Variance components and heritability of yield and yield components of wheat under drought-stressed and non-stressed conditions

Abstract

This study estimated the variance components and heritability of yield and yield related traits of a population of 96 diverse bread wheat genotypes under drought-stressed and non-stressed conditions. The genotypes were evaluated across eight testing environments during the 2014/2015 and 2015/2016 growing seasons using an alpha lattice design with two replications. Combined analysis of variance and variance components were analysed following the General Linear Model (GLM)'s procedure. Results indicated the presence of significant effects of genotypes, seasons, sites, and water regimes and their interactions. From the eight testing conditions, high levels of genotypic variance (σ2g) were estimated for spike length (73%), number of spikelets per spike (44.19%), plant height (51.26%), number of kennels per spike (32.98%), number of days-to-heading (44.24%) and thousand seed weight (22.98%), resulting in high broad-sense heritability estimates of > 0.50. Conversely, genotypic variation was relatively moderate for the number of days to maturity, grain yield and number of productive tillers per plant, contributing to 15.03%, 8.46% and 6.13% of the total variation, respectively. The heritability estimates of the later traits were 20% ≤ H2 < 50% which may limit their selection gains under droughtstressed environments. Further, quantitative trait loci analysis and progeny testing are required to discern the number of genes and associated genetic effect and to pinpoint genomic regions in the tested wheat genetic resources for effective breeding for drought tolerance.

Assessment of genetic variability among bread wheat genotypes for agronomic and morphological traits under optimum and stress condition

“…Under stress condition the tested genotypes exhibited highly significant (P≤0.01) variation for all traits studied. Several types of research have been conducted on bread wheat under drought condition and found highly significant variation for the traits reported herein our study (Rehman et al 2015;Mwadzingeni et al 2017;Abd-Allah et al 2018;Pour-Aboughadareh et al 2020). In contrary to the present result non-significant variation was reported for biomass yield and harvest index (Sahar et al 2016) in wheat under drought condition.…”

“…Similar to the present result, Rehman et al (2015) reported moderate heritability value for spike length under drought condition in bread wheat. Grain yield is a polygenic trait that is highly influenced by the environment under stressed condition; thus moderate heritability was expected for this trait (Mwadzingeni et al 2017). The author also found moderate heritability value for grain yield under drought stress condition which support present finding.…”

Variability and selection among mutant families of wheat for biomass allocation, yield and yield‐related traits under drought‐stressed and non‐stressed conditions

“…(2014) and Mwadzingeni et al. (2017) reported significant reduction in yield, seed size, plant height and tiller numbers due to drought stress, which were corroborated by the findings of this study. In contrast, drought stress resulted in an increase in root–shoot ratio, which implied that drought stress promoted root biomass accumulation or had higher negative impact on shoot compared with root growth in the mutant families.…”

“…Mwadzingeni et al. (2017) reported significant interaction between genotype and water regime influencing yield and yield component traits of wheat genotypes under contrasting water levels showing that water availability affects plant growth in general although the actual extent of impact is dependent on genetic constitution of the plant and the intensity of the stress. The selection of genotypes with superior agronomic performance and biomass allocation under drought stress could facilitate the development of cultivars adapted to water‐limited constrained environments.…”

“…The significant (p < .05) effects of the interactions involving genotype, environment and water regimes on the traits such as days to 90% maturity, shoot biomass, root biomass, total biomass, productive tiller number, spikelet per spike, thousand seed weight and grain yield (Table 1) suggest that genotypic and environmental factors are Marchin et al, 2020;Osakabe et al, 2014;Robbins & Dinneny, 2018;Tátrai et al, 2016). Mwadzingeni et al (2017) would be imperative to assess whether such genotypes would have dynamic stability and performance under improved moisture conditions to minimize potential yield penalties (Hooshmandi, 2019). For instance, it has been reported that some drought-tolerant genotypes with high yield potential under drought conditions did not exhibit any yield advantage under irrigated conditions (Abdolshahi et al, 2013;Hooshmandi, 2019;Mehraban et al, 2018).…”