Response Of Genotypes Research Articles

Response of Bread Wheat Genotypes for Drought and Low Nitrogen Stress Tolerance

Drought stress and nitrogen (N) deficiency are the major causes of yield losses in bread wheat (Triticum aestivum) production. Breeding wheat cultivars with combined drought and low N stress tolerance is an economical approach for yield gains. The objective of this study was to evaluate the response of diverse bread wheat genotypes under drought and low N stress conditions to select high-performing genotypes for developing breeding populations and production to mitigate against drought and low N stress. Fifty bread wheat genotypes were evaluated under drought-stressed (DS) and non-stressed (NS) conditions and N application rates of 50, 100 and 200 kg N ha−1. The experiments were conducted in a controlled environment and field conditions during the 2019/20 cropping season. Data on grain yield and yield components were collected and subjected to statistical analysis. The four-way interaction involving genotype, water regime, N treatments and testing environment had a significant (p < 0.05) effect on all assessed agronomic traits, suggesting that genotype response depended on the treatment combinations. Drought stress and 50 kg N ha−1 reduced grain yield by 20% compared to NS and 50 kg N ha−1. The grain yield ranged from 120 to 337 g/m2, with a mean of 228 g/m2 under DS. Under DS and 200 kg N ha−1, the genotype designated as SBO 19 had a higher grain yield of 337 g/m2, followed by SBO 22 (335 g/m2), SBO 16 (335 g/m2), SBO 04 (335 g/m2) and SBO 33 (335 g/m2). Grain yields under DS and 50 kg N ha−1, and NS and 50 kg N ha−1 had a positive and significant correlation (r > 0.5; p < 0.01) with most of the evaluated traits. Highly correlated traits directly contribute to total yield gain and should be incorporated during the selection of high-yielding genotypes. The study identified the 10 best lines that are high-yielding with early flowering and maturity under DS or NS conditions and the three N treatments. The selected lines are recommended as breeding parents to develop drought-adapted and N-use efficient genetic resources. The identified genotypes are important for sustainable wheat production and effective breeding of improved cultivars to mitigate drought stress and soil nutrient deficiencies, to ensure food security in Sub-Saharan Africa.

Tetrahydrobiopterin responsiveness in Phenylalanine hydroxylase deficient patients from North-east of Iran: Genotype-phenotype correlation, identification of a novel mutation and 7 new responsive genotypes

Phenylalanine hydroxylase enzyme defects result in a hereditary metabolic disorder called phenylketonuria. Sapropterin (tetrahydrobiopterin) is one of the treatment strategies for this disorder. Even though a correlation between genotype and BH4 responsiveness was established by earlier studies, a subset of mutations often presented inconsistent responses and/or phenotypes. Different genetic background is one of the potential reasons for this fact.In this study, the genotype of a total of 34 PAH deficient patients from Khorasan-Razavi providence in the north-east of Iran was obtained. Among this patients, 21 individuals took the 24 h and 48 h BH4 loading test and if the result was positive, their Phenylalanine tolerance was assessed. It is the first study of its type in patients from Iran to evaluate genotype role in predicting the most probable responsive individuals.The known pathogenic variant p.R169P and the novel variant p. Leu72_Asp75delinsTyr were first classified as responsive.Seven genotypes were reported as responsive for the first time. All patients carrying at least one pathogenic variant, which was previously reported as BH4 responsive, respond to BH4. Three patients with p.L48S, p.R261Q and p.A309V pathogenic variants were exceptions. There was no certain statistical correlation between genotype and response. Genotype and phenotype were significantly correlated and majority of patients with mild phenotype carried at least one non-null pathogenic variant.In Khorasan-Razavi province of Iran, patients with at least one non-null mutation are most probable to demonstrate mild phenotype and respond to BH4 phenotype.

Assessment of Promising Diverse Germplasm Accessions for Stability with Respect to Yield and Its Attributing Traits in Vegetable Amaranth

Vegetable amaranth is one of the popular leafy vegetable that occupies a prominent place in India owing to its high nutritive value and fast growing ability. The presence of considerable genetic variability in the amaranth along with very high phenotypic plasticity demands the development of stable genotypes to secure sustainable production. The present research was carried out to quantify the effect of genotype x environment interaction on the performance of 30 identified promising genotypes of vegetable amaranth. The experiment was laid out in the Randomized Complete Block Design with three replications at three locations viz., Arabhavi, Dharwad and Bagalkot during kharif 2018-19. Stability analysis was done as per the linear regression model described by Eberhart and Russell [1] that measures the genotypic response to changing environments. Variance due to environment + (genotype x environment) was significant for four of the studied traits viz., fresh green yield per hectare, fresh green yield per plant, plant height and leaf length which specified the existence of noteworthy interaction between the genotypes and the environmental conditions. The accessions, VA-16, CO-1, IC-553719 and IC-469645 have been identified as the high yielding stable genotypes for fresh green yield. Stable accessions for plant height include IC-536714, IC-541407, Arka amaranth, IC-469579 and IC-553719 and for leaf length were CO-1, IC-550143, IC-551472, IC-536714 and IC-469722. Further, some stable accessions for yield and its attributes were indicated that can be, commercialised or used in future breeding programs.

Morpho-physiological responses of iaa9 tomato mutants to different levels of PEG simulated drought stress

Abstract. Suminar E, Budiarto R, Nuraini A, Mubarok S, Ezura H. 2022. Morpho-physiologicalresponsesof iaa9 tomato mutants to different levels of PEG simulated drought stress. Biodiversitas 23: 3115-3126.This study aimed to analyze the morphological and physiological responses of iaa9 mutants and its WT-MT to different levels of drought stress in in vitro growing medium. This study applied a completely randomized design with two factors, i.e., tomato genotypes and polyethylene glycol (PEG) - induced drought stress levels. The factor of varieties consisted of three levels, i.e., WT-MT as control (G1), iaa9-3(G2), and iaa9-5 (G3). The factor of PEG-induced drought stress also consisted of four levels, i.e., 0% PEG as control (PEG0), 5% PEG (PEG5), 10% PEG (PEG10), and 15% PEG (PEG15). The results observed 12 weeks after culture showed the variations of the morpho-physiological response of WT-MT and mutant genotypes to PEG-induced in vitro drought stress. The WT-MT showed a higher reduction in plantlet height, root number, and root length than mutants under severe drought conditions. The plantlet fresh and dry weight of iaa9-3and iaa9-5were higher than its WT-MT under no drought conditions. The total chlorophyll content of WT-MT was lower than iaa9-5due to the significant gain of chlorophyll-b on that mutant rather than its WT-MT. However, the analysis of principal components and correlation revealed the reduction of morphological size and leaf pigment content in response to drought stress, irrespective of genotype factor. These results suggest that in vitro selection techniques using PEG is useful for the initial screening of drought-tolerant tomato.

Nitrogen Modulates Grain Yield, Nitrogen Metabolism, and Antioxidant Response in Different Rice Genotypes

Nitrogen Modulates Grain Yield, Nitrogen Metabolism, and Antioxidant Response in Different Rice Genotypes

Response of sugarcane genotypes to varying planting environments under two distinct agro-climatic zones of Punjab, India

Response of sugarcane genotypes to varying planting environments under two distinct agro-climatic zones of Punjab, India

Differential response of rice genotypes to nitrogen availability is associated with the altered nitrogen metabolism and ionomic balance

Nitrogen (N) uptake and its assimilation are crucial steps for plant growth and productivity. Plant's N balance largely depends on nitrate (NO 3 - ) and ammonium (NH 4 + ) forms present in the rhizosphere. Due to the fluctuating and heterogeneous availability of these N forms in the soils, plants encounter low to N deficiency. In contrast to low nitrogen, high N in the form of ammonium (NH 4 + ) severely hampers plant development and causes NH 4 + toxicity. In this study, we assessed eleven rice genotypes under sufficient (SN) and low N (LN) conditions. From the analysis, we identified a rice genotype, PB1, which is hypersensitive to SN and showed reduced root and shoot growth. In contrast to the SN condition, PB1 showed improved growth performance under the LN condition. Our data show that compromised growth of PB1 under SN condition is associated with increased activity of N responsive genes such as OsAMT1.1 , OsAMT2.3 , OsAMT3.1 and OsAMT3.2 , OsNRT1.1A and OsNRT1.1B . Strikingly, LN treatment improved the root and shoot biomass with a concomitant increase in levels of NO 3 - and NH 4 + transporter genes along with an increase in shoot: root NO 3 - ratio. Additionally, we show that increased levels of N in PB1 under SN condition are associated with the enhanced activity of the GS-GOGAT pathway. Further, our ionomic analysis highlighted the role of N-defined Fe accumulation which is partially associated with the N toxicity. Taken together, our study led to identifying a rice genotype ( Oryza sativa L.) which is associated with enhanced N levels and assimilation and could be used for raising N use efficient rice varieties using breeding approaches. • Screening of rice genotypes under high and low nitrogen (N) conditions led to identify a nitrogen-sensitive rice genotype. • Optimal N sensitive genotype, PB1 shows N toxicity and improved growth under LN condition. • N toxicity under optimal or high N supply is associated with altered growth physiology and N metabolism in PB1. • Increased N metabolism is associated with altered ionomic balance.

Individual variation in growth and physiology of symbionts in response to temperature.

In many cases, understanding species’ responses to climate change requires understanding variation among individuals in response to such change. For species with strong symbiotic relationships, such as many coral reef species, genetic variation in symbiont responses to temperature may affect the response to increased ocean temperatures. To assess variation among symbiont genotypes, we examined the population dynamics and physiological responses of genotypes of Breviolum antillogorgium in response to increased temperature. We found broad temperature tolerance across genotypes, with all genotypes showing positive growth at 26, 30, and 32°C. Genotypes differed in the magnitude of the response of growth rate and carrying capacity to increasing temperature, suggesting that natural selection could favor different genotypes at different temperatures. However, the historical temperature at which genotypes were reared (26 or 30°C) was not a good predictor of contemporary temperature response. We found increased photosynthetic rates and decreased respiration rates with increasing contemporary temperature, and differences in physiology among genotypes, but found no significant differences in the response of these traits to temperature among genotypes. In species with such broad thermal tolerance, selection experiments on symbionts outside of the host may not yield results sufficient for evolutionary rescue from climate change.

Enhancement of Androgenesis and Plant Regeneration From Wheat Anther Culture by Seed Pre-Sowing Gamma Irradiation

Combination breeding and mutation breeding are widely used methods in plant breeding. Intensive studies are carried out on biotechnological methods that will allow obtaining homozygous lines in a short time in populations obtained with these two techniques. Numerous studies have been carried out by different researchers on mutation breeding in wheat. There are few studies on anther culture response in mutagen-treated genotypes. Two different bread wheat promising advanced lines were used as the material in the study, in which the possibilities of combining mutation breeding with anther culture through ionizing radiation in high quality wheat breeding were investigated. In the study, the responses of advanced bread wheat mutant lines to anther culture, to which eight different doses of gamma rays (0, 100, 150, 200, 250, 300, 350, 400 Gy) were applied, including the control, were investigated. There are significant differences between genotypes and irradiation doses for all traits studied. It has been shown that it is possible to decrease albinism and increase the response of anther culture with dose-dependent gamma irradiation depending on bread wheat varieties. In the multiple comparison test to classify the difference between doses; statistically, 150 gray dose 5.60 is in the first statistical class and in the first place with the number of transferred green plants. After that, it ranks second in the same class with the number of green plants transferred with a 300 gray dose of 5.21. In the total number of regenerated green plants excluding controls (888), 635 unit (71.5%) and 205 unit (23.1%) haploids and spontaneous double haploid plants were obtained, respectively. In the study integrated into the bread wheat breeding program, a total of 205 spontaneous double haploid mutant lines were produced. According to the data obtained, it was shown that the gamma ray doses of 150 and 200 Gy had a significant stimulation effect on all parameters studied and ultimately the success index of anther culture in bread wheat compared to control.

Variation in leaf transcriptome responses to elevated ozone corresponds with physiological sensitivity to ozone across maize inbred lines.

We examine the impact of sustained elevated ozone concentration on the leaf transcriptome of 5 diverse maize inbred genotypes, which vary in physiological sensitivity to ozone (B73, Mo17, Hp301, C123, and NC338), using long reads to assemble transcripts and short reads to quantify expression of these transcripts. More than 99% of the long reads, 99% of the assembled transcripts, and 97% of the short reads map to both B73 and Mo17 reference genomes. Approximately 95% of the genes with assembled transcripts belong to known B73-Mo17 syntenic loci and 94% of genes with assembled transcripts are present in all temperate lines in the nested association mapping pan-genome. While there is limited evidence for alternative splicing in response to ozone stress, there is a difference in the magnitude of differential expression among the 5 genotypes. The transcriptional response to sustained ozone stress in the ozone resistant B73 genotype (151 genes) was modest, while more than 3,300 genes were significantly differentially expressed in the more sensitive NC338 genotype. There is the potential for tandem duplication in 30% of genes with assembled transcripts, but there is no obvious association between potential tandem duplication and differential expression. Genes with a common response across the 5 genotypes (83 genes) were associated with photosynthesis, in particular photosystem I. The functional annotation of genes not differentially expressed in B73 but responsive in the other 4 genotypes (789) identifies reactive oxygen species. This suggests that B73 has a different response to long-term ozone exposure than the other 4 genotypes. The relative magnitude of the genotypic response to ozone, and the enrichment analyses are consistent regardless of whether aligning short reads to: long read assembled transcripts; the B73 reference; the Mo17 reference. We find that prolonged ozone exposure directly impacts the photosynthetic machinery of the leaf.

Estimation of Genetic Variances and Stability Components of Yield-Related Traits of Green Super Rice at Multi-Environmental Conditions in Pakistan

Identifying adopted Green Super Rice (GSR) under different agro-ecological locations in Pakistan is crucial to sustaining the high productivity of rice. For this purpose, the multi-location trials of GSR were conducted to evaluate the magnitude of genetic variability, heritability, and stability in eight different locations in Pakistan. The experimental trial was laid out in a randomized complete block (RCB) design with three replications at each location. The combined analysis of variance (ANOVA) manifested significant variations for tested genotypes (g), locations (L), years (Y), genotype × year (GY), and genotype × location (GL) interactions revealing the influence of environmental factors (L and Y) on yield traits. High broad-sense heritability estimates were observed for all the studied traits representing low environmental influence over the expression of traits. Noticeably, GSR 48 showed maximum stability than all other lines in the univariate model across the two years for grain yield and related traits data. Multivariate stability analysis characterized GSR 305 and GSR 252 as the highest yielding with optimum stability across the eight tested locations. Overall, Narowal, Muzaffargarh, and Swat were the most stable locations for GSR cultivation in Pakistan. In conclusion, this study revealed that G×E interactions were an important source of rice yield variation, and its AMMI and biplots analysis are efficient tools for visualizing the response of genotypes to different locations.

​Effect of Sowing Dates on Phenological Traits, Yield and its Contributing Attributes on Snow Pea Genotypes

Background: Precise knowledge of sowing date of a particular variety at a specific location is critical to achieve high yield. Keeping this in view, experiment was planned to assess the response of snow pea genotypes for sowing dates. Methods: Four genotypes namely, DPEPP-15-1, DPEPP-10-1, Arka Apoorva and Mithi Phali were sown on three sowing dates (21st October, 5th November and 20th November) in split plot design, replicated thrice at Palampur during winter 2018-19 and 2019-20 and observations were recorded on different yield attributes. Result: Early sown pea (21st October) resulted in early flowering and first picking, higher pod yield, pods/plant and harvest duration followed by 5th November sown crop. DPEPP-10-1 showed significantly superior performance for early harvest while DPEPP-15-1 was the most promising genotype followed by DPEPP-10-1 for yield and its contributing parameters. Genotypes DPEPP-15-1 and DPEPP-10-1 had advantage of 36 and 27% for fresh yield over variety Arka Apoorva respectively. Interaction between sowing dates and varieties revealed that sowing of DPEPP-15-1 on 21st October followed by 5th November had significantly higher pod yield, pods/plant and harvest duration followed by DPEPP-10-1 and they significantly outperformed other varieties Arka Apoorva and Mithi Phali.

Understanding and Exploiting Transpiration Response to Vapor Pressure Deficit for Water Limited Environments.

More frequent droughts and an increased pressure on water resources, combined with social licence to operate, will inevitably decrease water resources available for fully irrigated cotton production. Therefore, the long-term future of the cotton industry will require more drought tolerant varieties that can perform well when grown in rainfed cropping regions often exposed to intermittent drought. A trait that limits transpiration (TRLim) under an increased vapour pressure deficit (VPD) may increase crop yield in drier atmospheric conditions and potentially conserve soil water to support crop growth later in the growing season. However, this trait has not been tested or identified in cotton production systems. This study tested the hypotheses that (1) genetic variability to the TRLim VPD trait exists amongst 10 genotypes in the Australian cotton breeding programme; (2) genotypes with a TRLim VPD trait use less water in high VPD environments and (3) variation in yield responses of cotton genotypes is linked with the VPD environment and water availability during the peak flowering period. This study combined glasshouse and field experiments to assess plant transpiration and crop yield responses of predominantly locally bred cotton genotypes to a range of atmospheric VPD under Australian climatic conditions. Results indicated that genetic variation to the limiting transpiration VPD trait exists within cotton genotypes in the Australian breeding programme, with five genotypes identified as expressing the TRLim VPD trait. A modelling study suggests that this trait may not necessarily result in overall reduced plant water use due to greater transpiration rates at lower VPD environments negating the water conservation in high VPD environments. However, our study showed that the yield response of cotton genotypes is linked with both VPD environment and water availability during the peak flowering period. Yield performance of the TRLim genotype was improved at some high VPD environments but is unlikely to out-perform a genotype with a lower yield potential. Improved understanding of integrated plant- and crop-level genotypic responses to the VPD environments will enhance germplasm development to benefit cotton production in both rainfed and semi-irrigated cotton systems, thereby meeting the agricultural challenges of the twenty-first Century.

Identification of Candidate Genes Associated With Tolerance to Apple Replant Disease by Genome-Wide Transcriptome Analysis.

Apple replant disease (ARD) is a worldwide economic risk in apple cultivation for fruit tree nurseries and fruit growers. Several studies on the reaction of apple plants to ARD are documented but less is known about the genetic mechanisms behind this symptomatology. RNA-seq analysis is a powerful tool for revealing candidate genes that are involved in the molecular responses to biotic stresses in plants. The aim of our work was to find differentially expressed genes in response to ARD in Malus. For this, we compared transcriptome data of the rootstock ‘M9’ (susceptible) and the wild apple genotype M. ×robusta 5 (Mr5, tolerant) after cultivation in ARD soil and disinfected ARD soil, respectively. When comparing apple plantlets grown in ARD soil to those grown in disinfected ARD soil, 1,206 differentially expressed genes (DEGs) were identified based on a log2 fold change, (LFC) ≥ 1 for up– and ≤ −1 for downregulation (p < 0.05). Subsequent validation revealed a highly significant positive correlation (r = 0.91; p < 0.0001) between RNA-seq and RT-qPCR results indicating a high reliability of the RNA-seq data. PageMan analysis showed that transcripts of genes involved in gibberellic acid (GA) biosynthesis were significantly enriched in the DEG dataset. Most of these GA biosynthesis genes were associated with functions in cell wall stabilization. Further genes were related to detoxification processes. Genes of both groups were expressed significantly higher in Mr5, suggesting that the lower susceptibility to ARD in Mr5 is not due to a single mechanism. These findings contribute to a better insight into ARD response in susceptible and tolerant apple genotypes. However, future research is needed to identify the defense mechanisms, which are most effective for the plant to overcome ARD.

Omics Path to Increasing Productivity in Less-Studied Crops Under Changing Climate-Lentil a Case Study.

Conventional breeding techniques for crop improvement have reached their full potential, and hence, alternative routes are required to ensure a sustained genetic gain in lentils. Although high-throughput omics technologies have been effectively employed in major crops, less-studied crops such as lentils have primarily relied on conventional breeding. Application of genomics and transcriptomics in lentils has resulted in linkage maps and identification of QTLs and candidate genes related to agronomically relevant traits and biotic and abiotic stress tolerance. Next-generation sequencing (NGS) complemented with high-throughput phenotyping (HTP) technologies is shown to provide new opportunities to identify genomic regions and marker-trait associations to increase lentil breeding efficiency. Recent introduction of image-based phenotyping has facilitated to discern lentil responses undergoing biotic and abiotic stresses. In lentil, proteomics has been performed using conventional methods such as 2-D gel electrophoresis, leading to the identification of seed-specific proteome. Metabolomic studies have led to identifying key metabolites that help differentiate genotypic responses to drought and salinity stresses. Independent analysis of differentially expressed genes from publicly available transcriptomic studies in lentils identified 329 common transcripts between heat and biotic stresses. Similarly, 19 metabolites were common across legumes, while 31 were common in genotypes exposed to drought and salinity stress. These common but differentially expressed genes/proteins/metabolites provide the starting point for developing high-yielding multi-stress-tolerant lentils. Finally, the review summarizes the current findings from omic studies in lentils and provides directions for integrating these findings into a systems approach to increase lentil productivity and enhance resilience to biotic and abiotic stresses under changing climate.

Potassium content is the main driver for salinity tolerance in sweet potato before tuber formation

AbstractSweet potato (Ipomoea batatas L.) is mostly grown in Asia, which accounts for 86% of global production. However, its production is under threat by salinity. Little is known about genotypic responses to salinity in sweet potato. Phenotypic responses or physiological processes linked to salt tolerance that could be developed into a reliable screening tool to assist breeding have not yet been developed for sweet potato. In a hydroponic cultivation system, 12 contrasting sweet potato genotypes were subjected to 0, 50, 100 and 150 mM root zone salinity (RZS). Genotypic thresholds for dry matter accumulation and the genotypic slopes for additional dry matter reduction when the RZS increased beyond the genotypic threshold were determined. Sodium, chlorine and potassium (K) were determined from above‐ground biomass and correlated with the genotypic thresholds found. Genotypic threshold levels were linearly negatively correlated with the difference in tissue K content at 75 mM RZS and the tissue K content at control levels. Based on the genotypic ability to retain high tissue potassium levels under increasing RZS, we propose a screening tool based on these experimental data that can distinguish between salt‐tolerant and salt‐sensitive genotypes and indicate the potential yield level of the sweet potato genotypes.

Identification of environment types and adaptation zones with self-organizing maps; applications to sunflower multi-environment data in Europe

Key messageWe evaluate self-organizing maps (SOM) to identify adaptation zones and visualize multi-environment genotypic responses. We apply SOM to multiple traits and crop growth model output of large-scale European sunflower data.Genotype-by-environment interactions (G × E) complicate the selection of well-adapted varieties. A possible solution is to group trial locations into adaptation zones with G × E occurring mainly between zones. By selecting for good performance inside those zones, response to selection is increased. In this paper, we present a two-step procedure to identify adaptation zones that starts from a self-organizing map (SOM). In the SOM, trials across locations and years are assigned to groups, called units, that are organized on a two-dimensional grid. Units that are further apart contain more distinct trials. In an iterative process of reweighting trial contributions to units, the grid configuration is learnt simultaneously with the trial assignment to units. An aggregation of the units in the SOM by hierarchical clustering then produces environment types, i.e. trials with similar growing conditions. Adaptation zones can subsequently be identified by grouping trial locations with similar distributions of environment types across years. For the construction of SOMs, multiple data types can be combined. We compared environment types and adaptation zones obtained for European sunflower from quantitative traits like yield, oil content, phenology and disease scores with those obtained from environmental indices calculated with the crop growth model Sunflo. We also show how results are affected by input data organization and user-defined weights for genotypes and traits. Adaptation zones for European sunflower as identified by our SOM-based strategy captured substantial genotype-by-location interaction and pointed to trials in Spain, Turkey and South Bulgaria as inducing different genotypic responses.

Infantile Spasms in Cardiofaciocutaneous Syndrome: Associations with Genotype, Phenotype and Treatment Response (P5-8.005)

Infantile Spasms in Cardiofaciocutaneous Syndrome: Associations with Genotype, Phenotype and Treatment Response (P5-8.005)

Visualising the pattern of long‐term genotype performance by leveraging a genomic prediction model

AbstractHistorical data from plant breeding programs provide valuable resources to study the response of genotypes to the changing environment (i.e. genotype‐by‐environment interaction). Such data have been used to evaluate the pattern of genotype performance across regions or locations, but its use to evaluate the long‐term pattern of genotype performance across environments (i.e. locations‐by‐years) has been hampered by the lack of common genotypes across years. This lack of common genotypes is due to the structure of the breeding program, especially for annual crops, where only a proportion of selected genotypes are tested in subsequent years. This has resulted in a sparse prediction of the performance of genotypes across years (i.e. a genotype‐by‐year table). A genomic prediction method that fitted both a relationship matrix among genotypes and a relationship matrix among environments (i.e. years) could overcome this limitation and produce a dense genotype‐by‐year table, thereby enabling some evaluation of long‐term genotype performance. In this paper, we applied the genomic prediction model to the yield data from CIMMYT's Elite Spring Wheat Yield Trials (ESWYT) to visualise the pattern of genotype performance over 25 years.

Modulation of Wheat Yield Components in Response to Management Intensification to Reduce Yield Gaps.

Appropriate genotype selection and management can impact wheat (Triticum aestivum L.) yield in dryland environments, but their impact on yield components and their role in yield modulation are not well understood. Our objectives were to evaluate the yield response of commercial winter wheat genotypes to different management practices reflecting a stepwise increase in management intensity (including a reduction in crop density under high input), and to quantify how the different yield components modulate wheat yield. A factorial experiment evaluated six management (M) intensities [“farmer practice” (FP), “enhanced fertility” (EF), “ecological intensification” (EI), “increased foliar protection” (IFP), “water-limited yield” (Yw), and “increased plant productivity” (IPP)] and four winter wheat genotypes (G) in four Kansas environments (E). Average grain yield was 4.9 Mg ha–1 and ranged from 2.0 to 7.4 Mg ha–1, with significant two-way interactions (E × M and E × G). The EF usually maximized yields in dry environments, while EI, which consisted of EF plus one fungicide application, maximized yields in environments with greater water availability. Across all sources of variation, kernels m–2 and aboveground biomass were the strongest modulators of yield as compared to kernel weight and harvest index, while spikes m–2 and kernels spike–1 modulated yields at a similar magnitude. Foliar fungicides improved yield through increased green canopy cover duration and greater radiation intercepted during grain filling. When crop density was reduced from 2.7 to 1.1 million plants per hectare in an otherwise high-input system, plants produced more productive tillers (with genotype-specific response); however, reduced green canopy cover at anthesis and reduced cumulative solar radiation intercepted during grain filling limited wheat yield—although large differences in canopy cover or intercepted radiation were needed to cause modest changes in yield. Treatments more intensive than EI were not warranted as EF or EI maximized yields at all environments, and practices that promote biomass and kernels m–2 are to be targeted for future increases in wheat yield.