Antagonism between fungicide-insecticide treatments and dietholate in irrigated rice seeds

Abstract: The plant safener dietholate can be used for seed treatments (ST) to improve the selectivity of clomazone in rice cultures, thus allowing the application of higher dosages of this herbicide. The objective of this research was to evaluate the interaction between seed fungicide-insecticide treatments with and the plant safener dietholate in irrigated rice. Three experiments were carried out, and the first of them was conducted in a laboratory, following a completely randomized experimental design with four replications. Different ST and treatment-to-sowing intervals were evaluated. The second and third experiments were performed in field conditions, in a completely randomized block design with four replications. In experiment two, seeds were treated with different fungicides, in association or not with dietholate; while in experiment three, the effect of the ST with fungicides and dietholate with clomazone application were assessed. The results evidenced that the association between carboxin + thiram + dietholate reduced seed germination, vigor, and the dry mass of shoot of rice plants. The longer it takes between ST and sowing, the more rice seed germination is negatively affected. The association between fungicides and dietholate may have been antagonistic, and thus interfered with the culture growth potential.摘要：植物安全剂乙氧呋草黄（dietholate）可用于种子处理（seed treatments，ST），以提升异恶草酮（clomazone）在水稻栽培中的选择性，从而允许该除草剂施用更高剂量。本研究旨在评估拌种杀菌剂-杀虫剂处理与植物安全剂乙氧呋草黄在灌溉水稻中的交互作用。共开展3组试验：第一组试验于实验室开展，采用完全随机试验设计，设置4次重复，对不同种子处理方案以及处理至播种的间隔时长进行了评价。第二、三组试验在大田条件下开展，采用完全随机区组设计，设置4次重复。试验二中，以不同杀菌剂单独或与乙氧呋草黄复配处理种子；试验三中，则评估了杀菌剂与乙氧呋草黄拌种结合异恶草酮施用的效果。结果表明，萎锈灵（carboxin）+福美双（thiram）+乙氧呋草黄的复配组合会降低水稻种子的发芽率、活力以及植株地上部干重。种子处理至播种的间隔时长越长，对水稻种子发芽的负面影响越显著。杀菌剂与乙氧呋草黄的复配可能存在拮抗作用，进而干扰水稻的生长潜能。