Low temperature becomes an important limitation for production of grains in wheat cultivars as altitude increases. An alteration of growth habit accompanied with changes in morphology of leaf, shoot and root characteristic and cool temperature induced sterility in florets seemed to be associated with yield loss. The extent of variability of these characters, their relationship and contribution to grain yield were examined among 9 wheat cultivars (viz., HPW 155, HPW 236, HPW 277, HS 473, SKW 323, Sonalika, VL 829, VL 832 and Local cultivar) at an elevation of 2100 m above mean sea level (msl) under field condition. The results revealed an increase in average growing degree x days for head emergence and number of days experiencing lower soil temperature than air temperature during anthesis both induced sterility in florets. An increase in thermal time at post anthesis grain filling period encouraged the production of grains. Grain yield did not show significant correlation with leaf, shoot and root characters. Susceptible cultivars, however, exhibited a greater percentage of sterile florets in population, low grain yield, high root to shoot ratio, less thickness of fresh leaves and less dry matter deposition. The varieties VL 829, HPW 236 and HS 473 showed superior in yield and higher tolerance to cool conditions at high altitude.
Key words: Wheat cultivars, high altitude, cold stress, floret sterility, grain yield.
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