Location: Application Technology Research
Title: Development of a pH management protocol for strawberry mother plants grown in deep water cultureAuthor
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Yafuso, Erin |
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Boldt, Jennifer |
Submitted to: HortScience
Publication Type: Abstract Only Publication Acceptance Date: 6/3/2024 Publication Date: 10/21/2024 Citation: Yafuso, E.J., Boldt, J.K. 2024. Development of a pH management protocol for strawberry mother plants grown in deep water culture. HortScience. 59(9S):S492 (Abstr.). DOI: https://doi.org/10.21273/HORTSCI.59.9S.S1 Interpretive Summary: Technical Abstract: Maintaining a target pH range is important for root zone management and overall plant growth and quality. Commercial soilless substrates often contain liming amendments to increase initial substrate pH to between 5.5 and 6.2. Hydroponic nutrient solutions are less-well buffered than soilless substrates and can experience pH drift in the absence of frequent monitoring and adjustment. Hydroponic deep water culture (DWC) was explored for strawberry (Fragaria × ananassa) research studies, to more-easily collect root growth parameters and root samples for elemental analysis, compared to soilless substrate culture. However, an effective strategy for pH management needed to be developed. The objective of this study was to develop a protocol for growing strawberry mother plants hydroponically. First, three hydroponic systems (drip-irrigated coarse perlite, drip-irrigated sand, and DWC) were compared to a peat-based soilless substrate control. Plants received a modified strawberry nutrient solution (Yamazaki) at a nitrogen (N) concentration of 100 mg·L-1. Plants grew similarly across the four growing systems. Deep water culture provided the easiest access to clean roots; however, root zone pH decreased <4.0 due to a lack of buffering capacity in the nutrient solution. Next, to address this issue of low pH, different nitrate to ammonium ratios (NO3- : NH4+), ranging from 0:100 to 100:0, were evaluated and potassium bicarbonate (KHCO3) was added to the nutrient solution as a buffer. Nutrient solution pH remained in the target range for only the 100% NO3- treatment. Nutrient solution pH decreased in all treatments containing NH4+, by approximately 1.5 pH units every two to three days. Therefore, a final study evaluated the efficacy of 2(N-Morpholino)ethanesulfonic acid (MES) as an alternative nutrient solution buffer. Using a 60:40 NO3- : NH4+ nutrient solution, 1, 3, and 5 mM MES were evaluated. Initially, 3 mM of MES provided adequate buffering of the nutrient solution and pH was 5.5 ± 0.1 (± SE). However, after 2 weeks, as plants grew larger, a higher concentration of MES was required to maintain the target pH range. Throughout the study, 5 mM of MES maintained a nutrient solution pH of 5.6 ± 0.2. The cost of adding 5 mM MES is approximately 50 times more expensive than adding 2 mM KHCO3 as a nutrient solution buffer, which should be factored in when growing strawberry mother plants in DWC. |