Impact of global warming and crop factors on the growth and productivity of four cassava (Manihot esculenta Crantz) cultivars in Nigeria

The integrated effects of weather change (Global warming), genotypic factors and cultivars on the growth and productivity of cassava (Manihot esculenta Crantz)were investigated in South-eastern Nigeria in 1999/2000 and 2000/2001 cropping seasons. Plant height (m), number of roots and fresh root yields (t/ha) differed among the seasons in response to global warming and were dependent on a combined optimum rate of each individual treatment. The optimum plant height (m) obtained during the two seasons ranged from 2.0 to 2.1 M and were obtained by the interaction of TMS 30572 x 750 kg/ha stake weight  x 3 shoots per stand. The highest fresh root yield of 28.0 and 13.6 t/ha were obtained by the interaction of cultivar NR 8082 x 875 kg stake weight x 3 shoots per stand. The combined analysis of variance for fresh root yields showed significant (P = 0.05) mean squares for cultivar, stake weight, number of shoots per stand and seasons (years). There was cultivar x stake weight x number of shoot x season interaction, indicating that the yields of the treatments responded differently relative to each other in different years. Higher plant height (2.1 m) and fresh root yield (28.0 t/ha) were obtained in 1999/2000 than in 2000/2001(1.9 m and 13.6 t/ha). Crop factors and weather change tremendously determined growth and productivity of cassava in Nigeria. Crop factors and weather were responsible for the variations in cassava yields in Nigeria.   Key words: Cassava, productivity, climatic factor, south eastern Nigeria, cultivars.