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Cultivation of the same varieties of mungbean and blackgram across different seasons and locations is constrained by their photo-and thermosensitive behaviour. Developing insensitive genotypes, which can fit well across all seasons, requires robust donors which would provide genes imparting this trait. This study was undertaken to identify such donors in the Vigna species. Forty-eight accessions belonging to 13 Vigna species and eight released cultivars were evaluated under natural field conditions. Among these, two accessions, viz. V. umbellata (IC251442) and V. glabrescens (IC251372) were found photo-and thermo-insensitive as these were able to flower and set pods at temperatures as high as 43.9°C and as low as 2.7°C. Pollen viability studies indicated viable pollen (>75% at 2.7°C and >85% at 41.9°C) and normal pollen tube growth at both the extremes of temperature. The identified V. glabrescens accession has long, constricted pods and dark green, mottled seeds while V. umbellata has smooth, curved pods and shining, oval, large seeds. Both these accessions can be utilized in developing photo-thermo insensitive genotypes in cultivated Vigna species.Key words: photo -thermo insensitivity -V. umbellata -V. glabrescens -wild VignaThe genus Vigna comprises more than 200 immensely variable species. Many of these are agronomically important and depict considerable economic and environmental importance. Amongare cultivated and consumed mostly in south and Southeast Asia and Africa. Many of the above species beside their high protein grains are valued as forage, green manure and cover crops. Mungbean and blackgram are the most popular and economically important crops of the Vigna group. India is the largest producer of these crops in the world and accounts for 65% of acreage and 54% of global production (Pratap et al. 2012). Keeping in view their short crop cycle, low input requirements and ability to survive in a wide range of adverse soil and climatic conditions, there is an ample scope of growing these crops across the seasons (spring, summer, winter and rainy seasons) in different parts of the country as a sole, relay or intercrop (Pratap et al. 2013). There is also a large scope of their further horizontal expansion in large areas, particularly in the rice fallows in peninsular India and in summer cultivation after the harvest of wheat, potato and rapeseed-mustard in Punjab, Haryana, Rajasthan and western Uttar Pradesh. However, the biggest hindrance in horizontal expansion of blackgram and mungbean in India is their photo-and thermo-sensitive nature which necessitates breeding of an array of genotypes for different agro-climatic zones of the country. Most of the varieties of mungbean and blackgram which have been bred till date are suitable only for a particular agro-climatic zone and cropping season. Nevertheless, most of the farmers usually recycle their seeds year after year and also across different seasons being unaware about the suitability of a particular variety in a specific season. In most of the...

Vigna is a large, pan-tropic and highly variable group of the legumes family which is known for its > 10 cultivated species having significant commercial value for their nutritious grains and multifarious uses. The wild vignas are considered a reservoir of numerous useful traits which can be deployed for introgression of resistance to biotic and abiotic stresses, seed quality and enhanced survival capability in extreme environments. Nonetheless, for their effective utilization through introgression breeding information on their genetic diversity, population structure and crossability is imperative. Keeping this in view, the present experiment was undertaken with 119 accessions including 99 wild Vigna accessions belonging to 19 species and 18 cultivated genotypes of Vigna and 2 of Phaseolus. Total 102 polymorphic SSRs were deployed to characterize the material at molecular level which produced 1758 alleles. The genotypes were grouped into four major clusters which were further sub-divided in nine sub-clusters. Interestingly, all cultivated species shared a single cluster while no such similarities were observed for the wild accessions as these were distributed in different groups of sub-clusters. The co-dominant allelic data of 114 accessions were then utilized for obtaining status of the accessions and their hybrid forms. The model-based population structure analysis categorized 114 accessions of Vigna into 6 genetically distinct sub-populations (K = 6) following admixture-model based simulation with varying levels of admixture. 91 (79.82%) accessions resembled their hierarchy and 23 (20.18%) accessions were observed as the admixture forms. Maximum number of accessions (25) were grouped in sub-population (SP) 6 and the least accessions were grouped in SP3 and SP5 (11 each). The population genetic structure, therefore, supported genetic diversity analysis and provided an insight into the genetic lineage of these species which will help in effective use of germplasm for development of cultivars following selective prebreeding activities.

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