Crescimento, produção e qualidade de morangueiro adubado com N, P e K

Abstract

The strawberry (Fragaria x ananassa) is a fast growing plant and has high nutritional requirement. Because of this an adequate supply of nutrients are required, particularly with nitrogem, phosphorus and potassium. These fertilizers are the most used by farmers because improve plant growth. The objective of this research was to evaluate the growth, fruit quality and physiology of strawberry plants under fertilization with nitrogen, phosphorus and potassium. Two experiments were conducted. The first in plastic pots with a capacity of 10 liters of soil and the second directly into the ground, in plant beds. The treatments of both experiments were determined by Central Composite Box and arranged in a randomized block design with four replications. The experimental unit had three plants. In the experiment on plastic pots, we used five doses of nitrogen (0.16, 0.37, 0.88, 1.4 and 1.6 g plant-1) and phosphorus five (0.3, 0.58, 1, 2, 1.8 and 2.1 g plant-1) with potassium (1.67 g plant-1) and without potassium. It also had an additional treatment (without nitrogen and no phosphorous). The dose used in the second experiment were: 0.0, 0.16, 0.37, 0.88, 1.4, 1.6 g of nitrogen plant-1 and 0.0, 0.5, 0.8, 1.9, 3.0, 4.4 g phosphorus plant-1. Treatment with organic fertilizer was added. The seedlings used were the cultivar Oso Grande. The variables studied were: number of leaves, plant height, mean crown diameter, leaf area, number of fruits, mean weight of fruit, productivity of the plants, soluble solids, titratable acidity, relationship between soluble solids/titratable acidity, net photosynthetic rate, stomatal conductance, internal CO2 concentration, transpiration and in instantaneous carboxylation efficiency. The results were submitted to analysis of variance considering 10% probability by F test. The treatments without fertilizer and organic manure was submitted to means contrast. In plastic pot, the doses of 0.8 and and 2.1 g plant-1 of nitrogen and phosphorus, respectively, provided improvements in most of the variables analyzed and the potassium favored more to nitrogen fertilizer than phosphorus. In the soil experiment, the best doses were 4.4 and 5.0 g plant-1 of phosphorus and nitrogen, respectively. The organic fertilizer has improved variables in at least 12% compared to the control treatment.