The difference between the micronutrients content of seedling's root and root hair in several plant species

It was reported in soybean that the content of Fe and Co microelements of the root hair invaded by rhizobium during the process of nodule formation was higher than that of the root. To confirm this point, a supplementary experiment was carried out using several applicable plants, soybeans, lupine, pea, corn and pumpkin. Root hair was separated in liquid nitrogen from the roots of those seedlings. The separated root hair of 20 mg, or the residual root of 200 mg was digested in a microwave wet digestion device of closed system by using hydrogen peroxide and nitric acid. After wet-digestion, the content of micronutrients (Mn, Fe, Co, Ni, Cu and Zn) was measured by using a furnace atomic absorption spectrometer. This result indicates that micronutrients except for Co could be measured in a small amount of about 20 mg. Fe content was higher in root hair than in root irrespective of a monocotyledonous, a dicotyledonous, a leguminous or a non-leguminous plant. In seedlings, it became clear that most of the Fe storage in seed was accumulated in the root hair. Mo was similarly accumulated in root hair and root of soybeans and pumpkin. In corn, Mo content in root hair was low in comparison with that of root. In other words, the Mo content in root hair of dicotyledonous plants was higher than that of monocotyledonous plants. There was no great difference in the content of Mn, Zn and Cu between root and root hair and among plant species. From these results, it appeared that the micronutrients stocked in seed of leguminous plants might be transferred to the root hair. Moreover, the accumulation of some peculiar element (Ca, Co and Fe) known in root hair could be guessed to be related to an active absorption from nutrient solution during germination.