Analysis of Genetic Diversity in Germplasm Accessions of Sunflower ( Helianthus annuus L.)

Genetic divergence (D 2 ) was studied in 64 genotypes of sunflower during the season Rabi 2009, to quantify the nature and extent of diversity by the Mahalanobis D 2 statistics. Analysis of variance revealed significant difference among the genotypes for all the 13 characters. Sixty two genotypes and two checks viz., DRSF 108, DRSF 113 were grouped into nine clusters. The pattern of distribution of genotypes into various clusters was at random indicating that geographical and genetic diversity were not related. The distinctness of clusters was proven by distance matrix as inter cluster distances than almost cluster distances, genotypes EC 601679, EC 601613, EC 601662, EC 601702, EC 601609, EC 601610, EC 601619 and EC 601654 could be utilized in breeding programme. Based on mean performance the genotypes viz. , EC 601618, EC 601619, EC 601621, EC 601664, and EC601702 for seed yield, the genotypes viz. , EC 601613, EC 601612, EC 601622, EC 601699 and EC601702 for oil content were identified as superior. Genotypes viz. , EC 601618, EC 601621, EC 601629, EC 601630 and EC 601702 for total number of filled seeds, genotypes viz. , EC 601613, EC 601614, EC 601618, EC601621 and EC601702 for head diameter, genotypes viz., EC 601610, EC 601617, EC 601619, EC 601621 and EC 601664 for 100 seed weight were identified as suprerior. These genotypes can be utilized in the breeding programme for improving the respective character, to develop superior varieties/hybrids in sunflower.

Sunflower has emerged as a potential oilseed crop in Indian agriculture.Owing to its photo insensitive nature it can be cultivated through out the year.Cultivation of sunflower is mainly for extraction of oil which ranges from 46-54 per cent.Crosses between divergent parents usually produce greater heterosis than those between closely related ones.(Moll and Stuber, 1971).Use of diverse parents in hybridization programme can serve the purpose of combining desirable genes or to obtain recombination.The multivariate D2 analysis (Mahalanobis, 1936) is one of the important biometrical tools in quantifying the genetic divergence in the germplasm.
An attempt was made to classify 64 genotypes of sunflower to quantify the magnitude of genetic divergence and using them in further breeding to evolve potential transgressive segregants.

Materials and Methods
The material for the present study comprised of 62 germplasm accessions of sunflower and two checks viz., DRSF 108, DRSF 113.The experiment was conducted at Directorate of Oilseeds Research, Hyderabad during Rabi 2009.Each accession was sown in two rows of 4m length with a spacing of 60 *Corresponding author email: madhu4reddy@gmail.comcm between rows and 30 cm between plants.The experiment was laid out in Simple Lattice Design with two replications.In each accession, five plants were randomly selected and used for collection of data on yield and yield related characters like days to 50 percent flowering, days to maturity, plant height, stem diameter, head diameter, number of filled seeds per head, number of unfilled seeds per head, total number of filled seeds per head, seed filling percent, 100 seed weight, seed yield per plant, hull content and oil content.The data were subjected to multivariate analysis using D2 statistics (Rao, 1952).The genotypes were further grouped into different clusters based on Euclidean cluster analysis.

Seed filling
Number of filled seeds percentage (%) = x 100 Total number of filled and unfilled seeds Oil content estimation was done by the nuclear magnetic resonance (NMR) technique.

Results and Discussion
Analysis of variance revealed highly significant differences among the genotypes for various characters.Sixty four genotypes were grouped into nine clusters based on D2 values such that the genotypes belonging to same cluster had smaller D2 values than those belonging to different clusters The average intra and inter cluster distance (Table 2) (Fig 2) revealed that the genetic diversity among the genotypes were generally superior for one or few characters which made them divergent from other clusters.Maximum distance (5616.96)was observed between clusters III and cluster IX followed by cluster II and IX (4627.39)and cluster I and IX (3425.71) .On the other hand clusters.VII and VIII (411.68) and V and VIII (413.04) were the closest.Similar results were reported by Mahalakshmi et al. (2006) and Ananda Kumar et al. (2007).
The cluster means (Table 3) indicated appreciable variation among various clusters, particularly for seed yield/plant, total number of seed/ head and seed filling per cent.However, variations were low for hull content, oil content, 100 seed weight, days to maturity and days to flowering.Based on cluster means, cluster IV include genotypes with high number of filled seeds/head, total number of seeds/head, high seed yield /plant and seed filling   (Singh and Ramanujam, 1981) and depending on breeder's interest more than one genotypes from a cluster could be selected for breeding programme.
The contribution of individual character towards the divergence (Table 4) indicated plant height (61.26) followed by stem diameter (19.79), head diameter (5.51), filled seed/head (3.22), had major contribution towards divergence, while oil content, days to maturity, days to flowering had negligible contribution.Similar results have been reported by Komaraiah et al. (2004)

Fig. 1. Cluster diagram representing diveristy for 64 sunflower genotypes
Srinivas et al. (2006) nine clusters formed, cluster III is the largest group with 14 genotypes, followed by cluster VI with 10 genotypes, cluster I with nine genotypes, while cluster V, VIII had eight genotypes each, cluster II, VII with five genotypes each, cluster IV with three genotypes, and cluster IX with two genotypes.These genotypes were superior for one or fewer characters which made them divergent from the other clusters.It was interesting to note that 64 genotypes of differences in origin were grouped in the same cluster, indicating absence of relationship between genetic diversity and geographic diversity.Similar results have been reported by ThirumalaRao et al. (2005)andSrinivas et al. (2006).

Minimum Variance Dendrogram Fig. 2. Ward's minimum variance diagram per
cent, where as cluster III scored for genotypes with high plant height, head diameter and hull content.Selection of genotypes from divergent clusters, might prove more useful and when they are selected with due consideration of per se performance.However, looking at subjective and arbitrary nature of grouping with D2 statistic

Table 4 . Contribution of different characters towards genetic divergence in sunflower genotypes
Plant height, head diameter and stem diameter are the important contribution factors.In that analogy, genotypes superior for one or more characters the genotypes viz., EC 601618 and EC 601619 for seed yield.The genotypes EC 601613and EC601612 were identified superior for oil content.The genotypes EC 601618 and EC601621 for total number of filled seeds.The genotypes EC 601613 and EC 601702 for head diameter.The genotypes EC601610 and EC 601 617 for 100 seed weight.These genotypes can be utilized in the breeding programm to develop superior varieties/hybrids in sunflower.