Genetic diversity analysis among Solanum tuberosum genotypes of potato under Indo-Gangetic plain

Introduction

Potato (Solanum tuberosum L.) is the fourth most important food crop globally, after wheat, rice, and maize [1] . It serves not only as a staple vegetable but also as a key raw material for various processed food products. In addition, potatoes are utilized in industries for the production of starch and alcoholic beverages. Developing varieties with desirable agronomic traits and good keeping quality remains a major challenge for potato breeders. Potato is a highly heterozygous crop, and greater heterozygosity contributes to increased hybrid vigor [2] . Crosses made between genetically diverse parents tend to produce progenies with higher heterotic expression [3] . In any plant breeding program, maintaining a pool of diverse and desirable donor parents is essential for enhancing productivity [4] . Genetic diversity in crop plants is essential to sustain the level of high productivity [5] . The most effective approach to enhance crop productivity is through genetic improvement [6] . The success of any plant breeding relies on the degree of existing genetic diversity within the species, as greater variability offers wider opportunities for effective selection and improvement [7] . Genetic diversity serves as an important tool for assessing genetic variability in both cross-pollinated and self-pollinated crops [8] . Therefore, the present study was undertaken to assess the genetic divergence and clustering pattern among potato genotypes for identifying suitable parents to be used in hybridization programs and to evaluate genetic parameters contributing to yield. Accordingly, 26 potato genotypes were analyzed to determine the nature and magnitude of genetic diversity using D² statistics.

Materials and Methods

The research was carried out in a Randomized Block Design (RBD) with three replications. Treated tubers were planted on ridges spaced 60 cm × 20 cm apart on 10th November 2023 The mean values of these five plants were used for statistical analysis. The recorded traits comprised plant height, percentage of plant emergence, number of shoots and compound leaves per plant, tuber count per plant, days to maturity, harvest index, tuber dry matter content, specific gravity (g/cm³), reducing and non-reducing sugar contents (mg/100g), and tuber yield per plant (kg). The genetic diversity or degree of divergence among the cultivars was computed using D 2 statistics had been suggested by [9] .

Results and Discussion

Significant differences among genotypes for all traits indicated substantial genetic diversity within the germplasm. Twelve characters were evaluated, and significance tests confirmed variation among genotypes. Using Wilks' (1932) criterion, multivariate significance was assessed for correlated traits (10). D² analysis was conducted by transforming correlated variables into standardized, uncorrelated ones. The D² value between two genotypes (i and j) was computed as the sum of squared differences of their mean values across traits and tested against tabulated χ² values. Genotypes were grouped using Tocher's method (11-12). Intra and inter-cluster distances were calculated from average D² values, with inter-cluster distances obtained by averaging all possible pairwise distances between clusters. Cluster diagrams illustrated genetic relationships, and genetic distances were derived as the square root of mean D² values. Based on D² analysis, 26 genotypes were grouped into seven distinct clusters using Tocher's method.

Contribution towards genetic diversity

The trait contributing most to genetic diversity was the number of tubers per plant, with a contribution of 35%, followed by the number of compound leaves, contributing 30.5%, number of shoots per plant 7.4%, reducing sugar 5%, plant height 4.8%, non reducing sugar 4.4%, harvest index 3.1%, days to maturity 2.8%, specific gravity 1.2%, plant emergence at 30 days after planting 0.95% and dry matter 0.90%. Cluster III showed superior performance for tuber weight per plant, specific gravity, number of compound leaves, and plant height. Therefore, genotypes such as CP2298, CP3674, and CP4404 from Cluster III can be utilized as donor parents in hybridization programs aimed at improving potato yield under Indo-Gangetic Plain conditions. CP1215, CP1157 and CP1596 genotypes can be used for the early maturing variety breeding programs since these cluster genotypes showed very less days to maturity. Additionally, genotypes CP7701, CP2150, CP3433, and CP3148, characterized by high dry matter and low reducing sugar content, can be suitable for developing processing-quality breeding programs.

References

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