Cultivation Systems, Vegetable Soil Covers and their Influence on the Phytosocyology of Weeds

ABSTRACT: Phytosociological studies are groups of methods that aim at the identification, composition and distribution of plant species in a community. The objective of this study was to identify and quantify the main weeds found in beans, maize and soybean cultivated in no-tillage and conventional systems. The experimental design was a randomized block one, with four replications. Experiments were conducted during three consecutive years, with summer crop (bean, maize and soybean) treatments, no-tillage system (NTS) composed by the covers, black oat, vetch and forage radish, in addition to their intercrop. In the conventional planting system (CTS), the area was left fallow in the off-season. The shoot dry matter of the covers was evaluated in each crop. The evaluated variables were: frequency, density, abundance, dry matter and the importance value index of the species in the area. Eighteen species of weeds and 12 families were identified, with Asteraceae and Poaceae families showing the highest number of individuals. The shoot dry matter production presented a difference among the covers; the cover black oat alone and intercrop with radish and vetch stood out, with the highest averages in the 3 years of the experiments. Cropping systems and different cover crops within the no-tillage system interfered in the number of encontered species. The emergence of Euphorbia heterophylla was favored, while the emergence of Lolium multiflorum was inhibited. E. heterophylla was the most encountered in the NTS areas, and its germination was negatively influenced by soil mobilization. The intercrop of black oat and vetch provided maximum weed control in soybean.

摘要：植物社会学研究（Phytosociological studies）是一类旨在鉴定群落内植物物种、明确其组成与分布的研究方法。本研究旨在鉴定并量化免耕系统（no-tillage system, NTS）与传统种植系统（conventional planting system, CTS）下种植的菜豆、玉米及大豆田中主要杂草的种类与数量。本实验采用随机区组设计，设置4次重复，连续开展三年。实验设置夏季作物（菜豆、玉米、大豆）处理组，免耕体系以黑燕麦、箭舌豌豆、饲用萝卜作为覆盖作物，并设置其间作处理；传统种植体系中，休耕季农田处于撂荒状态。各作物季均对覆盖作物的地上部干物质含量进行测定，本次测定的变量包括样地内杂草物种的频度、密度、多度、干物质含量以及重要值指数（importance value index）。本研究共鉴定出18种杂草，隶属于12个科，其中菊科（Asteraceae）与禾本科（Poaceae）的个体数量最多。不同覆盖作物的地上部干物质产量存在差异，单独种植黑燕麦以及与萝卜、箭舌豌豆间作的覆盖作物表现最优，实验三年间的平均产量均为最高。耕作体系以及免耕体系下不同的覆盖作物均会对样地内发现的杂草物种数量产生影响。多裂叶大戟（Euphorbia heterophylla）的出苗受到促进，而多花黑麦草（Lolium multiflorum）的出苗则受到抑制；多裂叶大戟（E. heterophylla）是免耕体系样地中最常见的杂草，其萌发过程会因土壤翻动而受到负面影响。黑燕麦与箭舌豌豆的间作模式在大豆田中实现了最优的杂草防控效果。