ABSTRACT

Studies were carried out on newly developed Intra-specific hybrids of Dioscorea rot undata to select higher tuber yielding and flowering intensity varieties, plant characters contributing to the genetic improvement of the yarn plant and to select varieties with tuber characteristics that appeal to the eye. The hybrids were grown in 2004 and 2005, using a two-factor factorial in a randomized complete block design replicated 6 times. The analysis of variance indicatd significant (P<0.001) year difference for all the morphological plant characters evaluated except crop growth rate at 4 months after planting, days to physiological maturity and number of pistillate flowers. There was also significant varietal variation at (P < 0.00 1) among the yarn plant genotypes except tuber shape index. There was significant (P<0.05) year effect for all the morphological 11ant characters except on number of tubers, tuber shape index and number of pistillate flowers per plant. Simple linear correlation coefficient indicated that inter-character association was highly stable (rl .00). Stepwise multiple regrcssion analysis indicated that fresh tuber yield in both years and days to male flower initiation in 2005 significantly (P<0.O contributed to tuber dry niatter yield per plant. These plant characters had significant positive. genotypic coefficient of variability and high heritability estimates in broad-sense. They also had positive significant genotypic and phenotypic correlation with other plant characters and were selected as superior characters that will significantly contribute to higher tuber yield. Also, number of staminate flowers in both years, days to female flower initiation in 2004 and leaf area index in 2005 were strong determinant (P<0.05) of flowering intensity in male and female yarn plants. Cultivars selected for high tuber yield were:- UYT/20/053 in 2004, UYT/20/052 and UYT/20/094 in 2005, UYT/20/044, UYT/20/00 1, UYT/20/092A and UYT/20/085 in both years. Cultivars recommended for high male flowering intensity were:- UYT/20/053, UYT/20/001 and UYT/20/044 in both years plus UYT/20/085 for female flowering in both years. Any of the tubers selected from the cultivars will appeal to the eye.