Abstract
Six tomato (Lycopersicon esculentum Mill.) cultivars and their fifteen F, hybrids were grown at four seasons; summer and late summer seasons of 2003 and 2004 to estimate phenotypic stability of the different 21 genotypes for fruit weight, fruit number, early and total yields. For a given trait, a stable genotype was defined as one with an individual mean greater than the grand mean, a regression coefficient (b(1)) <= 1, deviation mean squares from regression (S(2)d) = 0 and a coefficient of linear determination (R-2) > 0.50. Three hybrids (Strain B x Pakmore VF, Strain B x Tnshet Star and Pakmore VF x Tnshet Star) and two parental cultivars (Strain B and Pakmore VF) were considered high yielding and stable for all studied traits. While the hybrids Super Marmand x Shohba, Super Marmand x Indian and the parental cultivar Shohba were generally considered as low yielding and unstable. Some genotypes; such as Super Marmand x Tnshet Star, Shohba x Tnshet Star, Super Marmand and Tnshet Star; were considered stable but reflected low values for early yield, total yield and number of fruits. Some genotypes, i.e., Strain B x Shohba and Strain B x Indian, were considered unstable with high values for the three traits. Some genotypes, i.e., Indian, Shohba x Indian and Indian x Tnshet Star, were stable with low fruit weight. In contrast, other genotypes, i.e., Super Marmand, Pakmore VF x Super Marmand and Super Marmand x Tnshet Star, were unstable with high fruit weight. Generally, results indicated that tomato genotypes could be differentiated for phenotypic stability of yield and its components or for adaptability to diverse environments.