Performance of yield and stability of advanced wheat genotypes under heat stress environments of the indo-gangetic plains

A set of 25 advanced breeding lines and released varieties of wheat (Triticum aestivum L.) developed by different breeding centers in India were assessed for their adaptation in 18 different environments across the Indo-Gangetic plains. The study was aimed at identifying genotype(s) with high yield stability across the environments in general and heat stress environments in particular, Jaipur and Varanasi were hotter than any other locations considered in this study. Considerable intralocation variation in genotypic response pattern was observed over the years and dates of sowing, and this was more conspicuous at Varanasi. Longer crop duration and short grain growth duration at Varanasi were in contrast to shorter crop duration and relatively longer grain growth period that supported better grain growth at Jaipur. The genotype x environment interaction biplots for grain yield revealed that genotypes Raj 3765 and Raj 4027, developed at Jaipur, were more stable across all environments. This was due to their adaptability to high-temperature environments, and hence they are being proposed as promising germplasm sources for late-sown and/or warmer environments. Since the pattern of genotypic response observed at Jaipur was not similar to that observed at Varanasi, it is suggested that a common breeding strategy, if any, should emphasize grain yield stability for breeding for high-temperature tolerance. This can also take care of intralocation variation in genotypic response over the years and dates of sowing at Varanasi.