Phenotypic Performance of Quantitative Characters of Wheat ( Triticum Aestivum L.) Under Stress Environment

Abstract

Ten high yielding modern varieties maintained in BARI Farm, Satkhira, Bangladesh (Aghrani, Khanchan, Bejoy, Sufi, Satabdi, Potiva, Akbar, Gourab, Prodip and Barkat) and eight collections of wheat (Triticum aestivum L.) from local farmers were grown in two different sites, saline and less-saline soils in the coastal area of Bangladesh (Satkhira district). One of the sites was at Ishwaripur of Shymnagar Upazila with high salinity level (5.3 to 8.5 dS) and another was at Alipur (low salinity level (2.2.0 to 2.8 dS) in Satkhira district during the Rabi Seasons of 2008-09 and 2009-2010 under rain fed conditions. Juvenile characters scored at four and seven weeks (plants height, number of leaves, number of tillers fresh weight, dry weight), heading time characters (plant height, number of tillers, largest leaf area, flag leaf area) and harvest time characters (plant height, tillers with spike, number of florets, number of full grains, weight of full grains, number of half-filled grains, weight of half-filled grains and yield per plant) were scored and performances were compared, in the more saline and less-saline environments, among the ten high yielding varieties and eight farmers' collection over the two seasons (2008-2010). Nineteen juvenile and maturity characters scored as indicator of phenotypic variation for growth, flowering and yield expressed high level of variation, but the degree of variability was higher in less saline environment. Salinity was observed to affect some characters and some accessions more than others. Depending on the phenotypic performance of yield, earliness, number of tillers and half filled grains six betterperforming lines in the saline environment and two better performing lines from the less-saline environment were identified during the first experiment, and were used for trial during the next year in both saline and less-saline soils for further investigation. Results indicated that plant growth, number of tillers, number of leaves, leaf area, fertile tillers, number of florets, number of full grains weight of full grains were significantly decreased by salinity stress. Salinity stress also enhanced flowering and maturation. Tiller per plant was more stable in salinity tolerant lines, so is the number of grains in the main head, number of grains in other heads were more susceptible to salinity. The results also indicated that modem varieties were more susceptible than the local farmers' collection. Out of ten modern varieties, 3 Accessions A 1 (Aghrani), A6 (Protiva) and A8 (Gaurab) produced better yield among the IO lines in the Rabi season 2008-2009 in the saline area. Three Accessions (A 14, A 16 and A 17) out of 8 farmers' collections also gave better yield. On the other hand, in the less-saline area, Accessions A5 (Satabdi), A7 (Akbar), A8 (Gaurab) and A10 (Barkat) from modern varieties and Accessions A12, A 14, A 15 and A 17 from farmers' collections were better yielding. The three Accessions (A8, A 14, A 17) were good in both the saline and less-saline environments. All these better performing Accessions indicated an efficient combination of juvenile and yield contributing characters, thus producing improved yield. In the Rabi season of 2009-2010, number of fertile tillers had decreased with the increasing salinity level with time and this negative effect of salinity was more prominent in the less-saline environment. The reduced number of grains per spike and smaller grain size resulted from increasing salinity in the less-saline area were responsible for the yield loss. During the second year, Accession A14 and A 17 were high yield giving in the saline and in the less-saline environments. Accessions A 10 A 1 and A5 had also good combination of yield contributing characters and better performance. Results indicated that effect of salinity became more pronounced late in the season and affected heading and harvest time characters. In general, the stress factors related to high salinity enhanced the life cycle of wheat - plant growth, flowering and maturation were enhanced. Thus, the number of days to heading and maturity were decreased. Out of eight wheat Accessions, grown in the Rabi season of 2009-20 I 0, A10 (Barkat), A 14 and A 17 were likely to have salt tolerance based on their relative performance for yield components and grain yield. These lines were selected for further trial and farmer based selection and also for future genetic analysis.