Radiation Absorption and Use Efficiency in Relay Intercropping and Double Cropping of Winter Wheat and Maize

In many parts of the country farmers are faced with the problem of synchrony between sowing date of spring crops and the grain filling period of winter cereals. Competition for limited resources, mainly water results in delayed sowing in spring. In this research relay intercropping of winter/spring species was studied as an alternative practice for conventional double cropping system. Four intercrop treatments with ratios of 3:1, 3:2, 4:2 and 6:2 (wheat:corn) together with sole crop of each species was evaluated in a randomized complete block experiment with 3 replications. Corn seeds were sown in pre-established rows within wheat strips 32 days before harvesting wheat. During the growth period leaf area index, fraction of transmitted radiation and dry matter production was measured in two-weekly intervals and grain yield of species at harvest. Absorbed radiation during the season, radiation use efficiency of species, harvest index and land equivalent ratio were calculated based on the collected data. The results indicated that in all sowing ratios absorbed radiation by the intercrop canopy was significantly higher than sole crops. However, radiation use efficiency of species was not differed between treatments. As indicated by land equivalent ratio, relay intercropping treatments had yield advantage of 27 to 31% over sole crops which was mainly due to increased light absorption by the intercrop canopies. While the number of wheat rows had no drastic effects on the yield, the best results was obtained from 3:2 (wheat:corn) intercrop. It was concluded that relay intercropping of winter cereals with spring crops results in better utilization of resources and increased yield compared to double crop of the same species.