Plant functional diversity improves short-term yields in a low-input intercropping system

In natural ecosystems, plant communities composed of functionally diverse species produce more biomass overall than less diverse communities. This increased biomass production is thought to occur due to complementary use of resources such as nutrients and water, and facilitation during sub-optimal environmental conditions. Using the same concept in a crop setting may lead to increased yield (overyielding) in diverse cropping systems when compared to monocultures. Different combinations of peanut, watermelon, okra, cowpea, and pepper planted alone or in various intercropping combinations were investigated over two growing seasons in a low-input system in the peak of summer heat in Texas. Each species was selected to perform a specific function within the system. Results from land equivalent ratio (LER) indicate that the within-row combination with peanut, watermelon and okra (Wpwo) and peanut, watermelon, okra and cowpea (Wpwoc) consistently overyielded in 2011 and 2012. LER values were 1.17 each for Wpwo and Wpwoc in 2011 and 1.17 and 1.20 in 2012, respectively. In 2011, watermelon was the dominant crop and was up-regulated in all intercropping combinations while all other component crops were down-regulated. Watermelon per plant production was significantly higher in the combination containing all species (Wall) when compared to its monoculture, 5.50 and 2.09 kgfruit plant−1, respectively. In 2012, okra was the dominant crop and was up-regulated in all intercropping combinations while watermelon, cowpea, and pepper were down-regulated. Okra per plant production was significantly higher in Wpwoc and Wall than in monoculture, 2.28, 2.46, and 1.13 kgfruit plant−1, respectively. These findings suggest that three and four species intercropping combinations, whereby each crop is selected to perform a specific function within the system, may provide small-scale sustainably-minded producers a model system that can be utilized in suboptimal conditions and allow them to reduce inputs while increasing overall yields.