A CHANGES IN SOYBEAN SEED QUALITY AND VIGOUR UNDER DIFFERENT PLANTING DATES

Low seed quality resulting into poor stand establishment is one of the major constraint in promotion of soybean production. The present study aimed at assessing the seed quality of three indigenous varieties (Kulat brown, Kulat white, Mothi) and two improved varieties (NARC-II, Swat-84) planted at monthly interval from April to July, 2004 and 2005 at Agriculture University, Peshawar, Pakistan. The seed harvested from each treatment was subjected to accelerated aging, tetrazolium test, electrical conductivity and seedling dry weight. Maximum values for accelerated aging (73.9 %) and tetrazolium test (75.3 %) were recorded in seeds harvested from May and April planted crop respectively. However, maximum electrical conductivity (0.37 dsm-1) and seedling dry weight (15.7 mg) was recorded from July and June planted crops respectively. Maximum accelerated aging germination (72.2 %) and tetrazolium test values (82.4 %) were recorded for Kulat brown and Mothi respectively. Swat-84 exhibited maximum electrical conductivity (0.59 dsm-1) and seedling dry weight (15.9 mg). Land races demonstrated maximum values for accelerated aging test (71.2 %) and tetrazolium test (80.6 %). Improved varieties had greater electrical conductivity values (0.49 dsm-1) and seedling dry weight (15.7 mg). It is concluded that maximum seed quality and vigour values were determined for land races except seedling dry weight and electrical conductivity values.