Induction of tolerance with salicylic acid in sour passion fruit irrigated with water of different cationic compositions

Abstract

This study aimed to evaluate the physiological indices, growth, and seedling quality of the sour passion fruit cv. BRS SC1 as a function of irrigation with water of different cationic natures and exogenous application of salicylic acid. The experiment was conducted under plant nursery conditions at the CCTA/UFCG, Campus Pombal-PB, using a randomized block design set up in a 6 × 4 factorial arrangement referring to six cationic compositions of irrigation water (S1 – control, S2 - Na+, S3 - Ca2+, S4 - Na+ + Ca2+, S5 - Mg2+, and S6 - Na+ + Ca2+ + Mg2+) and four concentrations of salicylic acid - SA (0, 1.0, 2.0, and 3.0 mM), with three replications and two plants per plot. In the control treatment (S1), the plants were irrigated with the electrical conductivity level of 0.3 dS m-1, whereas the other treatments (S2, S3, S4, S5, and S6) used water with 4.0 dS m-1 obtained based on different cations, all in the form of chloride. The exogenous application of salicylic acid increased the content of chlorophyll b in the sour passion fruit seedlings. Salt stress negatively affected seedling growth. Seedling quality was affected by the electrical conductivity of irrigation water regardless of the cationic nature. Although showing reductions, the seedlings produced under high salinity showed a satisfactory Dickson quality index. The genotype cv. BRS SC1 is considered tolerant to salinity when irrigated with water salinized by Na+, Ca2+, Na+ + Ca2+, and Na+ + Ca2+ + Mg2+, and moderately tolerant when irrigated with water salinized by Mg2+.