Maize-coconut intercropping: effects of shade and root competition on maize growth and yield

Maize was grown simultaneously under artificial and under natural shade from coconut palms. Under artificial shade, the more solar radiation was intercepted, the less the maize developed and yielded. Under our experimental conditions, where photosynthetically active radiation (PAR) was the only limiting factor, there was a simple linear relation between yield and PAR. Applying this relation to a maize-coconut intercropping system gave an estimated yield slightly higher than the actual harvest. This may be due to the difference between radiation interception by shading canvas and that obtained with a coconut cover, A second explanation may be root competition between the two crops. Although this competition indeed exists, it was not detected in our experiment due to the excellent soil and climatic conditions. Our experiment also showed that in maize, net assimilation response to PAR did not depend on the received light treatment. ((C) Inra/Elsevier, Paris.).