Genetic Variability Studies in M5 Generations of Determinate Early Maturing Cluster Bean [Cyamopsis tetragonoloba (L.) Taub] (MDU-1) Mutants for Yield and Yield Attributing Characters

Background: MDU-1 is a high yielding, indeterminate cluster bean variety. In order to develop determinate mutant with high yield, MDU-1 cluster bean variety was irradiated using gamma rays, electron beam and combination of gamma rays and EMS with different doses and the variability induced in M5 generations were studied. Methods: Twenty one best individual plants from M4 generation were selected based on plant height and higher yield and forwarded to M5 generation where they were evaluated in RBD with three replications. Fourteen non-segregating mutant lines with desirable traits were identified in M5 generation and were evaluated for variability along with the parent MDU1. Result: Five best mutant lines namely ACMC-020-04, ACMC-020-11, ACMC-020-08, ACMC-020-10 and ACMC-020-11 were selected from the 14 accessions based on per se performance and variability analysis. The selected mutants needs to be forwarded for stability testing in different environments.

Nodulation Compatibility and Symbiotic Performance of Rhizobia spp. With Different Landraces of Bambara Groundnut (Vigna Subterranea (L.) Verdc.) Collections

The symbiosis of the legume bambara groundnut (Vigna subterranean L.Verde) with its rhizobial partners has not been studied sufficiently compared to several other legumes throughout Africa. In this study, a nodulation compatibility screening was conducted on 16 different landraces of this legume using five Rhizobia strains previously isolated from active nodules of Desmodium uncinatum, Arachis hypogaea, Cyamopsis tetragonoloba, Glycine max and Phaseolus vulgaris and deposited at the South African Rhizobium Culture Collection (SARCC). A screening assay was conducted under glasshouse to select compatible rhizobia strains that nodulate and enhance growth in one or more genotypes of V. subterranean (L.) Verdc. Pre-germinated seeds of each landraces planted in sterile river sand medium were inoculated with 108 cfu ml-1 of the rhizobial strains (2ml/seed) and monitored with regular watering for six weeks. Parameters such as nodule number, nodule color and positions, plant biomass were determined in test genotypes. Significant differences were observed among landraces in nodule number and plant biomass, and among rhizobial strains in nodule number. Principal component analysis (PCA) showed that root nodule rhizobia strains SARCC-388 and SARCC-578 characterized as Bradyrhizobium zhangiangens and Bradyrhizobium centrosematis, respectively exhibited the highest nodulation compatibility with one or more bambara groundnut landraces. This study demonstrated that many of the bambara landraces did not show nodulation preference to a unique group of rhizobia, confirming that V. subterranean (L) Verdc can be nodulated by more than one species of rhizobia, especially by rhizobia belonging to the cowpea miscellany cross inoculation group.

Economic Analysis of Cluster Bean [Cyamopsis tetragonoloba (L.) Taub] Entrepreneurs in Karnataka

Background: Karnataka is predominantly known for cluster bean production. The evidences claims that the cluster bean production is not a profitable option and has many constraints, which hinders farmers to take up this enterprise. The current study aims to analyze the growth in area, to forecast seed demand and to work out the economics of cluster bean production in Karnataka. Methods: The current study was based on the field survey conducted in Karnataka during 2019-20, to collect the primary data from cluster bean entrepreneurs. The study has also used secondary data for analysis. Four major districts in Karnataka were selected for the study, based on the maximum area and highest production. From each district, 30 farmers were randomly selected for collection of primary data, constituting a total of 120 farmers. The Compound Annual Growth Rate and cost-returns techniques were employed for data analysis. Result: The study indicated that Karnataka has registered a declined trend of 3.12 per cent per annum and the total estimated area under cluster bean would be 2,720 ha during 2021-22. Hence, the seed industry should cater seed demand to the tune of 544 quintals for the said period. Total cost of cultivation was worked out to be ₹ 35,176 per acre. The study emphasize that this enterprise provides higher gross and net returns to the tune of ₹ 70,851 and ₹ 35,675 per acre, respectively, with the Benefit-cost ratio of 2.01, indicating its profitability. Lack of availability of High Yielding Varieties/hybrid seeds and high wage rate were the major constraints notified in cluster bean enterprise.

​Genetic Diversity for Seed Yield and its Components in Clusterbean [Cymopsis tetragonaloba (L.) Taub]

Background: Clusterbean [Cyamopsis tetragonoloba (L.) Taub.] (2n=2x=14) is an under exploited legume belonging to family fabaceae. Clusterbean is a versatile legume crop cultivated mostly as animal feed, green manure green leaves as fodder, vegetable and cover crop. Clusterbean is a drought resistant, hardy, deep rooted annual legume crop. D2 statistics provides a measure of magnitude for divergence between two genotypes under comparison. For broadening the genetic base of cultivars, the genetic diversity present in cultivated and wild relatives must be explored. Generally, diverse germplasms are expected to give high hybrid vigor and hence, it necessitates studying genetic divergence among the existing varieties and genotypes for the identification of parents for hybridization programme. Methods: The present investigation was undertaken to study genetic variability in clusterbean [Cymopsis tetragonaloba (L.) Taub] with using a set of 40 genotypes at Agronomy Instructional Farm, Department of Agronomy, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar during Kharif 2019 in randomized block design with four replications. Mahalanobis (1928) D2 statistic was used for assessing the genetic divergence between different populations. Grouping of the genotypes in different clusters was done by using Tocher’s method. The inter-cluster distance was calculated by measuring the distance between clusters I and cluster II, between clusters I and cluster III, between clusters II and cluster III and so on. Likewise, one by one cluster was taken and their distances from other clusters were calculated. Result: The genetic diversity analysis revealed the formation of nine clusters suggested the presence of considerable genetic diversity among the 40 genotypes. The clustering pattern indicated that geographic diversity was not associated with genetic diversity. The analysis of per cent contribution of various characters towards the expression of total genetic divergence indicated that, the number of branches per plant followed by gum content, days to maturity, days to flowering contributed maximum towards total genetic divergence. On the basis of inter cluster distances, cluster IX was found to be more divergent. Therefore, it was concluded that the genotypes belonging to these cluster should be inter crossed in order to generate more variability.

Correlation and Path Coefficient Analysis in Cluster Bean [Cyamopsis tetragonoloba (L.) Taub.] Genotypes

Background: Climate change is a major challenge faced by the agricultural sector all over the world. Different adaptation and mitigation strategies are used to cope with these weather aberrations. Growing climate resilient crops and cultivars suitable for different regions is one of the adaptation strategy. Leguminous crops are well known for their resilience, adaptation and tolerance to adverse conditions, among these crops cluster bean is a hardy and drought tolerant crop extremely suitable for warm tropical regions. Hence identification and improvement of selected genotypes of cluster bean have paramount importance for combating the challenges possessed by the changing climatic scenario. Methods: Thirty accessions of cluster bean were evaluated during 2018. The experiment was laid out in randomized block design with two replications. Statistical analysis was employed for estimation of correlation and path coefficients. Result: The correlation analysis revealed that pod yield/plant had positive significant correlation with number of branches, number of pod clusters/plant, number of pods/plant and days to first harvest hence, selection of accessions having higher mean values for these traits could improve yield in cluster bean. Path analysis revealed that number of pods/plant had maximum positive direct effect on pod yield/plant followed by number of branches and plant height. Thus, while attempting selection for higher pod yield in cluster bean, number of pods per plant, number of branches and plant height have to be taken into account.