Year : 2005, Volume : 32, Issue : 1 and 2
Print ISSN : 0970-8235.
Heterosis and combining ability for yield and its components in potato in early planting heat stress conditions
Authors: Kumar Raj, Kang G.S.1
1Central Potato Research Station, Post Bag No. 1, Model Town P.O., Jalandhar 144 003, Punjab, India
In north Indian plains of Punjab the optimum time for planting potato crop is in the first week of October. The crop, if planted early in mid-September, suffers from high temperature/heat stress resulting in low yields. Potato varieties capable of withstanding early planting conditions can allow taking rice-potato-wheat as sequential crops in the region. Such varieties giving yield of about 20–25 tonnes/ha in 60–75 days can be sandwiched between the crops in different farming systems without limiting the biodiversity of associated crops (15). Knowledge of combining ability is important for planning hybridization for breeding programmes. Most of the studies on combining ability in potato have been carried out for main season crop. The information on combining ability under heat stress conditions is lacking. The present study was, therefore, undertaken to estimate combining ability of 16 parents and their crosses for 5 economic characters in September planted potato crop.
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.