Gas exchange and growth of soursop under salt stress and H₂O₂ application methods

Trocas gasosas e crescimento de graviola sob estresse salino e métodos de aplicação de H₂O₂

Abstract

The production of soursop seedlings in the Northeast region of Brazil has faced limitations due to the high concentrations of salts in the water, so it is necessary to use techniques that enable its cultivation, and the application of hydrogen peroxide to minimize the deleterious effects of salt stress stands out. In this context, the objective was to evaluate forms of application of hydrogen peroxide as an attenuator of salt stress on the gas exchange and growth of soursop seedlings cv. Morada Nova. The experiment was conducted under greenhouse conditions, in an Regolithic Neosol of sandy loam texture, from the municipality of Lagoa Seca - PB. A completely randomized design was used in a 5 × 4 factorial arrangement, whose treatments resulted from the combination of five levels of electrical conductivity of irrigation water - ECw (0.6 – control, 1.2, 1.8, 2.4 and 3.0 dS m^-1) and four forms of hydrogen peroxide application (M1 - without H₂O₂ application, M2 - application by seed soaking, M3 - application by foliar spraying, and M4 - application by seed soaking + foliar spraying), with four replicates and two plants per experimental unit, totaling 160 plants. The concentration of H₂O₂ used in the different forms of application was 20 µM. Irrigation water salinity from 0.6 dS m^-1 reduced the gas exchange and growth of soursop. The method of H₂O₂ application by foliar spraying minimized the effects of salt stress on gas exchange. The method of H₂O₂ application by seed soaking reduced the effect of salt stress on the growth of soursop at 85 days after sowing.

Keywords:
Annona muricata L; acclimatization; hydrogen peroxide; saline water