This study evaluated the effects of reduced glutathione (GSH) application on the production and quality of sour passion fruit irrigated with brackish water in the semi-arid region of Paraíba, Brazil. The experiment was conducted in drainage lysimeters under greenhouse conditions at the Center of Technology and Natural Resources of the Federal University of Campina Grande (UFCG). Treatments combined five levels of electrical conductivity of brackish irrigation water (Bw: 0.4, 1.2, 2.0, 2.8, and 3.6 dS m⁻¹) and four GSH concentrations (0, 40, 80, and 120 mg L⁻¹), arranged in a randomized block design with three replicates. Salinity levels above 0.4 dS m⁻¹ negatively affected fruit production and post-harvest quality of ‘BRS GA1’ sour passion fruit. Foliar application of 120 mg L⁻¹ GSH increased fruit yield, while 74 mg L⁻¹ GSH mitigated salt stress effects on production and pulp chemical quality. The ‘BRS GA1’ cultivar was highly sensitive to salinity, showing a 26.9% yield reduction per unit increase in Bw electrical conductivity above 0.4 dS m⁻¹. The results suggest that GSH can alleviate salt stress damage, improving crop productivity and fruit quality under semi-arid conditions.

Water scarcity caused by irregular rainfall and high evapotranspiration rates in the Brazilian semi-arid region is one of the main factors limiting watermelon cultivation, underscoring the need for irrigation strategies capable of mitigating the adverse effects of water deficit. This study aimed to evaluate the effects of foliar salicylic acid application on the induction of water-deficit tolerance in watermelon plants subjected to water restriction at different phenological stages under semi-arid conditions. The experiment was conducted using a randomized block design in a split-plot arrangement, with five irrigation management strategies based on crop evapotranspiration (ETc) and four salicylic acid (SA) concentrations, with three replications and three plants per plot. Water deficit adversely affected the morphophysiological traits of the plants and the physical and chemical attributes of ‘Crimson Sweet’ watermelon fruits, with water restriction during the vegetative and flowering stages causing the most severe effects. Foliar application of salicylic acid at concentrations ranging from 1.2 to 2.6 mM increased relative water content by 9.4%, reduced electrolyte leakage by 11.60%, and enhanced CO₂ assimilation by 18.82%, instantaneous water-use efficiency in 128.10%, and instantaneous carboxylation efficiency by 46.92%. Salicylic acid concentrations within this range also improved plant water status, gas exchange, photosynthetic pigment content, growth, and the physical and chemical attributes of the fruits. In contrast, concentrations above 2.6 mM reduced gas exchange, photosynthetic pigment accumulation, chlorophyll a fluorescence, and the physical and chemical quality of ‘Crimson Sweet’ watermelon fruits. Thus, salicylic acid may be an alternative to modulate the tolerance of watermelon plants under water deficit during phenological phases.

Saline water is a major constraint on irrigated fruit farming in the Brazilian semiarid region, negatively reducing both yield and fruit quality. Developing effective strategies to mitigate salt stress is therefore essential. This study evaluated the effects of foliar application of ascorbic acid (AsA) on guava production and post-harvest quality under different phase-specific saline water irrigation strategies. The experiment was arranged in a randomized block design with split-plots. The main plots consisted of six irrigation strategies, which consisted of continuous irrigation with moderately saline water (0.9 dS m⁻¹) and irrigation with saline water (3.3 dS m⁻¹) applied during specific growth stages (vegetative, flowering, fruiting, vegetative/flowering, and vegetative/fruiting). Subplots received a control and three AsA concentrations (0, 200, 400, and 600 mg L⁻¹). Irrigation with saline water (3.3 dS m⁻¹) did not reduce yield, as fruit number and weight were maintained relative to the control. The main effect of saline stress was on fruit chemical composition: flavonoid and anthocyanin contents increased under saline irrigation, while stress during the fruiting stage elevated non-reducing sugars and the maturation index. Foliar AsA application acted as a biostimulant, with 600 mg L⁻¹ improving production by increasing average fruit weight and enhancing nutritional quality through higher soluble solid, reducing sugar, and vitamin C contents. These results highlight the potential of combining phase-specific saline irrigation with AsA application to improve guava fruit quality in the Brazilian semiarid region.

The cultivation of okra [Abelmoschus esculentus (L.) Moench] has potential for expansion in Northeastern Brazil. However, irregular precipitation, associated with high evapotranspiration rates, is a limiting factor for agricultural development. In this context, the use of water-retaining polymers stands out as a promising alternative due to their capacity to retain water and ensure favorable conditions for plant growth. Thus, the present study aimed to evaluate the effects of a water-retaining polymer on the growth, production, and fruit quality of okra under different water replacement levels. The experiment was conducted in a greenhouse at CCTA/UFCG, Pombal Campus, PB, Brazil. The experimental design was a randomized block in a 5 x 4 factorial scheme, corresponding to five water replacement levels (40, 60, 80, 100, and 120% of the actual evapotranspiration - ETr) and four doses of a water-retaining polymer (0, 1.0, 2.0, and 3.0 g L-1), with three replications. A water replacement level of 80% ETr resulted in the greatest growth and production of okra cv. Carcará. Both deficit and excess water replacement caused growth inhibition and a decrease in the number of fruits. The application of the water-retaining polymer at a dose of 3.0 g L-1 had a beneficial effect on the growth, fresh mass, and mean diameter of the fruits, being indicated for okra cultivation in semiarid areas. Irrigation with 40% ETr combined with a 1.3 g L-1 of the water-retaining polymer increased the ascorbic acid content in the fruits of okra cv. Carcará.

Ascorbic acid is a non-enzymatic antioxidant compound essential for plant defense under salt stress conditions. It can induce salt stress tolerance and enable the use of saline water in hydroponic cultivation with substrates. This study evaluated the effect of foliar application of ascorbic acid on the yield and postharvest quality of ‘Laranja’ cherry tomatoes grown in saline nutrient solutions under a substrate-based hydroponic system. The experiment was conducted in a greenhouse in Campina Grande, Paraíba, Brazil, in a randomized block design in a 5 × 5 factorial arrangement, corresponding to five levels of electrical conductivity of the saline nutrient solution—SNS (2.1—Control, 2.8, 3.5, 4.2, and 4.9 dS m⁻¹) and five concentrations of ascorbic acid—AA (0, 150, 300, 450, and 600 mg L⁻¹), with four replications. Salinity above 2.1 dS m⁻¹ reduced yield components and phenolic compound content. However, the saline nutrient solution of 4.9 dS m⁻¹ combined with 600 mg L⁻¹ foliar application of AA increased fruit firmness, soluble solids, and titratable acidity. Additionally, SNS of 4.9 dS m⁻¹ enhanced the levels of vitamin C, flavonoids, and anthocyanins. While AA improved postharvest quality of cherry tomatoes, it did not increase production under salt stress. Foliar application is thus a promising approach for enhancing fruit quality of cherry tomatoes grown in hydroponic systems using saline water, supporting sustainable production in semiarid regions.

Water scarcity has intensified the use of saline water in irrigated agriculture, compromising the physiological performance and production of crops, particularly okra. Among management strategies, potassium fertilization has stood out as a promising alternative in mitigating the effects of salt stress on plants. The objective was to evaluate the influence of potassium fertilization on gas exchange, chlorophyll a fluorescence, and production components of okra under irrigation with saline water. The experiment was conducted in a randomized block design in a 5 × 5 factorial arrangement, with five irrigation water salinity levels (ECw = 0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and five potassium doses (50, 75, 100, 125, and 150% of the recommended K2O dose), with 100% corresponding to 150 mg K2O kg-1 of soil, with three replications. Gas exchange, chlorophyll a fluorescence, and production components of okra were evaluated. Salinity levels above 0.3 dS m-1 reduced the quantum efficiency of photosystem II, fruit length, and fresh fruit weight of okra cv. Santa Cruz. Fertilization with 150% of the recommended K2O dose decreased stomatal conductance, transpiration, and the CO2 assimilation rate of okra irrigated with water of 4.3 dS m-1. Under semi-arid edaphoclimatic conditions, fertilization with 150% K2O mitigated the effects of salt stress on the fruit diameter of okra irrigated under an ECw of 4.3 dS m-1.