Studies on Effect of Mutagens on Quantitative Characters in M2 and M3 Generation of Horsegram [Macrotyloma uniflorum (Lam.) Verdc]

Background: Induction of mutation plays an important role in the breeding programme among modern methods of plant breeding. Genetic variability is prerequisite for crop improvement and through induced mutation it was found to be very effective for creating variability in the quantitative and qualitative characters. Hence, the present study was aimed to induce genetic variability within short time. In the present investigation positive as well as negative impact on quantitative traits were recorded. Methods: The experiment material comprised of seeds of horsegram [Macrotyloma uniflorum (Lam.) Verdc] variety Paiyur 2 which was subjected to ethyl methane sulphonate (02, 0.3, 0.4 and 0.5%), gamma radiation (100, 200, 300 and 400 Gy) and combination treatments. The mutations affecting gross morphological changes in growth and yield characters such as plant habit, flowering, pod morphology, maturity and seed yield were scored as quantitative characters. The micro mutations at population level can be easily detected in the form of increased variations for quantitative traits in the segregation of mutagen treated populations. Micro mutations can alter morpho-physiological characters hence they are of a particular interest to the plant breeders. ANOVA test was performed to determine the significant differences and duncan’s multiple range test (p=0.05) to compare the differences among treatment means. Result: Among the twenty-five treatments studied both the mutagens, gamma radiations and Ethyl Methane Sulphonate proved to be very effective to induce variability in quantitative traits in M2 and M3 generations. The results of Duncan’s multiple range test analysis revealed that the treatment of mutagens in combinations induced more positive effects as compared to that of using alone. The combined treatments were found positive for improvement of primary branches per plant, no. of pods per plant, pod length, no. of seeds/pod and seed yield per plant in M2 and M3 generations whereas the treatment of gamma irradiation imparted its significant role for improvement of plant height, days required for 50% flowering, days to maturity and 1000 seed weight in both M2 and M3 generations whereas the treatment with Ethyl Methane Sulphonate is useful for improving no. of pods per plant and no. of seeds/pod in M2 generation alone.

Exploration, Collection and Characterization of Horsegram [Macrotyloma uniflorum (Lam.) Verd.] Germplasm

Background: Horsegram [Macrotyloma uniflorum (Lam.) verd.] is an underutilized arid food legume known to grow well in diverse environmental conditions like poor soils, low rainfall etc. Horsegram is a drought resistant crop used for fodder, feed, seed, green manuring and in ayurvedic medicine. It is grown as Rabi crop in Andhra Pradesh. Compared to other pulse crops, efforts in conservation horsegram germplasm is poor which is essential for the future breeding purpose. There will be a danger of loss of germplasm if they are not collected and conserved. The Eastern Ghats of Andhra Pradesh i.e., Araku region is a rich source of diversified germplasm of legumes, medicinal plants, millets and ancient crops. Among which, horsegram is one of the crop with wide diversified germplasm. Hence the present effort is done in collection and characterization of the germplasm for further use in the breeding process. Broadening the genetic base in horsegram through interspecific hybridization employing diverse germplasm will be useful in improving pest and disease resistance, grain quality, protein percentage and nutritional factors. Methods: Expedition was conducted during Rabi 2018 and 25 horse gram seed samples were collected from the local regions of tribal tracts of Eastern Ghats of Andhra Pradesh along with passport data using the GPS machine. The germplasm lines were evaluated and morphologically characterized during Rabi 2019 at Agricultural Research Station, Yellamanchili, Visakhapatnam, Andhra Pradesh, India, for fifteen characters. Principal component analysis was carried out to identify the diverse germplasm lines and to know the contribution of the variables. Result: The investigation showed that all the horse germplasm lines are inherited to the farmers from their ancestors. Study revealed that, the seed yield per plant showed a range of 2.40 to 6.40 g and the days maturity recorded a range of 87 to 106 days. Principal component analysis showed that all the variables except 100 seed weight (g) showed positive loading. Among the variables plant height (cm), dry haulm weight (g) and seed yield per plant recorded maximum percentage of contribution. The genotypes HG-24, HG-7, HG-19, HG-15, HG-22 recorded highest positive scores. The genotypes HG-5, HG-10, HG-3, HG-16, HG-8, HG-4, HG-10, HG-24 and HG-7 has shown wide divergence which may be further adopted in the breeding programme for horsegram improvement.

Diversity Analysis in Horse Gram [Macrotyloma uniflorum (Lam.) Verdc.] Mutants

Background: Horse gram is the potential rainfed legume in Indian farming. The major limitation in horse gram breeding is the narrow variability. Variability induction and its estimation would sustain food security. Methods: Variability was induced using gamma rays, electron beam and ethyl methanesulfonate and their combinations. The induced variation for the economic traits, their inheritance and genetic gain were ascertained. Result: The analysis of variance indicated the induction of significant variation for yield attributing traits. The population was grouped into 10 constellations by the virtue of induced variation. The groups I, II and V were the largest comprising of 38, 31 and 19 mutants respectively. The mutants exhibited significant intra and inter group variation. The mutagens induced the maximum variability for plant height (32.24%), 100 seed weight (25.42%) and number of pods per plant (19.18%). The mutants possessed high genotypic and phenotypic coefficients of variation for all the characters except flowering traits and duration. The induced variability for the yield attributing traits possessed significant breeding value as the heritability (86.66%-99.72%) and genetic advance as percent of mean (10.65-81.94) were high and the environmental influence was the minimum.

Gamma rays induced morphological, flowering and palynological modifications in horse gram (Macrotyloma uniflorum)

Aim: The quest was framed to analyse the effect of high dose of gamma rays on morphological, flowering, and palynological traits in horse gram (Macrotyloma uniflorum). Methodology: Two horse gram varieties PAIYUR 2 and CRIDA 1-18 R were mutated using 32 mutagenic combinations. Sterile plants produced by gamma rays: 400 Gy were utilized to study the alterations in morphological, flowering characters in 20 randomly selected plants, and palynological traits using scanning electron microscope. Results: Gamma rays (GR):400 Gy produced sterile plants with altered ideotype and reproductive traits. It reduced expression of yield attributing traits, delayed first flowering, modified anther, and pollen size. The palynological changes included genotype dependant variation in pili number, size and exine ornamentation. Interpretation: High gamma ray dose is lethal to horse gram which was evidenced through grave modifications in morphological and palynological traits. These alterations resulted in sterility. Sterile plants tried to repair the irradiation induced damages and hence failed to perform routine reproductive functions.

Genetic Divergence (D2) Evaluation in Horsegram [Macrotyloma uniflorum (L) Verdcout] Genotypes

The experiment was performed at Research cum Instructional Farm, Shaheed Gundadhoor College of Agriculture and Research Station, Kumhrawand, Jagdalpur, Chhattisgarh. A total of 56germplasm lines and 1 check variety of horsegram were assessed for 10 quantitative traits during kharif2018.Genotypes were grouped into eight clusters. Clusters VI had maximum intra cluster distance while inter cluster distance was maximum between cluster VI and cluster VIII. Cluster III and cluster VIII had highest mean values for seed yield per plant characters. The characters viz., pods per plant followed by days to maturity and seed yield per plant were main contribution to total divergence. Based on the result genotypes belonging to clusters II, III and VIII are recommended for hybridization, as these genotypes showed good performance for seed yield and belong to the diverse clusters.