Polímero e tratamento fitossanitário em sementes de soja e sua relação com a absorção de ingrediente ativo e desempenho em condições de estresse

Abstract

The use of high quality seeds is of fundamental importance for the correct establishment of plants in the field, in which this will provide a greater guarantee for the producer. Lots with inferior physiological quality may present greater difficulties in developing under stress conditions. However, sometimes, only the use of quality seeds is not enough to provide this guarantee, so the phytosanitary treatment of seeds appears as a possibility to reduce the damage caused by pests and pathogens and provide extra protection for the seed and seedling. In addition to the protective effect, seed treatment can have effects on plant physiology, which can assist in initial growth as well as development, and these products are called bioactivators. Another product applied via seed treatment is the polymer, in which it will provide better adhesion of the chemical treatment to the seed, which may reduce losses. However, there is a lack of information about the effect of the use of polymers and their influence on the absorption of the treatment by the seed. The objective of this study was to evaluate the active ingredient absorption and development under water stress conditions in soybean seeds treated with polymers associated with phytosanitary treatment. Three different experiments were carried out, the first aimed to evaluate the initial development of soybean seedlings and to quantify the absorption of active ingredient from seeds treated with chemical treatment and polymers. The results obtained through the analysis of soybean seedlings indicated that the use of polymer associated with phytosanitary treatment is an efficient method, as it can increase the absorption of the active ingredient. The second study aimed to evaluate the physiological responses in soybean seeds with different vigor levels treated with polymers and thiamethoxam subjected to simulated water deficit. In this work, the results indicated that, for both vigor levels, the simulated water stress reduced the physiological performance of the seeds and that the thiamethoxam molecule provided better development in low vigor soybean seedlings when submitted to water stress. Finally, the third study aimed to evaluate the responses in the production of plants originated from seeds with different levels of vigor and treated with the active ingredient thiamethoxam and polymers. The results showed that under stress conditions at the beginning of the crop cycle, seed treatment with thiamethoxam and polymers positively influences the development of seeds with lower vigor. Soybean plants are able to recover from reduced plant density through their plasticity characteristic. Under environmental climatic conditions such as favorable precipitation and temperature, yield is not influenced by seed vigor. In this way, it was possible to better understand the responses of the plant to the use of these products through their behavior in field and laboratory evaluations.