Component crop physiology and water use efficiency in response to intercropping

Authors: Franco, Jose; KING, STEPHEN - Millican Farms, Llc Tx; VOLDER, ASTRID - University Of California

Submitted to: European Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2017
Publication Date: 1/1/2018
Citation: Franco Jr, J.G., King, S.R., Volder, A. 2018. Component crop physiology and water use efficiency in response to intercropping. European Journal of Agronomy. 93:27-39. https://doi.org/10.1016/j.eja.2017.11.005.
DOI: https://doi.org/10.1016/j.eja.2017.11.005

Interpretive Summary: Intercropping is an integrated crop management approach to sustainably intensify food production systems. The benefits of intercropping are often due to interactions between crops that enhance resource use. Most intercropping studies have focused on two-species systems and there is a gap in our understanding of how component crops will respond physiologically to a functionally diverse intercropping system. Specifically, there is little information beyond two-species systems that investigates water use efficiency of component crops. Although the results from this study only give an insight into trends across systems, this study demonstrates the potential for a functionally diverse cropping system to enhance water use efficiency in dominant crops. This result is important to producers and water management officials, showing a method to increase overall crop production without increasing water inputs.

Technical Abstract: Interspecies specific interactions are generally regarded as drivers of plant productivity in multispecies agroecosystems. Complementary use of resource in diverse communities can enhance community productivity through optimal use of plant-available resources and positive interactions such as facilitation can ameliorate high abiotic stress conditions. We studied the effects on physiological response and water use efficiency of a multifunctional species intercropping system consisting of peanut, watermelon, okra, cowpea and pepper planted alone or in various intercropping combinations in a low fertilizer input system in the peak of summer heat in Texas. No differences in d13C composition, a measure of water use efficiency over the leaf lifespan, were detected across cropping system for each species. Differences in gas exchange measurements were detected only in watermelon in year 2 of the study when okra was the dominant crop. In this year, watermelon specific leaf area (SLA) was significantly higher when okra was present in a treatment and particularly in the three and four species combinations, Wpwo and Wpwoc, 27.5 and 31.0 m2 kg-1, respectively, as compared to watermelon grown in monoculture, strip intercropped with peanut (Spw) and within row intercropped with peanut (Wpw), 20.4, 20.1, and 19.8 m2 kg-1, respectively. This corresponds with an increase watermelon leaf N concentration and a decrease in leaf C:N ratio in Wpwo and Wpwoc. Water use efficiency based on per plant production (WUEyield) indicate an increase in water use efficiency in dominant crops such as watermelon in 2011 and okra in 2012, but a reduction in subordinate crops such as cowpea and pepper both years of the study. Peanut grown in monoculture and strip intercropped with watermelon had significantly lower leaf water potential values in 2012, -2.2 and -2.1 MPa, respectively, as compared to intercropping systems increasing in level of integration (Wpw = -1.1, Wpwo = -0.6, Wpwoc = -1.3, Wall = -1.1 MPa), indicating peanut benefited from alterations to microclimate and facilitative interactions with companion crops in some intercropping systems through a reduction in plant water stress. The results from this study suggest there may be a benefit to a multifunctional intercropping system in the form of enhanced water use efficiency in dominant crops and reduced water stress for some component species.