Vigor e germinação de sementes de soja com mancha-púrpura

Abstract

The importance of using seeds of high physiological quality for the high performance of a field production is unquestionable. In this sense, understanding the factors that impact and impair quality becomes fundamental. With the increase in the occurrence of diseases in the soybean crop, including Cercosporiosis, which causes the purple spot in seeds, there is a need to deepen the knowledge about the effects of this pathogen on seeds. In this way, this work aims to evaluate the effect of the purple blotch on soybean seeds in the seed phytosanitary potential. Seeds of the soybean cultivar NK 7201 IPRO with symptoms of purple spot were used, which were divided into 4 lots with different percentages of symptoms. The study was carried out in 2 phases, where the first consisted of a bifactorial 2 (treatment with fungicide or without treatment) x 4 (0, 10, 25 and 50% of purple spot) where evaluate the simultaneous effect of this parameters on the physiological quality of soybean seeds. The experimental design was completely randomized, and the number of repetitions was variable (four or eight) according to the evaluation. In the second phase, the experiment consisted of a trifactorial: 2 (fungicide treatment and no treatment) x 4 (0, 10, 25 and 50% purple spot) x 3 (storage temperature: 10, 20 and 25ºC) where the simultaneous effect of these factors on the physiological quality of soybean seeds was verified. The experimental design was completely randomized, and the number of repetitions was variable (three or eight) according to the attributes evaluated. Tests of germination, first count, electrical conductivity and length of seedlings were performed in the first phase and in the second, germination test and electrical conductivity. With the data obtained, it was concluded that there is an effect of the symptoms of infection by Cercospora kikuchii in the seeds on the physiological quality of soybean seeds, especially in size parameters that are related to the initial development of the seedlings; seed treatment with fungicide affects the viability and vigor of seeds stored or not and that high storage temperatures enhance the phytotoxic effect of fungicide treatment on seed vigor.