Genetic diversity analysis of horse gram [Macrotyloma uniflorum (Lam.) Verdc.] for moisture stress tolerance in south central laterites of Kerala

Abstract

The study entitled “Genetic diversity analysis of horse gram [Macrotyloma uniflorum (Lam.) Verdc.] for moisture stress tolerance in south central laterites of Kerala” was carried out at Farming Systems Research station, Sadanandapuram during October, 2020 – March, 2021 with the objective to identify superior genotypes of horse gram with moisture stress tolerance having high yield and quality, suitable for south central laterites of Kerala. The 30 horse gram genotypes collected from RARS Pattambi under KAU and other SAUs were evaluated for moisture stress tolerance at seedling stage in laboratory using two different concentrations of PEG 6000 (10% and 20%), in factorial completely randomized design replicated thrice. These 30 genotypes were further evaluated for water stress tolerance in field by withholding irrigation for 15 days at reproductive stage, in randomized block design replicated thrice. The seeds were sown on raised beds of 2.25 m2 size at a spacing of 30 cm х 30 cm and cultural operations were adopted as per the “Package of Practices Recommendations Crops 2016” of Kerala Agricultural University. The soil moisture was also measured during water stress-imposed period at weekly interval by following gravimetric method. In laboratory experiment, genotypes were evaluated for six different morphophysiological characters and in field experiment, genotypes were evaluated for 31 characters which included biometric, physiological, biochemical and seed quality characters. The genotypes showed significant differences for all the characters studied. Genetic parameter analysis was performed for nineteen characters and for all the characters PCV values were higher than GCV values indicating the influence of environment. High heritability coupled with high GAM was observed in days to 50% flowering, number of primary branches per plant, plant height, number of pods per plant, haulm yield per plant, harvest index, days to maturity, leaf area index, total phenol content of the seed, root dry weight, proline content, total chlorophyll content and seed yield per plant. 124 The correlation studies revealed significant positive correlation of the characters RWC, number of pods per plant, number of seeds per pod, total chlorophyll content, harvest index, proline content, root dry weight, root length, LAI and hundred seed weight with seed yield. However, days to 50% flowering, days to maturity, plant height and number of primary branches showed a significant negative correlation with yield. Path analysis of the thirteen characters showing significant correlation with seed yield revealed high positive direct effect of the number of pods per plant on seed yield. High indirect effect on yield was observed for number of seeds per pod through number of pods per plant. Genetic divergence analysis using Mahanalobis D2 statistic following Tocher’s method grouped the 30 genotypes into four clusters. Cluster II with 14 genotypes was the largest followed by cluster I (9 genotypes), cluster III (6 genotypes) and clusters IV was solitary cluster. Highest intra cluster distance was recorded among the genotypes of cluster II and lowest in cluster IV whereas highest inter cluster distance was observed between the genotypes of the clusters I and III, while lowest inter cluster distance was between the genotypes of the clusters III and IV. The present study revealed that the genotypes IC71841, IC139464 and IC22785 as water stress tolerant ones in laboratory experiment and in field experiment, genotypes IC22785, IC221105, IC22759 and IC139464 were identified as high yielding and moisture stress tolerant ones. The superior genotypes identified in the study can be recommended for cultivation and future breeding programs.