Freshwater depletion becomes a significant challenge as the population grows and food demand rises. We evaluated the responses of lettuce cultivars (Lactuca Sativa) under saline stress in photosynthetic responses, production, and ion homeostasis. We used a randomized block design in a 3 × 5 factorial scheme with five replications—the first factor: three cultivars of curly lettuce: SVR 2005, Simpson, and Grand Rapids. The second factor consisted of five treatments: T1—control (water of 0.53 dS m⁻¹); T2—saline stress (water of 4.0 dS m⁻¹); T3—saline stress + ascorbic acid; T4—saline stress + gibberellic acid; and T5—saline stress + salicylic acid. The Grand Rapids lettuce cultivar tolerated water salinity, obtaining the highest production. The Simpson lettuce cultivar was sensitive to salinity, reducing biomass production under saline stress by 11.47% compared to Grand Rapids. Salicylic acid was more effective at mitigating saline stress in the Simpson lettuce cultivar than ascorbic and gibberellic acids, with a 24.85% increase in production compared to saline stress. The findings suggest that the Grand Rapids lettuce cultivar is more resilient to saline conditions, while salicylic acid can significantly enhance production in the sensitive Simpson cultivar under saline stress.

The canonical correlation is used to correlate groups of distinct variables. The objective of this study was to use canonical correlation analysis to evaluate the interaction between water quality attributes clogging-causing and the hydraulic performance of non-pressure compensating drippers operating with dilutions of aquaculture effluent in well water. The experiment was in a completely randomized design in a split-split-plot scheme with three replicates, with five dilutions in the plots (Dilution 1: 100% aquaculture effluent; Dilution 2: 75% aquaculture effluent + 25% well water; Dilution 3: 50% aquaculture effluent + 50% well water; Dilution 4: 25% aquaculture effluent + 75% well water; and Dilution 5: 100% well water), three emitters in the sub-plots (ST (1.6 L h^-1), SL (1.6 L h^-1) and NJ (1.7 L h^-1)), and three operating times in the sub-subplots (0, 80 and 160 hours, in which 0 hours operating time means the start of evaluations). The statistical analyses performed were correlation matrix and canonical analysis. The canonical correlation analysis indicated that when the concentrations of attributes increase, the hydraulic performance of the drippers decreases. The interaction of this group of attributes indicates that the clogging of drippers operating with the five dilutions of aquaculture effluent in well water occurs by the combined action of physical, chemical, and biological agents. The ST dripper was the least sensitive to the group of quality attributes of the dilutions, whereas the most sensitive was the SL dripper.

The objective of this study was to evaluate the effects of different combinations of nitrogen and potassium fertilization on gas exchange and chlorophyll a fluorescence in seedlings of guava cv. Paluma irrigated with water of different salinity levels. The experiment was set up in a randomized block design and analyzed in 5 × 4 factorial scheme, with four replicates. The treatments were composed of the combination of the factor electrical conductivity of irrigation water - ECw (0.3, 1.1, 1.9, 2.7, and 3.5 dS m-1), with the factor combinations (C) formed from recommended doses of nitrogen (N) and potassium (K2O), 70% N + 50% K2O, 100% N + 75% K2O, 130% N + 100% K2O, and 160% N + 125% K2O. The fertilization combination 130% N + 100% K2O mitigated the effects of salt stress up to mean ECw of 1.3 dS m-1, resulting in increments in CO2 assimilation rate, transpiration, instantaneous carboxylation efficiency, and electron transport rate. For maximum quantum efficiency of photosystem II, only treatment irrigated with ECw 3.5 dS m-1 under the combination 160% N + 125% K2O showed damage to the photosynthetic apparatus.

Several studies have been conducted evaluating the management of fertilizers as strategies to mitigate the deleterious effects of salt stress, so the objective of this work was to evaluate the quality of ‘Crioula’ guava seedlings under irrigation with water of different salinity levels and fertilized with combinations of nitrogen and potassium. The experiment was performed in a protected (screened) environment using a randomized block design and analyzed in a 5 × 4 factorial scheme, with four replicates, with the plot formed by two plants. The treatments were formed from the combination of the factor electrical conductivity of irrigation water (ECw 0.3, 1.1, 1.9, 2.7 and 3.5 dS m^-1), with the factor combinations (C) of nitrogen (N) and potassium (K₂O) doses, being C1 = 70% N + 50% K₂O, C2 = 100% N + 75% K₂O, C3= 130% N + 100% K₂O and C4= 160% N + 125% K₂O. The recommended dose of 100% N and K, respectively, was 541.1 mg N dm^-3 soil and 798.6 mg K dm^-3 soil. The combinations of N and K fertilization corresponding to 70% N + 50% K₂O and 100% N + 75% K₂O of the recommended doses promoted greater growth of ‘Crioula’ guava seedlings. Water with ECw of 2.1 dS m^-1 promotes the formation of quality ‘Crioula’ guava seedlings.

Salt stress affects the development of several crops, being one of the limiting factors for irrigated agriculture in the semiarid region, where nitrogen and potassium fertilization can be an alternative for agricultural production. This study aimed to evaluate the viability of using water with different salinities associated with varying amounts of nitrogen and potassium fertilization in the production of seedlings of the guava cultivar Paluma in an experiment conducted in experimental areas of the Federal Rural University of the Semi-arid Region (UFERSA), campus of Caraúbas. The research was carried out from February to June 2021. The study was set up in a randomized block design and analyzed in a 5 × 4 factorial scheme with four replicates, and two plants per plot. Treatments were established by combining different levels of electrical conductivity of the irrigation water (ECw): 0.3, 1.1, 1.9, 2.7, and 3.5 dS m^-1, with Combinations (C) of nitrogen (N) and potassium (K₂O) levels of recommended fertilization: C1 = 70% N + 50% K₂O, C2 = 100% N + 75% K₂O, C3 = 130% N + 100% K₂O, and C4 = 160% N + 125% K₂O. Irrigation with electrical conductivity levels up to 2.1 dS m^-1 favored seedling growth for the guava cv. Paluma. Fertilization combinations C1 and C2 promoted the greatest increases in growth and biomass for guava seedlings cv. Paluma 125 days after sowing. Fertilizer combinations did not mitigate the harmful effects of salt stress from irrigation water on the production of young guava cv. Paluma.

Salt stress is a major constraint on cowpea cultivation in semi-arid regions, primarily due to excess salts in irrigation water and soils. We aimed to investigate the effects of foliar magnesium (Mg) application on the production, phenology, and seed vigor of the cowpea landraces “Pingo de Ouro” and “Costela de Vaca” under salt stress conditions. Two experiments were conducted. The first was carried out in a greenhouse using a randomized block design with five replicates, in a 2 × 3 × 4 factorial scheme: two cowpea landraces (“Pingo de Ouro” and “Costela de Vaca”), three irrigation water salinity levels (0.54, 3.50, and 5.00 dS m⁻¹), and four foliar doses of a product (0.0, 1.0, 2.0 and 3.0 mL L⁻¹) containing 8% magnesium. Morphological traits and seed production were evaluated. The second experiment was conducted in a laboratory using a completely randomized design, also in a 2 × 3 × 4 factorial, with four replicates of 25 seeds each. In the first experiment, the 1 mL L⁻¹ dose provided the best results for pod length in the variety “Pingo de Ouro” under an electrical conductivity salinity of 5.00 dS m⁻¹. In the variety “Costela de Vaca”, this same dose increased the number of seeds per pod and the 100-seed weight under the same salinity level. In the second experiment, seedlings of “Pingo de Ouro” grown from seeds produced by plants treated with 2 and 3 mL L⁻¹ doses showed greater shoot length, root length, stem diameter, and shoot fresh mass, particularly under 0.54 dS m⁻¹ salinity. Therefore, “Pingo de Ouro” exhibited superior seedling growth at doses of 2 and 3 mL L⁻¹, particularly under conditions of low salinity. These findings support the use of foliar magnesium fertilization as an effective agronomic strategy to enhance seed production and quality in cowpea landraces under salt stress conditions.