MUKTI RAM POUDEL*, RADHAKRISHNA BHANDARI, SHIVALAL NYAUPANE AND MADHAV PRASAD NEUPANE
Department of Plant Breeding and Genetics, Institute of Agriculture and Animal Science, Tribhuvan University, Paklihawa Campus, Nepal, 32900
*(e-mail: muktipoudel8@gmail.com; Mobile: +977 98570 29723)
(Received: June 10, 2023; Accepted: July 22, 2023)
ABSTRACT
Heat stress has been one of the major abiotic stresses in South Asian regions. Heat stress reduces yield by influencing physiological processes and yield related traits. To evaluate heat stress tolerance of 20 elite wheat lines comprising 18 genotypes and two commercial checks viz., Bhrikuti and Gautam, the field experiment was conducted for three continuous wheat growing seasons of 2019-20, 2020-21 and 2021-22 in the western region of Nepal at Paklihawa Campus under normal and heat stress conditions using an alpha lattice design having two replications and five blocks. The genotypic evaluation was done with nine stress tolerance indices (STIs). The ANOVA of the AMMI model revealed that yield performance was significant across tested environments and genotypes. The combined ANOVA showed that days to booting (DTB), days to heading (DTH), plant height (Ph), spike length (SL), spike weight (SW), spikelets per spike (SPS), grains per spike (GPS) and grain yield (GY) were significantly reduced by 14, 15, 8.6, 4, 14, 4, 7 and 34%, respectively under heat stress condition as compared to normal condition. For three years, BL 4919 and Bhrikuti were the highest yielding wheat genotypes under normal and heat stress conditions with mean GY of 4860.8 and 3415.41 kg/ha, respectively. Principal component analysis (PCA) performed across STIs extracted; Modified stress tolerance indices (MSTI2) and stress tolerance indices (STI). From MSTI2, Bhrikuti (1.39) and NL 1350 (1.16) were identified as high yielding stable genotypes and from STI, Bhrikuti (0.87) and BL 4919 (0.86) were identified as heat-tolerant genotypes. Selection based on MSTI2 and STI would be helpful to identify high-yielding stable and stress-tolerant genotypes under heat stress conditions, respectively.
Key words : Wheat, stress tolerance, irrigated, drought, heat stress