Cultivo de aceroleira enxertada irrigada com águas salinas e adubação potássica.

Abstract

The salinity of the irrigation water is an abiotic stress that can affect the growth and the production of the crops. One of the alternatives to minimize the deleterious effects of this stress in the plants, is the potassium fertilization, promoting increase of the tolerance of the crop to the salts. In this context, the aim of this study was to evaluate the cultivation of grafted West Indian cherry irrigated with saline water and fertilization with different doses of potassium. The research was carried out in pots adapted as drainage lysimeters under greenhouse conditions, from July 2016 to December 2017, at the Center of Technology and Natural Resources of the Federal University of Campina Grande (CTRN/UFCG). located in the municipality of Campina Grande, PB. The experimental design was a randomized block design, with three replications, using the 2 x 4 factorial arrangement. The treatments consisted of two levels of electrical conductivity of the irrigation water - ECw (0,8 and 3,8 dS m-1) and four potassium doses (50, 75, 100 and 125% of Musser's recommendation). The dose of 100% corresponded to 33.0 g of K2O per plant per year. Seedlings of West Indian cherry ‘Criolas’ originating from EMBRAPA AgroindusHtry Tropical were used as root stock and that of variety BRS 366 Jaburu as scion. The photosynthetic pigment contents and the growth of the cherry plant in the flowering phase were affected when irrigated with water of electrical conductivity of 3.8 dS m-1. Increased potassium doses reduced cell membrane damage caused by saline stress. Gaseous exchanges and chlorophyll a fluorescence were negatively influenced by the increase in the electrical conductivity of water (3.8 dS m-1). Increasing doses of potassium increased transpiration, chlorophyll a maximum fluorescence and chlorophyll b content of the cultivar under salt stress. Potassium doses up to 125% of the recommendation did not attenuate the negative effects of irrigation with water of 3.8 dS m-1 on the potential quantum efficiency of West Indian cherry leaves. Absolute and relative growth rates in stem diameter and mean fruit weight of the West Indian cherry are reduced when irrigated with water of 3.8 dS m-1salinity.Potassium fertilization mitigates the effects of saline stress on the relative growth rate of rootstock diameter, total number of fruits and total fresh mass of West Indian cherry fruits.