Gas exchange and productivity of yellow passion fruit irrigated with saline water and fertilized with potassium and biofertilizer

The salinity of irrigation water can affect the growth and development of most plants of commercial interest. Aiming to study these aspects in passion fruit culture, an experiment was performed to evaluate the effects of bovine biofertilizer and potassium fertilization on gas exchange and production of the passion fruit 'BRS Giant Yellow' irrigated with non-saline and saline water. The treatments were arranged in randomized blocks with sub-subdivided plots using the 2x(3x5) scheme, which refers to two levels of electrical conductivity of the irrigation water as the main plot (0.35 and 4.00 dS m(-1)) and the combination of three potassic fertilization practices (without fertilization, fertilized with conventional and slow release KCl) with five doses of bovine biofertilizer (0, 25, 50, 75 and 100% of dose of 15 L m(-2)) in the subplots, with three replicates and 12 plants per plot. The physiological variables and the productivity were evaluated in two harvests, and the data were submitted to statistical evaluation of samples repeated in time. The application of bovine biofertilizer and potassium in soil with a sandy texture irrigated with saline water did not inhibit the degenerative effect of the salts on the photosynthetic rates of the plants. The salinity of the irrigation water reduced stomatal conductance, transpiration and net photosynthesis of the plants, but in the second crop, the instantaneous water use efficiency was higher. Although the productivity decreased from the first to the second harvest, the biofertilizer associated with potassic fertilization increased the yield of the crop, which surpassed the average of Brazil, the Brazilian Northeast and the State of Paraiba, Brazil.