Growth and Yield Components of Sweet Potato (Ipomoea batatas L.) and their Relationships with Root Yield

Abstract

Aims: To assess the extent of the relationships of various growth and yield related characters. To evaluate the direct and indirect contributions of these characters to root yield, a basis of selection for further improvement. Study Design: Field Experiment, in Randomized Complete Block Design. Place and Duration of Study: Teaching and Research Farm of Bayero University, Kano (11°58’N and 8°25’E) and Agricultural Research Station Farm, Minjibir (12°11’N and 8°32’E) located in the Sudan Savanna of Nigeria between July-October, 2014. Methodology: Sixteen (16) sweet potato advanced lines: Centennial, AYT/08/055, TIS8164, TIS87/0087, NRSP/12/097, UMUSPO/2, UMOSPO/1, SOLOMON1, EA/11/022, EA/11/025, EA/11/003, UM/11/015, NRSP/12/095, UM/11/001, UM/11/022, and a local check (Kantayi idda) were evaluated using a randomized complete block design with three replications. Data were collected on number of leaves per plant, vine length, vine weight, number of roots per plant, average root weight and the root yield. Simple and partial correlations between root yield (Y), growth and yield components (X) and within the growth and yield components themselves were worked out. Results: Root yield was found to be significant (p<.01) and positively correlated with number of leaves per plant, number of roots per plant and average root weight. Vine length was negatively correlated to average root weight and root yield, whereas number of roots per plant was positively correlated to the average root weight and root yield. The path analysis also revealed that average root weight registered the highest direct contribution to root yield. The highest indirect effect on root yield also came from the number of roots per plant via the average root weight. Conclusion: The average root weight contribution to root yield was much higher than those of vine length and vine weight both directly and indirectly. Thus, emphasis should be given towards increasing the average root weight and number of roots per plant as criteria and basis of selection of sweet potato for higher root yield.