Reaction of rice bean [Vigna umbellata (Thunb.) Ohwi and Ohashi] landraces from Manipur to bruchid infestation

Rice bean (Vigna umbellata) is one of the under-exploited tropical food legumes and is regarded as a potentially valuable multipurpose (grain, fodder and green manure) crop for farmers in the marginal hill areas of north-eastern India, especially Manipur. The seeds of rice bean are comparatively resistant to storage grain pests including bruchids (Callosobruchus maculatus), which generally damage other pulses. However, there are reports of seed damage by bruchids during storage. In the present study, seeds of seven rice bean landraces collected from local markets in Imphal, Manipur and one landrace from the Himalayan region (later maintained at Agricultural Research Station, Virinjipuram, Vellore, Tamil Nadu) were used to determine their reaction against bruchid infestation. The results suggested no role of antixenosis (non-preference) mechanism in imparting resistance to bruchids. Understanding of factor(s) contributing to bruchid resistance is useful for development of rice bean cultivars. To date, rice bean has not been subjected to systematic breeding, despite the species' many useful characteristics. The results of the study will be particularly useful in identifying genotypes for use as parents in pulse breeding programmes.