Increasing human population and changing climate, which have given rise to frequent drought spells, pose a serious threat to global food security, while identification of high yielding drought tolerant genotypes remains a proficient approach to cope with these challenges. To offer a methodology for the evaluation of the drought-tolerant wheat genotypes based on the pheno-physiological traits, a field experiment was executed, entailing four wheat genotypes viz. BARI Gom 26, BAW 1158, BAW 1167, and BAW 1169 and two water conditions viz. control treatment (three times irrigation at 20, 50, and 70 DAS, i.e., 100% field capacity) and stressed treatment (no irrigation during the entire growing season). The results revealed that drought stress drastically reduced the days to booting, heading, anthesis and physiological maturity, relative water content (RWC), chlorophyll content, canopy temperature depression (CTD), and photo-assimilates-spike dry matter (SDM), grains spike−1 and grain yield of all wheat genotypes. In addition, the genotypes BAW 1167 and BARI Gom 26 remained more prone to adverse effects of drought as compared to BAW 1169 and BAW 1158. Furthermore, DS induced biosynthesis of compatible solutes such as proline, especially in BAW 1169, which enabled plants to defend against oxidative stress. It was inferred that BAW 1169 remained superior by exhibiting the best adaptation as indicated by the maximum relative values of RWC, total chlorophyll, CTD, proline content, SDM, grains spike−1, and grain yield of wheat. Thus, based on our findings, BAW 1169 may be recommended for general adoption and utilization in future wheat breeding programs aimed at developing potent drought-tolerant wheat genotypes to ensure food security on a sustainable basis.
Four wheat cultivars e.g., Aghrani, Kanchan, CB-30 and Sonora were tested under normal and post anthesis heat stress condition by seeding them on November 30 and December 30 to evaluate the heat tolerance of wheat in relation to proline content. Time to exceed 50% membrane leakage was about four times longer in Aghrani, and the cultivars were grouped as heat tolerant (HT) than in Sonora (30 min) which considered as heat sensitive (HS). Due to post anthesis heat stress condition the HS cultivar Sonora in comparison to heat tolerant (HT) genotype exhibited larger decrease in kernel proline (47.2%) along with larger increase in flag leaf proline (122%). The heat tolerant cultivars exhibited distinctly higher relative individual kernel dry weight, higher kernel number per spike, higher relative grain yield and low susceptibility index for grain yield under post anthesis heat stress condition compared to heat sensitive cultivar. Strong correlation existed between heat killing time in membrane thermostability test and relative change to normal in proline content (both in flag leaf and kernel) and between heat susceptibility index for grain yield and relative change to normal in proline content.
The performance of twenty wheat genotypes under Polyethylene Glycol (PEG) induced water stress during germination and early seedling growth stages were tested under three levels of water potential i) Control (Tap water), ii) -2 bars and iii) -4 bar at the Crop Physiology and Ecology Laboratory of Hajee Mohammad Danesh Science and Technology University, Dinajpur during September 2014 to October 2014. Rate of germination and vigor index of all wheat genotypes were delayed with the increment of water stress induced by PEG. Shoot and root lengths and seedling dry weight of 10 days old seedlings were found to be reduced due to the increment of water stress. However, the degree of reduction of these parameters with the increment of water stress was not similar for all wheat genotypes. Stress tolerance index (STI) based on seedling dry weight indicated a wide difference in stress tolerance among the wheat genotypes. At moderate water deficit stress, BARI Gom 25, E 34, E 28 and BAW 1170 showed more stress tolerance and the wheat genotypes-Sourav, E 23 and BAW 1140 showed greater stress sensitivity than the other wheat genotypes. At higher water deficit stress, BARI Gom 25, BARI Gom 28, E 28 and BAW 1170 showed more stress tolerance and the wheat genotypes-Satabdi, Sourav, BARI Gom 26, E 23, E 38, E 24, BAW 1163, BAW 1140 and BAW 1151 showed greater stress sensitivity than the others. Considering both moderate and high water deficit stress, BARI Gom 25, E 28 and BAW 1170 were found as tolerant and Sourav, E 23 and BAW 1140 were found as water deficit stress sensitive wheat genotypes.
The experiment was conducted at research field and laboratory of the Department of Crop Physiology and Ecology, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh during the period of December 2013 to April 2014. The experiment was laid out in two factors randomized complete block design with three replications including three concentrations of Indole Acetic Acid (0, 100 and 200 ppm) and three tomato varieties (BARI tomato 7, Manik and Ratan). Plant height, number of leaves and number of branches, days required for first flower initiation, days required for 50% flowering, days required for fruit setting, fruit cluster plant -1 , fruit plant -1, weight tomato -1 , yield plant -1 , yield plot -1 and yield hectare -1 were significant influenced by the combined application of IAA and varieties of tomato. BARI Tomato-7 had the highest fruit yield with 100 ppm IAA and the lowest yield was observed in Ratan with 0 ppm IAA. IAA treated plots showed better performance for growth parameters and yield compared to control condition and 100 ppm IAA was more suitable than the 200 ppm IAA for higher yield of tomato cultivation. Among the treatment combinations, BARI Tomato-7 with 100 ppm IAA was superior, Ratan with 0 ppm IAA was inferior and BARI Tomato-7 with 200 ppm IAA, Manik with 200 ppm IAA and Ratan with 200 ppm IAA treated plots showed the intermediate results for yield and yield components.
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