Effect of allelopathy on plant performance

Abstract

12Allelopathy (i.e. chemical interactions between plants) is known to affect individual performance, 13 community structure and plant invasions. Yet, a quantitative synthesis is lacking. We performed 14 a meta-analysis of 385 studies that measured allelopathic effects of one species (allelopathy plant) 15 on another species or itself (test plant). Overall, allelopathy reduced plant performance by 25%, 16 but the variation in allelopathy was high. Type of method affected allelopathic effect. Compared 17 to leachates, allelopathy was more negative when residues of allelopathy plants were applied, 18 and less negative when soil conditioned by allelopathy plants was applied. The negative effects 19 of allelopathy diminished with study duration, and increased with concentrations of leachates or 20 residues. Although allelopathy was not significantly related to life span, life form and 21 domestication of the interacting plants, it became more negative with increasing phylogenetic 22 distance. Moreover, native plants suffered more negative effects from leachates of naturalized 23 alien plants than of other native plants. Our synthesis reveals that allelopathy could contribute to 24 success of alien plants. The negative relationship between phylogenetic distance and allelopathy 25 indicates that allelopathy might drive coexistence of close-related species (i.e. convergence) or 26 dominance of single species. 27 28 Keywords: allelopathy, crop, invasive species, life history, meta-analysis, phylogeny, soil 29 microbes, succession 30 plants (see Table 1 for a summary of the major methods that have been used to test allelopathy). 54The differences in study design partly reflect the four pathways through which allelochemicals 55 are released into the environment, that is, leaching from plants by rain, decomposition of plant 56 residues (e.g. litter), exudation from roots and volatilization (Fig. 2; Rice 2 p309). However, 57 studies also differ with regard to the different life stages of plants (e.g. germination vs. growth) 58 and the duration of the experiment (Fig. S2). Disentangling the importance of the different 59 factors related to the study design can hardly be achieved in a single case study, but is feasible in 60 a meta-analysis. 61Variance in allelopathy can also arise from biological traits of plants. Several studies of 62 plant succession revealed that the effect of allelopathy may depend on life history. For example, 63Jackson and Willemsen 17 reported that ragweed (Ambrosia artemisiifolia) and wild radish 64 (Raphanus raphanistrum), which are short-lived and early-successional species, cannot 65 reestablish on soils on which the long-lived and late-successional species Aster pilosus grew 66 previously. Besides life history, domestication may also matter as crop species appear to be more 67 sensitive to allelopathy than weeds 18 . From an evolutionary perspective, individuals of short-68 lived species are associated with other species for a shorter period than long-lived species are 19 . 69

Allelopathy is pervasive in invasive plants

“…Allelopathy has not been tested in all invasive plants in our analyses. Despite the guidelines for testing and validating potentially allelopathic compounds suggested by Blair et al (2009) not everyone measures allelopathy the same way, or on the same plant stages and the degree to which the same species expresses allelopathy can differ across studies (Zhang et al 2020). Further, plants species synthesize a wide array of compounds.…”

“…Given the wide range of potentially allelopathic chemicals that plants produce, there are likely to be diverse mechanisms that underlie the success of an allelopathic invader ranging from direct plant inhibition to altered soil chemistry to disruption of beneficial plant-microbial mutualisms belowground (Hale and Kalisz 2012). Therefore, the degree to which the same species expresses allelopathy can differ across studies (Zhang et al 2020). Most studies test for direct effects on the plants (Zhang et al 2020) and do not test for beneficial plant-microbe mutualism disruption (e.g., reduction in biomass or diversity of beneficial belowground microbial symbionts), likely because it is easier to study direct effects.…”

“…Allelopathy, the production of chemicals by a plant species that can affect neighboring plants or soil microbes, has been long acknowledged as an important functional trait that can alter neighbor plant performance and ultimately plant community structure. Anti-plant allelopathic compounds can directly affect neighboring plant tissues, disrupting germination, and seedling or adult plant growth (reviewed in Zhang et al 2020). Indeed, a recent meta-analysis focused on the direct allelopathic effects on plants demonstrated that neighbor plant performance was reduced by 25%, on average (Zhang et al 2020).…”

“…Anti-plant allelopathic compounds can directly affect neighboring plant tissues, disrupting germination, and seedling or adult plant growth (reviewed in Zhang et al 2020). Indeed, a recent meta-analysis focused on the direct allelopathic effects on plants demonstrated that neighbor plant performance was reduced by 25%, on average (Zhang et al 2020). However, anti-microbial allelopathic compounds can also alter soil nutrient availability (Zhang et al 2019), or directly kill microbial cells in the soil, resulting in the disruption plant-microbial mutualisms (Hale and Kalisz 2012) that are fundamental for plant resource acquisition (Fletcher and Renney 1963;Kelsey and Locken 1987;Stachon and Zimdahl 1980;Yamamoto 1995;Hale et al 2011).…”

Allelopathic Mechanisms in Fire-Prone Ecosystems

“…However, there is no comprehensive study concerning the relationship between allelopathy and fire. In literature on allelopathy generally deals with the effects of allelopathy on germination and seedling (Aguilar-Franco et al, 2019), plant performance (Zhang et al, 2021) and invasive plant species (Uddin and Robinson, 2017). Although there are not also many studies in the Turkish literature on allelopathy, it mainly deals with the effects of allelopathy on plant production (Yarnıa et al, 2011;Gürsoy et al, 2013) invasive plant species (Arıkan and Elibüyük, 2015;Kı̇tı̇ş et al, 2016;Özen et al, 2017;Karakuş et al, 2019), seed germination and seedling development (Gülsoy et al, 2008;Akın et al, 2017;Bingöl and Battal, 2017;Özbay, 2018;Yorulmaz and Yergin, 2020).…”