Elevated CO2 and the Enhancement of Plant Medicinal Properties

By Craig D. Idso -- June 9, 2022

“Over the past quarter-century I have archived a number of such studies on my CO₂ Science website under the topic Health Effects (Carbon Dioxide: Health-Promoting Substances, Medicinal Plants. Read for yourself about this incredible benefit that the world is experiencing as the air’s CO₂ content continues its upward rise. It will give you a whole new perspective on the many benefits of atmospheric CO₂ enrichment.”

Over the past few decades an increasing number of studies have investigated whether or not rising atmospheric CO₂ will alter the amounts and concentrations of various health-promoting substances found in medicinal or “health food” plants.

For example, the research team of AbdElgawad et al. (2021) recently examined “the nutritive values, phytochemicals (i.e., pigments, phenolics, flavonoids, vitamins, mineral profiles and essential oil yields) and antioxidant activities of both caraway sprouts and mature plants.”

Caraway (Carum carvi) is an important medicinal plant. They are cultivated across the globe and used in treating a number of ailments, including diarrhea, asthma, cholera and hypertension. What is more, AbdElgawad et al. note that caraway fruits “have been prescribed in herbal mixtures as a drug for digestive, carminative and lactogenic disorders,” and they are also utilized as “antiallergic, antibacterial, anthelmintic, antifungal, bronchodilator and cholinergic agents.”

In light of these many traditional uses of caraway plants, it should come as no surprise that multiple strategies have been employed to improve its growth and medicinal properties, including CO₂ enrichment. Because rising levels of atmospheric CO₂ typically promote plant photosynthesis and the production of secondary compounds, the twelve-member research team anticipated that elevated CO₂ would also enhance the medicinal properties of caraway.

To explore their hypothesis, AbdElgawad et al. grew caraway in controlled-environment chambers under ambient (400 ppm) or elevated (620 ppm) CO₂ conditions, harvesting the plants after 9 or 45 days (as sprouts or mature plants, respectively). Thereafter, they performed a series of analyses designed to quantify the CO₂-induced differences in plant medicinal properties.

And what did those analyses reveal?

First, as shown in Figure 1, the 220 ppm increase in atmospheric CO₂ enhanced the photosynthesis, chlorophyll content, fresh weight and dry weight of the sprouts by 66%, 50%, 64% and 120%, respectively. Similarly, significant CO₂-induced enhancements in these four parameters were also observed in the mature plants (40%, 44%, 48% and 29% for photosynthesis, chlorophyll content, fresh weight and dry weight, again respectively).

AbdElgawad et al., further report that elevated CO₂ significantly increased the production of carbohydrates, proteins, fats and crude fibers in caraway, as well as organic and amino acids, regardless of growth stage (sprout or mature plants). Higher CO₂ also enhanced plant mineral content, vitamins and phenolics, as well as antioxidant and antibacterial activities.

Commenting on these several findings, the authors state the obvious: “overall, elevated CO₂ provoked changes in the phytochemical contents of caraway plants, particularly at the sprouting stage and, hence, improved their nutritive and health-promoting properties.” And they are not alone in this overall assessment. Many other studies conducted on a host of other plants have reported CO₂-induced enhancements of substances known to be effective at fighting cancers, diseases and numerous other medical maladies.

Over the past quarter-century I have archived a number of such studies on my CO₂ Science website under the topic Health Effects (Carbon Dioxide: Health-Promoting Substances, Medicinal Plants). Click the link and read for yourself about this incredible benefit that the world is experiencing as the air’s CO₂ content continues its upward rise. It will give you a whole new perspective on the many benefits of atmospheric CO₂ enrichment.

Figure 1. Fresh weight (FW) (mg/g FW), dry weight (DW) (mg/g DW), photosynthesis (µmol CO₂ m^-m s^-s), and pigments content (chlorophyll a + b) (mg/g FW) of caraway sprouts and mature plants grown under control (Cont., 400 ppm) and elevated (eCO₂, 620 ppm) concentrations of atmospheric CO₂. Data represent means of at least 3 replicates ± standard deviations. Different small letter superscripts (a, b, c and d) within a row indicate significant differences between control and eCO₂-samples. One-way analysis of variance (ANOVA) was performed. Tukey’s test was used as the post-hoc test for the separation of means (p < 0.05). The percentages in red text indicate the percent change due to CO₂ for a given parameter at either the sprout or mature stage. Source: AbdElgawad et al. (2021).

Reference

AbdElgawad, H., Okla, M.K., Al-amri, S.S., AL-Hashimi, A., Al-Qahtani, W.H., Al-Qahtani, S.M., Abbas, Z.K., Al-Harbi, N.A., Algafar, A.A., Almuhayawi, M.S., Selim, S. and Abdel-Mawgoud, M. Effect of elevated CO₂ on biomolecules’ accumulation in caraway (Carum carvi L.) plants at different developmental stages. Plants 2021, 10, 2434.