Intoxication and Physiological Aspects of Forage Plants and Weeds Submitted to Clomazone Atmospheric Waste

ABSTRACT: Herbicide volatilization may generate environmental and agricultural problems and result in visual or physiological contamination of non-target plant species. Thus, the goal of this research was to study the fluorescence of chlorophyll a in weeds and fodder plants under the effect of clomazone in the form of atmospheric waste. The experiment was conducted under field conditions designed in randomized blocks with four replications, in a 6 x 4 factor scheme, with six plant species: Dolichos lablab, bicolor Sorgum, Urochloa brizantha, Macrotyloma axillare, Portulaca oleracea and Sida rhombifolia. There were four solutions containing 0, 360, 720 and 1,080 g ha-1 of clomazone (0, 0.05, 0.10 and 0.15 mg L-1, considered as the volume). Seedbeds were built and covered with transparent polyethylene film of 150 μm, with a volume of 12 m³. Fodder plants were sown in line, while weeds were selected according to the incidence. On the sixteenth day after emergence, concentrations of herbicide diluted on three petri dishes were inserted. After 72 hours of exposure, the tunnels were opened and the dishes were removed, noticing evaporation of the product. The following evaluationswere performed: plant poisoning, initial fluorescence, maximum quantum yield of PSII, photochemical quenching, non-photochemical quenching and chlorophyll content. Even at concentrations that do not promote visual effect, clomazone can cause significant damage in the photosynthetic activity of the species. The physiological variables chlorophyll, maximum quantum yield of PSII and initial chlorophyll fluorescence can be effectively used to monitor clomazone waste in the atmosphere.

摘要：除草剂挥发可引发环境与农业问题，并对非靶标植物物种造成表观或生理性药害。为此本研究旨在探究大气废弃物形态的异恶草酮（Clomazone）胁迫下，杂草与饲用植物的叶绿素a（chlorophyll a）荧光特性。本试验于田间条件下开展，采用随机区组设计，设置4次重复，采用6×4因子试验方案，供试植物共6种：扁豆（Dolichos lablab）、双色高粱（Sorghum bicolor，原文作bicolor Sorgum）、旗草（Urochloa brizantha）、大翼豆（Macrotyloma axillare）、马齿苋（Portulaca oleracea）以及黄花稔（Sida rhombifolia）。试验共设置4种药液浓度，异恶草酮用量分别为0、360、720和1080 g·ha⁻¹（对应体积浓度为0、0.05、0.10和0.15 mg·L⁻¹）。搭建苗床并以150 μm厚的透明聚乙烯薄膜覆盖，苗床容积为12 m³。饲用植物采用条播方式种植，杂草则根据自然萌发情况选取定植。在植株出苗后第16天，将滴加了不同浓度除草剂的3个培养皿放置于苗床内。熏蒸72小时后，揭开薄膜并移除培养皿，可观察到药剂已发生挥发。后续开展了以下指标测定：植株药害情况、初始荧光、光系统II（Photosystem II，PSII）最大量子产额、光化学淬灭、非光化学淬灭以及叶绿素含量。即便在未产生表观药害的浓度下，异恶草酮仍可对供试植物的光合活性造成显著损伤。叶绿素含量、PSII最大量子产额及初始叶绿素荧光这三项生理指标，可有效用于大气中异恶草酮废弃物的监测。