Plant Growth, Germanium Accumulation and Distribution Pattern Under Various Ge-132 and GeO2 Treatment from Cucumber.

To investigate the effect of inorganic (GeO₂) and organic (Ge-132) germanium treatment on cucumber growth and Ge accumulation, growth characteristics and contents of Ge were examined under treatment with various inorganic or organic germanium concentrations (0, 1, 2.5, 5, 7.5, 10, 15 and 20 mg/L on 2 weeks grown seedlings) for 10 days, respectively. On early seedling growth, all treatments of exogenous inorganic GeO₂ significantly inhibited on plant growth characteristics such as root and shoot elongation as well as fresh weight. However, in organic Ge-132 treatment, total plant growth was not much inhibited until 20 mg/L. Total Ge contents in early seedlings with inorganic Ge (GeO₂) treatment were accumulated two times more than those with organic Ge treatment. In addition, Ge was primarily accumulated in the roots (90%) with organic Ge treatments, whereas Ge was primarily accumulated in the shoots (78%) with inorganic Ge treatments, suggesting that organic Ge was hardly moved from root to shoot. For further analysis to see the effect of Ge with different treatment methods (irrigation, spray and irrigation+spray), we treated the inorganic or organic Ge solution (final 10mg/L) for 50 days and then measured growth characteristics of plant and cucumber fruits such as fresh weight and length etc. In inorganic Ge treatment, both irrigation and irrigation+spray treatments significantly inhibited on plant growth, but spray treatment didn’t much inhibited. In organic Ge treatment, all treatment methods didn’t inhibit on plant growth. Ge was highly accumulated as follow. (1) In organic Ge irrigation treatments: Root>Leaf> Fruit> Stem> Petiole; In organic Ge spray treatments: Leaf> Fruit> Stem> Root> Petiole. (2) In inorganic Ge irrigation treatments: Leaf> Stem>Petiole> Fruit> Root; In inorganic Ge spray treatments: Leaf> Fruit> Stem> Petiole> Root. [This work was supported by a  grant from ARPC]