Identification of terminal heat-tolerant and foliar disease-resistant fortified genotypes in wheat (Triticum aestivum L.)

Terminal heat stress and foliar diseases like rusts and spot blotch are the major concerns for sustainable wheat production in South Asia. Eastern Indo-Gangetic plains witness the crucial role of heat stress during grain-filling duration (GFD) and occurrence of rust diseases and spot blotch in wheat. One hundred promising wheat genotypes were selected from five international wheat yield trials and evaluated at three sites in India for yield components and disease resistance. To identify potential donors, these lines were further screened under timely sown (normal sown) and late sown (heat stress) conditions. Analysis of variation in the studied traits revealed significant differences among all the genotypes in both environments. Grain yield showed a positive and significant correlation with NDVI, chlorophyll index, flag leaf length, flag leaf area, tiller per plant, number of grains per spike, peduncle length and 1000 grain weight (TGW) in both environments. Grain zinc and iron content was substantially increased under late sown condition. As per heat susceptibility index of GFD, TGW, NDVI and grain yield per plot, 10 tested entries were found heat tolerant. Ten promising entries with low disease score were listed as spot blotch donors. Markers linked with seven rust resistance genes, three spot blotch genes and two markers linked with quality-related traits, namely yellow pigment (Psy-A1) and polyphenol oxidase activity (Ppo-1A) and rust pathotypes, were also used to identify the presence of individual genes. Promising entries 46 (CWYT-613; GID 7631433) and 58 (41ESWYT-137; GID 8240588), common for both tested conditions, were identified and promoted under the breeding programme.