Radiation interception and use by maize/peanut intercrop canopy

The efficient use of solar radiation is one of the major criteria for obtaining a yield advantage through intercropping. Although various combinations of crops have been reported for intercropping systems, the maize/peanut association has yet to be analysed. This report presents the radiation-use efficiency (ɛ) results of a maize/peanut intercrop study. The experiment constituted three treatments: sole crops of maize and peanut, and a maize/peanut intercrop. The canopy light extinction coefficient (k) of peanut was reduced while intercropped with maize. The mean ɛ of intercropped peanut (2.13 g(DW) MJ−1) was 79% higher than that of peanut stands alone. The ɛ of combined intercropped stands (3.03 g(DW) MJ−1) was more than two-fold that of sole peanut, but slightly lower than that of maize stands alone (3.27 g(DW) MJ−1). The harvest index (HI) of intercropped peanut was about 13% lower than that of peanut grown alone, but produced 46% of the pods of the latter (299 g m−2), the parameter that represents the true output of this intercropping system. These results suggest that a maize/peanut intercropping would help to increase production through the efficient utilisation of solar energy. A simple model was developed to isolate the daily radiation interception of each of the canopies of the intercrop partners in separate strata, taking into account the alteration of the k of the understorey. The model may also be applicable in agroforestry systems.