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| Fig. 1: Chernobyl in 2016, lush with green trees and plants, but no people. (Source: Wikimedia Commons) |
How much radiation can plants survive? This question is important to agriculture, the nuclear energy industry, human space travel, and more. Long term space travel will require the cultivation of food, so understanding the effects of radiation on plants is important. The upcoming growth of nuclear energy for electricity will have consequences for the agriculture industry that must be understood in the context of how plants respond to radiation.
Looking at recent pictures of the disaster site around Chernobyl, such as Fig. 1, it is clear that plants can survive radiation. But the questions of how much radiation, and why plants can withstand higher doses than humans, are more complex. How long does it take for plants to be affected by radiation? Does it matter whether it is chronic or acute radiation? How resilient are plants to radiation poisoning?
Ionizing radiation is damaging because it affects the way cells reproduce. However, this process is fundamentally different in plants than animals, leading to different responses to radiation. Understanding how radiation damages cells and how plant biology works is necessary to answering the question of how much radiation plants can withstand. [1]
Plants cannot move. Thus, they must adapt to their environment with more versatility than humans. This has resulted in almost all plant cells being able to reproduce, unlike animals, who have special reproductive cells. Specific plant cells can undergo a process called dedifferentiation, where they revert to a less specialized state of cell allowing them to reproduce. Further, plants have no dedicated germline, which limits the multi-generational effects of ionizing radiation [2]. This creates a much higher resilience and resistance to negative effects from radiation. [3] Further, plants get energy from photosynthesis and therefore have higher levels of free radicals from photolysis. This means they have higher levels of antioxidants than animals, protecting them from radiation. [4] In addition, plant growth is modular, rather than centralized, and plant cells have rigid cell walls, so cells cannot metastasize in the same way as humans, protecting them from cancer. [3,4]
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| Fig. 2: The hierarchical effects of ionizing radiation on plants, from individual plants to the plant population. Image source: M. Mandyam, after Caplin and Willey. [2] |
In this section, we examine how different plants respond to ionizing radiation through experiment. We see that while radiation effects distinct plants differently, they all seem to do better than humans, who can only survive about 4 Gy. [5]
For example, quinoa increases in growth rate and biomass under low dose radiation, about 50 Gy. Under higher radiation doses, including up to 200 Gy, quinoa survives but has a lower growth rate. [6] This counterintuitive result could be due to mutations benefiting the growth of quinoa; quinoa is a plant that excels at high elevations with high UV radiation from the sun, so may have adapted to do better under radiation.
Rice plants are damaged by ionizing radiation, but often can still survive. It was found that rice plants continued growing under both chronic and acute radiation at 100, 200, and 300 Gy, albeit at slower rates. The photosynthetic efficiency and plant growth rate were severely negatively affected by acute radiation, and reproduction was harmed by chronic radiation. However, none of the doses were enough to kill the rice plants or completely stop reproduction. [7]
Lettuce was also found to have increased growth parameters when irradiated with 30 Gy or less. At 30-70 Gy, the growth rate decreased, but again, it did not stop. This confirms the finding that some plants, including lettuce, have stimulated growth from low doses of radiation. [8]
In general, trees do not fare well under ionizing radiation. They tend to have increased rates of morphological defects, such as deletions of the leader shoot. This is possibly due to the increased lifetime of trees which simply provides more opportunities for the radiation to negatively affect the cells of the plant. [4] It is difficult to run controlled studies on trees because they take much longer to mature than agricultural plants like rice, so researchers must rely on trees exposed to radiation from nuclear disasters.
The numbers do not tell the whole story. Radiation has many effects beyond a specific plant's survival. The effects of radiation can trickle down from plant, to population, as seen in Fig. 2. This hierarchy displays how plants respond to environmental stresses on land. As a plant adapts through generations, it may be responding to effects from ionizing radiation that were not incident on the plant itself. [2]
Plants can typically survive much more radiation than animals. They can survive at least 30 Gy, over 6x what humans can survive, and some can survive over 200 Gy, which is 50x what humans can survive. However, the effects of ionizing radiation vary widely by plant, both in terms of the amount of radiation that can be survived, and the effects of such radiation. Some amounts of radiation spur plant growth. Flowers and conifers tend to be the least resilient to radiation. Ionizing radiation has complex consequences on plant reproduction and plant populations which are not fully understood. Most research on radiation in plants has been done either with acute, high doses in laboratories, or observing low levels of chronic radiation from nuclear disasters. This leaves many gaps in the field that are important to target for space exploration, agriculture, and the nuclear energy industry.
© Maya Mandyam. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] S. Thompson, "How Plants Reclaimed Chernobyl's Poisoned Land," BBC, 1 Jul 19.
[2] N. Caplin and N. Willey, "Ionizing Radiation, Higher Plants, and Radioprotection: From Acute High Doses to Chronic Low Doses," Front. Plant Sci. 9, 847 (2018).
[3] S. Geras'kin, "Plant Adaptation to Ionizing Radiation: Mechanisms and Patterns," Sci. Total Environ. 916, 170201 (2024).
[4] Y. Watanabe et al., "Morphological Defects in Native Japanese Fir Trees Around the Fukushima Daiichi Nuclear Power Plant," Sci. Rep. 5, 13232 (2015).
[5] C. C. Lushbaugh, S. A. Fry, and R. C. Ricks, "Nuclear Reactor Accidents: Preparedness and Medical Consequences," Br. J. Radiol. 60, 1189 (1987).
[6] K. E. Song et al., "Hormesis Effects of Gamma Radiation on Growth of Quinoa (Chenopodium quinoa)," Int. J. Radiat. Biology 97, 906 (2021).
[7] H.-I. Choi et al., "Effects of Acute and Chronic Gamma Irradiation on the Cell Biology and Physiology of Rice Plants," Plants 10, 4439 (2021).
[8] D. Marcu, V. Cristea and L. Daraban, "Dose-Dependent Effects of Gamma Radiation on Lettuce (Lactuca sativa var. capitata) Seedlings," Int. J. Radiat. Biol 89, 219 (2012).
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