GENETIC STUDIES ON YIELD AND YIELD RELATED TRAITS IN WHEAT UNDER NORMAL AND WATER STRESS CONDITIONS

Abstract

Six wheat cultivars/lines viz; Baviacore, Nesser, 9247, 9252, 9258 and 9267 were crossed following complete diallel technique. The seed of F 1 crosses and parents was planted in the experimental area of Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. Planting was done under normal and water stress conditions following randomized complete block design with three replications in both of the cases. The data was recorded on ten guarded plants tagged for the purpose for each parent and cross in each replication under both of the conditions. The traits like plant height, peduncle length, specific flag leaf area, specific flag leaf weight, stomatal frequency (upper flag leaf surface), size of stomata, days to heading, number of spikes per plant, spike density, number of grains per spike, 100-grain weight, biological yield, grain yield and harvest index were recorded on tagged plants in each replication. The recorded data were subjected to the analysis of variance technique to determine the genotypic differences for the traits which were exhibited highly significant under both of the water availability conditions. Combining ability and gene action analysis was carried out for all of the parameters studies. Significant change in the mean performance of all the characters was observed under the water stress condition. Additive gene action was obtained in the characters like plant height, peduncle length, stomatal frequency, size of stomata, days to heading, spike density, and 100-grain weight when evaluation was made using Griffing’s approach while the characters like plant height, peduncle length, stomatal frequency, size of stomata, days to heading, spike density, 100-grain weight, biological yield and grain yield was observed when calculations were done using Hayman’s approach under irrigated condition. Non-additive gene action was exhibited in the characters like specific flag leaf area, specific flag leaf weight, number of spikes per plant, number of grains per spike, biological yield, grain yield and harvest index through the use of Griffing’s approach and over dominance in the characters like specific flag leaf area, specific flag leaf weight, number of spikes per plant and harvest index when Hayman’s approach was used for calculations under irrigated condition. The results under water stress conditions revealed that gene action exhibited in the characters like peduncle length, stomatal frequency, size of stomata, days to heading, spike density and 100-grain weight was additive when Griffing’s approach for analysis was adopted while using the 1analysis though Hayman’s approach, additive gene action was shown by the characters like peduncle length, stomatal frequency, size of stomata, days to heading, spike density, biological yield and grain yield. The characters like plant height, specific flag leaf area, specific flag leaf weight, number of spikes per plant, number of grains per spike, biological yield, grain yield and harvest index gave non-additive gene action in Griffing’s approach and plant height, specific flag leaf area, specific flag leaf weight, number of spikes per plant, 100-grain weight and harvest exhibited over dominance in Hayman’s approach under water stress conditions. Similar gene action was shown by both calculations i.e. Griffing’s as well as Hayman’s approach for most of the characters under irrigated as well as water stress conditions except number of grains per spike, biological and grain yield under irrigated and biological and grain yield under water stress conditions. The difference of results might be due to the reason that means were used in calculation by the numerical approach while variances in graphical approach. Multi disciplinary approach involving plant breeding, genetics, biotechnology, physiology, soil and crop management for the development of water stress tolerant/ resistant genotypes in wheat, is suggested.