Cultivo do coqueiro anão verde sob diferentes lâminas de irrigação e salinidade da água.

Abstract

The objective of the present work was to study the effect of irrigation and water salinity leveis on the development, production, fruit quality of Anão Verde coconut and on the soil salinity. The study was conducted at the EMPARN Experimental Station located in Parnamirim - RN during the period of June 2002 to October 2003. The treatments studied were four irrigation leveis based on the evaporation of water measured by a Class A evapotranspiration pan (30, 60, 90, 120 % of the evaporation pan) and four water salinity leveis interms of electrical conductivity (0.1, 5.0, 10.0, and 15.0 dS.m"'). The study was conducted in a completely randomized experimental design in split-plots. Analyses of variance, regression analyses and response surfaces were performed when necessary. The plant variables measured were: number of flowers, number of fruits, fiowers/fruit realationship, phytomass and quality of the production (volume of coconut water, fruit weight, °Brix, electrical condutivity and pH of the water, pulp weight, length and diameter of the fruit). Leaf samples were collected at the initial and final stages of the experiment to determine the N, P, K, Ca, Mg, Cl and Na content in the leaf. Soil samples were collected only at the end of the experiment to determine the electrical conductivity of the saturation extract. The increase of the irrigation levei increased the coconut production, the brix and the phytomass. It did not influence the weight of the fruit, the pulp weight and the volume or water. The increase of water salinity leveis increased the number of féminine flowers, the flower/fruit relationships, and the brix; decreased the production, the weight of the fruit and the volume of water. It did not influence the pulp weight. It was also observed that the fruit become less rounded with the increase of water salinity and that the salinity effects decreased with the irrigation leveis. The nutrient leveis in the leaf were always above the criticai leveis, with the exception of the K which remained below at the end of the experiment. The electrical conductivity of the soil at the end of the experiment, at the different soil depths, were very low.