Association Mapping for Yield Attributing Traits and Yellow Mosaic Disease Resistance in Mung Bean [Vigna radiata (L.) Wilczek]

Mung bean [Vigna radiata (L.) Wilczek] is an important short-duration grain legume widely known for its nutritional, soil ameliorative, and cropping system intensification properties. This study aims at evaluating genetic diversity among mung bean genotypes and detecting genomic regions associated with various yield attributing traits and yellow mosaic disease (YMD) resistance by association mapping. A panel of 80 cultivars and advanced breeding lines was evaluated for 10 yield-related and YMD resistance traits during kharif (monsoon) and summer seasons of 2018–2019 and 2019–2020. A total of 164 genome-wide simple sequence repeat (SSR) markers were initially screened, out of which 89 were found polymorphic which generated 317 polymorphic alleles with an average of 3.56 alleles per SSR locus. The number of alleles at each locus varied from 2 to 7. The population genetic structure analysis grouped different genotypes in three major clusters and three genetically distinct subpopulations (SPs) (i.e., SP-1, SP-2, and SP-3) with one admixture subpopulation (SP-4). Both cluster and population genetic structure analysis categorized the advanced mung bean genotypes in a single group/SP and the released varieties in other groups/SPs, suggesting that the studied genotypes may have common ancestral history at some level. The population genetic structure was also in agreement with the genetic diversity analysis. The estimate of the average degree of linkage disequilibrium (LD) present at the genome level in 80 mung bean genotypes unveiled significant LD blocks. Over the four seasons, 10 marker-trait associations were observed significant for YMD and four seed yield (SY)-related traits viz., days to flowering, days to maturity, plant height, and number of pods per plant using the mixed linear model (MLM) method. These associations may be useful for marker-assisted mung bean yield improvement programs and YMD resistance.

​Nodulation, Yield Attributes and Yield of Mungbean [Vigna radiata (L.)] Influenced by Different Level of Potassium Humate and Fertility Levels

Background: Optimum crop growth and yield is result of interlinking of several factors. In semi- tropical soil in central plateau and hills zone are deficit in organic carbon and NPK content; therefore inadequate fertilization may leads to pure quality and also lower crop productive capacity of soil. For the maintenance of sustainable and productive production, maintaining soil health is a critical factor. Under low fertility levels, mungbean gives low seed yield. Potassium humate, nitrogen and phosphorus (RDF) application may be increase yield of mungbean in this zone. Method: A field experiment was conducted to study, “Nodulation, yield attributes and yield of mungbean [Vigna radiata (L.)] influenced by different level of potassium humate and fertility. The experiment was carried out in factorial randomized block design with three replications and sixteen treatment combination. Result: Result showed that total number of root nodules, effective nodules, fresh and dry weight of root nodules, leghaemoglobin, nodule index, no. of pods/plant, no. of seeds/pod, test weight, seed and straw yield were observed significantly higher with application of potassium humate @ 4.5 kg/ha. Among different fertility level, the application of 100% RDF significantly increased the total number of root nodules and effective nodules, fresh and dry weight of root nodules, leghaemoglobin, nodule index, no. of pods/plant, no. of seeds/pod and test weight, seed and straw yield. With combined application of potassium humate @ 3.0 kg/ha + 75% RDF significantly higher no. effective nodules, dry weight of root nodules and seed yield were observed, as well as saving of 25% RDF and 1.5 kg potassium humate were also observed.

Multivariate Analysis and its Application for Screening Mungbean [Vigna radiata (L.) Wilczek] Landraces

Background: Mungbean [Vigna radiata (L.) Wilczek] is known as one of the important crop of the Vigna group. In order to determine morphological traits of mungbean, multivariate analysis will provide important advantages in the selection phase of future breeding programs. Multivariate statistical analysis was used to determine and classify these traits. Multivariate analysis, that includes principal component analysis (PCA) and cluster analysis (CA), is considered the best tool for selecting promising genotypes in the future breeding programs. Methods: Eighteen landraces and two species were used to classify morphological traits in this study. Nine different morphological traits were observed during the research period. These are; days to 50% flowering (DFT), plant height (PH), branches per plant (BPP), clusters per plant (CPP), number of pods per cluster (PPC), seed yield per plot (SYPP), biomass yield per plot (BYPP), harvest index (HI), 1000 seed weight (SW). Result: Principal component analysis (PCA) revealed a high level of variation among the genotypes. Therefore, high variability was observed in DFT (36-59 day), PH (39-76 cm), BPP (3-7), CPP (4-21), SYPP (231-824 g), BYPP (3300-10300 g), HI (6.77-11.25%) and 1000 SW (19.95-50.50 g). According to cluster analysis, landraces with the least genetic diversity distance between them in terms of morphological traits examined were determined as 2 and 3.

​Allelopathic Chemical Screening of Aqueous Extracts of Coir Pith on Seedling Growth of Black Gram (Vigna mungo L.) and Green Gram (Vigna radiata L.)

Background: Black gram (Vigna mungo L.) and Green gram (Vigna radiata L.) were mostly used as chemical residue indicators for testing the persistence of pesticides, fungicides and herbicides, etc. in the soil. Presently, the coir pith was used as a medium of nursery for many seeds and seedling production. This study evaluated the inhibition effects and screening of allelopathic chemicals from aqueous extracts of coir pith and composting coir pith on the back gram and green gram by response index method and GCMS/MS analysis. Methods: The coir pith and composted coir pith soaked the ratio of 1:10 for 24 hrs, filtered through Whatman No.1 filter paper. The inhibition effect tested for germination and seedling growth of black gram and green gram was sown in poly pots. The carbon: nitrogen ratio and the total organic carbon were analyzed by dry combustion method, Kjeldahl method and GCMS/MS analysis. Result: The phytotoxic substances are present in coir pith, which can be exterminated by composting the coir pith for better growth and development of seedlings. The negative response index (RI), high C: N ratio and chemical compounds like tocopherol, fucoxanthin, tetramethyl heptadeca, dichloroacetamide, tetrazole, hydroxyethyl palmitate, neocurdione and uridine derivations present in raw coir may have the phytotoxic effect and produced yellowing symptoms in young plants compared to composted coir pith. This is exterminated by composting the coir pith for better growth and development of seedlings as well as used for various agricultural and horticultural nurseries.