NPK Accumulation, Physiology, and Production of Sour Passion Fruit under Salt Stress Irrigated with Brackish Water in the Phenological Stages and K Fertilization

This research aimed to evaluate the effects of salt stress, varying the phenological stages, and K fertilization on NPK concentrations, physiology, and production of Passiflora edulis Sims. The research was carried out at the University Farm of Sao Domingos, Paraiba, Brazil, using a randomized block design with a 6 x 2 factorial arrangement. Six irrigation strategies were evaluated (use of low electrical conductivity water (0.3 dS m(-1)) during all stages of development and application of high-salinity water (4.0 dS m(-1)) in the following stages: vegetative, flowering, fruiting, successively in the vegetative/flowering, and vegetative/fruiting stages) and two potassium levels (207 and 345 g K2O per plant), with four replications and three plants per plot. The leaf concentrations of N, P, and K in the sour passion fruit plants found in the present study were below the optimal levels reported in the literature, regardless of the development stage and the cultivation cycle. The relative water content, stomatal conductance, and photosynthesis were reduced by salt stress in the first cycle. However, in the second cycle, irrigation with 4.0 dS m(-1) in the vegetative/flowering stages increased the CO2 assimilation rate. Passion fruit is sensitive to salt stress in the vegetative/flowering stages of the first cycle. In the second cycle, salt stress in the fruiting stage resulted in higher production per plant.

Automated summary

This research aimed to evaluate the effects of salt stress, phenological stages, and K fertilization on NPK concentrations, physiology, and production of Passiflora edulis Sims. The study found that the leaf concentrations of N, P, and K were below optimal levels regardless of the development stage and cultivation cycle. Salt stress reduced relative water content, stomatal conductance, and photosynthesis in the first cycle, but increased CO2 assimilation rate in the second cycle. Passion fruit plants were sensitive to salt stress in the vegetative/flowering stages of the first cycle, while salt stress in the fruiting stage increased production per plant in the second cycle.