Quantum yield, chlorophyll, and cell damage in yellow passion fruit under irrigation strategies with brackish water and potassium

Rendimento quântico, clorofila e dano celular em maracujazeiro-amarelo sob estratégias de irrigação com água salobra e potássio

Abstract

The occurrence of water sources with high concentrations of salts in the semiarid region of Northeast Brazil stands out as a limiting factor in the cultivation of irrigated yellow passion fruit. Thus the search for irrigation strategies with brackish water is fundamental for the sustainability of irrigated crops. The objective of the present study was to determine the quantum yield, chlorophyll levels, and cell damage in yellow passion fruit cultivated under different irrigation strategies with brackish water and potassium fertilization. The experiment was conducted under field conditions in São Domingos - PB, Brazil, adopting a randomized block design in a 6×2 factorial scheme, consisting of six strategies of use of brackish water applied in the different phenological stages of crop and two doses of potassium (60 and 100% of the recommendation), with four replicates. Two levels of irrigation water salinity were used, with low (1.3 dS m^-1) and high electrical conductivity (4.0 dS m^-1). The potassium dose of 100% recommendation corresponds to the application of 345 g of K₂O per plant per year. The use of brackish water (4.0 dS m^-1) increased chlorophyll fluorescence and negatively affected the photosynthetic pigments of yellow passion fruit, regardless of the phenological stage. Salt stress intensified intercellular electrolyte leakage in passion fruit plants under higher dose of potassium. Our results show that fertilization equivalent to 100% of the potassium recommendation is excessive for yellow passion fruit ‘BRS GA1’ in the tropical semiarid region under salt stress conditions.

Keywords:
Passiflora edulis Sims; salt stress; potassium fertilization; semiarid