Growth, foliar gas exchange and biomass accumulation in passion fruit seedlings irrigated with saline waters and due to the applications of salt stress attenuators

Abstract

The use of substances attenuating the harmful effects of salts on plants is an important strategy for the use of salt water in agriculture. The objective of this work was to evaluate the growth, gas exchange and biomass accumulation of passion fruit seedlings (Passiflora edulis Sims) irrigated with salt water due to the application of salt stress attenuators. The experiment was carried out in a randomized complete block design, in a 5 x 3 x 2 factorial scheme, with three replications, referring to the electrical conductivities of the irrigation water (1.5, 2.5, 3.5, 4.5 and 5.5 dS m-1), three doses of humic acids (0, 10 and 20 mL) and two doses of citric acid (0 and 10 mL) as attenuators, respectively. Increased salinity of irrigation water reduced growth, accumulation of dry shoot biomass and gas exchange (stomatal conductance, transpiration, net photosynthesis, CO2 internal concentration) of passion fruit sourced seedlings. Citric acid did not attenuate the negative effects of the salts and negatively interfered in the growth and accumulation of dry biomass of the shoots of passion fruit, mainly to the seedlings irrigated with water of low salinity. Humic substances at a dose of 20 mL promoted higher growth of passion fruit sprouts but were not sufficient to attenuate the negative effects of irrigation water salts. Therefore, citric acid and humic substances, under the conditions of the study, are not an option to use saline water in the production of passion fruit seedlings