A Study of genetic diversity for water stress tolerance in spring wheat (Triticum 14aestivum L.)

Abstract

In this study, seventy five genotypes were screened out for seedling parameters under water stress and selected on the basis of seedling survivability keeping in view survival after desiccation and evaluated for seedling growth response under water stress. The selected six water stress tolerant genotypes (Kohistan-97, Shafaq-2006, Sehar-2006, Inqlab-91, Chakwal-86 and Fsd-2008) and threewater susceptiblegenotypes (V08172, Punjab-81 and MH-97) were crossed using line x tester mating design. The hybrids along with their parents were sown in normal irrigation and water stress environment using a randomized complete block design. The objective of the study was to evaluate the effect of water stress on genetic diversity of parental lines as well as F1 generation of wheat genotypes. Plants for each treatment were randomly selected and data on yield and yield contributing traits was collected. Estimates of General combining ability (GCA) effects indicated that under water stress, the line Kohistan-97 and tester MH-97 exhibited the significant GCA effects for most of the traits under study. Estimates of Specific combining ability (SCA) effects showed that in normal conditions, cross combination Kohistan-97 × V08172 exhibited maximum significant SCA effects for days to heading, plant length, biological yield and stem reserve mobilization. Whereas, for number of tillers per plant, spike length, number of spikelet per spike, number of grains per spike, 1000-grain weight, leaf area and economic yield per plant hybrids Chakwal-86× Punjab 81 exhibited maximum SCA effects, respectively. In water stress condition, maximum SCA effects were observed, for days to heading, 1000-grain weight, plant length, biological yield and stem reserve mobilization. For number of tillers per plant, spike length, number of spikelet per spike, number of grains per spike, leaf area and economic yield per plant highest SCA effects were found in hybrids Kohistan-97 × V08172, Chakwal-86 × Punjab-81, Fsd-2008 × Punjab-81, Sehar-2006 × V08172 and Chakwal-86 × V08172, respectively. Intensity of aphid attack on wheat genotypes at different stages of growth under normal irrigation and water stress environment was also studied.The highest number of aphids per tiller (1.00 ± 0.01) was recorded on Shafaq-2006 cultivar, whereas the lowest one (0.10 ± 0.01) was recorded on Sehar-2006x Punjab-81, Kohistan-97x MH-97, Fsd 2008x Punjab-81 crosses Genetic analysis and combining ability of traits would be undertaken under normal irrigation and water stress environments. Collectively, results suggested that selection by combining seedling survivability, root-shoot parameters and growth response in lab as well as in field can be efficiently used for rapid evaluation of water stress tolerance in wheat breeding.