The electrical conductivity of the nutrient solution directly affects production and quality of the plants. We evaluated the electrical conductivity suitable for soilless cultivation of kohlrabi. The experiment was carried out in a completely randomized design, with four replicates and five treatments, composed of different nutrient solution’s conductivities (1.31, 1.71, 2.37, 2.98 and 3.75 dS m-1). We evaluated number of leaves, leaf area, specific leaf area, leaf area ratio, fresh and dry masses of leaves, bulb, roots and total, bulb volume, water content in the bulbs and pH, soluble solids, vitamin C, firmness, titratable acidity and SS/TA ratio of the bulbs. All variables related to growth were affected by the nutrient solutions, showing the highest values with the use of the nutrient solutions with EC close to 2.0 dS m-1. Considering the commercial part of the plant, the most developed bulbs were obtained with EC of 1.96 dS m-1, being 49.9 g and 41.15 cm3 per bulb. On the other hand, except for pH, the other variables responded to the increase of EC. Higher values for pulp firmness and titratable acidity occurred with EC close to 2.0 dS m-1, whereas the other variables showed higher values using a more concentrated nutrient solution.

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Reduction in plant growth under salt stress is due, among other factors, to changes in photochemical efficiency and, consequently, in photosynthesis. The objective of this study was to evaluate the effect of salt stress on the chlorophyll fluorescence variables in cultivars of basil (Ocimum basilicum L.). The experiment was conducted in a greenhouse, using a randomized block design in a 5 x 3 factorial scheme, corresponding to five basil cultivars (‘Grecco a Palla’, ‘Alfavaca Basilicão’, ‘Alfavaca Verde’, ‘Lemoncino’ and ‘Roxo’) and three salinity of the nutrient solution (2.0, 3.5 and 5.0 dS m-1), with three repetitions, and the experimental plot was represented by three pots containing 3.0 dm3 of coconut fiber. At the full flowering stage, plants were evaluated for chlorophyll fluorescence, when adapted to the dark, as well as under saturating light conditions. In general, there were changes in fluorescence variables only at salinity above 3.5 dS m-1. Fertigation using high-salinity water promotes strong changes in the chlorophyll a fluorescence of sensitive basil cultivars. The cultivars ‘Grecco a Palla’ and ‘Alfavaca Verde’ were little affected by the increase of salinity, being the most tolerant to salt stress. In the cultivars ‘Alfavaca Basilicão’, ‘Lemoncino’ and ‘Roxo’, chlorophyll fluorescence was strongly affected by salinity, being the most sensitive. The tolerance ranking based on chlorophyll fluorescence is: ‘Grecco a Palla’ = ‘Alfavaca Verde’ > ‘Alfavaca Basilicão’ > ‘Lemoncino’ > ‘Roxo’.

This study aimed to evaluate lettuce production in different pot volumes and different irrigation frequency under saline stress. The experiment was carried out at the Department of Environmental and Technological Sciences of the Federal Rural University of the Semi-Arid, in Mossoró, RN, Brazil. Randomized block experimental design was used in factorial scheme of 2 × 3 × 3, with 3 replicates. Treatments were consisted of 2 water’s salinity levels (0.5 and 2.0 dS m-1), 3 frequencies of irrigation (6, 9, and 12 daily events), and 3 different pots (0.5, 1.0, and 3.0 L). Data from parameters evaluated at harvest were submitted to variance analysis and means were compared. We verified that when the lower saline water (0.5 dS m-1) was used lettuce production increased when cultivated in pots of 3.0 L and submitted to 6 daily events of irrigation. When 3.0 dS m-1 water was used the best results were obtained in 0.5 L and nine daily events of irrigation. The combination of 0.5 L pot and six or nine daily events of irrigation better inhibited the damaging effects of salinity.

Potassium fertigation may be a strategy to reduce saline stress in okra. The objective of this study was to analyze the effect of potassium supplementation as a salinity-attenuating agent in okra. The experiment was conducted in a greenhouse at the Federal Rural University of the Semi-Arid Region, in Mossoró-RN, Brazil. The experimental design was completely randomized, in 2x5 factorial scheme with 4 replicates. Two okra cultivars (Santa Cruz 47 and Valença) fertigated with five fertigation managements [F1= irrigation with non-saline water (0.55 dS/m) and fertigation with a standard dose of potassium (6 g/plant); F2= irrigation with saline water (3.5 dS/m) and fertigation with 6 g/plant of K, F3= irrigation with saline water (3.5 dS/m) and fertigation with 9 g/plant of K, F4= irrigation with saline water (3.5 dS/m) and fertigation with 12 g/plant of K, and F5= irrigation with saline water (3.5 dS/m) and fertigation with 15 g/plant of K]. Plants were collected 110 days after emergence and evaluated for growth variables (leaf number, leaf area, leaf dry mass, stem dry mass, total dry mass) and yield (fruit number, average fruit mass and fruit production). Potassium influenced the growth and yield characteristics of okra irrigated with saline water. The highest yields of fruits occurred at 9.56 and 10.23 g/plant of K, being 330.24 and 733.36 g/plant obtained from cultivars Santa Cruz 47 and Valença, respectively. Okra irrigated with saline water is more demanding in potassium.