Foliar application of reduced glutathione in sour passion fruit cultivation under salt stress

Aplicação foliar de glutationa reduzida no cultivo de maracujazeiro-azedo sob estresse salino

Water scarcity caused by irregular rainfall is a major challenge for agriculture in the semi-arid region of the Northeast Brazil, making it necessary to use irrigation with high-salinity water. However, excess salt in irrigation water compromise plant growth and development. Therefore, it is crucial to adopt strategies that mitigate the effects of saline stress, ensuring both crop productivity and agricultural sustainability in this region. This study was to evaluate the morphophysiology and physical characteristics of sour passion fruit under saline water irrigation and foliar application of reduced glutathione (GSH) in the semi-arid region of Paraíba, Brazil. The experiment was conducted under greenhouse conditions, at the Center of Technology and Natural Resources of the Universidade Federal de Campina Grande - UFCG, in Campina Grande, PB, Brazil. Treatments consisted of a combination of two factors: five levels of electrical conductivity of irrigation water - ECw (0.4, 1.2, 2.0, 2.8, and 3.6 dS m^-1), associated with four concentrations of GSH (0, 40, 80, and 120 mg L^-1). Plants were distributed in a randomized block design, in a 5 × 4 factorial arrangement, with three replicates, totaling 60 experimental units. Irrigation water salinity compromised the physiology and physical traits of the fruits of ‘BRS GA1’ sour passion fruit. Foliar application of GSH at concentration of 120 mg L^-1 promoted increase in the CO₂ assimilation rate of ‘BRS GA1’ sour passion fruit. The application of GSH did not significantly affect fruit size or peel thickness, but it did contribute to increase pulp weight. Applying GSH at a concentration of 67 mg L^-¹ to plants irrigated with water of 0.4 dS m^-¹, resulted in the highest pulp weight (103.58 g), which represents a 4.6% increase compared to plants exposed to the same salinity level without GSH application. Foliar application of reduced glutathione at concentrations up to 120 mg L^-¹ resulted in an increase in the CO₂ assimilation rate of passion fruit under semi-arid conditions.

Key words:
Passiflora edulis Sims; oxidative stress; antioxidant; salinity; Physical characteristics of fruit