Saline Water, Pit Coating and Calcium Fertilization on Chlorophyll, Fluorescence, Gas Exchange and Production in Passion Fruit

Abstract

In plants sensitive to salinity, such as passion fruit, irrigation with saline water can cause physiological disturbances and reduce fruit production, necessitating the use of cultural practices that mitigate saline stress. The objective of this study was to evaluate the effects of water salinity, pit coating with high-strength polyethylene film, and calcium fertilization on the physiological and productive aspects of passion fruit ‘BRS Gigante Amarelo’. The treatments were arranged in split plot in the scheme 2WS × (2LP × 5DC), corresponding to water salinity (0.3 and 4.0 dS m-1) as the main plot, side coating of pits (without and with) doses of calcium (0; 30; 60; 90 and 120 kg ha-1). During the flowering phase, we evaluated leaf chlorophyll indices, fluorescence kinetics, and gas exchange. The increase in calcium doses up to 60 kg ha-1 increased leaf chlorophyll and quantum efficiency. The stomata did not restrict gas exchange, but salinity resulted in reduced net photosynthesis and plant production. The lateral coating of the pits intensified the reduction in salinity-promoted production, while calcium mitigated the effects of the salts. Entisol cultivated with passion fruit should not be irrigated with saline water of 4.0 dS m-1; lateral pit coating is not advised. In an Entisol with an initial calcium level of 1.92 cmolc dm-3, the recommended application dose is 60 kg ha-1 for passion fruit cultivation.