Distantly related crops are not better rotation partners for tomato

Abstract

Although crop rotation has been used for centuries to enhance agricultural production, there are surprisingly little data justifying the use of one rotation over another. Growers typically avoid growing plants in succession that belong to the same genus or family, but it is not clear whether closely related crops are indeed poor rotation partners and whether evolutionary history, overall, predicts legacy effects in agricultural soils. Here, we use a plant–soil feedback framework to test the relationship between species relatedness and crop growth. Using tomato Solanum lycopersicum as our focal crop, we determined how 36 common crop and weed species that vary along a spectrum of phylogenetic relatedness influence tomato growth in subsequent plantings. We also tested whether soil conditioning affects the performance of an above‐ground insect herbivore, the tobacco hornworm Manduca sexta. Phylogenetic relatedness did not predict plant–soil feedback effects on tomato biomass or hornworm performance; rather, impacts of soil conditioning were highly species‐ or family‐specific. For example, tomatoes growing in soil previously containing plants in the Asteraceae family were notably resistant to caterpillar feeding. There was also a disconnect between which plant species caused negative feedbacks on tomatoes vs. hornworms (e.g. thistle Cirsium discolor soil had strong negative effects on herbivory but no impact on plant growth). Hence, negative feedbacks on hornworms are likely due to enhanced defence instead of simply reducing leaf availability. Synthesis and applications. These data demonstrate that, despite being widely recommended by agronomists in most cropping systems, phylogenetic relatedness is a poor predictor for the success of crop pairings in rotation, especially in tomato. Better understanding of species‐specific effects of soil conditioning will lend insight into how polycultures can be better designed to optimize crop growth while reducing susceptibility to insect pests, which is particularly useful on diversified farms that cultivate a variety of crop species.

Domesticated tomatoes are more vulnerable to negative plant–soil feedbacks than their wild relatives

“…Because the impact of soil associations on plant performance is the net effect of traits that both suppress pathogens and recruit mutualists, either mechanism could be at play. However, the proximate factors mediating plant–soil feedbacks remain unknown; attention has generally focused more on ultimate mechanisms such as plant phylogeny (Fitzpatrick, Gehant, Kotanen, & Johnson, ; Ingerslew & Kaplan, ; Mehrabi & Tuck, ), functional group (Heinen, Sluijs, Biere, Harvey, & Bezemer, ; Ma et al, ) and growth rate (Baxendale, Orwin, Poly, Pommier, & Bardgett, ; Cortois, Schröder‐Georgi, Weigelt, Putten, & Deyn, ). Wild tomatoes possess a diversity of pathogen resistance traits, some, but not all, of which have been introgressed to crop tomatoes via traditional breeding (Bai & Lindhout, ).…”

“…Historically, coupled plant-soil management in agricultural ecosystems, such as crop rotation, has been used to ameliorate negative conspecific plant-soil feedbacks associated with monocultures, with variable success (see Huang et al, 2013;Ingerslew & Kaplan, 2018;Mariotte et al, 2018). However, conventional agronomic practices may contribute to negative plant-soil feedbacks in agroecosystems through both ecological and evolutionary processes (Barber, Kiers, Theis, Hazzard, & Adler, 2013).…”

Phylogenetic farming: Can evolutionary history predict crop rotation via the soil microbiome?

“…Seeds for each of the 36 species were germinated in the laboratory in the spring and fertilized weekly beginning 2 weeks after transplanting seedlings into pots in the greenhouse. See Ingerslew and Kaplan (2018) for details on germination procedures and seed sources. Because seedling size varied across species, we standardized germination times.…”

“…Despite pleas for integrating a phylogenetic perspective on applied sciences (Ness, Rollinson, & Whitney, 2011) and insights that phylodiversity has offered in various applied disciplines (e.g., forest management, Jactel & Brockerhoff, 2007; habitat restoration, Verdú, Gómez‐Aparicio, & Valiente‐Banuet, 2012; ecosystem function, Srivastava, Cadotte, MacDonald, Marushia, & Mirotchnick, 2012; invasive species, Pearse & Altermatt, 2013; urban planning, MacIvor, Cadotte, Livingstone, Lundholm, & Yasui, 2016), the existing agricultural literature virtually ignores evolutionary history (but see Ingerslew & Kaplan, 2018; Miller & Menalled, 2015; Schellhorn & Sork, 1997). In some cases, crops may be taxonomically clustered, either intentionally or unintentionally, because of similar growing requirements (i.e., related species possess comparable tillage, fertility, and/or irrigation needs).…”

Applying the Aboveground-Belowground Interaction Concept in Agriculture: Spatio-Temporal Scales Matter

“…As belowground processes are local and can last for long periods of time, we propose to take these processes as a starting point for steering abovebelowground interactions. It will be essential to design spatiotemporal configurations of crops by combining principles from crop rotation and intercropping (Brooker et al, 2015;Dias et al, 2015;Mariotte et al, 2018) to maximize the benefit of soil legacy effects on both neighboring and follow-up crops (Barel et al, 2018;Ingerslew and Kaplan, 2018 ; Figure 2). Whereas intercropping itself may yield higher crop biomass via enhanced nutrient uptake or reduced disease spread (Brooker et al, 2015), rotating intercrops designed to maximally benefit from belowground legacy effects can further enhance crop production (Figure 2).…”