Composições catiônicas da água e peróxido de hidrogênio na produção de mudas de maracujazeiro amarelo.

Abstract

Due to its economic importance, the passion fruit quickly spread throughout all Brazilian regions, especially in the Northeast, which has led its production in recent years. However, the semi-arid region of northeastern Brazil, due to water scarcity for most of the year and a high evapotranspiration rate, is the region most affected by the water and soil salinity, highlighting the need for new strategies that enable satisfactory crop production under these growing conditions. The hydrogen peroxide (H2O2) application, in low concentrations, has caused positive results in the activation of several physiological responses that increase or allow the tolerance of plants to salinity. This work aimed to evaluate the growth, development and physiological indices of yellow passion fruit under different cationic compositions of irrigation water and exogenous application of H2O2. The experiment was installed in polyethylene plastic bags and conducted under greenhouse conditions at the Center of Agrifood Science and Technology of the Federal University of Campina Grande, Pombal, Brazil. The experimental design was in randomized blocks, in a 6 x 4 factorial scheme, with four replications, whose treatments resulted from the combination of six cationic water compositions [S1 – Control (0.3 dS m-1); S2 - Na+; S3 - Ca2+; S4 - Na+ + Ca2+; S5 - Mg2+ and S6 - Na+ + Ca2+ + Mg2+, with a 1:1 ratio between Na+ + Ca+ and 7:2:1 between Na+ + Ca2+ + Mg2+, respectively] and four concentrations of H2O2 (0, 20, 40 and 60 μM). With the exception of S1, the other treatments were irrigated with 3.6 dS m-1 water, prepared from different cations in the form of chloride. Foliar applications began at 20 DAS, irrigation with water of the respective cationic nature at 25 DAS and evaluations were made at 60 DAS. The 40 μM concentration of H2O2 reduced the percentage of cell damage in the passion fruit BRS ‘GA1’ plants, 60 days after sowing. The 40 μM concentration of H2O2 reduces the percentage of cell damage in passion fruit BRS ‘GA1’ plants, 60 days after sowing. The chlorophyll a synthesis from passion fruit is inhibited by irrigation with waters consisting of Na+, Ca2+, Mg2+ and Na2+ + Ca2+ + Mg2+. Irrigation with water with electrical conductivity of 3.6 dS m-1 negatively affected root dry mass and stem diameter of 'BRS GA1' passion fruit plants, regardless of the cationic water composition. The 40 μM concentration of H2O2 reduces the salt stress effect on leaf area of plants irrigated with water consisting of Na+, Na+ + Ca2+ and Na+ + Ca2+ + Mg2+. The 20 and 40 μM concentrations of H2O2 increases Dickson's quality index of plants irrigated with water consisting of Na+ + Ca2+ + Mg2+, making them able for the field.