GAS AND BIOCHEMICAL EXCHANGE OF THE 'TOMMY ATKINS' MANGO TREE: APPLICATION OF BIOSTIMULANTS IN THE BRAZILIAN SEMI-ARID REGION

Abstract

In the cultivation of mango trees in the climatic conditions of the Brazilian semi-arid region, the plants undergo metabolic variations due to abiotic stresses. The present study aimed to evaluate the gas exchange and biochemical responses of the 'Tommy Atkins' mango tree, on the application of  humic substance-based biostimulants during the phenological fruiting phase in the Brazilian semi-arid region. The studies were carried out at the Surubim farm, located in the municipality of Petrolina - PE, and two distinct experiments were conducted simultaneously, with applications of two biostimulants via fertigation. The experimental design was in randomized blocks, in a 2 x 5 factorial scheme, with two production cycles (2021 and 2022), and five doses of the products: Sagersolo^® (BST1): (0.0, 7.0, 14.0, 21.0 and 28.0 L ^ha-1) and Fulvumin^® (BST2): (0.0, 10.0, 20.0, 30.0 and 40.0 L ^ha-1). The treatments were applied in the periods of 60, 75, 90 and 105 days after full flowering. Gas exchange and biochemical responses in leaf tissue were evaluated. BST1 doses ranging from 17.5 to 23.0 L ^ha-1 provided maximum increase in stomatal conductance and internal CO2 concentration compared to the control treatment. For BST2, the doses between 24.2 and 25.0 L ^ha-1 favored the maximum increase in leaf transpiration and CO2 assimilation. For both BSTs, the increase in doses during the fruiting phase promoted a linear reduction in starch contents and an increase in total free amino acids, proteins and total soluble carbohydrates in the leaf tissues of the 'Tommy Atkins' mango tree.