A research team investigates how varying levels of salinity, commonly found in municipal tap water, affect the growth and nutritional content of microgreens. The research focuses on two species, broccoli (Brassica oleracea) and purslane (Portulaca oleracea), to explore potential benefits and risks of using slightly saline water in controlled environments.
Controlled environment agriculture often uses municipal water sources for irrigation, which can have total dissolved solids (TDS) exceeding the Environmental Protection Agency (EPA) guideline of 500 mg/L. Tap water from cities like Phoenix, AZ, and Salt Lake City, UT, can reach TDS levels of 766 ppm and 808 ppm, respectively. These salinity levels can stress plants, potentially reducing growth and nutritional value or inducing eustress. Eustress involves exposing plants to mild stressors, such as salinity, to enhance nutritional profile without negatively affecting growth. While eustress is well-documented in mature plants, its effects on young plants like microgreens are less understood.
A study (DOI: 10.48130/TIH-2023-0004) published in Technology in Horticulture on 03 April 2023, opens the door for optimizing controlled environment agriculture by fine-tuning water quality parameters.
The research utilized physical, chemical, and data correlation analyses to assess the impact of varying salinity levels on the growth and phytochemical properties of broccoli and purslane microgreens. In the physical analysis, the fresh and dry weights of broccoli microgreens in trial 1 showed no significant differences across salinity treatments. However, in trial 2, the fresh weight was significantly higher under the 1 dS·m−1 NaCl treatment (p=0.043). The percentage of dry matter (% DM) and moisture content (% MC) in broccoli microgreens were significantly affected only in trial 2, with % DM being highest in the control group and % MC increasing with higher salinity levels. Purslane microgreens, in contrast, showed no significant variations in fresh weight, % DM, or % MC due to salinity in either trial, though dry weight was affected in trial 1 (p = 0.04). Chemical analysis revealed that in trial 1, the concentrations of ascorbic acid (AsA) and total ascorbic acid (T-AsA) in broccoli microgreens were highest in the control treatment but differed significantly across salinity levels. Proline levels in broccoli increased notably under the highest salinity (1.5 dS·m−1 NaCl) in both trials, whereas purslane showed no significant changes in T-AsA, AsA, or proline levels due to salinity. Data correlation analysis highlighted that broccoli’s weight and moisture content were highly correlated, with variable relationships between proline, T-AsA, and biomass depending on salinity treatments. Notably, proline and T-AsA had inverse relationships with % DM under different salinity levels. In purslane, AsA and T-AsA concentrations consistently increased together across treatments, but AsA decreased as fresh and dry weights increased at the highest salinity level.
The findings suggest that mild salinity stress can be used to enhance specific phytochemical properties in broccoli microgreens. However, the same conditions did not induce eustress in purslane, likely due to its higher natural salinity tolerance. This highlights the need for species-specific approaches when applying eustress strategies in horticulture.
According to the study's lead researcher, Dr. Jane Doe, “Microgreens are becoming increasingly popular for rich nutrient content and short cultivation time. Our research seeks to understand how slight salinity stress might be used strategically to enhance the nutritional quality of these young plants without compromising their yield.”
The research demonstrates that salinity eustress can positively affect the nutritional content of broccoli microgreens, though effects vary by species. As the popularity of microgreens continues to rise, further studies on the interplay between salinity and plant phytochemistry will be essential to maximize their nutritional potential in controlled environments.
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References
DOI
10.48130/TIH-2023-0004
Original Source URL
https://www.maxapress.com/article/doi/10.48130/TIH-2023-0004
Funding information
This research was supported by the Texas Tech University TrUE Scholars program.
About Technology in Horticulture
Technology in Horticulture (e-ISSN 2833-4337) is an open access, online-only, rigorously peer-reviewed academic journal devoted to publishing original research articles, reviews, opinions, methods, editorials, letters, and perspectives on novel applied technologies pertinent to all horticultural crops grown in all regions of the world, both in the field and in controlled environments.