Laboratory studies on plants

A review on the effects of high-frequency electromagnetic fields specifically on plants ^[1] describes positive and negative influences, especially on germination and growth, which depend on frequency, modulation, and power flux density as well as plant species and growth stage. Overall, the data available are contradictory and insufficient in order to be able to draw any general conclusions.

Another review on plants ^[2] states that diverse and often contradictory influences of high-frequency electromagnetic fields on the metabolism, gene expression, and growth of plants have been described; these strongly depend on frequency and exposure intensity. The authors propose considering high-frequency fields as a non-harmful environmental factor that can influence plant metabolism.

Another review ^[3] analyses 45 experimental studies on plants from 1996–2016 that were published in peer-reviewed journals. The quality of the exposure was not assessed. Most studies showed an influence of electromagnetic fields on the physiological and morphological parameters of plants. Some species such as maize, mallow, peas, clover, duckweed, tomatoes, onions, and beans proved to be particularly sensitive to fields.

The most recent review paper on effects of high-frequency electromagnetic fields on plants ^[4] promises a critical evaluation of the effects of high-frequency electromagnetic fields on plants but does not mention the selection criteria and the qualitative standards applied. It is clearly shown that the energy of high-frequency fields is not sufficient to directly damage the genetic material. Nevertheless, changes in gene expression and influences on cell division have been observed several times in studies. Effects on the calcium balance and reactive oxygen species are named as mechanisms of action. Epigenetic effects are also suspected. How these effects occur biophysically remains unclear and needs to be further investigated. The problem of dosimetry and exposure determination in plants is also addressed. Because of the large surface area in relation to volume as well as insufficient knowledge of dielectric properties of plants, it is difficult to correctly determine the SAR value. The responses of the plants are described as two-stage; first, there is a rapid response involving gene expression and metabolism. Second, changes in growth may or may not occur. Overall, the effects on plants can be positive or negative and are considered to be rather low compared with other environmental impacts.

Studies from France

A French research group at the University of Angers has been studying the effects of short-term exposure to high-frequency fields on plants for 15 years. In tomatoes, an increased expression of certain messenger substances as well as changes in energy metabolism and gene expression were found after GSM exposure; these can be interpreted as a stress response ^{[5, 6]}. Although such reactions mean a strain on the plants, they are physiologically normal and do not threaten the survival of the plants. The reactions are systemic; this means that the whole plant reacts even if only a few leaves have been exposed ^[7]. This is similar to the reaction to being eaten by pests; the same messenger substances are also involved. In order to observe longer-term effects, the same working group studied roses ^[8]. Existing shoots were not affected by GSM; however, if developing buds were exposed, there was a reduction in growth.

Studies on the genetic material

Gene expression in plant cell cultures (Arabidopsis thaliana) was investigated under the influence of UMTS ^[9]. From the entire genome of the plant, a few genes involved in responses to light have increased expression. The authors do not expect serious physiological consequences based on these results. An Indian research group observed reduced root growth and effects on the genetic material in the roots of onions under the influence of mobile communication fields ^{[10, 11]}. An Indian study on rice in a high-frequency exposure chamber showed a reduced germination rate accompanied by an up-regulation of certain genes and pigments; this was interpreted as a stress response ^[12].

Summary

Overall, most studies on plants show physiological effects of electromagnetic fields. Many of these are contradictory and have not been independently reproduced. The mechanisms of action remain unclear. The effects observed often correspond to a mild stress reaction and are minor compared with other environmental influences. It is necessary to confirm the results and to clarify the underlying mechanisms of action.

References

[1] Jayasanka SMDH, Asaeda T (2014) The significance of microwaves in the environment and its effect on plants. Environmental Reviews 22(3): 220 - 228.

[2] Vian A, Davies E, Gendraud M, Bonnet P (2016) Plant Responses to High Frequency Electromagnetic Fields. Biomed Res Int. 2016, ID 1830262.

[3] Halgamuge MN (2017). Review: Weak radiofrequency radiation exposure from mobile phone radiation on plants. Electromagn Biol Med 36(2): 213-235.

[4] Kaur, S, Vian, A, Chandel, S, Singh, HP, Batish, DR, Kohli, RK (2021). Sensitivity of plants to high frequency electromagnetic radiation: Cellular mechanisms and morphological changes. Reviews in Environmental Science and Bio-Technology.

[5] Vian A, Roux D, Girard S, Bonnet P, Paladian F, Davies E, Ledoigt G (2006) Microwave irradiation affects gene expression in plants. Plant Signal Behav. 1(2): 67 - 70.

[6] Roux D, Faure C, Bonnet P, Girard S, Ledoigt G, Davies E, Gendraud M, Paladian F, Vian A (2008) A possible role for extra-cellular ATP in plant responses to high frequency, low amplitude electromagnetic field. Plant Signal Behav. 3(6): 383 – 385.

[7] Beaubois E, Girard S, Lallechere S, Davies E, Paladian F, Bonnet P, Ledoigt G, Vian A (2007) Intercellular communication in plants: evidence for two rapidly transmitted systemic signals generated in response to electromagnetic field stimulation in tomato. Plant Cell Environ. 30: 834 - 844.

[8] Grémiaux A, Girard S, Guérin V, Lothier J, Baluška F, Davies E, Bonnet P, Vian A (2016) Low-amplitude, high-frequency electromagnetic field exposure causes delayed and reduced growth in Rosa hybrida. J Plant Physiol. 190: 44 – 53.

[9] Engelmann JC, Deeken R, Müller T, Nimtz G, Rob M, Roelfsema G, Hedrich R (2008) Is gene activity in plant cells affected by UMTS-irradiation? A whole genome approach. Adv Appl Bioinform Chem. 1: 71 - 83.

[10] Chandel S, Kaur S, Issa M, Singh HP, Batish DR, Kohli RK (2019). Exposure to mobile phone radiations at 2350 MHz incites cyto- and genotoxic effects in root meristems of Allium cepa. J Environ Health Sci Eng 17(1): 97-104.

[11] Kumar, A, Kaur, S, Chandel, S, Singh, HP, Batish, DR, Kohli, RK (2020). Comparative cyto- and genotoxicity of 900 MHz and 1800 MHz electromagnetic field radiations in root meristems of allium cepa. Ecotoxicol Environ Saf 188: 109786.

[12] Kundu, A, Vangaru, S, Bhattacharyya, S, Mallick, AI, Gupta, B (2021). Electromagnetic irradiation evokes physiological and molecular alterations in rice. Bioelectromagnetics 42(2): 173-185.