Efeito da temperatura na germinação de sementes de soja com diferentes tamanhos

Abstract

The effect of sieve size and the ideal temperature for optimal initial growth of soybean seedlings are characteristics that are difficult to analyze and are infrequently studied by some authors, with varied results. This indicates a need for research that offers greater clarity for seed producers and marketers. Therefore, the aim of this study was to evaluate the interaction between temperatures and sieve sizes on soybean seed germination. To assess the effects of different temperatures and sieve sizes on the initial growth of soybean plants, seeds from the cultivar 55157RSF IPRO (ZEUS) were used, provided by Sementes Giovelli, located in Rolador, RS. The seeds were classified into three sieve sizes (6,0 mm, 6,5 mm, and 7,0 mm) from the 2024/2024 harvest. The experiment was conducted at the Seed Laboratory of the Federal University of Fronteira Sul (UFFS) - Cerro Largo campus, in June 2024. A completely randomized design (CRD) with a bifactorial arrangement (5x3) was used, consisting of 5 temperature levels (8°C, 16°C, 24°C, 32°C, and 40°C) and 3 sieve sizes (6,0 mm, 6,5 mm, and 7,0 mm), with 4 repetitions, totaling 60 experimental units, each consisting of 25 seeds, or 100 seeds per treatment. In the laboratory, the treatments were evaluated through germination tests, germination speed index (GSI), radicle length, and radicle fresh weight. The data obtained were subjected to analysis of variance (ANOVA) using the F-test, and means were compared using Tukey's test at a 5% probability level. The smaller seeds (6,0 mm) showed better GSI values, regardless of the temperature. Larger seeds (6,5 mm and 7,0 mm) had better radicle length results compared to smaller seeds (6,0 mm). The largest seeds (7,0 mm) showed higher values of radicle fresh weight at 24,4°C. Smaller seeds (6,0 mm) were more stable in both radicle length and fresh weight. Seeds classified into different sizes (6,0 mm, 6,5 mm, 7,0 mm) showed no differences in germination percentages. The ideal temperature for maximum soybean seed germination was found to be 28,3°C.