USE OF SURFACTANT WITH DIFFERENT VOLUMES OF FUNGICIDE APPLICATION IN SOYBEAN CULTURE

ABSTRACT Application volume, adjuvants that act on the drop surface tension and droplet spectrum are the main factors affecting leaf surface coverage and the spray penetration droplets inside the canopy of the soybean crop, which may have an impact on fungicide efficiency, since those used in the handling of Asian-rust, including those that are absorbed by the plant, present a small displacement from the point of deposition. Thus, it was sought to determine the impacts on the use of the organosilicone surfactant compared to the changes in the spray volumes. For that, five spray volumes and the combination of two adjuvants were compared in randomized blocks with a factorial arrangement 5×2. Reductions in volume negatively impacted the number of drops cm−2 affecting the leaf surface cover which did not exceed 13% in the lower third, in the absence of the surfactant. Also, the reduction in the volume provided decreases in the control of Asian-rust, and the use of surfactant minimized the negative impacts of the disease, reflecting on the index of the leaf area which varied up to 6.5 times on changes in the spray volume, and up to 2.8 times against the use of the surfactant in relation to the mineral oil isolated. Grain yield was negatively affected as reductions in the spray volumes, occurred with less impact when the surfactant was used. Thus, coverage of the leaf surface and the number of drops cm−2 along the plant profile respond to the addition of the surfactant and to the increase of the spray volume, having relation with the control of soybean Asian-rust, and affecting the leaf area index and productivity.

摘要：影响大豆作物叶面覆盖率及雾滴穿透冠层内部能力的核心因素包括施药液量、作用于雾滴表面张力与雾滴谱的助剂，上述变量会对杀菌剂防效产生显著影响——因用于防治亚洲大豆锈病（Asian-rust）的药剂（包括植物内吸性药剂）在沉积点的位移能力极弱。为此，本研究旨在探究相较于施药液量变化的效应，有机硅表面活性剂（organosilicone surfactant）的使用所带来的影响。试验采用5×2因子排列的随机区组设计，对5种施药液量与2种助剂的组合开展对比分析。结果显示，在未添加表面活性剂的组别中，药液量缩减会对每平方厘米叶面的雾滴数量产生负面影响，且该负面影响在植株下部冠层未超过13%。此外，药液量降低会削弱亚洲大豆锈病的防治效果，而表面活性剂的使用可有效缓解该病害带来的负面效应，这一点体现在叶面积指数的变化上：施药液量变化可使叶面积指数产生最高达6.5倍的差异；相较于单独施用矿物油助剂，添加表面活性剂可使叶面积指数产生最高达2.8倍的差异。籽粒产量同样会因施药液量缩减而受到负面影响，但添加表面活性剂可显著减轻该负面影响。综上，叶面覆盖率与沿植株垂直剖面分布的每平方厘米雾滴数量，会随表面活性剂的添加与施药液量的提升而得到优化，且该变化与大豆亚洲锈病的防治效果密切相关，进而对叶面积指数与籽粒产量产生影响。