Heterosis and combining ability for yield and its components in potato in early planting heat stress conditions

Forty-eight populations developed according to line x tester (12 x 4) mating design alongwith their parents were studied for the relative magnitude of combining ability variances and combining ability effects under heat stress September planting condition at Jalandhar, Punjab. These were studied for total yield, marketable yield, average tuber weight, tuber number/plot and plant vigour in third and fourth clonal generations. The variances due to general and specific combining ability showed that non-additive component was predominant and additive variance was of little value for most of the char-acters. CP 1458, JEB/A 53, CP 1515 and MS/89-1095 were found to be good general combiners for yield and yield contributing characters like tuber number and/or average tuber weight. Based on per se performance and specific combining ability effects, the crosses CP 1458 x JEX/A 805, JEB/A 53 x MS/89-1095, JEB/A 53 x CP 1704, MS/78-62 x CP 1406 and CP 1659 x CP 1704 were found promising.