Physiological indices and growth of 'Gigante Amarelo' passion fruit under salt stress and silicate fertilization

Abiotic stresses are responsible for the loss of agricultural production in different regions, especially in semiarid regions, which have long periods of drought and high evapotranspiration, leading to the use of saline water as an alternative for the expansion of irrigated areas. In this context, the objective was to evaluate the physiological indices and the growth of the 'Gigante Amarelo' passion fruit as a function of the salinity of irrigation water and fertilization with silicon. A randomized block design was used in a 5 x 2 factorial scheme, whose treatments consisted of five electrical conductivities of irrigation water ECw (0.3; 1.0; 1.7, 2.4 and 3.1 dS m(-1)) associated with two doses of silicion (150 and 300 g of silicon plant(-1)) with four repetitions. Salt stress causes changes in gas exchange, chlorophyll a and b synthesis and growth of 'Gigante Amarelo' passion fruit plants, 60 days after transplanting. Fertilization with silicon dose of 300 g plant(-1) promotes increments in CO2 assimilation rate and instantaneous water use efficiency, being able to mitigate the deleterious effects of salinity. Passion fruit plants fertilized with silicon dose of 300 g plant(-1) attained greater growth in stem diameter and relative growth rate in stem diameter, from 30 to 60 days after transplanting.