Abstract

Cassava is the sixth most important crop in terms of global annual production and the most widely grown root crop in tropical Africa, Latin America and Asia. Researchers in most cases evaluate cassava for Storage Root Yield (SRY) at 12 Months After Planting (MAP) except on few occasions when earliness is the objective of the breeding program while farmers harvest when they desire with little knowledge on peak of root yield of the cassava cultivars. However, in Nigeria, the major cassava growing belt has rainfall for about 7-9 months. Hence, the objective of this study was to evaluate some cassava varieties for Storage Root Yield (SRY) and related traits at different harvesting ages. Ten cassava varieties commonly cultivated by Nigerian farmers were evaluated at 8, 10 and 12 MAP for the traits. The data were subjected to descriptive analysis and analysis of variance at 5% level of significance. Variety, age at harvesting and year had significant influences on SRY, number of storage roots and harvest index but the interaction among variety, age at harvesting and year did not significantly affect any of the traits. Varieties IITA-TMS-I011371, IITA-TMS-I070539, IITA-TMS-I920057, IITA-TMS-I972205, IITA-TMS-I980505 had higher SRY at 12 MAP than other harvesting ages while varieties IITA-TMS-I011412 and TMEB419 had significantly higher yield at 10 MAP than 12 MAP. Varieties IITA-TMS-I011368, IITA-TMS-I070593, IITA-TMS-I30572, IITA-TMS-I920057, IITA-TMS-I972205, IITA-TMS-I980505, TMEB419 had SRY of 18.54t/ha and above at 8 MAP. These seven varieties may fit better into areas with short rainy season to use vast land in such areas currently not cultivated to cassava on large scale. To enhance cassava transformation in Nigeria, there is need to evaluate these varieties across different agro-ecologies for storage root yield at different harvesting age and varied planting dates. This will enable identification of more adapted variety in relation to harvesting age for each location and ensure an appropriate plating date is adopted at each location.

Keywords:Storage root yield; Harvesting age; Harvest index; Early bulking cassava genotypes; Number of storage roots