Tolerance to salt stress in soursop seedlings under different methods of H2O2 application

The aim of this study was to evaluate the effect of different methods of hydrogen peroxide application on biomass production and quality in soursop seedlings under salt stress. The study was conducted in a greenhouse, in a Psammitic Regolithic Neosol of a sandy-loam texture. The treatments were distributed in a completely randomised design, in a 5 x 4 factorial scheme, with five levels of electrical conductivity for the irrigation water - ECw (0.6, 1.2, 1.8, 2.4 and 3.0 dS m(-1)) and four methods of hydrogen peroxide application (Control, application by soaking the seeds, application by spraying, and application by soaking and spraying), with two plants per plot and four replications. From 0.6 dS m(-1), the salinity of the irrigation water inhibited dry matter production and altered the leaf morpho-physiological index of the soursop seedlings 145 days after sowing. The method of hydrogen peroxide application by soaking the seeds minimised the effect of salt stress on root dry matter production and the quality of the soursop seedlings, and increased leaf succulence, standing out as a tolerance mechanism to salt stress. The application of hydrogen peroxide by soaking the seeds favoured an increase in the root to shoot ratio in soursop exposed to salinity of the irrigation water.