Growth and gas exchange of soursop under salt stress and hydrogen peroxide application¹

Crescimento e trocas gasosas de gravioleira sob estresse salino e aplicações de peróxido de hidrogênio

HIGHLIGHTS:

The decrease in stomatal conductance restricts soursop leaf transpiration under salt stress.

Exogenous application of hydrogen peroxide at low concentration favors soursop growth and transpiration.

Application of high concentrations of hydrogen peroxide intensifies salt stress in soursop.

ABSTRACT

The cultivation of irrigated soursop in semiarid Northeastern Brazil highlights the need for information regarding its responses to the salinity of irrigation water and the use of techniques that allow its exploration, such as the use of hydrogen peroxide. Thus, the study aimed to evaluate the effect of soaking of seeds and foliar application of hydrogen peroxide on soursop plant growth and physiology under conditions of salt stress. The study was conducted in lysimeters in a greenhouse, and the treatments were distributed in a randomized block design and 4 × 4 factorial scheme, with four values of electrical conductivity of the irrigation water - ECw (0.7, 1.7, 2.7, and 3.7 dS m^-1) and four concentrations of H₂O₂ (0, 25, 50, and 75 μM), with three replicates and one plant per plot. H₂O₂ concentrations were applied via seed imbibition and foliar spray. Irrigation with water from 0.7 dS m^-1 impairs gas exchange and absolute growth rates of plant height and stem diameter and relative growth rate in height of soursop plants. Concentrations of 35, 33 and 23 µM of hydrogen peroxide favored the relative and absolute growth rates of plant height and transpiration, respectively. Compared to the aerial part, the root of soursop plants is more affected when irrigated with water from 1.6 dS m^-1.

Key words:
Annona muricata L.; salinity; acclimatization