Genotype X Environment interaction of carotene content of yellowfleshed cassava genotypes in Nigeria

Cassava is an important starchy root crop and a major staple for more than 70 million people in Nigeria. New yellow-fleshed genotypes are being developed to combat vitamin A deficiency. Trials of 18 yellow-fleshed genotypes and two officially released white-fleshed clones, used as checks for 2008/2009 and 2009/2010 seasons in five major cassava growing agroecological zones of Nigeria. The trial locations were Ikenne (humid forest), Ibadan (forest-savanna transition), Ubiaja (subhumid forest), Mokwa (southern Guinea savanna) and Zaria (northern Guinea savanna). At each location, the trial was established in a randomized complete block design with four replications. The objective of the study was to assess genotype performance and genotype × environment interaction for total carotene concentration (TCC), total carotene content per root (TC-R), and total carotene content per plant (TC-P). Significant differences (P < 0.001) among genotypes, environments and genotype × environment interaction for all the traits evaluated were observed. For TCC, TC-R and TC-P, the best genotypes across the 10 environments were TMS I051601, TMS I050311, and TMS I050998. Variation among genotypes accounted for most of the Total Sum of Squares for TCC (67.9%), TC-R (39.0%) and TC-P (35.9%). These characteristics of total carotene were also highly correlated. This study revealed that cassava with total carotene concentration can be assessed using either the TCC, or the TC-R, or the TC-P.