Current Advances in Agricultural Sciences 3(2): 96-99 (December 2011) ISSN 0975-2315 Studies of genetic diversity in quality protein maize ( Zea mays L.) inbreds VINAY KUMAR, PK SINGH 1 and ASTHA GUPTA 2 Department of Genetics and Plant Breeding, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi-221 005 (Uttar Pradesh), India Email of corresponding author: vinayscorpio01@gmail.com Received: July 2011; Accepted: November 2011 ABSTRACT Using D 2 analysis, twenty inbreds of maize (Zea mays L.) were categorized based on genetic diversity into six clusters. Among them, clusters III, IV, V and VI were monogenotypic, rest cluster I and II were polygenotypic based on genetic divergence. Intra cluster values ranged from zero (monogenotypic cluster III, IV, V, VI) to 172.92 (cluster II). Minimum inter cluster distance was observed between cluster III and V (204.20), while maximum inter cluster distance was observed between cluster I and V (1512.43) suggesting that genotype of these clusters may be used in hybridization programme. Phenotypic coefficient of variability (PCV) was slightly higher than that of genotypic coefficient of variability (GCV) for all characters. Estimates of heritability (in broad sense) ranged from 0.926 (ear diameter without husk) to 0.999 (1000- grain weight). 1000-grain weight showed highest heritability with genetic advance followed by yield plot -1 and yield plant -1 , respectively. Key words: Genetic advance, Genetic divergence, Heritability, Quality protein maize Maize assumes a significant role in Indian agriculture. Due to its high production potential and wide adaptability, it occupies third place in area and production among cereals after wheat and rice worldwide. In addition, among the field crops, it has valuable and the biggest gene pool. Genetic diversity in crop plant was generally determined from pedigree data (Lubberstedt et al., 2000) and morphological traits (Yee et al., 1999). Goodman (1972) used phenotypic marker and quantitative traits for selection. Genetic divergence for metric traits was greatly influenced by environment. Information on genetic relationship within species is used to identify heterotic groups and to facilitate selection in breeding materials (Lee, 1995; Karp et al., 1996). Study of genetic diversity is frequently used by the breeders as an alternative to parent selection (Diniz et al., 2005) and allows lines to be arranged into groups so when lines belong to extreme groups intercrossed will provide the most promising result and reduces the expense and time. MATERIALS AND METHODS Twenty entries obtained from the All India Co-ordinated Maize Improvement programme were evaluated in a randomized block design with three replications during rabi 2009-10 at,Department of Genetics and Plant Breeding, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (Uttar Pradesh). Each entry was planted in two rows of 3 meter length keeping row to row and plant to plant spacing of 70 and 20 cm, respectively. Observation were recorded on 5 competitive randomly taken plants from each plot of each replication. The characters studied were days to 50 per cent tasseling, days to 50 per cent silking, ear height (cm), plant height (cm), ear length without husk (cm), ear diameter without husk (cm), number of kernel row -1 , number of kernel row ear -1 , 1000-grain weight (g), plant stand at maturity, yield plant -1 (g), yield plot -1 (g). The mean data recorded on various yield contributing characters were subjected to different statistical analysis such as analysis of variance (ANOVA), genetic variability, mean and range, phenotypic and genotypic coefficient of variability, heritability and genetic advance, genetic divergence (D 2 ) using Mahalanobis D 2 statistics. RESULTS AND DISCUSSION Analysis of variance for the design revealed that treatment differences were highly significant for all characters (Table 1). The significant differences represent large extent of variability among treatments for different characters. Genetic divergence analysis for twenty germplasm lines was done through Mahalanobis D 2 statistics as described by Rao (1952). Germplasm lines of maize inbred were grouped into six clusters (Table 3). Cluster I and II had eight equal but different germplasm lines, followed by cluster III, IV, V and VI with single genotype. The inter cluster values were found greater in magnitude than intra cluster distance suggesting the presence of diversity among the clusters indicating that genotypes 1,2 Department of Genetics and Plant Breeding, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi-221 005 (Uttar Pradesh), India; Email: pksbhu@gmail.com, sucessfulastha33@gmail.com