Influence of cassava population density on the growth and yield performance of cassava - maize intercrop with a relayed cowpea

摘要

Experiments were conducted during the growing seasons of 1996, 1997 and 1998 at the Institute of Agricultural Research and Training, Ibadan on latitude 7o 30'N and longitude 3o54'E in the degraded rain forest vegetation zone of Nigeria to assess the effects of cassava population densities on the growth and yield of Maize - Cassava intercrop with a relayed Cowpea. The treatments were four cassava population densities (CPD) viz.: CPD 1 = 12,300 Cassava plants / ha (0.9 m x 0.9m); CPD 2 = 10,000 Cassava plants / ha (1m x 1m): CPD 3 = 8,888 cassava plants / ha (1.5 x 0.75m) CPD 4 = 6,666 cassava plants / ha (1.5m x 1.0m). The controls were: Sole Cassava, Sole Maize and Sole Cowpea. Results showed that cassava population density (CPD) had significant effects on maize plant height and average leaf area at tasselling. It also significantly reduced yield and yield components of maize. Cowpea yield was also reduced with increasing cassava population densities. Cassava root yield decreased by 15%,25%, 40% and 44% at CPDs 12,300,10,000, 8,888, and 6,666 plants/ha respectively relative to yield obtained under sole cassava. The marginal rate of return (MRR) for the intercrops also increased with decreased cassava population densities. The highest average MRR of 81% was got with cassava intercropping at 6,666 plants/ha. The lowest return of 49% was got from 12,300 cassava plants/ha. Total productivity per unit land and total income was highest at cassava population density of 6,666 plants/ha followed by 8,888 plants/ha. It was concluded that, although higher yields could be obtained by planting cassava, maize and cowpea in monoculture, the benefits derivable in terms of shared labour costs could not make sole cropping sustainable.