SCREENING OF ELITE WHEAT GERMPLASM AGAINST NORMAL AND HEAT STRESS CONDITIONS USING AGRO-MORPHOLGICAL APPROACHES
Keywords:heat stress tolerance, wheat genotypes, yield and yield attributes
Alarming climate change is a worldwide documented phenomenon and increase in abiotic (temperature stress, drought, salinity) and biotic stresses (diseases, pests) have been reported worldwide in agricultural crops. Terminal heat stress is one of the yield limiting factors for wheat crop in South Asia, including Pakistan. To address this core issue, a field study was carried out at Experimental Farm of Nuclear Institute of Agriculture, Tandojam for two consecutive years 2013-14 and 2014-15 by using 20 wheat genotypes (mutants and advance lines) along with four check varieties. The breeding material was exposed to different temperature levels by sowing on two different dates viz. sowing date-1 abbreviated as SD-1 (November 15 as normal sowing <350C at grain filling) and SD-2 (December 25 as late sowing >400C temperature stress at grain filling). The observations on various important traits (days to maturity, grain yield, 1000-grain weight and harvest index) were recorded for both the years. The two years agro-morphological data revealed variable response of wheat genotypes for grain yield and other traits under normal and heat stress conditions. Grain yield under normal sowing ranged from 5050 to 6385 kg ha-1 in potential genotypes. Seven genotypes i.e. DH-12/1, NIA-10/8, Kiran-95, NIA-Amber, NIA-28/4, NIA-8/7 and BWS-78 were found tolerant to heat stress and produced higher grain yields (varied from 3850 to 4905 kg ha-1) under heat stress conditions during both the years.
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