Association and Path Coefficients Analysis of Fresh Root Yield of High and Low Cyanide Cassava (Manihot esculenta Crantz) Genotypes in the Humid Tropics

Abstract

Thirty-eight high- and low-cyanide cassava genotypes were examined in the 2004 and 2005 cropping seasons at Umudike, southeastern Nigeria using RCBD with three replications. Simple correlation associations and path coefficients analyses were computed among agronomic characters with the aim of understanding the interrelationships of these characters and the extent of their contribution to the root yield of cassava. There was a significant (P 2 0.05) positive correlation between root yield and number of roots plant-1 with correlation coefficients (r) of 0.57, average weight of root (r = 0.58) in high-cyanide cassava genotypes, while in low cyanide cassava genotypes, fresh root yield was highly significantly (P 2 0.01) correlated with average weight of root (r = 0.74). Path analysis showed that average weight of root had the highest direct effect in high (0.66) and in low cyanide (0.67) cassava genotypes. Also, the number of roots plant-1 in both types of cassava exerted a positive direct effect on fresh root yield, however, a minimum effect was obtained by number of leaves plant-1 (0.22) in high-cyanide cassava and number of stems plant-1 (-0.13) in lowcyanide cassava genotypes. Average weight of roots in high- and low-cyanide cassava genotypes had 98 and 89% direct effects, respectively, on yield of cassava. The results indicated the importance of average weight of roots and other characters such as number of roots plant-1, plant height, and number of leaves plant-1 in determining increased yield hence priority must be accorded it during selection aimed at increasing cassava root yield.