Effects of saline water and exogenous application of hydrogen peroxide (H2O2) on Soursop (Annona muricata L.) at vegetative stage

Abstract

Soursop is a fruit of great socioeconomic importance for the northeastern region of Brazil. However, the quantitative and qualitative limitation of the water resources of this region has reduced its production. The objective of this study was to evaluate the growth of ‘Morada Nova’ soursop plants irrigated with saline water and subjected to exogenous application of hydrogen peroxide through seed immersion and foliar spray. The study was conducted in plastic pots adapted as lysimeters, using a eutrophic Regolithic Neosol with sandy loam texture under greenhouse conditions. Treatments were distributed in randomized blocks, in a 4 x 4 factorial arrangement, corresponding to four levels of irrigation water electrical conductivity – ECw (0.7; 1.7; 2.7 and 3.7 dS m-1) and four concentrations of hydrogen peroxide – H2O2 (0, 25, 50 and 75 µM), with three replicates and one plant per plot. Foliar applications of H2O2 began 15 days after transplanting (DAT) and were carried out every 15 days at 17:00 h, after the sunset, by manually spraying the H2O2 solutions with a sprayer in such a way to completely wet the leaves (spraying the abaxial and adaxial faces). Treatment effects were evaluated based on plant height (PH), stem diameter (SD), number of leaves (NL) and leaf area (LA) at 60 and 90 DAT, and dry phytomass of leaves (LDP), stem (SDP), roots (RDP) and total (TDP) and leaf succulence (LS) at 90 DAT. Irrigation using water with estimated ECw of 1.55 dS m-1 caused acceptable mean reduction of 10% in soursop growth. Increasing concentrations of hydrogen peroxide did not attenuate the effects of salinity on plant height and leaf area during the vegetative stage. Hydrogen peroxide concentration of 20 µM led to higher leaf succulence in soursop plants.