Abstract
ABSTRACT The objective of this study was to evaluate the effects of saline water irrigation management strategies and potassium doses on the concentration of photosynthetic pigments, gas exchange, and fruit production of ‘BRS GA1’ yellow passion fruit. The experiment was carried out under field conditions using a randomized block design, with treatments based on a 6 × 2 factorial scheme, related to six management strategies for irrigation with saline water (irrigation with low-salinity water throughout the crop cycle-WS; irrigation with high-salinity water in the vegetative stage-VE; flowering stage-FL; fruiting stage-FR; and successively in vegetative/flowering stages-VE/FL and vegetative/fruiting stages-VE/FR) and two doses of potassium (60 and 100% of the recommendation), with four replicates. The dose of 100% recommendation corresponded to 345 g of K2O plant-1 year-1. High electrical conductivity irrigation water (4.0 dS m-1) was used in different phenological stages according to treatment, alternating with water of low electrical conductivity (1.3 dS m-1). The synthesis of chlorophyll a and b, stomatal conductance, instantaneous carboxylation efficiency and water use efficiency of ‘BRS GA1’ yellow passion fruit were reduced under irrigation with water of 4.0 dS m-1 in all strategies adopted. Fertilization with 60% of the K recommendation promoted greater number of fruits and yellow passion fruit yield. Irrigation with 4.0 dS m-1 water in the vegetative/flowering and flowering stages reduced the yield of yellow passion fruit.
Highlights
Yellow passion fruit has stood out among the fruit crops of economic importance in Brazil, due to the physicochemical quality of its fruits and acceptance by the Brazilian consumers (Santos et al, 2014), is destined for fresh consumption and industry in the preparation of various products, especially carbonated and mixed beverages, syrups, jellies, dairy products, ice cream, and canned foods (Santos et al, 2017).In the semiarid region of Northeast Brazil, due to climatic adversities, the production of yellow passion fruit is conditioned on irrigation management
High salt concentration reduces the osmotic potential of the soil solution and induces the plant to close its stomata to prevent the loss of water to the atmosphere, limiting transpiration and the photosynthetic rates (Andrade et al, 2019)
The treatments were distributed in randomized blocks in a 6 × 2 factorial scheme, corresponding to saline water irrigation management strategies (IMS) (irrigation with low electrical conductivity water throughout the cultivation cycle; irrigation with high-salinity water in the vegetative-VE; flowering-FL; fruiting-FR; and successively in the vegetative/flowering-VE/FL and vegetative/fruiting-VE/FR stages) and two doses of potassium (60 and 100% of K2O recommendation of Costa et al (2008), with four replicates, totaling 48 experimental units, and each plot consisted of four plants
Summary
In the semiarid region of Northeast Brazil, due to climatic adversities, the production of yellow passion fruit is conditioned on irrigation management. The water used in irrigation commonly has high concentrations of salts, both in surface and underground water found in dams and wells (Silva et al, 2014). High salt concentration reduces the osmotic potential of the soil solution and induces the plant to close its stomata to prevent the loss of water to the atmosphere, limiting transpiration and the photosynthetic rates (Andrade et al, 2019). Salt stress decreases leaf osmotic potential, increases intercellular leakage and inhibits photosynthetic pigment synthesis due to the action of the enzyme chlorophyllase and structural destruction of chloroplasts (Cavalcante et al, 2011; Lima et al, 2020a). Among the alternatives used to reduce the effects of salt stress in plants, the application of saline water in the phenological stages of greater tolerance stands out, along with the period and time of exposure of plants to the salts
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