ABSTRACT In India, soybean is a rainy (kharif) season crop which faces excessive moisture stress (EMS) between seedling and flowering. This stress is remarkable especially in Madhya Pradesh (MP) state that accounts for 35% of national soybean production. Therefore, there is need to evaluate current popular cultivars and advanced lines under EMS conditions in MP. A field evaluation was conducted at Jawaharlal Nehru Agricultural University in Jabalpur, MP. A total of 25 soybean cultivars and lines were exposed to EMS condition at 15-20 DAS, 35-40 DAS and 55-60 DAS. As the control, the same set of soybean genotypes was grown in a well drained field condition with general cultivation practices. The EM condition resulted in drastic reduction in nodule numbers, fresh weight and dry weights at flowering, but no change in number of branches per plant, days to 50% of flowering and days of maturity. However, for some cultivars, e.g. NRC-37, highest dry weight was recorded in EMS condition. At harvest, number of seeds per plant, hundred seed weight, grain yield and harvest index decreased with EMS, relative to the control. In the control condition, the high yielding popular cultivars were Bragg (2759 kg ha-1), JS 97-52 (2407 kg ha-1), and NRC-37 (2398 kg ha-1), JS 335 (1305 kg ha-1) and JS 95-60 (1222 kg ha-1). Slightly higher yield per hectare was observed for advanced lines in control as follows: JS 20-71, 3120 kg; JS 20-87, 2991 kg; RVS2001-4, 2602 kg; JS 20-50, 2583 kg. The consistently lower yields in EMS condition over lines and cultivars suggest that a further effort to expand screening of genotypes is required for genetic improvement of EM stress tolerance.

Keywords: Excessive moisture stress (EMS) soybean, DAS (days after sowing)