The Study of Genetic Divergence in Rice (Oryza Sativa L.) Genotypes with Grain Yield and Different Morpho Physiological Traits using Mahalanobis’ D2 Analysis

Abstract

  The current study attempted to study genetic divergence in rice (Oryza sativa L.) genotypes with grain yield and 
different morpho-physiological traits among 18 rice varieties using Mahalanobis' D2 analysis. Keeping this in mind, the 
performance of the studied genotypes, as well as the association between various morpho-physiological and yield 
contributing traits among the genotypes, were evaluated in the field. The experiments were conducted from July to December 
2018 at the Agronomy Field, Department of Agronomy and Agricultural Extension, Faculty of Agriculture, Rajshahi 
University. In terms of grain yield and other morpho-physiological traits, the genotypes differed significantly. The genotypes 
were classified into five clusters using Mahalonobis' D2 statistics and Tocher's method (Table 3). Cluster IV was the smallest 
of the clusters. Cluster l is the largest, with six genotypes. Clusters II and lV each contained three and two genotypes. The 
pattern of genotype distribution among various clusters reflected the significant genetic variability present in the genotypes, 
which may be due to adaptation of these genotypes to specific environmental conditions. Genotypes from different clusters 
are expected (inter-cluster). The intra (bold) and inter-cluster distances from D2 analysis (Table 4). Cluster I has the greatest 
intra cluster distance (0.956), while Cluster IV has the smallest (0.3583). The greatest inter-cluster distance is observed 
between cluster IV and (8.190), while the smallest inter-cluster distance is observed between cluster II and IV (2.924). In both 
vectors, the average inter-cluster distances were greater than the average intra-cluster distances, indicating the presence of 
greater genetic diversity among genotypes from different clusters than those from the same cluster. These findings indicated 
that these five traits contributed the most to the divergence among the eighteen rice genotypes. The results revealed that the 
clusters were remarkably distinct for the majority of the traits, indicating proper clustering. The most effective tiller, grain 
panicle, effective grain panicle, and days to maturity were found in Cluster V. The intra-cluster mean for grain yield was the 
lowest in this cluster. Cluster III had the lowest grain yield per acre. This was the cluster with the lowest initial grain yield. 
The intra-cluster mean for effective tiller and days to maturity was highest in this cluster. Cluster II had the smallest grain 
yield and the second smallest thousand grain weight. Cluster V had the shortest panicle length intra-cluster.