ABSTRACT
Potassium is a nutrient with the potential to increase plant tolerance to salt stress. The aim of this study was to evaluate the production and quality of kale subjected to salt stress and potassium concentrations in a protected environment. The experimental design was in split plots, with plots composed of five nutrient solutions (control treatment, S1 - standard nutrient solution prepared in low-salinity water, 0.5 dS m-1 (500 mg L-1 of KNO3), and four nutrient solutions prepared in brackish waters (3.5 dS m-1) containing four concentrations of KNO3 (S2 - 500 mg L-1, S3 - 625 mg L-1, S4 - 750 mg L-1, S5 - 1,000 mg L-1), and subplots represented by two leaf kale cultivars (Manteiga and Manteiga da Geórgia). Leaf production variables and post-harvest physical and chemical qualities were evaluated. The saline nutrient solution with the addition of NaCl (S2) reduced production but did not reduce the post-harvest quality of kale. The extra addition of KNO3 at 25% (S3) was efficient in reducing the deleterious effects of salt stress on the variables leaf length, leaf area, leaf production, and number of bunches. The cv. Manteiga da Geórgia was more tolerant to salt stress than the cv. Manteiga.
Key words:
Brassica oleracea L.; salinity; potassium fertilization; post-harvest quality
HIGHLIGHTS:
The cv. Manteiga da Geórgia of kale is more tolerant to salinity than the cv. Manteiga.
Extra KNO3 concentration of 25% in nutrient solution increases tolerance of kale to salinity.
Kale quality, in terms of soluble solids, is increased by salt stress and KNO3 concen-rations.
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S1 - Standard nutrient solution (500 mg L-1 of KNO3); S2 - Saline nutrient solution (500 mg L-1 of KNO3); S3 - Saline nutrient solution (625 mg L-1 of KNO3); S4 - Saline nutrient solution (750 mg L-1 of KNO3); S5 - Saline nutrient solution (1,000 mg L-1 of KNO3). Bars with the same uppercase letter referring to cultivars in the same type of nutrient solution, and lowercase letters referring to nutrient solutions in the same cultivar, do not differ significantly by the Tukey test (p ≤ 0.05).