Performance of maize, beans and ginger as intercrops in Paulownia plantations in China

Yield, morphology and specific leaf weight of summer crops maize, beans and ginger were studied in relation to tree proximity and PAR transmissivity in a 7-year old plantation of Paulownia elongata grown at a spacing of 15 m x 5 m in Eastern China. The yield of beans and maize was significantly reduced, compared to controls, at all positions relative to the trees. This yield depression was particularly marked at positions closest to the trees. Beans grown at 2 m from the trees had reduced height and specific leaf weight. These crops would yield more at wider tree row spacings. Ginger gave high yields when intercropped and is an ideal shade crop for these systems. Further research is required on optimisation using a bioeconomic approach. Further agronomic, physiological and biochemical work is required on ginger and other economic members of its family as these appear to have compatibility with dense agroforestry plantings.