Pulsed drip irrigation modulates the photosynthetic responses of melon plants to abiotic stresses

Pulsed drip irrigation has been highlighted as a strategy to mitigate limitations associated with water and saline stress. This study was conducted to analyze whether pulsed drip irrigation modulates photosynthetic and water-related responses in melon plants subjected to combined water and salt stress. The experiment was conducted in a protected environment located within an urban Atlantic Forest conservation zone on Northeastern Brazil. A randomized block design in a 4 × 3 + 1 factorial arrangement with four blocks was used. Irrigation was performed daily to maintain four soil moisture levels (100, 85, 70, or 55% of pot capacity) using brackish water (0.5, 2.0, or 3.5 dS m⁻1) via pulsed drip irrigation. The control treatment consisted of daily continuous drip irrigation to maintain 100% of pot capacity, using water with an electrical conductivity of 0.12 dS m⁻1. Variables related to photochemical efficiency, water relations, and photoassimilate partitioning were evaluated. The results showed that water and saline stresses compromised the photosystem II and partitioning of biomass, reducing shoot biomass while increasing the root-to-shoot ratio. When comparing drip irrigation systems, pulsed drip proved more effective in preserving photochemical efficiency and water relations, while continuous drip favored greater accumulation of shoot biomass.