Abstract

                                Heterosis and combining ability analysis were made on 30 F1 hybrids, obtained through direct and reciprocal crosses of six parents in two seasons during 2002. Majority of the hybrids exhibited unfavorable heterotic response and reciprocal differences for all the traits studied, were observed. Eleven out of 30 hybrids recorded heterobeltiosis for yield per plant. The hybrids LCR 9 x H 24, H 24 x LCR 9 and H 24 x LCR 1 registered heterosis over the best parent in respect of total disease resistance. Additive gene action played an overall role in the inheritance of fruit weight, total and ortho_x0002_dihydroxy phenol (OD) and tomato leaf curl virus (TLCV) resistance. The parent H 24 possessed high favorable gca for five out of six characters viz., yield, total and OD phenol, TLCV and Tospovirus (Tv) resistance followed by CLN 2123A for total and OD phenol and TLCV resistance. The hybrid H 24 x CLN 2123A exhibited high heterosis and sca for yield, total phenol, TLCV and Tv resistance. Influence of modifiers and environment on the expression of resistance to viral diseases by the hybrids was evident. The hybrids showing favorable sca for the studied traits seldom had high x high gca parental combinations

Key words : Tomato, heterosis, combining ability, tomato leaf curl virus, tospovirus