Genetic Studies of Agronomic and Physiological Traits in Tomato (Lycopersicon lycopersicum Mill.) Under Heat Stress Conditions

Field experiments were conducted at National Horticultural Research Institute, Bagauda (11°33´N; 8°23´E) in the Sudan Savannah and Institute for Agricultural Research, Samaru (11°11´N; 07°38’E) in the Northern Guinea Savanna ecological zones of Nigeria between July-October, 2014 rainy season to estimate Genotypic Coefficient of Variation (GCV), Phenotypic Coefficient of Variation (PCV), heritability, Genetic Advance (GA) and Genetic Advance as percent of Mean (GAM) for agronomic and physiological traits of tomato under heat stress conditions. The study comprised 15 hybrids, their parental lines along with four checks were laid out in partially balanced lattice design with three replications. Analysis of variance revealed significant variation among the genotypes for all traits except fruit diameter, indicating sufficient variability existed among the genotypes. The estimates of PCV were higher than GCV. High GCV and PCV values were recorded for number of clusters per plant, and number of fruits per plant suggesting high genetic variability for these traits. Broad-sense heritability varied from 5.20% to 98.92%, while the estimates of GA showed a wide range from 0.09 to 161.13. High estimates of Broad-sense heritability coupled with high GAM were observed for the number of clusters per plant, number of flowers per cluster, number of fruits per cluster, number of fruits per plant, fruit length, fruit shape index and yield per plant indicating additive gene effects for the hereditary pattern of roles. Based on the results of the study, simple selection based on phenotypic performance of these traits would provide better response and also considered for higher fruit yield under heat stress conditions.