Na improves the growth of K-deficient but not K-sufficient kale.

The decrease in the use of K fertilizers may be relevant for developing countries that depend on imports, as well as for specific groups such as patients with chronic kidney disease, who have restricted K in their diets. However, the decrease in the use of K affects plant yield, requiring the study of alternatives to mitigate nutritional stress. Sodium is a beneficial element that can mitigate K deficiency, but studies on kale plants are lacking. We investigated the role of Na in kale grown with and without K in nutrient feed solution. Four treatments were used: abundant K, abundant K plus Na, deficient K, and deficient K plus Na. Low Na (2 mmol L) attenuated the symptoms of K deficiency in kale by minimizing leaf water loss and increasing pigment content, leaf area, and plant dry mass. The synergism between K and Na negatively affected the growth of kale plants.