Genotype-by-Environment Interaction Effects under Heat Stress in Tropical Maize

Abstract

Spring maize area has emerged as a niche market in South Asia. Production of maize during this post-rainy season is often challenged due to heat stress. Therefore, incorporating heat stress resilience is an important trait for incorporation in maize hybrids selected for deployment in this season. However, due to the significant genotype × environment interaction (GEI) effects under heat stress, the major challenge lies in identifying maize genotypes with improved stable performance across locations and years. In the present study, we attempted to identify the key weather variables responsible for significant GEI effects, and identify maize hybrids with stable performance under heat stress across locations/years. The study details the evaluation of a set of prereleased advanced maize hybrids across heat stress vulnerable locations in South Asia during the spring seasons of 2015, 2016 and 2017. Using factorial regression, we identified that relative humidity (RH) and vapor pressure deficit (VPD) as the two most important environmental covariates contributing to the large GEI observed on grain yield under heat stress. The study also identified reproductive stage, starting from tassel emergence to early grain-filling stage, as the most critical crop stage highly susceptible to heat stress. Across-site/year evaluation resulted in identification of six high yielding heat stress resilient hybrids.

Genomic-regions associated with cold stress tolerance in Asia-adapted tropical maize germplasm

“…In the current study, we used GWAS approach to identify SNP markers associated with cold stress tolerance in a panel of tropical maize lines screened under field conditions. The current panel of lines had a high LD decay which is typical of tropical germplasm 63 – 65 , which indicates the diversity among the lines involved and the amenability to high resolution mapping studies.…”

“…The current panel of lines had a high LD decay which is typical of tropical germplasm [63][64][65] , which indicates the diversity among the lines involved and the amenability to high resolution mapping studies. The current study identified a suite of significant SNPs for various traits recorded under cold stress at different crop stages across various locations.…”

Impact of adoption of heat-stress tolerant maize hybrid on yield and profitability: Evidence from Terai region of Nepal

“…Zaidi). In general, spring maize segment in South Asia comprises >37 • C temperature leads to heat-stress (Thayil et al, 2020). Day maximum-minimum temperature data was collected for January 2020-April 2021 from the Directorate of Agricultural Research, Khajura, Banke (Nepalgunj) district at the time of the survey, and given in Figure 2.…”

“…In maize, the favorable soil temperature for seedling growth is 26 • C, and when this temperature rises, root and shoot mass both decline by 10% for each degree of increase until 35 • C when growth is severely retarded (Walker, 1969). The most critical stages for heat stress are from tassel emergence to early grain filling (Nejad et al, 2017;Thayil et al, 2020). At elevated temperatures, the number of fertilized ovules that develop into grain decreases (Schoper et al, 1987a,b).…”

Effects of Raised Ambient Temperature on the Local and Systemic Adaptions of Maize

“…Improving heat tolerance in maize has become one of the top priorities for maize-breeding programs. In maize, a large variation in heat tolerance exists in germplasm collections due to its successful acclimation from the tropics to temperate regions in the Northern and Southern Hemispheres [ 87 , 88 , 89 , 90 , 91 , 92 ]. The development of heat-tolerant maize hybrids is urgently needed, and this goal largely depends on the study of physiological, biochemical, and molecular mechanisms.…”