Heterosis in relation to genetic diversity in pearl millet (Pennisetum glaucum L.)

Abstract

In the advent of failure of some transgenics at the field level and concerns due to biosafety and bioethical issues, there much thrust on natural plant genetic diversity as a means of adaptive value. Plant breeding basing on natural genetic diversity has gained momentum along with marker assisted breeding technologies for increased production and sustenance to various kinds of stresses. In the present investigation, divergence classification (DC) – a method devised by Arunachalam and Bandyopadhyay (1984) were used to classify 28 Pearl millet genotypes to draw a limit of parental diversity in expressing maximum heterosis. Mahalanobis D2 (D2 Values) statistic was used to measure the genetic diversity and then the genotypes were classified in to four divergence classes based on mean and standard deviation of all D2 values. According to divergence classification DCI involved most distantly and DCIV the most closely related parents where as DCII and DCIII involved the medium divergent parents. A scoring system was adopted to work out the relative order of importance of the divergence classes. The overall scores for each divergence classes based on the proportion of crosses (q) showing significant heterosis (heterosis over better parent) in desired direction and mean (y) of such crosses for ten characters were carried out to rank the divergence classes. According to the scoring system, the most desirable class would be with the lowest total score. Results clearly showed the superiority of class DCIII followed by DCII, as both the classes received low overall score and maximum number of heterotic cross combinations. In conclusion it can be said that divergence classification appears to be effective in clubbing the pearl millet genotypes for parental diversity and suggested that pearl millet parents with intermediate diversity would be used to produce heterotic cross combination.