Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection
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The Ohio State University / OhioLINK
2019
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1563205720634412 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu15632057206344122021-08-03T07:11:54Z Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection Gillespie, Daniel Patrick Agricultural Chemicals Agricultural Education Agriculture Agricultural Economics Horticulture Plant Pathology hydroponic pH pythium leafy greens nutrient solution herbs basil spinach controlled environment agriculture plant pathology plant physiology horticulture nutrient uptake nutrient concentration In recent years, the increased demand for locally grown produce and outbreaks of E. coli linked to leafy greens has led to hydroponic leafy green production in controlled environments becoming a viable addition to the fresh produce food supply. Prevention of plant pathogen introduction in hydroponics is critical, as effective control agents for root diseases of edible crops are limited and may not be registered for use in greenhouses or indoors. This study examined lowering nutrient solution pH as a new management strategy to mitigate the risk of oomycete root disease incidence without negatively influencing plant growth. Although pH below 5.0 has been shown to negatively affect oomycete pathogen growth and reproduction, hydroponic nutrient solution is typically maintained within pH 5.5-6.5, as plants tend to exhibit growth inhibition outside of this range. Nevertheless, growth inhibition can typically be attributed to pH-dependent factors affecting nutrient uptake and availability, which may be mitigated if precautionary measures are considered. We hypothesized that if plants can be grown in pH below 5.0, the risk of oomycete disease incidence may be reduced. As first steps towards the development of a new nutrient solution management strategy, we determined if adjusting micronutrient concentrations in nutrient solution based on reported availability levels were effective in mitigating nutrient disorders and plant growth inhibition typically experienced at low pH. Basil and spinach plants were grown in deep-water hydroponic systems with pH maintained at 4.0, 4.5, 5.0, or 5.5. Two nutrient solutions (with and without micronutrient adjustments) were applied at each pH level, where concentrations of copper, zinc, manganese, and boron were decreased by one-half and molybdenum concentration was doubled in the adjusted solution. To our surprise, even though most elemental concentrations of leaf tissue decreased with decreasing pH, basil plant growth was not affected by pH for a range of 4.0-5.5 or nutrient solution adjustment. Alternatively, spinach plant growth was significantly reduced in pH below 5.0. Using basil plants, we then examined the efficacy of lowering pH in preventing Pythium infection. Nutrient solution pH was maintained at 4.0 or a conventional range (pH 5.5-6.5) and inoculated with Pythium aphanidermatum zoospores five days subsequent to transplanting. Disease symptomology was almost exclusively limited to pH 5.5-inoculated treatments. In addition, fresh plant mass was significantly reduced in pH 5.5-inoculated treatments. The results of this study indicate that low pH (pH 4.0) can effectively suppress Pythium aphanidermatum disease incidence after zoospore inoculation without influencing basil plant growth. For spinach, further nutrient adjustments or precautionary measures may alleviate growth reductions observed at low pH. These results indicate that low nutrient solution pH is an effective, low cost, and environmentally sustainable root disease management strategy if crops can tolerate continuous exposure to low pH. 2019 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1563205720634412 http://rave.ohiolink.edu/etdc/view?acc_num=osu1563205720634412 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center. |
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NDLTD |
| language |
English |
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NDLTD |
| topic |
Agricultural Chemicals Agricultural Education Agriculture Agricultural Economics Horticulture Plant Pathology hydroponic pH pythium leafy greens nutrient solution herbs basil spinach controlled environment agriculture plant pathology plant physiology horticulture nutrient uptake nutrient concentration |
| spellingShingle |
Agricultural Chemicals Agricultural Education Agriculture Agricultural Economics Horticulture Plant Pathology hydroponic pH pythium leafy greens nutrient solution herbs basil spinach controlled environment agriculture plant pathology plant physiology horticulture nutrient uptake nutrient concentration Gillespie, Daniel Patrick Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| author |
Gillespie, Daniel Patrick |
| author_facet |
Gillespie, Daniel Patrick |
| author_sort |
Gillespie, Daniel Patrick |
| title |
Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| title_short |
Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| title_full |
Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| title_fullStr |
Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| title_full_unstemmed |
Effects of Low Nutrient Solution pH on Hydroponic Leafy Green Plant Growth, NutrientConcentration of Leaf Tissue, and Pythium Zoospore Infection |
| title_sort |
effects of low nutrient solution ph on hydroponic leafy green plant growth, nutrientconcentration of leaf tissue, and pythium zoospore infection |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2019 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1563205720634412 |
| work_keys_str_mv |
AT gillespiedanielpatrick effectsoflownutrientsolutionphonhydroponicleafygreenplantgrowthnutrientconcentrationofleaftissueandpythiumzoosporeinfection |
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1719455850522738688 |