Outcrossing in Mungbean (Vigna Radiata (L.) Wilczek) Depends on Cultivars and Seasons

Mungbean (Vigna radiata (L.) Wilczek) are mainly cultivated in aouthern and eastern Asia and sporadically in hot and dry regions of southern Europe and the southern USA. Traditionally small/medium seeded types are cultivated in India in all seasons depending upon particular area and climate. The recent introductions of short duration bold seeded varieties of mungbean from AVRDC, Thailand have shown great promise due to their short maturity duration. However, the basic information on extent of natural outcrossing in bold seeded mungbean varieties would be desirable for implementing suitable methodology in breeding program as it increases the risk of cultivar impurity and seed admixture. Therefore, the experiment was carried out at IARI, New Delhi during spring and rainy season of 2006 and 2007 using seed coat colour as marker to estimate the natural outcrossing affecting seed impurity. Varieties with shinning seed coat (Pusa Vishal, Pusa Ratna and Pusa 9531) were planted in the plot with dull seed coat variety (Pant Mung 4) and the outcrossing rate was estimated from frequency of dull seed coat plants in the progeny of shinning seed coat plants. The degree of outcrossing ranged from 0 to 8.26%. The extent of outcrossing in mungbean was strongly influenced by varieties and season. The outcrossing rate of individuals also varied within cultivars. The bold seeded varieties had more outcrossing in comparison to small seeded and rainy season has greater incidence of natural outcrossing.