Sweet potato is a dicotyledonous plant belonging to family Convolvulaceae. The genus Ipomoea includes more than 40 species out of which Ipomoea batatas is of economic importance. Sweet potato (Ipomoea batatas L) ranks fifth in importance for its calorific contribution in developing countries after rice, wheat, maize and cassava. It is one of the world’s highest yielding crops and is widely grown as an important staple food crop in many parts of the tropics and sub-tropics over a wide range of environmental conditions. It is hexaploid species with 96 chromosomes (2n= 6X= 96).

Collection and evaluation of genotypes of any crop is a pre-requisite for any breeding programme which provides a greater scope for exploiting genetic diversity. A quantitative assessment of the genetic divergence among the collection of germplasms and relative contribution of different traits towards the genetic divergence provide essential and effective information to a breeder in hybridization programme and thereby genetic improvement of yield.

The present investigations were conducted to study the genetic divergence in sweet potato (Ipomoea batatas L) cultivars at instructional cum research farm of Section of Horticulture, RCSM College of Agriculture, Kolhapur, Maharashtra during kharif season. Sixteen genotypes of sweet potato were evaluated in randomized block design with two replications. Each plot measuring 3.00 m x 2.40 m comprising 60 vines of individual genotype was planted in six rows with one vine per hill plot at a spacing of 60 cm × 20 cm. All agronomical operations and plant protection measures were carried out regularly to ensure satisfactory crop growth.

The experimental material consisted of 16 genotypes viz X-108-2, H-85/70, IB-90-15-9, IB-90-11-1, DR-64, Shree Vardhini, CIPSWA-2, S-56-2, 365/ 2, SV-98, Konkan Ashwini, Shree Bhadra, Ozarde Local, 1870-1, DR-17 and Kamala Sundari. Observations on length of vine, number of primary branches per vine, intermodal length, volume of tuber, length of tuber, number of tubers per vine, girth of tubers, weight of peel, weight of flesh, flesh to peel ratio, average weight of tuber, tuber yield per vine, marketable yield, days required for maturity of tubers, per cent incidence of root weevil and total yield of tubers were recorded. Genetic diversity was studied using Mahalanobis’s D² analysis (Mahalanobis 1936).

The D² values corresponding to all the possible combinations among the sixteen genotypes were computed. These 16 genotypes were grouped into 5 clusters; the clusters I and III comprised 5 genotypes, cluster II comprised 3, cluster IV comprised 2 whereas cluster V was monogenic having single genotype X-108-2 (Table 1). The formation of solitary clusters might be due to total isolation preventing the gene flow or intensive human selection for diverse adaptive complexes.

The present investigations confirm the earlier findings of Karuri et al (2010) in sweet potato, Ahmadizadeh and Felenji (2011) in potato and Kabeya et al (2012), Turyagyenda et al (2012) and Malualem et al (2013) in cassava.

The intra- and inter-cluster D² values among seven clusters are presented in Table 2. The intra-cluster distance varied from 0.00 in cluster V to the maximum distance in cluster III (4,828.64). This reveals the presence of divergence in cluster III. The maximum inter-cluster distance for D² value (34,082.51) was recorded between clusters IV and V.

The data on means of all the sixteen characters are presented in Table 3. A wide range of variation was observed among different clusters or all the cluster means. Cluster II recorded the maximum mean values for vine length (1.78 m) and internodal length (2.59 cm); cluster III had the maximum value for tuber length (17.08 cm); cluster IV had maximum mean value for tuber volume (166.35 ml), number of tubers per vine (2.55), tuber girth (17.66 cm), peel weight (19.10 g), flesh weight (204.63 g), flesh to peel ratio (11.04), average tuber weight (223.70 g), tuber yield per vine (0.54 kg) and marketable yield (43.30 tonnes/ha) while cluster V recorded the maximum mean for number of primary branches per vine (4.80). In the present study, the possibility of choice of highly divergent and desirable types based on D² cluster means and inter-cluster distances was also examined.

Selection of genotypes is recommended from the clusters showing higher inter-cluster distance (clusters IV and V) also with total yield of tubers as parents in recombination breeding programmes for obtaining desirable seggregants.

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