GENETIC ANALYSIS OF YIELD AND ITS COMPONENTS IN F 1 AND F 2 POPULATIONS OF TOMATILLO (Physalis ixocarpa Brot. / Physalis philadelphica Lam.)

Abstract

A tomatillo (Physalis ixocarpa Brot. /Physalis philadelphica Lam.) core collection consisting of five parental genotypes viz., SAU tomatillo 1 (G1), SAU tomatillo 2 (G2), PI003 (G3), PI004 (G4) and PI005 (G5) was explored for variation in plant growth, yield and fruit quality traits, in order to develop improved plants with desirable traits from subsequent tomatillo diallel crossing program. Twenty F populations of tomatillo were derived from 5x5 diallel crosses to combine desirable genes from different parents and to produce pure-breeding progeny superior in many respects to the parental types. F 1 population was developed in order to select superior genotyes as the greatest genetic variability exists in the F xviii 2 population and the most effective selection occurs there. The experiments were conducted at replicated plots following RCBD design in the central experimental field and central laboratory of Sher-eBangla Agricultural University, Dhaka during Oct/2017 to Mar/2020. Analysis of variance for

agromorphogenic

traits of five parental and twenty hybrids of tomatillo showed significant variation in yields and in quality traits. Maximum yield was found in parent G3 (740.67 g/plant), in F 1 population G1×G3 (1060.66 g/plant) and in F population G1×G3 (1021.33 g/plant). Cross ability analysis of tomatillo showed excellent cross ability in G3, G1 and G4 and their crosses in three years. Estimation of heterosis, assessment of combining ability and gene actions for different characters were performed. Maximum standard heterosis was found 2 in G1×G3 (19.35%) followed by G1×G2 (10.94) for yield/ha. These crosses deserve attention for their heterotic responses. The ANOVA of combining ability analysis showed highly significant results for most characters which suggested the presence of both additive and nonadditive

gene action for inheritance. The GCA effects revealed that the parents G1and G3 showed the best general combiner. The highest positive significant SCA effect was found in G3×G1 (11.51**) and the cross G1×G3 was the best specific combiner for yield per ha. Genetic analysis in F 1 , F

populations revealed that both additive and non-additive genetic effects were important for different characters. Extent and direction of heterosis in F 2

varied greatly for different characters. Diallel analysis was performed using the Hayman’s approach chiefly comprises the aspects, Hayman’s ANOVA, Vr, Wr analysis with graphical representation and components of variation and genetic parameters. Vr-Wr graph suggested that partial dominance and/or over dominance gene actions were involved for all the characters in F . The ranks of parental dominance were: G5 > G4 > G1 > G2 > G3 in the increasing order for the trait yield. Magnitude of E for each character was much less compared to their respecting D and H1 suggesting the characters were influenced less by environment. The ratio of (H2/4H1) estimated the average frequency of positive and negative 1 alleles in all the parents. The significant correlation was found in fruit pH, lycopene content (502) and fruit moisture content at genotypic level and in fruit moisture and lycopene content at phenotypic level. Based on the value of yield components, the highest selection score was found in G1×G3 (1065.57) having ranked 1 followed by G1×G2 (1032.15) with rank 2. The lowest ranked genotype was found in G2×G4 (701.66) with rank of 20 followed by G4×G2 (725.09) having ranked 19. The highest selection score was found in G1×G3 (18.719) having ranked 1 followed by G3×G1 (17.409) with rank 2 for quality traits. G1×G3 and G1×G2 could be recommended for further selection trial for higher yield towards variety development of tomatillo. Different gene actions underlying these traits provides valuable insight in the further selections and can be used to support breeding strategies for tomatillo crop improvement.