Growth and resource use studies in an intercrop of pearl millet/groundnut

Abstract

Growth and resource use data are presented for the sole crops and an intercrop of an 82-day millet and 105-day groundnut. The intercrop row arrangement was 1 millet: 3 groundnut and the within-row spacing of each crop was the same in sole crop and intercrop. In groundnut, yield/plant and yield components were similar in intercropping and sole cropping. In millet, on a per plant basis the dry matter accumulation, leaf area development and tiller production were all substantially greater in intercropping compared with sole cropping; final seed yield/plant was just over twice as high in intercropping, this being achieved by increases in heads/plant and seeds/head. Calculated on the basis of a Land Equivalent Ratio (LER) intercropping gave 28% more total dry matter (LER = 1.28) and 26% more reproductive yield (LER = 1.26) than growing the two crops separately; both these yield increases were statistically significant. There were even greater increases in the total leaf area index of the combined intercrop canopy (maximum LER = 1.39) but increases in the total root length of the combined rooting system were rather smaller (maximum LER = 1.18). The higher intercrop yield appeared to be achieved by an increased efficiency in converting light energy into dry matter and not by any increase in the amount of light energy intercepted. It is suggested that this increased efficiency may have been because the combined intercrop canopy resulted in light being more efficiently spread over a greater surface of leaf. Total water use was rather higher in intercropping and the total water use efficiency was improved because a greater proportion of the water was used by the crop rather than lost as evaporation from the soil surface. The LER values for total uptake of N, P and K in intercropping were 1.25, 1.28 and 1.26, respectively, indicating that the higher yield in intercropping was associated with a commensurately greater uptake of nutrients.