Morphophysiology of soursop under salt stress and H₂O₂ application in the pre-flowering phase¹

Morfofisiologia de gravioleira sob estresse salino e aplicação de H₂O₂ na fase de pré-floração

HIGHLIGHTS:

Increase in the electrical conductivity of water above 0.8 dS m^-1 negatively affects the growth of soursop plants.

Stomatal conductance is reduced when the electrical conductivity of irrigation water is above 0.8 dS m^-1.

Application of 30 µM of H₂O₂ increases electrolyte leakage in the leaf blade.

ABSTRACT

In the semi-arid region of the Brazilian Northeast, water sources generally have high levels of salts, standing out as one of the abiotic stresses that restrict the growth and development of plants. In this context, the objective of the present study was to evaluate the effects of foliar applications of hydrogen peroxide on the morphophysiology of soursop under salt stress in the pre-flowering phase. The experiment was carried out in a greenhouse, using a randomized block design and a 4 × 4 factorial arrangement, with four values of electrical conductivity of the irrigation water - ECw (0.8, 1.6, 2.4, and 3.2 dS m^-1) and four concentrations of hydrogen peroxide - H₂O₂ (0, 10, 20, and 30 μM), with three replicates. An increase in water electrical conductivity from 0.8 dS m^-1 reduced stomatal conductance, CO₂ assimilation rate, instantaneous carboxylation efficiency, and leaf water saturation deficit. It inhibited the growth of soursop plants at 370 days after transplanting. Hydrogen peroxide at concentrations of up to 10 μM increased leaf transpiration and water use efficiency of soursop plants irrigated with 1.8 dS m^-1 water in the pre-flowering phase.

Key words:
Annona muricata L.; acclimatization; salinity; reactive oxygen species