Potassium-Deficient Nutrient Solution Affects the Yield, Morphology, and Tissue Mineral Elements for Hydroponic Baby Leaf Spinach (Spinacia oleracea L.)

Abstract

Nutrient supply in hydroponics can significantly influence the nutrition, taste, texture, color, and other characteristics of fruit and vegetable crops. Chronic kidney disease (CKD) is a global health problem that frequently restricts a patient’s consumption of high-potassium foods. CKD patients are advised to limit their consumption of many vegetables that are potassium (K)-rich. At the same time, reducing vegetable intake reduces the intake of healthy compounds such as vitamins, fibers and antioxidants, which are beneficial to CKD patients. In our study, we investigated the reduction of the K concentration in a hydroponic nutrient solution as a possible technique to decrease the K tissue concentration of baby leaf spinach, a dark green that is frequently recommended to be consumed in moderation for patients with CKD. A previously developed hydroponic fertilizer recipe that provides a platform to adjust individual nutrients was used to adjust K to 0, 10, 25, and 100% of the control K concentration. Tissue K levels were reduced by up to 91% with a consequent 61% reduction in dry weight and 76% reduction in fresh weight (yield) with respect to the control treatment. Overall, the results suggest that using a nutrient solution without K can significantly reduce K concentrations in baby spinach, although this will consequently reduce yields.

Soilless cultivation systems to produce tailored microgreens for specific nutritional needs

“…3(D)). This result, in accordance with other studies, 7,8,34 is likely due to a compensatory phenomenon occurring in the plant, where it partially substitutes K with cations, including Na, which have similar roles in physiological processes such as pH control and osmotic regulation. 36 Compared to the control with 100 mg L −1 of K, the decrease in K concentration in the NS (50 and 0 mg L −1 ) leads to a significant reduction in Al content only in Swiss chard microgreens, 4(A)).…”

“…3(B)). Similar results have been found by other authors in different microgreens and baby leaf crops 7,34 grown with reduced levels of K in the NS. Potassium is a crucial macronutrient for plants, constituting up to 10% of their DW.…”

“…8 However, other authors have observed a reduction in DM in spinach baby leaves grown with reduced levels of K in the NS. 34 Regarding production, expressed in kg m −2 , radish and pea are the highest yielding species, followed by rocket and Swiss chard (Fig. 3(B)).…”

“…The main purpose of the second experiment was to provide subjects with impaired kidney function an alternative food product (K-reduced microgreens) to limit K intake. Similarly to the first experiment, the agronomic trial was conducted in a commercial greenhouse to verify how the extensively documented experimental protocols from other studies 7,8,[33][34][35] can be readily applied in a commercial greenhouse context.…”

Trial Protocol for Evaluating Platforms for Growing Microgreens in Hydroponic Conditions

“…Production of microgreens using hydroponic systems must be planned and controlled with care for controlling environmental factors in order to increase quality parameters [3][4][5][6]. This is in comparison to more conventional production methods using soil, considering all the controllable factors in hydroponic systems that have been shown to influence the accumulation of bioactive substances [7,8], the harvest timeframe [9][10][11], and the quality of the finished product [12][13][14]. Furthermore, the lack of a soil's microbiome in hydroponic systems is also important to consider, as unsuccessful parameterization leaves the plants vulnerable to harmful spoilage by microorganisms [15][16][17].…”