Salicylic acid improves physiological indicators of soursop irrigated with saline water¹

O ácido salicílico melhora os indicadores fisiológicos de gravioleira irrigada com águas salinas

HIGHLIGHTS:

Low concentrations of salicylic acid promote synthesis of photosynthetic pigments in soursop.

Salicylic acid concentrations above 1.4 mM intensify the deleterious effects of salinity on chlorophyll synthesis.

Irrigation with water of electrical conductivity above 1.8 dS m^-1 negatively affects chlorophyll a fluorescence.

ABSTRACT

Plants grown under salinity are subject to osmotic and ionic stresses that cause several physiological changes, so searching for strategies that minimize the deleterious effects is essential for the development of irrigated agriculture. In this context, the objective was to evaluate the effects of foliar applications of salicylic acid on the mitigation of the effects of salt stress on photosynthetic pigments and chlorophyll a fluorescence of soursop cv. Morada Nova. The study was conducted in a greenhouse, in a randomized block design and 5 × 4 factorial arrangement, with five values of electrical conductivity of irrigation water - ECw (0.8 - control, 1.6, 2.4, 3.2 and 4.0 dS m^-1) and four concentrations of salicylic acid - SA (0, 1.2, 2.4 and 3.6 mM), with three replicates. Foliar application of salicylic acid at a concentration of 1.4 mM mitigated the effects of salt stress on chlorophyll a, chlorophyll b, chlorophyll total, and carotenoids of soursop when irrigated with water of up to 1.5 dS m^-1. Salicylic acid at concentrations above 1.4 mM combined with irrigation with saline water intensified the deleterious effects on photosynthetic pigments. Chlorophyll a fluorescence was not influenced by salicylic acid sprays up to the concentration of 3.6 mM.

Key words:
Annona muricata L.; salinity; physiology; acclimatization