Abstract
Four new cassava varieties ( NR 8082, TMS 00033, TMS 91/ 453 and TMS 00447) were fertilized with NPK ( 20-10-10) at the rates of 0, 200, 400, and 800 kg/ha in an experiment with the crop planted early (April) in 1999 and then late (September) in 2000. Tuber yield was 28% higher in early-planted cassava than in the late cultivation. Yield was reduced by 44% in NR8082, 15% in TMS 00033 and 45% in TMS 00447 as a result of late planting. Tuber yield from NR 8082 (44t /ha) was the highest for early-planting while TMS 00033 gave the highest yield (31 t/ha) in late planting. Fertilizer influence on tuber yield was not significant in early-planted cassava. In late-planted cassava, significant reduction in yields was observed from the application of 400 and 800kg/hectare of fertilizer. Incidence of tuber rot was influenced by varietal differences rather than fertilizer rates. Incidence of rot was lowest in NR8082 (910%) and TMS 00033 (10-11%) in both plantings and the severity was mild in all the varieties. TMS 00033, a low cyanide variety, have tuber yields above 30 t/ha in both early and late plantings and is therefore recommended for adoption trials by farmers.
Highlights
Cassava is planted throughout the rainy season in southwestern Nigeria
Planting was done at the onset of rainy season in an experiment with the crop planted early (April) 1999 and fertilizer was applied at one month after planting (1MAP) and three months after planting (3MAP)
Tuber yield was higher in 1999 early season planting than in 2000 late season planting by 28 percent
Summary
Cassava is planted throughout the rainy season in southwestern Nigeria. The early plantings have enough moisture for growth, and the tubers partly mature into the dry season. Cassava planted late often experience water stress during vegetative and tuber development stages and the tubers mature within the rainy season. Water stress has negative influence on cassava tuber yield. Season stress significantly reduce top and root biomass than late or terminal stress which occurred during tuber maturity in cassava. To increase the yield potential of cassava, the crop had been reported to respond to good soil fertility and adequate fertilizer (Gomez et al, 1980; Wilson and Ovid, 1994; Howeler, 1996). Fertilizer requirement for optimum yield in cassava is determined by the following factors, soil fertility status of the farmland, cropping
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