Du Hyun Kim

Cadmium and zinc interaction and phytoremediation potential of seven Salix caprea clones

We evaluated the interaction between Cd and Zn in the bioaccumulation of seven clones of Salix caprea, which were exposed both to Cd and Zn alone and to a combination of Cd and Zn. Cadmium (Cd) and Zn concentration in the four treatments were administered in the following order: root > leaf > stem, and obvious differences were noted among the treatments and clones. The leaf Cd concentration of clone BH2 and stem Cd concentration of clone BH5 in the combined Cd and Zn treatment group was increased by 62% and 110%, respectively, relative of that of the Cd alone treatment group. On the other hand, the leaf and stem Zn concentration of clone BH8 in the combined Cd and Zn treatment group was reduced by 66% and 61%, respectively, relative to that of the Zn alone treatment group. Translocation of Cd and Zn from the root was higher in the leaf than in the stem, and the combined Cd and Zn treatment stimulated the translocation of Cd from the root to the leaf and stem, whereas it suppressed the translocation of Zn from the root to the leaf and stem. Therefore, the interaction effects were considered strongly synergistic with Cd in the presence of Zn, but proved antagonistic to Zn in the presence of Cd in the combined Cd and Zn treatment group. The phytoremediation potentials of the seven clones, which were estimated from standard indices of Cd and Zn concentration in Cd and Zn alone and the combined Cd and Zn treatment groups, were highest in clone BH3, and lowest in clone BH5. Therefore, we recognize S. caprea as an appropriate material for phytoremediation, and this is particularly the case with clone BH3. However, further research will be required to evaluate the effects of Cd and Zn on the physiological changes as well as tolerance mechanisms against metal toxicity in S. caprea clones.

Direct Effects on Seed Germination of 17 Tree Species under Elevated Temperature and CO2 Conditions

Abstract Effects on seed germination characteristics of 17 tree species were investigated under elevated temperature and CO2. Seeds of 5 needle-leaf and 12 broad-leaf species were germinated under four conditions: 24°C + 400 μmol CO2 mol air–1, 24°C + 750 μmol CO2 mol air–1, 27°C + 400 μmol CO2 mol air–1, and 27°C + 750 μmol CO2 mol air–1. The elevated temperature and CO2 affected germination percent (GP) of 7 tree species seeds.GPs of Pinus densiflora, P. thunbergii, Betula ermanii, and Maackia amurensisseeds were affected by the elevated temperature, while only that of P.jezoensis seed was influenced by the elevated CO2. GPs of Malus baccata and Zelkova serrataseeds were influenced by both the elevated temperature and CO2. In addition, the elevated temperature and CO2also affected mean germination time (MGT) of 12 tree species seeds. Particularly, MGTs of P. thunbergii and Rhododendron tschonoskii seeds were influenced by both factors. In conclusion, elevated temperature and CO2 affected seed germination characteristics, which were reflected by significant differences among tree species. Specifically, these two factors exerted stronger influence on germination pattern such as MGT rather than seed germination percent.

Effects of cryoprotectants and post-storage priming on seed germination of sugi (Cryptomeria japonica D. Don).

Abstract Among the ex situ methods for the preservation of forest tree germplasm, conventional seed banking is considered the most efficient method for the majority of species whilst cryopreservation has an important role in long-term conservation. The influence of cryoprotectants prior to liquid nitrogen (LN) storage and osmoconditioning priming treatments with polyethylene glycol (PEG) after LN storage were evaluated for germination (%), germination value (GV) and mean germination time (MGT) in seeds of Cryptomeria japonica. Sugi seeds were treated with two cryoprotectants (DMSO and PVS2) before immersion into LN and stored for three days. Although the C. japonica seeds survived liquid nitrogen treatment, their viability was reduced from 25% of intact seeds to 17% in LN. The seeds treated with 35% DMSO showed higher germination (28%) as compared with seeds directly-immersed in LN without cryoprotectant treatment. In contrast, PVS2 pretreated seeds decreased germination (13%). Two concentrations of PEG priming treatments were carried out. Osmoconditioning treatment in -0.4 MPa PEG solution after removal from LN enhanced the subsequent germination percentage and decreased MGT. PEG treatments at both -0.4 and -1.2MPa to PVS2 pretreated seeds before cryopreservation partially alleviated the negative effect of PVS2. DMSO pretreated seeds immersed into LN and treated with -0.4MPa PEG maintained the 28% of germination obtained in the control conditions and reduced the mean germination time (MGT). It can therefore be summarized that pretreatment with 35% DMSO was suitable for the cryopreservation of C. japonica seeds whilst the PEG priming treatment circumvented imbibitional damage after LN exposure.