Salinidade da água e peróxido de hidrogênio na formação de mudas de maracujazeiro-azedo.

Abstract

The semi-arid region of the Brazilian Northeast is also characterized by the quantitative and qualitative scarcity of water resources. Water sources in this region usually contain high concentrations of dissolved salts in their composition, standing out as a limiting factor for the formation of fruit tree seedlings. Among the strategies that have been employed to reduce the effect of saline stress on plants, the foliar application of hydrogen peroxide stands out. In this context, the objective of the present work was to evaluate the morphophysiology of passion fruit seedlings under irrigation with saline water and foliar application of hydrogen peroxide. The research was carried out in a greenhouse in Pombal, Paraíba. The experimental design was in randomized blocks, in a 5 × 3 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water - ECw (0.3; 1.1; 1.9; 2.7 and 3.5 dS m-1) associated with three concentrations of hydrogen peroxide – H2O2 (0; 15 and 30 μM), with three replicates and two plants per replicate, totaling 90 plants. Water salinity from 0.3 dS m-1 increased the leakage of electrolytes in the leaf blade and reduced the growth in stem diameter of passion fruit seedlings, 50 days after sowing. Foliar application of 15 μM hydrogen peroxide reduced the effects of salt stress on stomatal conductance, plant height and leaf area of passion fruit. Hydrogen peroxide in a concentration of up to 30 μM increased the absolute and relative growth rate in height of passion fruit plants, in the period of 30 – 50 days after transplanting. There was an increase in the accumulation of dry mass of leaves of passion fruit seedlings with application of hydrogen peroxide at concentrations of 15 and 30 μM and dry mass of root under application of 30 μM, at 50 days after sowing.