Plant functional diversity improves short-term yields in a low-input intercropping system Jose G. Franco a, *, Stephen R. King b , Joseph G. Masabni b , Astrid Volder c a Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, United States b Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843, United States c Department of Plant Sciences, University of California – Davis, Davis, CA 95616, United States A R T I C L E I N F O Article history: Received 8 July 2014 Received in revised form 8 January 2015 Accepted 16 January 2015 Available online xxx Keywords: Agroecology Biodiversity Functional groups Intercropping Land equivalent ratio Sustainable agriculture A B S T R A C T 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 (W pwo ) and peanut, watermelon, okra and cowpea (W pwoc ) consistently overyielded in 2011 and 2012. LER values were 1.17 each for W pwo and W pwoc 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 (W all ) when compared to its monoculture, 5.50 and 2.09 kg fruit 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 W pwoc and W all than in monoculture, 2.28, 2.46, and 1.13 kg fruit 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. ã 2015 Elsevier B.V. All rights reserved. 1. Introduction In natural ecosystems, increased plant species diversity has been shown to increase net primary productivity (Tilman et al., 1996). Two possible explanations have been proposed to explain this; the sampling effect hypothesis and the complementarity effect hypothesis. Multispecies systems may include highly productive species that dominate the community (Hector, 1998), leading to what is known as the “sampling effect”. The likelihood of including species that contribute disproportionately to overall community productivity increases as the number of species in the community increases (Loreau, 1998; Gastine et al., 2003). Therefore, an increase in total community productivity may be due to one or few dominant species rather than the biological interactions underlying the complementary effect hypothesis. In multispecies systems, complementarity and facilitation can offset the negative effects of competition (Hooper et al., 2005). Complementarity results from niche partitioning and a reduction of interspecies competition (Vandermeer, 1989), while facilitation occurs when neighboring plants have a beneficial effect on each other (Chu et al., 2008). Facilitation can occur during times of suboptimal environmental conditions when one species alleviates those conditions or provides a resource for neighboring species (Hooper et al., 2005). Complementarity occurs when species use different resources or use the same resource but separate its utilization in time or space. This can result in more efficient use of resources by the community as more of the total available resources * Corresponding author at: HFSB 305, 2138 TAMU, Texas A&M University, College Station, TX 77843, United States. Tel.: +1 979 220 6846. E-mail address: jose.g.franco.jr@gmail.com (J.G. Franco). http://dx.doi.org/10.1016/j.agee.2015.01.018 0167-8809/ ã 2015 Elsevier B.V. All rights reserved. Agriculture, Ecosystems and Environment 203 (2015) 1–10 Contents lists available at ScienceDirect Agriculture, Ecosystems and Environment journal homepage: www.elsev ier.com/locate /agee