Abstract
Significant variability among the genotypes were noted for all of the traits studied including approximately 11 days for flowering, 19 days for physiologic maturity, 35 cm for plant height, 32 t/ha for tuber yield and 12% for dry matter content. The phenotypic coefficient of variation (PCV) ranged from 1.07% to 74.29% for tuber specific gravity and late blight score, respectively. Similarly, the lowest genotypic coefficient of variation (GCV) was recorded for tuber specific gravity (0.77%) and the highest for late blight score (57.31%). Except for stem number per hill, late blight score and tuber yield, the difference between GCV and PCV for all other traits was smaller indicating that these traits were less influenced by environment. Heritability (h2) estimate ranged from 18.6% (tuber yield) to 99.3% (dormancy period) signifying that selection for dormancy period was dependable while selection for tuber yield was difficult. The expected genetic advance (GA) in selecting the top 5% of the clones varied from 0.01% to 30.02% for specific gravity and tuber dormancy, respectively. Selection for dormancy period and plant height was most likely to be more effective because they had higher h2 estimates coupled with relatively higher GA. Overall, the study indicated the existence of wide diversity in the collection which could be exploited for the improvement of the crop for different attributes.
