17:15 〜 19:15
[HTT16-P06] Behavior of hazardous elements and nitrogen isotope signatures in soybean (Glycine max (Linn.) Merr.)
キーワード：有害元素、窒素同位体、大豆
Recently, environmental pollution caused by hazardous elements has become a significant concern, and soybeans (Glycine max (Linn.) Merr.), a crop with high global demand, are among those most affected by stress induced by these elements. Major sources of hazardous elements include contaminated soil surrounding abandoned mines, where elevated concentrations of these elements accumulate in plant cells and potentially impair growth. For instance, iron and zinc are essential for soybeans to grow; however, an excessive supply of these elements may impair growth. Investigating the behavior of trace elements during the growth of soybean tissue is essential for assessing the source of environmental pollution. Moreover, understanding nitrogen isotope behavior throughout the development of soybeans serves as a key factor evaluating of its growth.
This study examined the distribution of trace elements and nitrogen isotope signatures in each soybean tissue. For the experiment, three comparison groups were established: Group 1 (non-treated), Group 2 (Fe-treated), and Group 3 (Zn-treated). In the case of Group 2, overexposed to zinc, zinc accumulation was observed in all soybean tissue. In contrast, Group 3, exposed to excessive iron, rarely showed significant iron enrichment. It may be due to the precipitation of iron hydroxides in the cultivation soil, which prevented absorption by the roots. Meanwhile, the accumulation of hazardous elements is typically most pronounced in the pod, suggesting that soybeans absorb these elements from polluted soil through their roots and ultimately sequester them in the pod (Figure 1). In addition, due to the ability of soybean species (i.e., Williams 82) to primarily fix atmospheric nitrogen (δ15N= av. 0‰), the nitrogen isotope ratios of soybean tissue (δ15N= -2.3 to +1.5‰, av. -0.3‰) converged more closely with the atmospheric nitrogen isotope ratio than with that of the cultivation soil (e.g., alkaline granite soil, δ15N= av. 7.7‰). Simultaneously, nitrogen isotope fractionation occurred among soybean tissues, with heavier values observed in the following order: Pod (δ15N= -2.3 ~ +0.2‰, av. -1.2 ‰) < Stem (δ15N= -1.1 ~ +0.6 ‰, av. -0.3‰) < Root (δ15N= -0.5 ~ 0‰, av. -0.3‰) < Seed (δ15N= -0.3 ~ +0.6‰, av. 0.3‰) < Leaf (δ15N= -0.3 ~ +1.5‰, av. +0.3‰). Moreover, a significant variation in the distribution of hazardous elements and nitrogen isotope ratios was observed across different soybean tissues, suggesting that these characteristics may serve as valuable indicators in assessments of environmental pollutant sources.
This study examined the distribution of trace elements and nitrogen isotope signatures in each soybean tissue. For the experiment, three comparison groups were established: Group 1 (non-treated), Group 2 (Fe-treated), and Group 3 (Zn-treated). In the case of Group 2, overexposed to zinc, zinc accumulation was observed in all soybean tissue. In contrast, Group 3, exposed to excessive iron, rarely showed significant iron enrichment. It may be due to the precipitation of iron hydroxides in the cultivation soil, which prevented absorption by the roots. Meanwhile, the accumulation of hazardous elements is typically most pronounced in the pod, suggesting that soybeans absorb these elements from polluted soil through their roots and ultimately sequester them in the pod (Figure 1). In addition, due to the ability of soybean species (i.e., Williams 82) to primarily fix atmospheric nitrogen (δ15N= av. 0‰), the nitrogen isotope ratios of soybean tissue (δ15N= -2.3 to +1.5‰, av. -0.3‰) converged more closely with the atmospheric nitrogen isotope ratio than with that of the cultivation soil (e.g., alkaline granite soil, δ15N= av. 7.7‰). Simultaneously, nitrogen isotope fractionation occurred among soybean tissues, with heavier values observed in the following order: Pod (δ15N= -2.3 ~ +0.2‰, av. -1.2 ‰) < Stem (δ15N= -1.1 ~ +0.6 ‰, av. -0.3‰) < Root (δ15N= -0.5 ~ 0‰, av. -0.3‰) < Seed (δ15N= -0.3 ~ +0.6‰, av. 0.3‰) < Leaf (δ15N= -0.3 ~ +1.5‰, av. +0.3‰). Moreover, a significant variation in the distribution of hazardous elements and nitrogen isotope ratios was observed across different soybean tissues, suggesting that these characteristics may serve as valuable indicators in assessments of environmental pollutant sources.