Mineral nutrition of Acrocarpus fraxinifolius Wight & Arn. grown in the greenhouse and under field fertilization

Abstract

The objective of this study was to evaluate the mineral nutrition in Acrocarpus fraxinifolius seedlings in a controlled environment and the growth of seedlings in the field under doses of P and N. The experiment I was evaluated seven treatments: one complete and six with omission of N, P, K, Ca, Mg and S. A completely randomized design with four replicates. Experiment II was evaluated seven treatments: one complete and six with omission of B, Cu, Fe, Mn, Mo and Zn. The interim randomized design with four replicates. The experiment III was evaluated five treatments of doses of K (0, 50, 100, 150 and 200). The completely randomized design being three ratios of Ca: Mg (1: 1, 3: 1 and 1: 3), four replicates. Experiment IV was evaluated in five treatment doses of P (0, 20, 40, 80 and 160 g per cova-1) and N (0, 25, 50, 100, and 200 g per cova-1). A randomized complete block design with four replicates. The results of experiments I, II, III and IV demonstrate that the omission of N, P, K and Ca limited the growth of plants (H and D) in relation to the complete treatment and the accumulation of SDW, in the following order: N> P> K. The omissions of macronutrients resulted in morphological changes, where N, P, K and Ca, when missing, cause the first symptoms, followed by Mg and S. The nutrient content found in the aerial parts of the seedlings was higher in treatments with the omission of N, P and K than in the treatments with the omission of Mg and S. The omission of Fe was more limiting in the growth and accumulation of SDW, followed by treatments with the omission of Cu, B, Mn, Mo and Zn. Omission of Fe developed acute chlorosis and foliar necrosis, followed by death. The deficiency of B, Mo and Zn increased the Fe content in the aerial part and reduction of the Cu content. Acrocarpus fraxinifolius does not develop well in soils with the unbalanced Ca:Mg ratio. The highest growth and SDW production, content and accumulation of Ca, Mg and K in the aerial part were obtained when applying doses of K in the soil between 70 - 100 mg dm -3. In poor soils the Ca: Mg ratio in the soil should be close to the 3: 1 ratio. The plants of Acrocarpus fraxinifolius respond to nitrogen and phosphate fertilization. The best doses applied for P were between 90 to 100 g of cova-1and for N between 70 to 120 g of cova-1.