Development of a hydroponic growing protocal for vegetative strawberry production

Authors: Yafuso, Erin; Boldt, Jennifer

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/2/2024
Publication Date: 2/16/2024
Citation: Yafuso, E.J., Boldt, J.K. 2024. Development of a hydroponic growing protocal for vegetative strawberry production. HortScience. 59(3):384–393. https://doi.org/10.21273/HORTSCI17523-23.
DOI: https://doi.org/10.21273/HORTSCI17523-23

Interpretive Summary: Hydroponic growing systems are useful for nutrient studies. They reduce the time required to wash roots, and minimize the loss of roots during the cleaning process. They are also generally suitable for growing a range of crops, but optimal growing conditions need to be individually tailored for each crop. Strawberries are a crop of interest for hydroponic deep water culture. However, the pH of the nutrient solution tends to decrease over time, and different strategies were examined to potentially minimize this pH drift. When the nitrogen form in the nutrient solution was composed of 20% or more ammonium, the pH decreased below the target range. The addition of 2(N-Morpholino)ethanesulfonic acid (MES) was found to be a better buffer than potassium bicarbonate to maintain the nutrient solution pH. These recommendations can be used by growers and researchers to grow strawberries in a deep water culture hydroponic system and keep the pH of the nutrient solution stable over time.

Technical Abstract: Hydroponic growing systems are advantageous for nutrient studies where root data are important, as they alleviate the laborious and time-consuming task of washing roots to remove soilless substrate particulates from them. However, the growing system should be optimized for the crop of interest. Our overall objective was to develop a protocol for hydroponic strawberry (Fragaria ×ananassa) production that provided growth suitable to or better than soilless substrate. Plants were initially grown in perlite, sand, deep water culture (DWC), or a peat-based soilless substrate. Plant growth in DWC was similar to those grown in the peat-based substrate, and required minimal effort to harvest the entire root system for growth data and elemental analysis. However, strawberry plants grown in DWC pushed the pH down to 4.0 ± 0.1 (mean ± SE) when provided a modified Yamazaki nutrient solution with a nitrate (NO3-) to ammonium (NH4+) ratio of 80:20. As a result, a subsequent trial was conducted to evaluate the buffering capacity of potassium bicarbonate (KHCO3) added to nutrient solutions with NO3- to NH4+ ratios of 0:100, 20:80, 50:50, 60:40, 80:20, or 100:0. Up to 2.6 mM KHCO3 did not provide adequate buffering in nutrient solutions containing NH4+. Nutrient solution pH decreased by approximately 1.5 units every two to three days. The 100% NO3- nutrient solution maintained a stable pH of 5.9 ± 0.1 when buffered with 0.8 mM potassium bicarbonate. Lastly, 2(N-Morpholino)ethanesulfonic acid (MES) was evaluated as a potential buffering agent for DWC strawberry production. Plants were grown in a nutrient solution with a 60:40 NO3- to NH4+ ratio. The buffering capacity of MES increased as the concentration supplied increased from 1 to 5 mM, and the 5 mM MES treatment maintained a pH of 5.6 ± 0.2. In summary, strawberry plants can be grown hydroponically in DWC, provided that nutrient solution pH is adequately managed. The addition of MES buffer provided better pH stability than KHCO3.