SILVA, Fellype Jonathar Lemos da.
Résumé:
In the Brazilian semiarid region, due to the use of water sources with high salt content,
plants are constantly exposed to saline stress conditions. Therefore, it is extremely
important to identify strategies capable of mitigating the deleterious effects of saline
stress on plants, among which the foliar application of ascorbic acid stands out. The
objective of this study was to evaluate the effect of foliar application of ascorbic acid on
the physiological indices, growth, production and postharvest quality of ‘Laranja’ cherry
tomatoes grown in brackish nutrient solutions in a hydroponic system with substrate. The
research was conducted under greenhouse conditions at the Federal University of
Campina Grande, Campina Grande Campus, Paraíba, using a randomized block design
in a 5 × 5 factorial scheme, corresponding to five levels of electrical conductivity of the
nutrient solution - ECsn (2.1-Control; 2.8; 3.5; 4.2 and 4.9 dS m-1) and five concentrations
of ascorbic acid - AsA (0; 150; 300; 450 and 600 mg L-1) with 4 replicates. According to
the results, the electrical conductivities of the nutrient solutions from 2.1 dS m-1
negatively affected the physiological indices, growth, production components and
phenolic compounds of the cherry tomato plant ‘Laranja’. However, in relation to the
other treatments, the foliar application of ascorbic acid at a concentration of 600 mg L-1
associated with the nutrient solution with EC of 2.1 dS m-1 increased the stomatal
conductance, transpiration, CO2 assimilation rate, variable fluorescence, leaf area, plant
height and number of leaves of the cherry tomato ‘Laranja’. The brackish nutrient solution
with ECsn of 4.9 dS m-1 plus the application of AsA at a concentration of 600 mg L-1
increased the parameters of firmness, total soluble solids and total titratable acidity. AsA
at a concentration of 600 mg L-1 increased the instantaneous efficiency in water use, the
instantaneous efficiency of carboxylation, maximum fluorescence and the synthesis of
chlorophylls a and b. The ECsn of 4.9 dS m-1 increased the contents of ascorbic acid,
flavonoids and anthocyanins.
