Brackish water irrigation strategies and potassium fertilization in the cultivation of yellow passion fruit

Abstract

The high concentration of salts in water sources in the semi-arid region of the Brazilian Northeast stands out as one of the limiting factors for the expansion of irrigated cultivation of fruit crops. Thus, the search for a strategy capable of mitigating the effect of saline stress on plants is of paramount importance. In this context, the objective of this study was to evaluate the gas exchange and yield of yellow passion fruit cultivated under brackish water irrigation strategies and potassium fertilization in two production cycles. The experiment was conducted under field conditions, using the randomized block design in a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with brackish water applied in the different phenological stages of the crop: WS - without stress, irrigation with low-salinity water throughout the crop cycle; irrigation with high-salinity water only in the vegetative stage - VE; flowering stage - FL; fruiting stage - FR; and successively in the vegetative and flowering stages - VE/FL; and vegetative and fruiting stages - VE/FR, and two potassium doses (60 and 100% of the recommendation), with four replicates and three plants per plot. In irrigation, water with high (4.0 dS m-1) or low (1.3 dS m-1) electrical conductivity was used. The potassium dose of 100% recommendation corresponded to 345 g of K2O per plant per year. The yellow passion fruit ‘BRS GA1’ was more sensitive to salt stress applied successively in the vegetative and flowering stages and vegetative and fruiting stages, showing reductions in the intercellular CO2 concentration, CO2 assimilation rate, instantaneous water use efficiency, number of fruits, and yield. Irrigation with water of 4.0 dS m-1 in the fruiting stage is a promising strategy, as it does not compromise production. The dose of potassium equivalent to 60% was better than 100% of recommendation in terms of gas exchange and yield.

Physiological indices of sour passion fruit under brackish water irrigation strategies and potassium fertilization

“…However, the tolerance and/or sensitivity to salinity in plants may vary between cultivars of the same species, development stage, water management strategy, salt concentration of water, and the time of exposure to salts (Lima et al, 2020a). In research on the sour passion fruit crop, Pinheiro et al (2022a;2022b) concluded that the cv. BRS GA1 is sensitive to salt stress applied successively in the vegetative and flowering stages.…”

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

“…It is important to highlight that the intensity of salt stress effects depends on the species, genotype, duration of exposure, fertilization, irrigation management, and development stage [ 12 ], in addition to stress tolerance mechanisms, including the maintenance of ion homeostasis and the osmotic balance and the elimination of reactive oxygen species [ 13 ]. Thus, the use of water with a high concentration of salts in the phenological phase(s) in which the crop expresses tolerance is a promising alternative for reducing the effects of salt stress [ 14 , 15 ]. Soares et al [ 16 ] observed that salt stress in the initial stages leads to earlier flowering in cotton and does not compromise its production.…”

“…Another strategy capable of mitigating salt stress in plants is potassium fertilization [ 12 , 13 , 14 , 15 ]. Potassium is involved in almost all plant physiological processes that require water.…”