Abstract
ABSTRACT Maize is one of the main cereals cultivated worldwide and wild poinsettia is among the weeds that cause damage in grain production. The objective of this study was to evaluate the relative competitive ability of maize hybrids in the presence of a wild poinsettia biotype through experiments in replacement series. In preliminary experiments, it was determined the plant population in which the dry mass becomes constant. For the maize hybrids ‘Agroeste’, ‘Morgan’, ‘Nidera’, and ‘Velox’, as well as the wild poinsettia, the population was 20 individuals vase-1. Subsequently, experiments were carried out in replacement series in different combinations of species that varied the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of the species' competitiveness was carried out using diagrams applied to the replacement experiments and by the relative competitiveness indexes. The height (PH), chlorophyll index (CI), leaf area (LA), and the shoot dry mass (DM) of the plants were evaluated 50 days after emergence. There was competition between the maize hybrids and the wild poinsettia; both were negatively affected, regardless of the proportion of plants, causing reductions in the species' PH, CI, LA, and DM. The competition between maize and wild poinsettia occurs for the same resources in the environment, and interspecific competition caused greater damage to maize and wild poinsettia than intraspecific competition. In general, it was observed that only the hybrids ‘Nidera’ and ‘Velox’ were more competitive than the wild poinsettia.
Highlights
Weeds compete with maize for water, light, and nutrients, making it difficult to manage crops, pests, and diseases, or they may even release allelopathic substances that interfere with the growth and development of the crop (MORAES et al, 2013; FRANDOLOSO et al, 2019; GALON et al, 2021)
The variance analysis of the data demonstrated a significant effect between the proportions of plants of each maize hybrid and/or wild poinsettia for the variables, plant height (PH), chlorophyll index (CI), leaf area (LA) and shoot dry mass (MS)
Replacement experiments between maize hybrids versus wild poinsettia indicated competition between species, in which the productivity values obtained in different proportions between the two species, in general, deviated from the expected yield line (RP and RTP)
Summary
Weeds compete with maize for water, light, and nutrients, making it difficult to manage crops, pests, and diseases, or they may even release allelopathic substances that interfere with the growth and development of the crop (MORAES et al, 2013; FRANDOLOSO et al, 2019; GALON et al, 2021). Losses caused by weeds can reduce maize production by up to 70% and reduce the quality of the product if no management is adopted to control these species (MORAES et al, 2013; FARIA; BARROS; TUFFI SANTOS, 2014; GALON et al, 2019) In this context, the wild poinsettia (Euphorbia heterophylla), a species widely found in crops, stands out as one of the weeds with the highest potential for damage, especially for its high competitive ability, high capacity for shading and seed production, and due to its multiple resistance mechanisms, which make it difficult to control using acetolactate synthase-ALS, protoporphyrinogen oxidase-PROTOX and 5 enolpyruvylshikimate-3phosphate synthase-EPSPs-inhibiting herbicides (TREZZI et al, 2006; VARGAS et al, 2013; WANDSCHEER; RIZZARDI; REICHERT, 2013; AGOSTINETTO et al, 2017; HEAP, 2020). In competition studies, it is not enough to evaluate only the plant population in the competitive process, and the influence of variation in the proportions between species (BIANCHI; FLECK; LAMEGO, 2006; FLECK et al, 2008; AGOSTINETTO et al, 2013)
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