Comportamento do girassol à adubação fosfatada e água disponível em um argissolo.

Abstract

The sunflower is a crop that has been vvidely spread in Brazil, with emphasis on the Northeast, due to its economic value and adaptability to various climatic variations, but for this there is a need to gain knowledge of the climatic region, water availability. soil quality and mainly because it needs to favorable conditions for good development. Thus, the objective of the present study was to evaluate the behavior of sunflower (EMBRAPA 122/V- 2000) to different leveis of phosphate and available soil water on a Ultissol. The experimental design was completely randomized 4 x 4 with four phosphorus leveis (0, 80. 100 and 120 kg ha-1) and four leveis of available soil water (55, 70, 85 and 100%) with three replicates. totalizing 48 experimental units. The results were submitted to variance and regression analyses. Soil available water did not affect sunflower growing however the phosphorus leveis affected it significanfly. Phytomass production and chapter diameter were affected significantly by the available soil water and phosphorus treatments with the leaf phytomass exception that was affected only by the phosphorus. The fresh and dry stem. leaves. chapter and total phytomass and the chapter diameter increased linearly with phosphorus and available soil water. The best results for the seed number and weight were obtained with the maximum doses of phosphorus (120 kg ha"1 de P) along with 100% available soil water.