Desempenho de sementes de soja sob hidratação e tratamento químico

Abstract

Despite the great economic importance of soybeans, there are several factors that hinder production, among which is the establishment of an inadequate plant stand. Seed treatment aims to provide protection against biological agents in the early stages of establishing the crop by applying formulations containing one or more active ingredients. It is known that seeds need to absorb water to start germination processes and that soybean seeds need to hydrate around 50% of their weight. Likewise, salts are known to be hygroscopic compounds which have high affinity for water. However, there is little information on their possible influence on the process of water gain by the seeds. Thus, the objective of the present study was to verify if the treatment of soybean seeds with commercial products interferes with its imbibition, as well as to evaluate the effect of the controlled hydration process together with chemical treatment on the physiological parameters of the seeds. Two studies were conducted, and the first one evaluated the imbibition curves for samples from two lots of soybean seeds, treated with three commercial standards of chemical treatments. In the second study, the physiological quality of the treated samples of the two lots was evaluated by germination tests, seedling vigor classification, accelerated aging, seedling length and dry mass. The results allowed to conclude that the chemical treatment with imidacloprid and thiodecarbe + carbendazim and thiram provided higher water uptake by the seeds in relation to the other chemical treatments and the control in both lots. In this case, the treatment of seeds did not impair the absorption of water by them. For seed from lot 1, controlled hydration provided lower germination, a difference of approximately 6 percentage points. In the seeds of lot 2 that underwent controlled hydration, higher germination values were observed, with an increase of approximately 11 percentage points. For accelerated aging, there was an isolated effect on the controlled hydration factor. In the variable length of seedlings and dry mass there was no significant effect of the treatments. The chemical treatment of Imidacloprid and Tiodecarbe + Carbendazim and Tiram exerts a significant influence over the water absorption by the seeds. In seeds submitted or not to prehydration, but treated with Imidacloprid and Tiodecarbe + Carbendazim and Tiram, the physiological quality and vigor of the seeds is variable according to the seed lot used.