GROWTH ANALYSIS OF SOYBEAN LANDRACES UNDER EXTENDED PLANTING DATES

Growth potential of three indigenous landraces (Kulat brown, Kulat white, Mothi) and two improved varieties (NARC-II and Swat-84) of soybean planted under four dates from April to July during 2004 and 2005 growing season were compared. Relative growth rate (RGR) was determined at 1) early vegetative growth 2) bloom and 3) seed filling stages and seed yield. Differences in RGR due to planting dates, varieties and planting dates x varieties were significant at early vegetative and bloom stages. At seed filling stage, varieties and planting dates x varieties did not show variation in RGR. Maximum RGR at the early vegetative growth, bloom and seed filling stages was recorded for July (89mg g^-1 day^-1) May (58.8 mg g^-1 day^-1) and April (8 mg g^-1 day^-1) planted crops, respectively. Similarly maximum seed yield (1459 kg ha^-1) was observed in April planted crop. The average RGR recorded for early vegetative growth, bloom and seed filling stages was 71.6, 40.1 and 4.8 mg g^-1 day^-1 respectively. At early vegetative growth, maximum RGR (79.6 mg g^-1 day^-1) was observed for Kulat brown. At bloom, maximum RGR (46.3 mg g^-1 day^-1) was recorded for Kulat white. At seed filling no difference was observed in RGR among the varieties. The overall average RGR for the landraces (42.4 mg g^-1 day^-1) was greater than the RGR of improved varieties (34.1 mg g^-1 day^-1). Improved varieties produced maximum seed yield (1306 kg ha-1) as compared to landraces (1245 kg ha^-1).