Wednesday, November 7, 2007
246-1
Reduction of Cadmium Concentrations in Eggplant (Solanum melongena) by Grafting onto Root Stock Solanum torvum (2).
Tomohito Arao1, Hiroyuki Takeda2, Shinsuke Mori1, Eiji Nishihara3, and Takashi Nakano2. (1) National Institute for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba, Ibaraki, Japan, (2) Niigata Horticultural Research Center, 177 Mano, seirou, Niigata, Japan, (3) Tottori University, 4-101 Koyama-Minami, Tottori, Tottori, Japan
A maximum concentration of 0.05 mg Cd [kg fw]–1 in fruiting vegetables was adopted by Codex Alimentarius Commission. About 7% of 381 samples of eggplant (Solanum melongena) contained Cd concentrations above this limit in a study during 1998–2001 in Japan. Under these circumstances, we urgently need to develop technologies to suppress Cd absorption by crops.
In this study we investigated Cd concentrations in eggplant (S. melongena) grown on different rootstocks in Cd-polluted soil and unpolluted soil. Grafting onto Torubamubiga- (Solanum torvum) and Tonashimu (S. torvum) reduced eggplant fruit Cd concentrations by 63% to 74% in Cd-polluted soil and unpolluted soil compared with grafting onto Daitarou (S. melongena) and Hiranasu (Solanum integrifolium). There were no significant differences in fruit concentrations of any metals except Cd. The average fresh weights of fruits were 82.6 g on Hiranasu (S. integrifolium), 86.0 g on Torubamubiga-(S. torvum), and 88.3 g on Tonashimu(S. torvum). There were no significant differences in average fresh weight of fruits between S. torvum and S. integrifolium rootstocks.
Stem and leaf Cd concentrations of scions Senryou2 (S. melongena) on S. torvum were about 30% of those on S. integrifolium, so Cd translocation from roots to shoots was apparently reduced in grafted plants on S. torvum. Stem and leaf Cd concentrations of S. torvum were also lower than those of Senryou2 (S. melongena) and Daitarou (S. melongena), so Cd translocation from roots to shoots was reduced in self-rooted S. torvum plants also.
In conclusion, we have developed a practical method for reducing the Cd concentration of eggplant fruits by grafting onto S. torvum rootstock. The research also showed that the mechanism of Cd translocation on S. torvum is totally different from that on S. melongena. However, the mechanism responsible for the low Cd translocation characteristic of S. torvum remains unknown.
In this study we investigated Cd concentrations in eggplant (S. melongena) grown on different rootstocks in Cd-polluted soil and unpolluted soil. Grafting onto Torubamubiga- (Solanum torvum) and Tonashimu (S. torvum) reduced eggplant fruit Cd concentrations by 63% to 74% in Cd-polluted soil and unpolluted soil compared with grafting onto Daitarou (S. melongena) and Hiranasu (Solanum integrifolium). There were no significant differences in fruit concentrations of any metals except Cd. The average fresh weights of fruits were 82.6 g on Hiranasu (S. integrifolium), 86.0 g on Torubamubiga-(S. torvum), and 88.3 g on Tonashimu(S. torvum). There were no significant differences in average fresh weight of fruits between S. torvum and S. integrifolium rootstocks.
Stem and leaf Cd concentrations of scions Senryou2 (S. melongena) on S. torvum were about 30% of those on S. integrifolium, so Cd translocation from roots to shoots was apparently reduced in grafted plants on S. torvum. Stem and leaf Cd concentrations of S. torvum were also lower than those of Senryou2 (S. melongena) and Daitarou (S. melongena), so Cd translocation from roots to shoots was reduced in self-rooted S. torvum plants also.
In conclusion, we have developed a practical method for reducing the Cd concentration of eggplant fruits by grafting onto S. torvum rootstock. The research also showed that the mechanism of Cd translocation on S. torvum is totally different from that on S. melongena. However, the mechanism responsible for the low Cd translocation characteristic of S. torvum remains unknown.