Germinação de sementes e crescimento de plântulas de soja sob diferentes concentrações de zinco

Abstract

The soils of southern Brazil have satisfactory levels of zinc and such concentrations would sufficiently meet the nutritional requirements of plants, but due to the constant application of swine manure with high concentrations of zinc in areas subject to annual crop cultivation, such as the soybean, the excess zinc can cause problems of phytotoxicity to the crop. In this way, we tried to analyze experimentally the effect of different doses of zinc under the germination and initial development of soybean. The experiment was carried out at the Seeds and Grains laboratory of the Federal University of the Southern Border in a plot of plots subdivided into blocks at random, with cross - classification and 4 replications. The seeds were divided into 4 batches of 16 replicates of 50 seeds and each replicate was seeded on germitext paper, previously moistened with a volume of water corresponding to 2.5 times the weight of the paper. The water used to soak the 4 batches was increased by different concentrations of zinc sulphate (ZnSO4), so that the final concentrations of zinc were 0.0, 100.0, 200.0 and 400.0 mg / L, generating four different treatments. The paper rolls were kept in germinators at a constant temperature of 25ºC, and the evaluations were performed in 4 replicates of each treatment in the fifth, sixth, seventh and eighth days after sowing. The germination had an increase in its percentage until the dose 100.0 mg / L of zinc, but when raising the element concentration it was noticed a decrease in the percentage of germination of the soybean. The root length was not significantly affected until the dose of 200.0 mg / L, but the higher zinc dose limited root growth of the seedlings. When no zinc was used, it was observed a greater length of the aerial part of the soybean seedlings in relation to the seeds treated with zinc, showing the phytotoxic effect of the element under the analyzed variable.