The present study aimed to evaluate the effects of the foliar application of hydrogen peroxide on the attenuation of salt stress on the growth, photochemical efficiency, production and water use efficiency of ‘All Big’ bell pepper plants. The experiment was conducted under greenhouse conditions in Campina Grande, PB, Brazil. Treatments were distributed in a randomized block design, in a 5 × 5 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water (0.8, 1.2, 2.0, 2.6 and 3.2 dS m⁻¹) and five concentrations of hydrogen peroxide (0, 15, 30, 45 and 60 μM), with three replicates. Foliar application of hydrogen peroxide at concentration of 15 μM attenuated the deleterious effects of salt stress on photochemical efficiency, biomass accumulation and production components of bell pepper plants irrigated using water with an electrical conductivity of up to 3.2 dS m⁻¹. Foliar spraying of hydrogen peroxide at a concentration of 60 μM intensified the effects of salt stress. The ‘All Big’ bell pepper was classified as moderately sensitive to salt stress, with an irrigation water salinity threshold of 1.43 dS m⁻¹ and a unit decrease of 8.25% above this salinity level.

Salinity restricts the growth of irrigated fruit crops in semi-arid areas, making it crucial to find ways to reduce salt stress. One effective strategy is using eliciting substances like ascorbic acid. In this context, the objective of this study was to evaluate the effects of application methods and concentrations of ascorbic acid on the morphophysiology and production of sour passion fruit irrigated with saline water. The experiment was organized using a factorial randomized block design (3 × 3 × 2) with three application methods (soaking, spraying, and soaking and spraying), three concentrations of ascorbic acid (0, 0.8, and 1.6 mM) and two levels of electrical conductivity of irrigation water—ECw (0.8 and 3.8 dS m⁻¹). Foliar spraying of ascorbic acid at a concentration of 0.8 mM mitigated the effects of salt stress on the relative water content of leaves, the synthesis of photosynthetic pigments, gas exchange, and total production of sour passion fruit when irrigated with ECw of 3.8 dS m⁻¹. Plants grown with water of 0.8 dS m⁻¹ and under foliar application of 0.8 mM of ascorbic acid achieved the maximum growth in stem diameter and the greatest volume of pulp in the fruits.

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.

A salinidade é um dos principais estresses abióticos que restringe o crescimento das plantas e causa perdas significativas no rendimento. Os efeitos do estresse salino são mais severos em regiões semiáridas, devido as condições climáticas e a ocorrência de fontes hídricas com teores elevados de sais. Neste contexto, a busca por estratégias que viabilizem o uso de águas salinas na irrigação é fundamental para garantir a necessidade de produção de alimentos. Assim, objetivou-se com este estudo avaliar os efeitos das aplicações foliar de concentrações de prolina nos índices fisiológicos de maracujazeiro-azedo irrigados com águas salinas na fase de formação de mudas. A pesquisa foi conduzida em casa de vegetação pertencente à Unidade Acadêmica de Engenharia Agrícola da Universidade Federal de Campina Grande, em Campina Grande – PB, utilizando-se o delineamento experimental inteiramente casualizado, em esquema fatorial 5 × 4, sendo cinco níveis de condutividade elétrica da água de irrigação CEa - (0,6; 1,2; 1,8; 2,4 e 3,0 dS m^-1) e quatro concentrações de prolina (0, 5, 10 e 15 mM) com quatro repetições e cada parcela continha duas plantas, totalizando 160 unidades experimentais. A salinidade da água a partir de 0,6 dS m^-1 reduziu o conteúdo relativo de água, trocas gasosas, e elevou o extravasamento de eletrólitos no limbo foliar das plantas de maracujazeiro-azedo. A irrigação com água de condutividade elétrica entre 1,3 e 1,8 dS m^-1 estimulou a biossíntese de pigmentos fotossintéticos do maracujazeiro-azedo ‘BRS GA1’, aos 66 dias após a semeadura. A aplicação foliar de prolina nas concentrações variando de 4,5 e 6,5 mM aumentou a condutância estomática, a transpiração, a taxa de assimilação de CO₂, a eficiência instantânea de carboxilação e os teores de clorofilas do maracujazeiro-azedo.

Practices that mitigate the deleterious effects of water deficit are of great importance for agricultural production in the semi-arid region of Northeastern Brazil. The objective of this study was to evaluate the effect of foliar application of salicylic acid on mitigating water deficit in the morphophysiology and yield components of sour passion fruit during different phenological stages. Treatments were arranged in a randomized block design in a 6 × 2 factorial scheme, consisting of six irrigation strategies under water deficit, based on reference evapotranspiration (ETr) [irrigation with 100% ETr throughout the entire cultivation cycle—IS1; irrigation with 50% ETr during the vegetative stage—IS2; flowering—IS3; fruiting—IS4; vegetative/flowering—IS5; and vegetative/fruiting—IS6], combined with or without salicylic acid (SA) application (0 and 1 mM). The application of 1.0 mM salicylic acid alleviated the effects of water deficit during the flowering stage, improving gas exchange, photochemical efficiency, relative water content, growth, and yield of sour passion fruit. In addition, it contributed to reducing electrolyte leakage in the leaf blade. Therefore, foliar application of salicylic acid represents a promising strategy to maintain the integrity of the photosynthetic apparatus and the productive performance of sour passion fruit under water deficit conditions.

This study aimed to evaluate the effect of selenium concentrations in mitigating salt stress on the physiology, growth, and yield of okra plants irrigated with brackish water. Treatments consisted of four irrigation water salinity levels (ECw: 0.4, 1.3, 2.2, and 3.1 dS m⁻¹) combined with four selenium concentrations (0, 5, 10, and 15 mg L⁻¹), arranged in a randomized block design in a 4 × 4 factorial scheme, with three replicates and one plant per plot. Increasing irrigation water salinity from 0.4 dS m⁻¹ reduced relative water content, gas exchange, initial chlorophyll a fluorescence, plant growth, and production of okra, while increasing the percentage of electrolyte leakage. Irrigation Water salinity levels above 0.4 dS m⁻¹ impaired plant water status, gas exchange, growth, chlorophyll a fluorescence, yield, and water-use efficiency, while increasing electrolyte leakage. Salinity above 1.0 dS m⁻¹ also inhibited photosynthetic pigment synthesis. Selenium did not mitigate salinity-induced reductions in chlorophyll and carotenoids. However, foliar Se at 8.6–15 mg L⁻¹ enhanced gas exchange, chlorophyll a fluorescence, growth, and fruit yield under salinity up to 3.1 dS m⁻¹. These results support Se induced attenuation of salinity stress, warranting further mechanistic studies.