Long-Term Gamma Radiation Effect on Functional Traits of <i>Tradescantia Flumnensis</i> L.

Abstract

The effect of radioactivity on the environment, especially on plants, has always been one of the vital researches of radio-ecology. However, long-term irradiated ecosystems are very rare. Occasionally, one special miniature ecological environment object consisted of thorium mineral (Th-232) and Tradescantia flumnensis L. over 10 years is carried out to evaluate the effect of long-term low-radioactivity gamma radiation on herbaceous plant. Several functional features of Tradescantia flumnensis L. are selected and measured with physical measurement (PM), HPGe portable gamma-ray spectrometer (HPGe PGS), wavelength dispersion X-ray fluorescence (WDXRF), and advantage isotope ratio mass spectrometer (AIR-MS). The results show that functional traits varied with the increasing of radiation dose rate. These results also indicate that the plants can adapt to low-intensity gamma radiation (<332.6 nGy•h-1) through adjustment of physical properties. In addition, low-intensity gamma radiation has positive influence on plant's water use efficiency, growth and nutrition acquisition of roots. Restrictions on plant phosphorus demand have also been eased. However, high-intensity gamma radiation (>528.7 nGy•h-1) has exceeded the tolerance of plants, making most functional traits unhealthy or abnormal. This rare case is of great reference significance of setting biological indicators of long-term radiation system.

Plant–microorganism–soil interaction under long-term low-dose ionizing radiation

“…We found that LiP activity has significant positive correlations with radiation intensity, C/N ratio, C%, N%, and abundance of Ectomycorrhizal fungi and Rhizobiales, and plant δ 15 N increase with increasing radiation intensity, which is consistent with the hypothesis of the “symbiotic microbial effect.” In addition, the symbiotic microbial effect can also explain some physiological changes in plants to adapt to long-term ionizing radiation. For example, the plants in the low group improve their damaged nutritional status due to radiation by enhancing the nutrient absorption ability of the root system, which makes the specific root length of the plants in the low group significantly lower than that of the blank group, while the root dry matter proportion is significantly higher than that of the blank group ( Li et al, 2022 ). Moreover, the abundance of Ectomycorrhizal fungi in the high group is 6 times that of the medium group, 13 times that of the low group, and 0 in the blank group.…”

“…In order to cope with the adverse effects of the radiation environment, plants under different radiation intensities have made adaptive changes to the varying radiation intensity, such as reducing specific leaf area, increasing leaf thickness, and shortening plant length ( Li et al, 2022 ). In this case, the plants do not have excess root exudates to stimulate soil microorganisms for nitrogen mineralization.…”

“…In general, plants usually enhance their resistance by stimulating root-driven microbial communities when facing environmental stress and the same is true when subjected to nuclear radiation stress ( Guesmi et al, 2022 ). Recent studies also indicated that under LLR conditions, plants tend to reduce aboveground biomass and invest more organic matter underground, thereby promoting the nutrient acquisition of the root-microbial system and improving the ecosystem’s adaptability to long-term nuclear radiation ( Li et al, 2022 ; Cheng et al, 2023 ). According to previous studies, there are mainly two ways for plants to promote the nutrient acquisition of the root-microbial system, namely the “nitrogen mineralization effect” and the “symbiotic microbial effect,” which will lead to changes in soil carbon and nitrogen cycling and enzyme activity.…”

Soil Microbes and Plant-Associated Microbes in Response to Radioactive Pollution May Indirectly Affect Plants and Insect Herbivores: Evidence for Indirect Field Effects from Chernobyl and Fukushima

“…In Cheng et al (2023) [ 104 ], ectomycorrhizal fungi in soil irradiated by low-dose 232 Th for more than 10 years were positively correlated with radiation intensity. The hyphae of these fungi wrap around plant root cells and form a biomembrane that not only protects plants from pathogens, chemical pollutants [ 136 , 137 ], and radiation but also helps plants absorb soil nutrients, including nitrogen and phosphorus [ 138 ]. Therefore, it is quite conceivable that the growth and defense system of plants are influenced by increasing or decreasing the abundance of plant-associated microbes or the emergence of more toxic pathogens in Chernobyl and Fukushima.…”

The effect of aboveground long-term low-dose ionizing radiation on soil microbial diversity and structure

“…Additionally, ectomycorrhizal fungi can help plants absorb soil nutrients, such as nitrogen and phosphorus (Liu et al, 2022), and are beneficial for carbon fixation (Zak et al, 2019). Thus, ectomycorrhizal fungi improve the nutritional status of plants damaged by radiation (Li et al, 2022), increase the soil C/N ratio, and change the soil microbial diversity and community composition (Zheng and Song, 2022). However, more research is needed to prove that ectomycorrhizal fungi have the function of resisting radiation.…”