EVALUATION OF CASSAVA/SOYBEAN INTERCROPPING SYSTEM AS INFLUENCED BY CASSAVA GENOTYPES
AbstractThe effects of three cassava genotypes (NR 8212, TMS 91934 and TMS 30572) grown sole or intercropped with soybean were investigated in two field experiments in 2000/2001 and 2001/2002 cropping seasons at Umudike in the lowland humid forest zone of south-eastern Nigeria. The plant height, canopy diameter, number of leaves per plant and leaf area index (LAI) of soybean and cassava were significantly (P<0.05) affected by intercropping but days to 50 per cent flowering of soybean were not affected. Canopy diameter, number of leaves per plant and LAI of cassava were highest with TMS 30572 in sole or intercropping cultures and least with sole or intercropped TMS 91934 genotype in both seasons. Soybean plants were taller when intercropped with NR 8212 or with TMS 30572 than in sole soybean, which had similar height with soybean in soybean/TMS 91934 mixture. The soybean canopy diameter, number of leaves per plant and LAI were higher with sole soybean. Within the soybean intercrops, canopy diameter, number of leaves per plant and LAI were higher with soybean/TMS 91934 and soybean/NR 8212 than with soybean/TMS 30572 mixture. The yield and yield components of cassava (total number of tubers per plant, number and weight of marketable tubers per plant and fresh tuber yield per hectare) were not affected by intercropping. The number of pods per plant, pod dry weight per plant and grain yield of soybean were significantly (P<0.05) affected by intercropping but 100-seed weight was not. Grain yields of soybean in mixtures (449.28 and 387.85 kg/ha) were lower than that in sole crop (670.10 and 566.35 g/ha). Among the soybean intercrops, the highest soybean yields (533.67 and 462.00 kg/ha) were with soybean/TMS 91934 whereas the lowest (385.91 and 339.52 kg/ha) were with soybean/TMS 30572 mixture in 2000/2001 and 2001/2002 seasons, respectively. Yield increment for cassava ranged from 1.42-3.43 per cent (2000/2001) and 3.72-7.74 per cent (2001/2002) for fresh tuber yield/ha while yield reduction for soybean ranged from 20.36-42.41 per cent (2000/2001) and 18.43-40.05 per cent (2001/2002) for grain yield/ha. There was yield advantage due to intercropping. The productivity of cassava/soybean mixture showed yield advantage of 59-84 per cent (2000/2001) and 64-90 per cent (2001/2002). The highest monetary returns (N133,786.00 and N156,161.00/ha) were achieved with TMS 30572/soybean intercropping system in both years.
Keywords: Cassava, soybean, intercropping, genotypes, productivity.
[Niger Agric. J. 33 (2002): 11-18]