Manejos da irrigação e da fertirrigação potássica na cultura da videira, nas condições semiáridas.

Abstract

The irrigation of crops and their proper fertilization are on the main techniques used when it is aimed at increasing productivity in the different vegetable crops. However, previous studies have provided little information regarding the application of water and macronutrient potassium (K) in the cultivation of the vine. As a result, in order to evaluate the productivity and biometric characteristics of the grape (Vitis vinifera L.) under different irrigation levels and in different intervals and increasing levels of potassium applied through fertigation, three trials were conducted concurrently in the city of Limoeiro do Norte -CE (05°06’S, 37°52’W,151 m), in the period of September/08 to January/09. The experimental design used in all experiments was a randomized block design with four replications. In experiment 1, we tested five different irrigation quantified on the basis of the class “A” pan evaporation: 50%, 75%, 100%, 125% and 150% of the class “A” pan evaporation. In experiment 2, we studied five different interval of fertigation potassium, which are: treatment 01, the fertigation occurred every 2 days, treatment 02, the fertigation occurred every 4 days, treatment 03, the fertigation occurred every 6 days, treatment 04, the fertigation occurred every 8 days and treatment 05, the fertigation occurred every 10 days. In experiment 3, we analyzed six levels of potassium fertigation: 0%, 50%, 75%, 100%, 125% and 150% of the recommendation used by agribusiness (368 kg.ha- 1 of K2O). Through the software SAEG 9.0 - UFV, the data were subjected to analysis of variance and significant later when the F test was carried out regression analysis, trying to adjust equations with biological meanings. In experiment 1 it was concluded that the varying number of clusters per plant, size of the bunch, number of berries, total soluble solids and yield significantly different, with all these variables, except the soluble solids, obtained its peak with the greatest water depth experimental. In this experiment it was found that the linear model was best suited to explain the variables. In experiment 2, the intervals of fertigatio n did not affect directly the productivity of the vine, but allowed statistically significant differences for the variables average mass of clusters, width and number of clusters of berries. In the experiment 3, the different levels of potassium fertigation evaluated produced different responses in the productive characteristics of the vine, being statistically significant, analysis of variable number of clusters per plant, average weight of the bunches, the mean weight of 10 berries, berry width, content s oluble solids and productivity. In all variables in experiments 2 and 3, we found that the quadratic polynomial model as the most adequate to explain the behavior of biometrics.