Genotypic variation for starch yield in cassava (Manihot esculenta Crantz) in Ibadan, Nigeria

ABSTRACT Starch is a key nutritive component of major staple crops, with cassava giving the highest yield of starch per unit area of any crop known. Cassava breeding should focus on dry (utilizable) root yield, which determines the yield of the final products. Six cassava genotypes (COB-4-75, COB-4-100, COB-5-4, COB-5-53, COB-6-4, and COB-7-25) and two checks (TMS30572 and TMEB419) were evaluated for dry starch yield (DSY) in two seasons in Ibadan, Nigeria. The experiment was conducted using randomized complete block design with two replications. The plants were harvested 12 months after planting, and data were collected on the fresh root weight and total biomass. The harvest index (HI) and fresh storage root yield (FSRY) were estimated using the field data. Starch content of each genotype was determined and, along with FSRY, was used to estimate the starch yield. The data were subjected to ANOVA and correlation analysis. Significant differences were observed among the genotypes for FSRY, HI, and DSY. Genotype COB-4-100 had the highest mean FSRY and DSY of 30.72 and 4.29 t/ha, whereas COB-5-53 had the lowest values of 13.19 and 1.71 t/ha, respectively. The highest HI (0.57) was recorded for COB-7-25, whereas COB-5-53 had the lowest HI (0.28). Correlation coefficients were significant for DSY versus each of HI (r = 0.65) and FSRY (r = 0.91) and also for FSRY versus HI (r = 0.66). Genotypes COB-4-100, COB-5-4, and COB-7-25, with significantly higher DSY than the checks, should be good candidates for release to farmers and further improvement of cassava starch yield.