Sunflower subjected to boron doses in the semi-arid from Northern Minas Gerais, Brazil

Abstract

The sunflower [Helianthus annuus L. (Asteraceae)] is an annual dicotyledon, and its seeds can be used for animal and human consumption, for extracting fixed oil and for producing biodiesel. This plant is sensitive to boron (B) deficiency, with the scarcity of this micronutrient leading to lesions in the leaves and stem of the sunflower, causing the collapse of the capitulum and decreased photosynthesis. The objective of this study was to evaluate the development and the productive response of the sunflower genotypes BRS 321 and BRS 323, subjected to four doses of B (0, 1, 2 and 4 kg ha -1 ). The experimental design was in randomized blocks with three replicates and 8 treatments. Plant height, plant diameter , capitulum diameter, number of leaves, weight of 1000 achenes, grain yield, fixed oil content and oil yield were all evaluated. Doses greater than 1 kg ha -1 of B caused toxicity symptoms in the vegetative phase in the BRS 321 genotype, however, the 4 kg ha -1 dose of B promoted productive gains to this same genotype. The BRS 323 genotype was more productive in grain and fixed oil than the BRS 321 genotype, regardless of the B doses. In order to avoid phytotoxicity, applications of B to the BRS 321 genotype are recommended.