LAND USE EFFICIENCY, CANOPY DEVELOPMENT, DRY MATTER PRODUCTION AND PLANT NUTRITION OF CASSAVA-GRAIN LEGUME INTERCROPPING SYSTEMS
Abstract
A two-year field study was conducted to evaluate land use, and inter-specific competition effects on canopy development, dry matter production and nutrient status in cassava (Manihot esculenta Crantz) - cowpea (Vigna unguiculata (L.) Walp) and cassava-peanut (Arachis hypegaea L.) intercropping systems. The influence of varying P application rate on inter-specific competition in a cassava-cowpea intercropping system was also studied. Intercropping cassava with either cowpea or peanut resulted in approximately 25 percent greater land use efficiency for the 11-month growing season than did sole cropped cassava and sole cropped cowpea or peanut. The greater land use efficiency when intercropped was associated with significantly greater leaf area and dry matter production during early growth than for those of sole cropped cassava, although at harvest the total leaf area and dry matter produced were similar for these cropping systems. Cassava yields were reduced from 0 to 35 percent when intercropped with cowpea or peanut. These yield reductions were associated with production of fewer storage roots per plant and lower LAIs between 50 and 100 days after planting, when storage root initiation occurs. Intercropping with cowpea or peanut reduced cassava dry matter production by 200 to 600 g m('-2) in both years, which accounted for most yield differences between sole cropped and intercropped cassava. However in 1982 when intercropped with peanut, cassava yield was further reduced, apparently due to sink size limitations caused by production of only 8.8 storage roots per plant. Nutrient concentrations of intercropped cassava leaves were reduced when cowpea and peanut were growing most rapidly. Both cowpea and peanut seed yields and dry matter production were reduced 26 to 40 percent when these crops were intercropped with cassava, while leaf area indices were reduced 10 to 30 percent. Increasing the P application rate from zero to 44 kg ha('-1) in intercropped cassava and cowpeas resulted in increased cowpea seed yield both years, and increased cassava yield in 1981. No further cassava or cowpea yield increases occurred at P application rates greater than 44 kg ha('-1). Leaf area and dry matter production, and nutrient uptake were more responsive to P application for cowpea than cassava.
Degree
Ph.D.
Subject Area
Agronomy
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