Effect Of Cowpea Planting Density On Growth, Yield And Productivity Of Component Crops In Cowpea/Cassava Intercropping System
Field trials were conducted at the research farm of the National Root Crops Research Institute (NRCRI), Umudike (07° 33΄ E, 05° 29΄ N) in 2004/2005 and 2005/2006 cropping seasons to determine the effect of cowpea planting density on growth, yield and productivity of component crops in cowpea/cassava intercropping system. Cassava at a density of 10,000 plants per hectare was intercropped with cowpea at four planting densities (20,000; 40,000; 60,000 and 80,000 plants per hectare). Both crops were also planted in monoculture and in intercrop. The experiment was arranged in a randomized complete block design (RCBD) with three replications. The leaf area index (LAI) of cassava was highest with the highest cowpea planting density in 2005/2006, but in 2004/2005 cropping season both cropping system and planting density did not influence the LAI of cowpea. Cowpea LAI was similar in the 2 seasons with the highest planting density (80,000 plants/ha) producing the highest LAI. Similarly, fresh root yield (t/ha) of cassava was influenced by cropping system and population density in 2005/2006, but not in 2004/2005 cropping season. Cassava tuber yield was highest with the cowpea planting density of 80,000 plants/ha. Cowpea grain yield (kg/ha) was not significantly (P>0.05) affected by intercropping in the two cropping season. Grain yield of cowpea was highest with the highest cowpea density in 2005/2006 but in 2004/2005 season, there was no cowpea density effect. The relative yield total, expressed as land equivalent ratio of the two crops was greater than 1.0 in all intercrops. At the prevailing market price level (N 7.50 per kg for cassava and N 33 per kg for cowpea), cassava intercropped with 80,000 cowpea plants/ha gave a higher monetary returns than when intercropped with other population densities of cowpea or in monoculture of the two crops. Similarly, cowpea at highest population density gave the highest monetary returns.
Agro-Science Vol. 7 (2) 2008: pp. 106-113