SCREENING OF WHEAT (Triticum aestivum L.) GENOTYPES FOR DROUGHT TOLERANCE USING COMBINATION OF MORPHO- PHYSIOLOGICAL AND BIOCHEMICAL TRAITS

A Thesis Submitted to the Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, In partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN GENETICS AND PLANT BREEDING SEMESTER: January-June, 2018

The experiment was conducted during the period from November 2017 to April 2018 in rabi season in the experimental field of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka to unravel the role of morpho-physiological and biochemical characters in spring wheat under drought stress. Twenty diverse genotypes including 16 lines from the Wheat Research Center (BARI)’s heat and drought nurseries, and four local checks were evaluated under field conditions. Mean performance, genetic parameters, Pearson’s correlation coefficient, and principal component biplot analysis were calculated. The longest plant (84.20 cm) was recorded in genotype Shatabdi, while the shortest plant (63.96 cm) was found in wheat genotype BARI GOM-30. The highest grain yield per plant (5.57 g) was recorded in Prodip, while the lowest grain yield per plant (4.15 g) was observed in the wheat genotype SAWYT-312. Phenotypic coefficient of variation was higher than the genotypic coefficient of variation for all the yield contributing traits. In correlation study, significant negative association was recorded for grain yield per plant of wheat genotypes with days to 50% of heading (-0.397), while the non-significant negative association for number of grains/spike (-0.183), chlorophyll content (-0.097), dry matter content (-0.003) and root length (-0.058). On the other hand, significant positive association was recorded for grain yield per plant with plant height (0.688), number of spike/m 2 (0.269), number of spikelet’s/spike (0.630), peduncle length (0.640) and weight of 1000 grains (0.201), while non-significant positive association was observed with leaf area index (0.007). The positive correlation observed between grain yield and proline content under-drought stress conditions provides evidence that proline accumulation might ultimately be considered as a tool for effective selection of drought tolerant genotypes. The study selected 8 genotypes with high grain yields under drought stressed conditions and favorable adaptive traits useful for breeding. In consideration of yield contributing characters and yield Prodip performed better under drought condition followed by DTWYT-22, SAWYT-326, SAWYT-331, Shatabdi, BARI Gom-28, and BARI Gom-30. The proline content hight found in SAWYT-312 (220.2), and also found in SAWYT-303 (194.74), SAWYT-345(178.53) and lowest in SAWYT-324(46.16). Key words: wheat, drought, physiology, biochemical