Background: Blackgram [Vigna mungo (L.) Hepper] is an important food legume crop of India. Mungbean yellow mosaic virus (MYMV) disease is the major problem in blackgram. The disease can reduce seed yield upto 100% or even kill a plant infected at an early vegetative stage. The most effective way to prevent the occurrence of this disease is to develop genetically resistant cultivars of blackgram. However, a major difficulty in breeding MYMV disease resistant in blackgram is field screening for the virus disease. Hence identification of QTL followed by Marker-assisted selection (MAS) is highly useful for genetic improvement of crops. With this background, a study was made for identification as well as validation of quantitative trait loci (QTL) for MYMV disease resistance in blackgram.Methods: A total of 112 F2:3 lines were evaluated for MYMV disease resistance along with parents viz., MDU 1 (MYMV disease susceptible) and Mash 1008 (MYMV disease resistant) at the National Pulses Research Centre, Tamil Nadu Agricultural University, Vamban, Tamil Nadu during July-September 2018 under Augmented Design in the field. Each line was sown in one row of 3 m in length with a spacing of 30 cm as between row and 10 cm as within row. Susceptible genotypes CO 5 and MDU 1 were sown as disease spreader rows after every eight rows and also around the plots. The MYMV disease score was recorded on 60 DAS, by using phenotype rating scale from 1 (resistant) to 9 (highly susceptible), as suggested by Singh et al. (1995). The mean of each progeny was calculated and used as phenotypic data. A total of 525 SSR primers were used to test polymorphism between parents MDU 1 and Mash 1008. Genotyping was carried out for 112 F2:3 RILs of the cross MDU 1 x Mash 1008 with 35 polymorphic SSR markers. Linkage and QTL analyses were performed using QTL IciMapping (version 4.1.0.0) (Wang et al. 2016) and QGene 4.4.0 (Joehanes and Nelson 2008) respectively. Two mapping populations MDU 1 x Mash 114 and CO 5 x VBN 6 in F2:3 and F2 generations respectively were used in this study to validate the identified QTL regions.Result: QTL study indicated the presence of two major QTLs for MYMV disease score in LG 2 and LG 10 at 60 DAS with 20.90 and 24.90% of phenotypic variation respectively. Validation of these QTLs in two other mapping population indicated that QTL on LG 10 was validated with high phenotypic variation of 45.40-46.00%. Hence it may conclude that qmymv10_60 may be utilized for MAS/MABC with assured improvement on MYMV disease resistance in blackgram.

Background: Blackgram [Vigna mungo (L.) Hepper] is a rich source of protein. It is one of the major crops essentially involved in daily human diets. However, storage pest bruchine [Callosobruchus maculatus (F.)] is a major production constraint for legumes. A research was formulated to assess the bruchine resistance in 20 blackgram genotypes along with the biochemical analysis to find out the active biochemical components responsible for the resistance activity.Methods: The experiment was carried out during August- October, 2019 at Entomology Laboratory, National Pulses Research Center, Vamban, India. The experimental material comprised of 20 blackgram genotypes which were screened for bruchine resistance. Further, confirmatory trial was conducted with selected resistant entries and highly susceptible entries during October- December, 2019. Both experiments were carried out in completely randomized design and replicated three times. GC-MS analysis on the resistant and susceptible entries were performed to ascertain the active biochemical components conferring resistance.Result: Among the genotypes, TU 68 had comparatively late developmental time (days), less number of adult emergence, higher mean developmental period (days), less susceptibility index, less seed damage (%) and less seed weight loss (%). Genotype TU 68 was found to be resistant in the confirmatory trial also. Less number of adult emergence and higher mean developmental period indicated the delayed developmental period which is a mechanism of bruchine resistance. GC-MS analysis on resistant (TU 68) and susceptible (MDU 1) genotypes indicated the presence of active biochemical compounds with insectifuge activity in TU 68. Hence, TU 68 could be utilized in the hybridization programmeas donor for bruchine resistance.

Background: Bruchine is one of the notorious pests that renders both the quantity and quality of pulses stored produce especially blackgram. Hence the present study was carried out to ascertain the essential selection indices among the bruchine resistance traits involved. Methods: A laboratory experiment was conducted to estimate the variability parameters for traits related to bruchine infestation in various crosses of blackgram viz., MDU1 × TU68, VBN6 × TU68 and VBN8 × TU68 at National Pulses Research Centre, Vamban. Observations were recorded for eight bruchine resistance traits on each single plants from three crosses. Result: The results indicated that all traits viz., total number of adult emergence, developmental time, mean developmental period, index of susceptibility, seed damage (%) and seed weight loss (%) recorded high PCV and GCV in all crosses except developmental time which had moderate to low variation. All traits also recorded high heritability and genetic advance as per cent of mean in all crosses except developmental time. Developmental time had moderate to high heritability and genetic advance over the crosses. Considering skewness and kurtosis, the cross MDU 1 × TU 68 had a wide variation for total number of adult emergence and seed damage. Hence the cross MDU 1 × TU 68 could be selected for the selection of bruchid resistant individuals. The association studies revealed that traits viz., developmental time, total number of adult emergence, index of susceptibility and seed damage were reliable selection indices for the seed weight loss.

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