Seong Han Lee

Physiological and biochemical traits of different water and light intensities on cork oak (Quercus suber L.) seedlings

The present study was conducted to assess the impacts of different water and light intensities on the physiological and the biochemical aspects of cork oak (Quercus suber L.) seedlings from acorns collected from Tabarka (Northern Tunisia). The experiments were divided into two treatments: Water stress (well-watered: 25 to 35%, moderate drought stress: 15 to 20%, and severe drought stress: 7 to 10%) and light intensity stress (full sunlight: 100% of full sunlight, 1,200 μmol m -2 s -1 , moderate sunlight: 65 to 70% of full sunlight, 800 μmol m -2 s -1 , low sunlight: 20 to 25% of full sunlight, 300 μmol m -2 s -1 , and extremely low sunlight: 3 to 4% of full sunlight, 40 μmol m -2 s -1 ). Proline accumulation was higher in the severe drought stress and extremely low sunlight compared with other water and light intensity levels. Total nitrogen concentration (T-N) on a dry mass basis was significantly higher in seedlings grown in the low sunlight and the extremely low sunlight than in the full sunlight and the moderate sunlight. The photosynthetic rate (PN), the stomatal conductance (Gs), and the transpiration rate (Tr) of the seedlings of Q. suber showed similar tendencies both in the three drought water levels and in the four light intensity levels during treatment periods, while the water use efficiency (WUE) was not significantly different among each treatment. PN for the full sunlight was lower at a maximum value (≈ 8.2 μmol m -2 s 1 ) compared with the moderate sunlight. On the other hand, the maximum photosynthesis was higher for the moderate sunlight seedlings when compared to the full sunlight seedlings, although the leaf from the full sunlight was light saturated at near 1000 μmol m -2 s -1 compared with the moderate sunlight. In all treatments, both maximum Rubisco activity and electron transport capacity expressed from the A/Ci response curves (Vcmax and Jmax) increased with well-watered (WW) and the full sunlight (FL). Under water treatments, the slopes and explained variances for severe drought stress were considerably lower than those under WW and moderate drought stress (MDS) at 60 and 90 days of treatment. In conclusion, the different water and light intensity levels affected the physiological and the biochemical parameters of Q. suber. The lower assimilation rate was associated with lower stomatal conductance, the nitrogen allocation to photosynthetic functions, maximal Rubisco activity (Vcmax) and electron transport rate (Jmax).

Comparison in disease development and gas exchange rate of Pinus densiflora seedlings artificially inoculated with Bursaphelenchus xylophilus and B. mucronatus

Four‐year‐old seedlings of Pinus densiflora were inoculated with a suspension of B. xylophilus, or B. mucronatus adjusted to 3,000 nematodes per 50 μL sterilized distilled water in a greenhouse on July 21, 2008 to evaluate initial symptom development and the changes of gas exchange rate. B. xylophilus and B. mucronatus were distinguished by four restriction enzymes except Rsa I, and the result of ITS‐RFLP of B. xylophilus used in this experiment was completely matched to that of pine wood nematode reported previously. Needle dehydration and subsequent yellowing were observed in all seedlings inoculated with B. xylophilus isolate while the appearance of the seedlings was normal in all seedlings inoculated with B. mucronatus and control. Needle dehydration was observed in most seedlings inoculated with B. xylophilus between 2 and 3 weeks after inoculation. In seedlings inoculated with B. xylophilus, continuous decrease in photosynthetic rate was observed after 6 days of inoculation. Photosynthetic rate decreased more markedly after 12 days of inoculation when external symptoms appeared in most seedlings, and ceased almost completely 19 days after inoculation. Photosynthetic decline in seedlings inoculated with B. mucronatus was only observed at 19 days after inoculation but recovered above control level after 25 days of inoculation. We found that disease development and the changes of gas exchange rate in the seedlings of Pinus densiflora inoculated with B. xylophilus were not observed on those inoculated with B. mucronatus.

Evaluation of Bioenergy Potential and Relative Impact of Microclimate Conditions on Fuel Pellets Production and Carbon Storage of Short-Rotation Coppices (Populus uramericana) in Reclaimed Land, South Korea: Three-Year Monitoring

It is required to manage sustainable Short-Rotation Coppices (SRCs) as an important role 17 on carbon sink and bioenergy output, because most of SRCs were established in reclaimed land in 18 South Korea. However, during the last three years, growth pattern of the SRCs was remarkably 19 changed with soil condition. This study aimed to identify the sustainability of SRCs on carbon 20 storage, biomass and fuel pellet production, monitoring the neighboring vegetation of SRCs by 21 land-use exchange, physiological change of poplar on seasonal trend, and to evaluate whether 22 poplar is suitable for making wood pellets. The calculated biomass yield per area of poplar grown 23 was 103.07 Mg per total area (55.6 ha), and volumes of carbon dioxide absorption was estimated to 24 be 330 Mg CO2. Wood pellet quality based on the criteria scored third grade, indicating that poplar 25 is suitable for manufacturing fuel pellets. Moreover, monitoring of the flora distribution in SRCs 26 revealed changes in species composition. As halophyte was increased during drought, soil organic 27 matter, net growth and total chlorophyll of poplar were significantly decreased. These findings 28 indicated that photosynthesis and growth pattern of SRCs may be negatively affected by 29 microclimate and will provide valuable information for effective management of SRCs. 30