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High temperature stress unfavorably affects plant growth and reduces grain yield (GY). This study was conducted with an aim to identify the terminal heat tolerance of one hundred and two wheat genotypes with three checks. They were sown under normal (non-stress) and late (stress) conditions at Regional Agricultural Research Station (RARS), Tarahara; RARS, Nepalgunj and National Wheat Research Program (NWRP), Bhairahawa, Nepal. The trial was sown in Augmented design during 2014/15 winter season as a Nepal heat tolerance wheat screening nursery (NHTWSN). Grain yield, maturity, stress susceptibility and tolerant indices were estimated to assess the heat tolerance of the genotypes. Combined analysis among the tested wheat lines (102 new entries + 3 checks) showed that KACHU//KIRITATI/WBLL1 ((Heat tolerance index (HTI) = 1.78) possessed the highest level of heat tolerance, followed by SLVS /3/ CROC_1/ AE.SQUARROSA (224)// OPATA/5/ VEE/LIRA//BOW/3/BCN/4/KAUZ/6/ 2*KA/NAC//TRCH (HTI=1.57) while SUP152/VILLA JUAREZ F2009 (HTI=0.83) appeared to be the least heat tolerant. Correlation analysis showed that yield under stress environment had positive (r=0.083) and significant (p<0.05) association with that of non-stress environment. Grain yield (Kg/ha) under both environments had significant positive correlation with mean productivity (MP), geometric mean productivity (GMP) and HTI. Thirty seven wheat genotypes possessing heat tolerance will be considered in further heat tolerance trial and can also be used directly in varietal development and in the crossing program to breed more heat tolerant genotypes.
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