Growth and nutrient accumulation metrics of Diodia saponariifolia plants as a potential native cover crop in southeastern Brazil

Abstract

Competition for resources between crops and weeds hinders the increase of production in agroecosystems. The trait-based plant species selection of cover crops can be a useful tool to suppress competing plants in addition to providing environmental services. Here, we assessed the growth and macronutrient accumulation metrics in Diodia saponariifolia (Rubiaceae) plants, a native cover crop found in family farming systems in southeastern Brazil. Under greenhouse conditions, three viable D. saponariifolia cuttings were planted per tray. The experimental design was entirely randomized, with treatments consisting of plant sampling times, at regular intervals of 7 days between 16 and 93 days after transplanting (DAT) and 15 days between 93 and 138 DAT. Based on dry mass and chemical analysis of leaves, stems, and roots; we fitted the logistic model to explore the metrics of growth and macronutrient accumulation. Overall, the increment in plant dry mass was slow about halfway through the experimental period, being subsequently replaced by a phase of rapid growth. The stem was the plant fraction with the highest relative biomass accumulation. The total macronutrient concentration followed the descending order of K > N > Ca > Mg > P, varying along the plant ontogeny. Considering the nutrient content, the estimated 200 g m−2 of aboveground dry mass, and 0.3 m2 of leaf area, it is suggested to perform the first mechanical weeding along the third month of growth. Our results suggest that D. saponariifolia has satisfactory agronomical features for its establishment as a cover crop in different agricultural contexts.