Genetic Diversity and Selection Among Drought Tolerant Genotypes of Sugarcane Using Microsatellite Markers

The present study is an attempt to combine drought tolerance with yield and quality traits guided by molecular diversity estimates. Using thirty primers of sugarcane specific sequence tagged microsatellite markers, genetic diversity of 28 elite clones used in sugarcane improvement was estimated. Similarity indices among 378 possible cross combinations involving these parental clones estimated by Jaccard’s coefficient analysis showed that 85 combinations were more similar (SI ≥ 0.80), 45 combinations were diverse (SI ≤ 0.60) and the remaining 248 combinations exhibited intermediate diversity (SI values between 0.60 and 0.80), indicating the existence of moderate genetic divergence in the clones studied. Twenty-five out of 28 genotypes being drought tolerant, use of genetic diversity information in family selection for realizing higher yield and quality with drought tolerance was explored through progeny analysis of 14 crosses comprising of six genetically diverse, five with medium diversity and three less diverse crosses. Screening of 1,448 progenies from these crosses in first clonal trial under normal and drought conditions for juice quality quantified as Hand refractometer Brix, cane diameter and single cane weight at maturity and per cent reduction for these parameters due to drought led to 766 selections. Higher percentages of selection from genetically less similar crosses (SI below 0.80) and a significant negative correlation (−0.7976) between selection per cent of each cross and similarity index highlighted the usefulness of selecting more diverse combinations for the genetic improvement of sugarcane for combining drought tolerance with yield and quality characters in sugarcane.