Tolerância de porta-enxerto de goiabeira à salinidade da água de irrigação sob adubação nitrogenada.

Abstract

The crop of guava at the irrigated areas of the Brazilian semiarid northeast has great socioeconomic importance. Above all, due to limitation quality water for irrigation in this region, it is necessary to study techniques that make feasible the use of saline water in the species of cultivation. In this sense, aim of this work was to evaluate the guava rootstock tolerance to increased salinity in irrigation water, under fertilization with different nitrogen levels. The experiment was developed in greenhouse of the Center for Science and Technology Agrifood the Federal University of Campina Grande (CCTA / UFCG), located in the city of Pombal – PB. The experimental outline was a randomized block in a factorial 5 x 4, with treatments related to the five levels of electrical conductivity of irrigation water (ECw) 0.3; 1.1; 1.9; 2.7 and 3.5 dS m-1 interacting with four nitrogen (N): 70, 100, 130 and 160% N of the recommended dose for guava seedlings. Four replications were used, with two plants per experimental unit, where to evaluate the guava genotype Paluma. Begin the application the treatments from 25 days after seedling emergence (DAE). The morphological variables plant height, stem diameter, number of leaves and leaf area to 130 and 190 DAE, and physiological regarding absolute growth rate and relative plant height and stem diameter were evaluated in periods of 25 -130 and 130-190 DAE. The variables fresh biomass and dry stem, leaves and shoots, root dry biomass, total dry and Dickson quality index were evaluated at 190 DAE. The increase ECw from 0.3 dS m-1 negatively affect the morphologic variables to 130 DAE and physiological in the range of 25 to 130 DAE. At 190 DAE morphological variables and fitomassas of guava rootstocks are tolerant to ECw levels from 2.1 to 2.8 dS m1. Physiological variables relating to the period of 130-190 DAE, relative growth rate of the height plant is tolerant to ECw level of 3.5 dS m-1. The dose of 70% of N stimulates the growth of morphophysiological variables and biomass production of guava rootstock in the evaluated periods, with exception of plant height to 130 DAE and its absolute growth rates and relative of 25-130 DAE, where the highest values are obtained at doses of 88-100% of N. The use of nitrogen fertilizer in doses of 100 to 130 and 70-130% N reduces the effect of salinity of irrigation water under root dry biomass and the Dickson quality index, respectively, of guava rootstocks to 190 DAE.