EVALUATION OF WHEAT GENOTYPES FOR SUSTAINING YIELD UNDER WATER DEFICIT CONDITION

Abstract

Drought is a worldwide problem, constraining wheat production seriously and recent global climate change has made this situation more staid. Selection of drought tolerant wheat genotypes as well as to development of proper crop management techniques is useful tools to enhance the drought tolerance. Regarding these issues, four experiments were conducted during 2014 to 2017 at Hajee Mohammad Danesh Science and Technology University and Bangladesh Wheat and Maize Research Institute (BWMRI), Dinajpur. Effect of PEG 6000 induced water stress (0, -2, -4 bars) on the germination and seedling growth of 30 wheat genotypes was evaluated in petri-dishes on September 2014. Wheat genotypes (BARI Gom 25, E 38, BAW 1118, E 18, Shatabdi, BAW 1138, E 34, E30, BAW 1135 and E 3) showing less affected speed of germination (rate of germination (%), co-efficient of germination and germination vigour index) and seedling growth (length and dry weights of shoot and root) along with higher STI (Stress tolerant index) based on seedling dry weight were considered as comparatively water deficit stress tolerant genotypes. The wheat genotypes (BAW 1151, E 42, BAW 1170, E 29, BAW 1161, E 2, BAW 1157, E 23, BAW 1130 and BARI Gom 26) showed reverse value of the aforesaid traits due to severe stress designating comparatively water deficit stress susceptible genotypes. To screen out more authentically based on yield traits and yield, all genotypes were grown in the field in 2014-15 under three water regimes viz. well watered (three irrigations), one irrigation and no irrigation condition. In no irrigated plots, wheat genotypes- BARI Gom 25, E 18, E 38, BAW 1118, BAW 1170, E 24, E 28, E 3, BAW 1171 and E 34 showed higher relative yield attributes and yield indicating tolerant, while BARI Gom 26, BAW 1130, BAW 1140, BARI Gom 27, BAW 1143, BARI Gom 28, BAW 1138, BAW 1157, E 23 and Sourav showed lower relative value signifying susceptible genotypes. Considering experiments I and II, four water deficit stress tolerant (BARI Gom 25, E 18, E 38 and BAW 1118) and two susceptible genotypes (BARI Gom 26 and BAW 1130) were evaluated physiologically in the third experiment. In view of chlorophyll content, SPAD value, water status (Relative water content, water retention capacity), canopy temperature depression, cell membrane stability (CMS), production of osmolytes (proline and soluble sugar), yield traits and yield, the genotype E 38 showed the highest stress tolerance and the genotype BAW 1130 showed the lowest stress tolerance. To ameliorate the adverse effect of drought stress, these two genotypes (E 38 and BAW 1130) were evaluated with five potassium fertilizer treatments in combination with water regimes during 2016-17. Additional soil and foliar application of potassium enhanced water stress tolerance in relation to LAI, LDW, TDW, water relation, nutrients (N, P, K) uptake, yield traits and yiled. However, considering the results of seed germination, seedling growth, physiology, yield traits and yield, the E 38 can be declared as a drought tolerant genotype, and addition of 75 kg K ha-1 may advised to apply for cultivation of wheat under rainfed condition in the drought prone area of Bangladesh.