Dongsu Choi

Effect of ectomycorrhizal infection on growth and photosynthetic characteristics of Pinus densiflora seedlings grown under elevated CO2 concentrations

The effect of ectomycorrhizal Pisolithus tinctorius (Pt) infection was studied on the growth and photosynthetic characteristics of Pinus densiflora seedlings grown at ambient (360 µmol mol−1, AC) and elevated (720 µmol mol−1, EC) CO2 concentrations. After 18 weeks, Pt inoculation had led to significantly increased dry mass and stem diameter of P. densiflora at both CO2 concentrations, relative to non-inoculated seedlings. Moreover, EC significantly increased the ectomycorrhizal development. The phosphate content in needles inoculated with Pt was about three times higher than without inoculation at both CO2 concentrations. The PAR saturated net photosynthetic rates (Psat) of P. densiflora inoculated with Pt were clearly higher than for control seedlings at both CO2 concentrations, and the maximum net photosynthetic rate (PN) at saturated CO2 concentration (Pmax) was higher than in controls. Moreover, the carboxylation efficiency (CE) and RuBP regeneration rate of the PN/Ci curve for P. densiflora inoculated with Pt were significantly higher than for non-inoculated seedlings at both CO2 concentrations, especially at EC. The water use efficiency (WUE) of seedlings inoculated with Pt grown at EC was significantly raised. Allocation of photosynthates to roots was greater in Pt inoculated pine seedlings, because of the enhanced activity of ectomycorrhiza associated with seedlings at EC. Moreover, PN of non-inoculated seedlings grown for 18 weeks at EC tended to be down regulated; in contrast, Pt inoculated seedlings showed no down-regulation at EC. The activity of ectomycorrhiza may therefore be enhanced physiological function related to water and phosphate absorption in P. densiflora seedlings at EC.

Microbial biomass and activity along a natural pH gradient in forest soils in a karst region of the upper Yangtze River, China

Mountain closure, considered an effective and economic measure for natural restoration of degraded forest ecosystems, has been widely carried out in the karst region of southwest China. The aim of this study was to evaluate microbial aspects of soil quality after mountain closure by analyzing soil microbial biomass, basal respiration, metabolic quotient, and relationships with basic chemical properties in Guizhou Province, a karst region of the upper Yangtze River. Soil quality was considered poor from the low levels of microbial biomass carbon (MBC), nitrogen (MBN), and microbial quotient (MBC/total C and MBN/total N), but high metabolic quotient (qCO2). Soil pH, showing marked variation from 4.1 to 7.9 in this karst region, was proved to significantly affect soil microbial biomass and activity. Soil microbial biomass, microbial quotient, and soil basal respiration declined significantly with decreasing soil pH, while qCO2 showed an apparently increasing, but not statistically significant, trend. The changes in microbial biomass and activity following the change in soil pH could possibly be because of a change in soil microbial composition, and more detailed research is necessary. Compared with soil pH, soil organic matter content was another, more important, factor that directly restricted microbial growth because of the serious loss as a result of disturbance. As a practical application based on microbial aspects, introduction of some N-fixing tree species may be an active and effective measure to improve soil fertility and thus to accelerate restoration of the forest ecosystem in the karst region.

Comparison of growth characteristics and tolerance to serpentine soil of three ectomycorrhizal spruce seedlings in northern Japan

Picea glehnii is distributed widely on serpentine soils in northern Japan. Serpentine soil is characterised by the presence of heavy metals (Ni, Cr) and excessive Mg; these elements often suppress plant growth. We have examined the tolerance to serpentine soil and its effects on growth of P. glehnii, P. jezoensis (distributed in the same region) and P. abies (planted for timber production).The dry mass of each organ was not reduced in P. glehnii planted in serpentine soil contained nursery (serpentine nursery). In contrast, growth of P. jezoensis and P. abies was suppressed. Concentrations of Ni and Mg in needles and roots of P. glehnii planted in serpentine nursery were the lowest of the three species. Moreover, the photosynthetic rate of P. glehnii planted in the serpentine nursery was not reduced. P. glehnii has high capability to maintain low concentration of Ni, and ectomycorrhizal symbiosis may have a positive effect to excluding Ni. As a result, P. glehnii has a high tolerance against Ni toxicity, and its photosynthetic capacity is not suppressed by accumulation of Ni.

The growth of Larix gmelinii seedlings as affected by charcoal produced at two different temperatures

Fires burn forest with spatially heterogeneous intensity and charcoals generated at various temperatures during fires exhibit variable physical and chemical characteristics. These variable properties of charcoal may, in turn, influence germination and growth of tree seedlings. To examine the effects of different charcoal properties on the growth of Gmelin larch (Larix gmelinii) seedlings, we conducted an experiment with larch-branch-derived charcoals produced at 400°C (low charcoal) and 800°C (high charcoal); charcoal was combined with sand at three different rates (5%, 20% and 50%, v/v charcoal in sand). The high charcoal had no significant effects on any measured property while the low charcoal application stimulated growth and the effect increased with the addition rate. The low charcoal application resulted in the greater available P content, a lower N/P in needles and the greater growth of seedlings than high charcoal application. The growth of seedlings was not affected by the application of the high charcoal at any rate probably because the high charcoal inhibited the seedling growth due to its high pH. These results indicate that charcoal produced at different temperatures during forest fires can affect the growth of Gmelin larch seedlings differently.

The Role of Ectomycorrhiza in Boreal Forest Ecosystem

The ectomycorrhizal fungi (ECM fungi) are both abundant and widespread in boreal forests. Host plant provides the assimilated carbon to the infecting ECM fungi. Many studies indicate that at most 10-30% of the assimilated carbon by the host plant photosynthesis may be used by the fungal partner for the production and sustenance of its external biomass (Smith and Read 1997). On the other hand, ECM fungi exude extracellular enzymes that are able to break down complex organic substances and consequently transmit the inorganic nutrients to their hosts. Such ECM activity results in greater plant growth under severe environmental conditions of the boreal forests (Read 1991; Chalot and Brun 1998). Tree seedlings infected with ECM can significantly improve their growth when compared with nonmycorrhizal seedlings.

Characteristics of 137Cs accumulation by Quercus serrata seedlings infected with ectomycorrhizal fungi

ABSTRACT To study the effects of inoculation with ectomycorrhizal fungi on the accumulation and distribution of radiocesium (137Cs) in different plant organs (leaves, stems and roots), we measured the uptake and internal distribution of 137Cs by ectomycorrhizal and non-ectomycorrhizal Quercus serrata seedlings in contaminated forest soil. Contamination was a result of the Fukushima Dai-ichi nuclear Power Plant accident. We also estimated the transfer factor (TF), photosynthetic rate and growth of Q. serrata seedlings during the study period, which lasted a full year. The seedlings were grown in plastic pots under field conditions. The soils used in this study had been contaminated with 7200 Bq kg−1 dm of 137Cs at Fukushima in 2011. The concentration of 137Cs in the plant organs varied between 148, 252 and 294 Bq kg−1 dm in the non-ectomycorrhizal treatment regime for stems, leaves and roots, respectively, and was 47, 69 and 219 Bq kg−1 dm in the ectomycorrhizal treatment regime. The TF was significantly lower (P < 0.01) in the ectomycorrhizal treatment regime EC, and apparent quantum yield (α) and maximum photosynthetic rate at light saturation (Pmax) was significantly higher (P < 0.01), although the growth parameters (stem diameter, height and dry mass) did not differ significantly.

The Effect of UV-B Irradiation and Far-red Light Reduction on the Growth of Laurus nobilis in Indoor

실내 광환경은 자연 상태와 달라 실내 조경 식물의 생장 및 생리활성에 영향을 줄 것으로 생각된다.본 연구는 광질(光質)이 월계수의 생장 및 생리활성에 미치는 영향을 평가하기 위해 실시하였다. 월계수 묘목은 4개의 다른 광원 처리구(control, +UV, -FR, +UV-FR 처리구)에서 180일 동안 생육시켰다. 자외선 추가 처리구(+UV)에서 생육한 월계수는 건중량 및 잎 면적이 감소되었지만, 잎 두께 및 잎내 자외선 흡수 물질의 함유량은 증가했다. 반면, 원적외선 차단 처리구(-FR)에서 생육한 월계수는 큰 변화를 나타내지 않았다. 하지만, 자외선 추가 및 원적외선 차단 처리구(+UV-FR)에서 생육한 월계수는 신장생장 및 광합성 속도가 유의적으로 저하했다(P 【The main purpose of this research is to evaluate the effect of light quality on the growth and physiological activities of Laurus nobilis plants growing indoors, the L. nobilis seedlings were grown under four types of lighting for 180 days. The seedlings were grown under 4 different treatments((n=9 seedlings per treatment): control, control supplemental UV-B irradiated(+UV), FR reduced(-FR) and simultaneously supplemental UV-B irradiated and FR reduced(+UV-FR)). It was found that UV-B irradiation(+UV) reduced dry weight and leaf area, and increased leaf thickness and the amount of UV-absorbing compounds per unit leaf area. In contrast, a reduction in far-red(FR) light did not affect any of these parameters. Interestingly, however, the elongation growth and net photosynthetic rate of the L. nobilis seedlings grown under simultaneous UV-B irradiation and FR reduction(+UV-FR) were significantly decreased than the control treatment. From these results, it is concluded that the light quality has a large effect on the indoor growth of L. nobilis. This study can suggest basic information for managed in the L. nobilis in indoor using light quality.】

Growth and Physiological Responses of Two Pine Species Grown under Polluted Ansan Industrial Region

We investigated the effects of pollutants on two pine species (Pinus koraiensis and Pinus rigida) in an industrial region, using a physiological approach. We measured the growth and physiological parameters (photosynthetic activity and chemical contents) of the pine trees in relation to environmental pollutants. The concentrations of manganese (Mn), fluorine (F) and chlorine (CI) in needles of two pine species at the damaged site were significantly higher than those at the control site, and concentrations of essential elements (P) and chlorophyll in needles at the damaged site were significantly lower than at the control site. The light-saturated net photosynthesis , apparent quantum yield , carboxylation efficiency (CE) of both pines at the damaged site were significantly lower than those at the control site. The length of shoots and survivorship of needles of two pines at the damaged site were significantly lower than those at the control site. Especially, at damaged site, growth of shoots and needle longevity of P. koraiensis are larger than those of P. rigida.