Photochemical efficiency and growth of moringa irrigated with brackish water and foliar application of biostimulant

Abstract

Salinity affects the photosynthetic capacity of plants, reducing their efficiency and productivity. Therefore, it is necessary to seek alternatives to mitigate these negative effects, such as the application of biostimulants based on Ascophyllum nodosum, which can help restore photosynthetic function. This study aimed to evaluate the effects of foliar application of the biostimulant on mitigating salt stress on the photochemical efficiency of Moringa oleifera. The experiment was conducted at the Federal University of Paraíba, Areia, Paraíba, Brazil. The experimental design was a randomized block design, with four replicates and two plants per plot, with five levels of irrigation water electrical conductivity (ECw – 0.50, 1.88, 5.25, 8.62, and 10.00 dS m^-1) and five concentrations of foliar-applied biostimulant (0.00, 1.45, 5.00, 8.55, and 10.00 ml L^-1). The brackish water caused reductions in photochemical efficiency and stem diameter of moringa seedlings, with significant damage starting at an ECw of 5.25 dS m^-1. The application of the biostimulant at concentrations of 5 mL L^-1 and above improved photochemical activity and growth of moringa seedlings under salt stress of up to 10.0 dS m^-1 at 60 days after sowing.