Analyses of the Genetic Parameters (Variability, Heritability, Genetic Advance, Relationship of Yield and Yield Contributing Characters) for some Plant Traits among Brassica Cultivars under Phosphorus Starved Environmental Cues

The potential of a crop favorably respond to breeding/selection and bioengineering programs depends upon the nature and magnitude of genetic variability. For effective selection, information on nature and magnitude of variation in population, association of character with dry matter yield and among themselves and the extent of environmental influence on the expression of these characters are necessary. The estimates of genetic parameters help in understanding the role of various plant traits in establishing the growth behavior of cultivars under a given set of environmental conditions. Genetic analysis leads us to a clear understanding of different morphological, physiological and genetic characters and also the type and extent of their contribution to dry matter yield. Six Brassica cultivars were grown in a P-deficient sandy loam soil for 49 days after sowing. Significant variations were observed for all the characters in all the cultivars used in the experiment. All the characters showed high　heritability coupled with high genetic advance. Heritability (h(2)) is an approximate measure of the expression of a character. The highest estimates of broad sense heritability (h(2)= 0.90) and relative expected genetic advance (85.72%) were noted for root dry matter (RDM), while the estimate of expected genetic advance at 10% selection intensity was quite high (ΔG = 85.30c㎡) for leaf area per plant. The estimates of coheritability were positive and relatively higher for rootshoot ratio (RSR) in combination with shoot dry matter (SDM) (coh(2) = 2.002) and phosphorus use efficiency (PUE) (coh(2) = 1.875), whereas coheritability estimates were negative between leaf area per plant and RSR (coh(2) = -0.2010) indicating lack of association between these traits. High heritability with high genetic advance was exhibited by all the studied plant traits of cultivars evidencing that the traits could be further improved through individual plant selection. The innate variations within the Brassica gene-pool impel to drive a concentrated effort to understand the basis of adaptability. Access to the relevant genetic traits and information will provide necessary tools to select the optimal combinations of alleles adapted to local and changing growing environments especially nutrient stress conditions such as phosphorus (P) starvation.