Non-additive effects of domestication and soil origin shape resource-use strategy and biomass allocation in chaya (Cnidoscolus aconitifolius I.M. Johnst.)

Background: Domestication-driven shifts to a relatively more acquisitive strategy and increased biomass allocation in plant organs have been demonstrated in some major crops. However, the extent to which this pattern is influenced by the relatively more resource-rich conditions prevailing in agroecosystems is less clear. Although soil is the main source of nutrients for plants, it remains unknown if the effect of domestication on resource-use strategy and biomass allocation patterns is contingent upon soil origin. Hypothesis: The effects of domestication and soil origin on the resource-use strategy and biomass allocation are not additive. Studied species Chaya (Cnidoscolus aconitifolius I.M. Johnst.). Methods: The effects of domestication (wild vs. domesticated plants) and soil origin (forest, homegardens, and intensive orchards) on leaf traits associated with the leaf economic spectrum and biomass allocation to above- and below-ground organs were assessed experimentally. Results: A domestication-driven shift to a relatively more acquisitive strategy was found. This effect was contingent upon soil origin. Domesticated plants reverted to a more conservative strategy when they were grown in forest soil. Increased biomass allocation and decoupling among different organs were observed in domesticated plants. Leaf production and the root:shoot ratio were also contingent upon soil origin, with greater values observed when domesticated chaya was grown in orchard soil. Conclusions: This study supports the existence of an intraspecific leaf economic spectrum in chaya. While domestication, as a main effect, tends to shift the resource-use strategy to the acquisitive side of the spectrum, this effect is clearly contingent upon the soil origin.