of India.

Knowledge about the yield gain over the years due to associated changes in the yield component traits is essential for a critical understanding of yield-limiting factors. To estimate genetic gain in grain yield (GY) and component agronomic traits of wheat varieties released between 1900 and 2016 for northwestern plain zone (NWPZ) of India and to identify agronomic and/or genetic basis of the realized gains, two sets of wheat varieties comprising mega varieties and two recently developed varieties were evaluated under timely sown, tilled, and early sown conservation agriculture (CA) conditions for four consecutive years under irrigated conditions. The average annual genetic gain in GY since 1,905 under timely sown irrigated conditions was found to be 0.544% yr−1 over the average of all varieties and 0.822% yr−1 (24.27 kg ha−1 yr−1) over the first released variety, NP4. The realized mean yield increased from 2,950 kg ha−1 of the variety NP4 released in 1,905–5,649 kg ha−1 of HD3086 released in 2014. Regression analysis revealed a linear reduction in height and peduncle length (PL) over the years with a simultaneous and linear increase in biomass at the rate of 43.9 kg ha−1 yr−1 or relatively at 0.368% yr−1 mainly because of delayed heading and increased crop duration. Regression analysis showed no linear trend for tiller number and thousand-grain weight (TGW). Though harvest index (HI) was found to linearly increase relatively at the rate of 0.198% per annum, polynomial regression improved the fitness of data with the indication of no increase in HI since 1982. Interestingly, genetic gain evaluation under early sown CA conditions for 4 years showed similar relative gain (RG) [a relative improvement in varieties across breeding periods (BP)] (0.544% yr−1) but with a higher absolute value (29.28 kg ha−1 yr−1). Major mega varieties like Kalyan Sona, HD2009, PBW 343, HD2967, and HD3086, which occupied a comparatively larger area, were found highly plastic to the improvements in the production environment under timely sown conditions.

Historical Trends in Sweet Corn Plant Density Tolerance Using Era Hybrids (1930-2010s).

Over the last six decades, steady improvement in plant density tolerance (PDT) has been one of the largest contributors to genetic yield gain in field corn. While recent research indicates that PDT in modern sweet corn hybrids could be exploited to improve yield, historical changes in PDT in sweet corn are unknown. The objectives of this study were to: (a) quantify the extent to which PDT has changed since introduction of hybrid sweet corn and (b) determine the extent to which changes over time in PDT are associated with plant morpho-physiological and ear traits. An era panel was assembled by recreating 15 sugary1 sweet corn hybrids that were widely used at one time in the United States, representing hybrids since the 1930s. Era hybrids were evaluated in field experiments in a randomized complete block design with a split-plot arrangement of treatments, including hybrid as the main factor and density as the split-plot factor. Plant density treatments included “Low” plant density (9,900 plants/ha) free of crowding stress or “High” plant density (79,000 plants/ha) with crowding stress. On average, per-area marketable ear mass (Mt/ha) increased at a rate of 0.8 Mt/ha/decade at High densities, whereas per-plant yield (i.e., kg/plant) remained unchanged over time regardless of the density level. Crate yield, a fresh market metric, improved for modern hybrids. However, processing sweet corn yield metrics like fresh kernel mass and recovery (amount of kernel mass contributing to the fresh ear mass) showed modest or no improvement over time, respectively. Modern sweet corn hybrids tend to have fewer tillers and lower fresh shoot biomass, potentially allowing the use of higher plant density; however, plant architecture alone does not accurately predict PDT of individual hybrids.

Genetic progress in grain yield radiation and nitrogen use efficiency of dryland winter wheat in Southwest China since 1965: Progress and prospect for improvements

AbstractInvestigations of critical physiological traits associated with the genetic yield gain in wheat (Triticum aestivum) are essential to determine future crop breeding and management strategies. This study grew 32 cultivars released from 1965 to 2017 for two cropping seasons (a dry year, 2016–2017, and a humid year, 2017–2018) to examine yield potential achieved through efficiencies in canopy light interception, solar energy conversion, harvest index (HI), and nitrogen (N) uptake and utilization. Yield gain for wheat (25.0 ± 1.8 kg ha−1 yr−1) resulted from increases in plant biomass, HI, and N utilization efficiency (NUtE). Modern cultivars with an erect canopy and slender flag‐leaves optimized light interception and could achieve higher biomass yield. The introduction of semi‐dwarf genes (Rht‐8) reduced plant height (0.05 yr−1) and improved HI (0.004 yr−1) and NUtE resulting from both increased pre‐anthesis accumulated biomass and plant dry matter mobilization after anthesis. Greater biomass partitioning to spikes resulted in higher fruiting efficiency and grain number. Due to greater tillering capability through increased N uptake efficiency, increased fertile spikes and grain yield were observed. Among these newer cultivars, the rate of yield gain was slow, and yield stability was more affected by accumulative rainfall than diurnal temperature. The future challenge of wheat breeding is to maintain the genetic yield gain without increasing the reliance on chemical fertilizers under an increasingly variable climate.