Ontogênese e produção de girassol submetido a diferentes lâminas de irrigação e adubação nitrogenada.

Abstract

Sunflower (Helianthus annuus L.) is inserted between the greatest potential plant species for biofuel production, as well as for the supply of human food and forage. Although there exist plenty research of the growing of sunflower in Brazil, in the North East still there is a need for further research to optimize its productivity. Thus, the objective of the present study was to evaluate, under semicontrolled conditions, the growing, developing and production of the BRS-323 sunflower cultivar when submitted to four water contents (50, 75, 100 e 125% of soil water available for plants) and four levels of nitrogen in the soil (80, 100, 120 e 140 kg ha-1). All growth and development variables were measured at 45, 61 and 77 days after sowing and the production variables at harvest. The experimental design was a 4x4 factorial randomized block design with three replicates, totalizing 48 experimental units. Available soil water content increased significant and linearly the growth and production of the sunflower. With the exception of the leaf number the available soil water content it also increased in similar way the sunflower developmet. Nitrogen levels did not affect sunflower behavior and the available soil water and nitrogen level interaction alwso was not significant. The otimum irrigation depth for sunflower production, found on the present experiment, was that corresponding to the higher available soil water content, 125%.