Funções de resposta da goiabeira a lâmina de água e fertirrigação nitrogenada.

Abstract

The objective of this was study the effects of the irrigation and of the fertilization nitrogen applied using fertigation in the productivity of the guava tree, variety Paluma, with four years old, under microirigation system with 6x5 m. It was, also, determined the economical great leveis of these two factors in the productivity of the guava tree. The experiment was carried in the Experimental Station of Veludo, in Itaporanga city, PB. The experimental design was randomized blocks, in 4x4 factorial with four repetitions, four irrigation leveis, Li=0,60 Lb, L2=1,00 Lb, L3=l,40 Lb and L4=l,80 Lb (Lb in the depth of water calculated according to the daily evaporation of class A Pen and the coeffícient of the crop) and four leveis of nitrogen, Ni=50, N2=100, N3=150 and N4=200 kg.ha"1. The irrigation was accomplished daily during the cycle of the culture (198 days) after fructification pruning. The fertigation was realized three days a week during the cycle of the crop (80 applications). The total amount of water by treatments (irrigation + precipitation) was Li = 1.144, L2 = 1.465, L3 = 1.785 and L4 = 2.106 mm. The effects of the treatments were evaluated by production, number of fruits by plant, total weight of fruits by plant end médium weight of the fruits. It was, also, analyzed the effects of the treatments under the physical economical productivity of guava, being considered the cost of the water R$ 0,65 mm.ha"1 and the cost of the nitrogen R$ 1,15 kg"1. The results of the analysis of variance and the components of regression presented a square effect of the water and nitrogen factors. The maximum number of fruits by plant is estimated on 466 units with total weight of 112,67 kg/plant with the application L3N3. The maximum economic productivity of 37.258 kg.ha"1 with application L = 1.766 mm and N = 144 kg.ha"1, the total income was R$ 14.143,78 ha"1 on the other hand, the nitrogen levei presented the maximum economic productivity of 42.425 kg.ha"1 with application N=144 kg.ha"1 and L = 1.785 mm, the total income was R$ 18.715,18 ha"1. The productivity for the two factors (L x N) was 35.594 kg.ha"1 with the application of L = 1.721 mm and N = 167 kg.ha"1, with total income of R$ 13.154,68 ha"1.