培養液中の亜鉛濃度がトウモロコシの重金属必須微量要素含有量におよぼす影響

抄録

In the present paper, investigations on the content of zinc, iron, manganese, and copper, and uptake and distribution of ⁵⁹Fe and ⁵⁴Mn in maize plant cultured in the nutrient solutions in which zinc concentration was changed in 0, 0.005, 0.05 and 20 ppm were carried out. Results were obtained as follows: 1. Zinc content in each organ of plant grown at the standard plot (0.05 ppm Zn) was greater than that of both the Zn-lacking plot (0 ppm Zn) and slightly Zn-added one (0.005 ppm Zn). Especially, it was the greatest in the roots at the excess plot (20 ppm zn) and also showed heavily at the other organs (Table 1). 2. Iron content in leaf blades, leaf sheaths and stems at both the lacking and slightly Zn-added plots was greater than that of the standard one after tassel-shooting time, and it was the greatest in roots at the excess plot. In the excess plot this element was prevented from translocating for the top when it was accumulated in roots, moreover it was occurred chlorosis in the upper green leaves (Table 2). 3. Manganese content in each organ at the standard plot was less than that of both the lacking and slightly Zn-added ones. This element was the least in each organ at the excess plot, and it was inhibited to be absorbed into the plant at the excess plot (Table 3). 4. Copper content in the leaf blades and stems was few difference among various plots. Its content in the leaf sheaths and roots of the lacking plot was remarkably increased at the tassel shooting time, and in the roots of all plots it was greater than that of other organs (Table 4). 5. Concerning about Fe-Zn ratio at the harvesting time, it was the greatest in the roots at the standard plot. On the other hand, in other organs it was greater at the lacking and slightly zn-added plots, and very smaller at the excess one. Mn-Zn ratio in each organ at both the lacking and slightly Zn-added plots was greater than that of the standard plot, however, it was the smallest at the excess one. Relating to Cu-Zn ratio at the tassel-flowering time, it was very high in the leaf sheaths and roots at the lacking plot. This ratio was found few difference among the standard, the lacking and the slightly Zn-added plots, and especially the lowest at the excess one (Table 5). 6. ⁵⁹Fe distribution in the leaves was the greatest at the standard plot compared to the others. On the other hand, distribution and distributed concentration of this element in the roots were the greatest at the excess plot, however, in the leaves and stems distribution ratio of ⁵⁹Fe was the least (Table 6). 7. ⁵⁴Mn distribution in the leaves was greater at the standard plot than that of the others, and the least at the excess one. This distribution in the stems was great in between at the slightly Zn-added and standard plots, and in the roots was the greatest at the slightly Zn-added one. Distributed concentration of this element was high in the leaves and stems at the lacking plot, and also in the roots at the slightly Zn-added one. That was the lowest in each organ at the excess plot. Distribution ratio of ⁵⁴Mn was the highest in the leaves at the standard plot and in the roots at the slightly Zn-added one, but lower in the stems at each plot (Table 7).