Aspectos fisiológicos do Maracujazeiro-Azedo irrigado com águas salinas e adubação potássica.

Abstract

The passion fruit crop has great socioeconomic importance for the semi-arid region of Northeast Brazil. However, is this region, it is common for the water used in irrigation to contain soluble salts in excess, being one of the limiting factors for the expansion of irrigated agriculture, due to the effects of osmotic and ionic nature. In this context, the objective of this work was to evaluate water content, percentage of cell membrane damage, photosynthetic pigments (chlorophyll a, b and Carotenoids) and gas exchange of passion fruit ‘BRS SC1’ as a function of irrigation with water with different levels of electrical conductivity of the irrigation water and potassium doses. The experiment was carried out in vessels adapted as smooth drainage under field conditions in the experimental farm of CCTA/UFCG in São Domingos – PB. The experimental design was a randomized block, in a 5 × 4 factorial scheme, whose treatments were constructed by combining two factors: five levels of electrical conductivity of the irrigation water – ECw (0.3; 1.1; 1.9; 2.7 and 3.5 dS m-1), associated with four doses of potassium (60; 80; 100 and 120% of the K2O recommendation), with three repetitions. The 100% dose corresponded to 345 g of K2O per plant year-1. There was an interaction between water salinity levels and potassium doses for stomatal conductance, for transpiration, for intercellular concentration of CO2 and instantaneous efficiency of carboxylation of the sour passion fruit ‘BRS SC1’. Water with electrical conductivity greater than 0.3 dS m-1 reduced the relative water content, chlorophyll a and b contents, CO2 assimilation rate and instantaneous water use efficiency of ‘BRS SC1’ passion fruit plants. The electrical conductivity of the irrigation water of up to 2.8 dS m-1 increased the electrolyte leakage in the leaf blade and the carotenoid contents. Potassium doses of 100% of the recommendation increased the extravasation of electrolytes in the leaf blade.