Selection of diverse genotypes for heterosis in yield and response in toria (Brassica campestris L.).

Thirty-one genotypes of toria (Brassica campestris L.) were grown in twelve environments and subsequently analysed in order to select potential parents which expressed diversity for both 12 different characters (estimated by Mahalanobis' D(2) technique) and response to the environments (estimated on the basis of negative correlation between deviations in seed yield of a pair of genotypes from their respective environmental means). Coefficients of determination (r(2)) were also used to measure the reliability of correlation, which is the basis of diversity of response. Stability parameters (b and S(2)d) and mean seed yield were also considered in selecting potential parents. On the basis of these criteria, three pairs of genotypes (ITSA and TCSU-1, TCSU-7 and TH-8 and Ludhiana Composite-1 and TH-4) are recommended to be used as parents for hybridization programmes so that heterosis both in seed yield and response may be exploited.