Agronomic and physiological response of wheat (Triticum aestivum L.) Genotypes under terminal heat stress conditions
By: Sajid Ali, Sami Ullah Khan, Ali Raza Gurmani, Ayub Khan, Shah Masaud Khan, Abid Farid, Ibrar Khan, Rimsha Zainab
Key Words: Wheat genotypes, heat stress, proline, chlorophyll, yield and yield components.
Int. J. Biosci. 8(5), 1-7, May 2016.
Heat stress is one of major limiting factor in wheat (Triticum aestivum L.) productivity in arid, semiarid, regions of world. Wheat is grown as winter cereal crop in Pakistan. The crop experiences moderate to severe high temperature at most of its physiological stages of growth. A research experiment was carried out to assess the agronomic and physiological response of wheat genotypes under terminal heat stress conditions at Agriculture farm of the University of Haripur in winter, 2012. Six genotypes were sown in pots using Completely Randomized Design (CRD) replicated thrice. Two separate sets of plants were maintained for heat stress and control. Pre-anthesis growth stage (80 days after sowing), one set plants of were subjected to heat stress treatment of 35 to 40°C and 10 to 14h day and night, 50 to 70% relative humidity and illumination of 335 µ mol m-2s-2 in glass house. After high temperature treatment for 3h daily for five consecutive days, pots were moved back to normal temperature (average day/night temperature 30 ± 8 and 13 ± 5°C) conditions in open atmosphere. After heat stress treatment, flag leaf from the control and stressed plants were sampled for analysis of proline, chlorophyll a, chlorophyll b content and membrane thermos-stability. Analysis of variance for agronomic parameters revealed significant (p≤0.05) differences among wheat genotypes for days to 50% flowering, plant height, number of grains per spike, number of spikelets per spike and seed yield per pot,the proline accumulation could be used as markers in the breeding program for the development of heat tolerant wheat genotypes. Overall PSK-91, LU-26S and SARSABZ showed best performance under imposed heat stress for physiological and yield parameters. There is a dire need to further evaluate the performance these genotypes under field conditions in the areas of heat stressed environment.