Resposta fisiológica de sementes de couve-manteiga (Brassica oleracea l. Var. Acephala) a doses de boro isolado e complexo de micronutrientes

Abstract

The objective of the presente study was to evaluate the influence of fertilization with isolated boron and a micronutriente complexo n the physiological quality of kale seeds (Brassica oleracea L. var. acephala). The research was conducted at the Juruti University Campus of the Federal University of Western Pará, under laboratory and greenhouse conditions, using a completely randomized design (CRD), with five treatments and four replications. In the first experiment, seeds were treated with different doses of boron (0, 2, 4, 8, and 16 mg of B per kg of seeds), using commercial boric acid. In the second experiment, different doses of the commercial fertilizer Dripsol Micro (0, 0.02, 0.04, 0.08, and 0.16 g per 10 g of seeds), containing a micronutrient complex, were applied.The variables analyzed included germination index (GI), germination speed index (GSI), emergence speed index (ESI), shoot length (SL), root length (RL), shoot dry mass (SDM), and root dry mass (RDM). Data were subjected to analysis of variance, followed by regression analysis, using the statistical software R (version 4.3.0), considering the assumptions of normality, homogeneity, and independence of residuals.The results obtained from boron application indicated a positive influence on morphological variables, especially root and shoot length, with the optimal doses estimated at 10.07 mg/kg for roots and 10.75 mg/kg for shoots. However, doses above these levels resulted in reduced GSI, indicating an inhibitory effect on the initial seedling vigor.In the treatment with the micronutrient complex, only the GSI was significantly affected, with a decrease in germination speed as the doses increased. The other physiological and morphological variables did not show significant differences. The control (distilled water) showed better performance in terms of initial vigor, suggesting that excess micronutrients may impair the germination process.The results indicate that, although micronutrient supplementation is essential for plant metabolism and development, its application via seed treatment should be done with caution. Inadequate doses may negatively interfere with seedling vigor, especially during the early stages of growth.It is concluded that boron, when applied at appropriate doses, can favor the morphological development of kale, while the micronutrient complex, although not negatively impacting morphology, showed a reduction in vigor. Thus, accurately determining the concentrations used in seed treatment is essential to ensure the successful establishment of the crop in the field.