Produção de porta-enxerto de goiabeira irrigada com águas salinizadas e adubada com nitrogênio.

Abstract

The guava culture has increasingly demonstrated its agricultural importance, arousing the interest of small, medium and large producers, both for export and for domestic consumption. Salinity gives irrigation water can affect the exploitation of crop mainly in semi-arid regions; however, some alternatives may favor agricultural exploitation in these conditions. The objective of this work was to evaluate the morphophysiology and the quality of rootstock of guava cv. Paluma irrigated with saline waters and fertilized with increasing doses of nitrogen. The experiment was carried out in a greenhouse (protected environment) using a eutrophic regolithic neosol of sandy-loam texture, located in the municipality of Pombal-PB. The experimental design was a randomized complete block design in a 5 x 4 factorial scheme, with the treatments resulting from the combination of five levels of electrical conductivity of the irrigation water CEw (0,3; 1,1; 1,9; 2,7 e 3,5 dS m!) and four DN doses (70, 100, 130 and 160% N of the recommended dose for guava seedlings, the dose being 100% corresponding to 773 mg of N dm), with four replicates and two useful plants per experimental unit. The application of the treatments began 30 days after the emergence of the seedlings (DAE). The variables plant height, stem diameter, leaf number and leaf area at 80 and 170 days after emergence were evaluated, and the physiological variables related to the absolute and relative growth rate of plant height and stem diameter in the periods of 50-110 DAE. The variables of fresh and dry stem, leaf and shoot phytomass, dry root phytomass, total dry matter and the Dickson Quality Index were evaluated at 170 DAE. The highest growth and phytomass production for the guava rootstock cv. “Paluma” is obtained with water of electrical conductivity of 0,3 dS m! in both studied epochs. Nitrogen fertilization at the dose of 160% N reduced the effect of salinity of irrigation water on the stem diameter of guava rootstocks at 170 DAE. The irrigation of CEw water of up to 1,33 dS m'!, in the production of Paluma guava rootstock promotes an acceptable reduction in growth, phytomass production and seed quality of 10%. The 115% N dose promotes higher values in absolute growth rates, and relative plant height in the period 50-110 DAE.