Efeitos do L-triptofano exôgeno na germinação de sementes e crescimento de plântulas de Glycine max submetidas ao teste do frio

Abstract

The genetic potential of seeds does not guarantee uniform establishment and plant stand quality in commercial crops. This demand has led to the development of various agricultural inputs, often applied to seeds, including L- tryptophan. The objective of the present study was to evaluate the effect of L-tryptophan on the germination process and seedling development of soybean (Glycine max) subjected to a cold test, using the following parameters: germination, root length, shoot length, and dry matter. The experiment was conducted in the Seed and Grain Laboratory at the Universidade Federal da Fronteira Sul, Chapecó campus, in the second semester of 2024. Soybean seeds of the 60163IPRO cultivar were used. The trial was set up in a completely randomized design with a factorial experimental arrangement, consisting of two factors and four replications. The first factor comprised two sub- factors: cold test (CT) and absence of cold test (ACT), while the second factor consisted of doses of 0, 0.02, 0.04, and 0.08 g of tryptophan per kg of seed. Seeds were sown in previously moistened Germitex paper substrate. The rolls of paper were kept in a germinator at a constant temperature of 25°C, with germination evaluations performed on the fifth and eighth days after sowing. Data were converted to the percentage of normal, abnormal, hard, and dead seedlings. The primary root length and shoot length were also measured, and the average results were expressed in cm per seedling. Dry matter determination was performed on normal seedlings, quantifying both the shoot and root parts. Analysis of variance (F-test at 5%) was used to analyze the variables, with mean comparisons for each replication performed using Tukey's multiple comparison test and regression analysis, both at 95% confidence. L-tryptophan exhibited a protective effect on soybean seeds subjected to the cold test, although the parameters of germination percentage, dry matter accumulation, root length, and shoot length did not match those of the ACT treatment. However, the amino acid proved to be an attractive alternative for seed treatment in environments where sowing occurs under low temperatures and high soil moisture.