Productivity of cassava intercrop as influenced by cassava variety and time of introducingrice into cassava

The study was carried out to determine the most appropriate time of introducing rice into cassava with the aim of improving the total productivity of the intercrop. The rice variety Rok 16 was introduced into cassava at four different times—planted at the same time with cassava, and then at 2, 4, and 6 wk after cassava. The cassava varieties used were 80/40, an improved clone, and the local Cocoa. Both variety and time of introducing rice into cassava affected tuberous root yield of cassava. Variety 80/40 significantly out yielded Cocoa, while cassava tuberous root yield significantly increased the later rice was introduced into cassava. Rice grain yield significantly decreased as planting was delayed. At each planting date sole rice yield was significantly higher than that of intercropped rice which did not vary with cassava variety. Land equivalent ratio (LER) increased as the time of introducing rice into cassava was delayed. Results of the study indicate that for improved productivity of the system, rice should be introduced between 4 and 6 wk after planting cassava and that growing rice with the improved variety 80/40 resulted in higher productivity than with Cocoa

Intercrop yields of cassava and rice as influenced by cassava variety and population

The cassava variety and population, which when intercropped with rice leads to increased productivity of the system were identified. Two cassava varieties (Cocoa, a local variety; and 80/40, an improved one) were each planted at four populations (6 666, 10 000, 13 333, and 16 666) as sole crops or intercropped with the rice variety Rok 16. Variety 80/40 significantly out yielded Cocoa (17.2 and 4.1 t/ha, respectively). There was no significant difference in yield between sole and intercropped cassava. Tuberous root yield significantly increased as population increased, with the highest yield (13.0 t/ha) obtained at 16 666 and the lowest (8.3 t/ha) at 6 666. Rice yield did not vary significantly with cassava variety. Increase in cassava population significantly depressed rice yield. All intercropping systems had LER values greater than one. Highest LER was obtained when rice was intercropped with cassava at 6 666 (1.85 for 80/40 and 1.73 for Cocoa). LER decreased as cassava population increased. Thus productivity of the cassava-rice intercropping system can be improved by increasing the cassava population up to 6 666 and by growing the improved variety 80/40

Cassava improvement in sub-Saharan Africa: contributions of IITA and its partners

Cassava is well recognized for its capacity to address food needs of vulnerable communities in unstable environments in SSA. IITA and colleagues in African NARS, in collaboration with CIAT and ARIs have played leading roles in the development of improved cassava varieties which are disease and pest resistant, early maturing, and high yielding. Through a combination of conventional and new approaches, over 400 cassava genotypes have been developed. The characteristics of the new generation of cassava germplasm broke what had been an apparent yield barrier in cassava improvement increasing yields in many locations by at least 50–100% without the use of fertilizer. The improved germplasm is shared with NARS within the region as specific genotypes or improved seed populations for evaluation and selection under local conditions. Improvement programs in Africa that received these materials have tested them under local conditions, selected varieties that outperform local varieties, and released them to farmers in virtually every major cassava producing country. Today, about 30% of the area cropped with cassava in Africa is planted with improved varieties. Without the introduction of more productive cultivars with multiple diseases and pest resistance, the effective biological control of the cassava mealybug and, to a certain extent, of the green mite, cassava production in SSA would be 50% or less of what it is today. That translates to over 13 million tons of dry cassavayear, enough to meet the calorie requirements of 65 million people. The significant gains in the crop’s output in farmers’ fields are not only contributing to the African diet but also propelling commercialization of the crop. This paper highlights contributions to cassava improvement in SSA since 1970 by IITA and its partners, and suggests areas needing strengthening in the drive to produce better crop varieties for different regions and enduses in Africa