Variabilidade dos componentes de produtividade em pomar de pessegueiro irrigado em função da granulometria do solo

Abstract

The region of Pelotas is responsible for 90% of the peach production in the state of Rio Grande do Sul (RS) having favorable conditions of climate and soil for its production. Some aspects related to the peach production system in this region still need special attention, especially related to irrigate or not the peach orchard. This study aimed to evaluate the yield variability of an irrigated peach orchard, Esmeralda cv., on the basis of irrigation and as a function of soil particle size distribution. The study was carried out in a peach orchard situated in the city of Morro Redondo-RS. By applying the theory of regionalized variables, two homogeneous areas were demarcated based on soil textural classes, which were classified as sandy loam and sandy clay loam. Four rows of peach plants were evaluated, being two irrigated and two not irrigated. Twenty plants were selected in each soil textural class by evaluating the trunk diameter along each row (10 plants in each homogenous area) totaling 80 assessed plants. The experimental design was a completely randomized design in a 2x2 factorial scheme. The drip system was used to irrigate peach plants, and the irrigation management was based on the replacement of the crop evapotranspiration twice a week. A pressure chamber type "Scholander" was utilized to monitor the water potential in the branch (w) at one peach plant of each combination of soil textural class with irrigation and without irrigation. The soil water content was monitored near to the plants where w was measured using a capacitance probe Diviner Model 2000® at soil depths of 0.10 m, 0.20 m and 0.30 m. The number of fruits per plant (NF), the production per plant (PP), the weight of fruits per plant, the pulp firmness and the total soluble solids were evaluated and considered as yield components. The fruit and branch growth rates and the relative stem diameter growth (CC) were evaluated and considered as growth parameters. First of all, each data set was submitted to an exploratory analysis using descriptive statistics tools. The variance analysis was also applied to each data set considering two levels of irrigation (with and without irrigation) and two levels of soil textural class (sandy loam and sandy clay loam). It is concluded that: i. the irrigation increases the variability of the peach yield independent of the evaluated soil textural class, ii. the potential evapotranspiration is negatively related to the water potential in the peach tree branch, showing to be an indicative of the water status of the plant, iii. the irrigation increases the vegetative growth of peach trees, but has no influence on crop yield, iv. the irrigation management, based on the replacement of potential 11 evapotranspiration twice a week, was not enough to keep the peach plants in an adequate moisture status as a function of the measurements of the branch water potential, v. the irrigation increases the peach pulp firmness promoting an adequate product for industrialization, vi. the peach crop can tolerate little water deficits increasing the total soluble solids content becoming the fruit better for fresh consumption, and vii. the irrigation anticipated the harvest moment in the peach orchard, increases the growth rates of the fruit diameter and the branch size independent of the evaluated soil textural class.