Productive and physiological response of Pereskia grandifolia Haw. irrigation deficit with grey and brackish water in the Brazilian Semiarid Region

Abstract

Water scarcity in semiarid regions, such as in Brazil, is intensified by irregular rainfall and prolonged droughts, compromising agricultural production. The use of alternative water sources, such as treated greywater and saline water, has emerged as a strategy to reduce pressure on water resources. However, these practices require careful management to avoid adverse effects on the soil. In this context, adapted crops such as Ora-Pro-Nóbis (Pereskia grandifolia Haw.), which is tolerant to poor soils, water deficit, and salinity, represent a sustainable option for the Brazilian Semiarid. Given this scenario, the present study aimed to evaluate the vegetative and physiological responses of Ora-Pro-Nóbis irrigated with deficit irrigation levels using saline water from greywater and well water in the Brazilian Semiarid. The variable assessed included plant growth, stomatal conductance, biomass accumulation and soil salinity. Plants irrigated with filtered greywater produced higher shoot biomass (up to 380 g) compared to saline water (maximum 292 g) and exhibited improved stem diameter and flowering at intermediate soil moisture levels (60 %–80 % of available water). Despite similar salinity levels in both water sources (1.6 dS m⁻¹), irrigation led to significant soil salinization (EC > 5.5 dS m⁻¹), highlighting the need for leaching and appropriate drainage. Ora-Pro-nóbis demonstrated strong tolerance to both water and salt stress, reinforcing its potential for sustainable cultivation in Semiarid environments using alternative water sources. Although the use of wastewater represents a sustainable strategy for agriculture in the Semiarid region, Ora-Pro-Nobis is still considered a restricted-use crop for irrigation with wastewater due to the risk of microbiological contamination of its leaves and flowers. Nonetheless, the promising results with wastewater irrigation indicate its potential for sustainable production systems.