MAIZE CROP PHYTOTOXICITY IN RESPONSE TO SUB-DOSES OF SULFOMETURON-METHYL

ABSTRACT The use of ripeners has been a common practice in the sugarcane culture. The application of these products is often performed through aerial spraying, which increases the chances of drifting of the ripeners- molecules over the surrounding crops, such as maize. In order to study possible phytointoxication on maize caused by sulfometuron-methyl application, a field experiment was conducted to evaluate the effects of sulfometuron-methyl sub doses on maize when applied at the V4 and V8 development stages. The experiment was installed in a randomized block design with four replications. The treatments followed a 2 x 5 factor scheme, with the first factor corresponding to development stages of maize during which the ripener was applied (V4 and V8) and the second factor was related to sulfometuronmethyl sub doses (0; 0.45; 0.90; 1.35 and 1.80 g a.i. ha 1). The maize crop showed phytotoxicity with the use of 0.45 g a.i. ha-1 of sulfometuron-methyl; it was more severe when the application occurred at the development stage V8, leading the plant to death at the highest used dose. Furthermore, it was also possible to observe negative changes in the morphological and production components of maize plants. The SYN 7G17 maize hybrid is highly susceptible to sulfometuron-methyl. The occurrence of sulfometuron-methyl deposits at higher doses or at different development stages of the crop may reflect more severe phytotoxic effects than the ones observed in this study.

摘要 甘蔗种植中使用催熟剂已是常规操作。这类产品通常通过航空喷施方式施用，这会增加催熟剂分子向周边作物（如玉米）发生飘移的风险。为探究施用甲磺隆（sulfometuron-methyl）可能对玉米造成的植物毒害，本研究开展田间试验，评估在V4和V8生育期施用甲磺隆亚剂量对玉米的影响。试验采用随机区组设计，设置4次重复，处理方案遵循2×5因子设计：第一个因子为催熟剂施用的玉米生育期（V4和V8），第二个因子为甲磺隆亚剂量梯度（0、0.45、0.90、1.35和1.80 g a.i.·ha⁻¹）。当施用0.45 g a.i.·ha⁻¹的甲磺隆时，玉米即出现植物毒害症状；若在V8生育期施用，毒害症状更为严重，最高剂量处理下玉米植株甚至会死亡。此外，还可观测到玉米植株的形态及产量构成要素出现不良变化。SYN 7G17玉米杂交种对甲磺隆具有极高的敏感性。若作物生育期内出现更高剂量的甲磺隆沉积，或在不同生育期发生飘移，可能会产生比本研究观测到的更为严重的植物毒害效应。