Abstract:In order to understand the characteristics of nutrient requirement in Pinus massoniana and Cunninghamia lanceolata forests in Fujian, China, the concentrations of seven nutrient elements, including C, N, P, S, K, Ca, and Mg, in needles collected from 25 P. massoniana plots and 31 C. lanceolata plots were determined. The results showed that the concentrations of needle K, Ca and Mg in P. massoniana were only 68%, 14% and 50% of those in C. lanceolata, respectively, indicating the demand for mineral elements, particular Ca, were markedly higher by C. lanceolata than by P. massoniana, with an important implication that P. massoniana has much higher potential adaptability to poor nutrients, particular Ca impoverished sites than C. lanceolata. Both tree species showed similar homeostasis either in concentrations of C, N, P and S or in their stoichiometric ratios. In contrast, large variabilities of Ca, Mg and K concentrations and their stoichiometric ratios were observed in both species, revealing the large influence of site condition on these elements. Both species showed positive synergy relationships for the demands of N, P and K, while negative correlations were observed between N and Ca. This suggests that atmospheric N deposition or long-term application of N fertilizers through forest management may cause the inhibition of Ca uptake.

Abstract:In order to understand the effect of supplying phosphorus (P) on growth and nutrient status of Mytilaria laosensis, its growth character, nutrient content and accumulation, and uptake efficiency of P were studied treated with different P levels under soil culture. The results showed that with the supplying P increment, the plant height, biomass, and nutrient accumulation increased initially and then decreased, and the base diameter rose firstly and then kept stable. As supplying P levels increased, the changes in nutrient content of leaves and whole plant were not different, nitrogen (N) content had no obvious change, the content of potassium (K) decreased firstly and then increased, while the P content obviously enhanced, the uptake efficiency of P showed the trend of drop-rise-drop. Supplied with 30 mg P per plant, the biomass of leaves and root, the N accumulation in leaves and uptake efficiency of P were the highest. The plant height, biomass of stem, total biomass, K and P accumulation in leaves, N, P and K accumulation in the plant reached peak supplied 45 mg P per plant. As supplied 60 mg P per plant, the plant height, biomass, nutrient accumulation and uptake efficiency of P declined significantly. Therefore, the optimum supplying P level for plant growth of M. laosensis seedlings was 30-45 mg per plant, and beyond that, some obvious inhibitory effects would occur.

Abstract:Bidens frondosa L. is an exotic annual herb native to North America, which often co-occurs with native congener B. tripartita L. in habitats, such as abandoned arable land, farmland etc. In order to understand the invasiveness of B. frondosa, the effects of compound fertilizer on competitive response of B. frondosa and B. tripartita were studied. The results showed that the competitive response of B. frondosa declined with nutrient increment, while that of B. tripartita increased. Furthermore, the competitive response of B. frondosa was greater than that of B. tripartita under low nutrient level and on the contrary under high nutrient level. The growth of B. frondosa was suppressed by competitor under low nutrient, while did that of B. tripartita under high nutrient. Therefore, it was suggested that the competitive ability of B. frondosa was enhanced with nutrient increasing, meanwhile that of B. tripartita decreased. Human activities cause nutrient increase, which increase the competitive capacity of B. frondosa to B. tripartita, and then improved the exotic species invasion.

Abstract:In order to understand the soil stoichiometry of forests in Moon Mountain, Guizhou Province, the contents of C, N and P in soil collected from five forest types were studied, and their stoichiometry characters. The results showed that the largest variability in surface soil (0-20 cm) was P content, and that in 20-100 cm soil was C content, the smallest was N content. The C, N contents in 0-10 cm soil of 5 forest types were much higher than mean contents in 0-10 cm soil of China lands, while P content was much lower than that. There were significant differences in C, N and P contents between hard broad and soft broad nature forests. Soil C content in hard broad nature forest was bigger than that in soft broad nature forest, while soil N, P contents were diametrical. The soil C:N in hard broad nature forest was significantly greater than that in soft broad nature forest, and the soil C:N in coniferous and broad mixed forest was significantly higher than that in Chinese fir plantation and Pinus plantation. The soil N:P and C:P in hard broad nature forest, soft broad nature forest, coniferous and broad mixed forest decreased with the depth of soil layer. However, the soil C:P and N:P in Chinese fir plantation and Pinus plantation decreased at first then increased and decreased again with depth of soil layer. All of them had accumulation peaks at 30-50 cm layer. Correlation analysis showed that there were significantly positive correlations among contents C, N, and P in 0-100 cm soil, as well as contents of C, N and C:N, C:P, N:P, and P content with C:N. Therefore, the soil nutrient contents and stoichiometry characteristics of five forest types and different soil layers in Moon Mountain are significantly different.

Abstract:The aim was to understand the characters of Fagus hayatae community in different habitats. The species composition, flora character, life form, importance value and species diversity along altitudinal gradient in Micangshan National Nature Reserve, Sichuan were studied. The results showed that species number in F. hayatae community was different with increment of elevation. The north temperate distribution was dominant in F. hayatae community, and the proportion of dominant floristic distribution had positive correlation with elevation. The main life-form spectrum was phanerophytes. The important value of F. hayatae in tree layer increased along altitude. The diversity indexes of F. hayatae community in middle altitude were lower than those in high and low altitudes, showing the characters of less species and low diversity. Therefore, the characteristics of F. hayatae community had obvious difference in different altitudes.

Abstract:In order to understand the soil microbiology characters of subtropical ecosystem, the soil microbial physio-chemical properties were studied in five ecosystems, such as barren grassland (BG), Cunninghamia lanceolata forest (CL), Cinnamomum camphora forest (CC), Cunninghamia lanceolata-Cinnamomum camphora mixed forest (CL-CC) and nature recovery (NR). The results showed that soil microbial biomass carbon, nitrogen and phosphorus (SMBC, SMBN and SMBP) and soil basal respiration (SBR) in CC, CL-CC and NR were significantly higher than those in BG and CL (P<0.05) at 0-20, 20-40 and 40-60 cm soil layers, whereas metabolic quotient (qCO₂) in CC, CL-CC and NR was significantly lower than that in BG and CL (P<0.05). SMBC, SMBN, SMBP and SBR significantly decreased with increment of soil depth (P<0.05), while qCO₂ significantly increased in all ecosystems (P<0.05). Soil bulk density (SBD) had significantly negative correlation with SMBC, SMBN, SMBP, and SBR (P<0.05), significantly positive correlation with qCO₂ (P<0.05). SMBC, SMBN, SMBP, SBR had significantly positive correlation with soil total porosity (STP), soil water stable macro-aggregate (SWSM), soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), and available phosphorus (AP) (P<0.01), and qCO₂ had significant negative correlation with STP, SWSM, SOC, TN, AN, AP (P<0.05). Therefore, NR, CC and CL-CC could significantly improve soil quality, but BG and CL had not obvious amelioration to soil quality.

Abstract:In order to understand the characters of resource allocation and seed germination of figs, the allocation to vegetation and reproduction in figs, and seed germination of four monoecious Ficus species in Xishuangbanna, such as F. benjamina, F. altissima, F. racemosa and F. concinna were studied. The results showed that the allocation of nutrition resources was significantly different among four Ficus species. The heavier fig had more pulp and larger fruit size, and the fig with larger cavity had more seeds, but the number of male flowers and fig wasps were not always like that. The proportions of flowers that fig allocated to male (fig-pollinating wasps) and female (seeds) function were different. The allocation to female function in F. racemosa was more than that to male function, while those in F. benjamina, F. altissima and F. concinna were just the opposite and had different degrees. Besides, there were significant differences in seed size and weight among four Ficus species so that they influenced on seed germination rate and the growth of roots and stems. Ficus racemosa had the largest fig size and most seeds, its seed germination rate also high, but the growth of root and stem was the slowest because of the small-sized seeds. Both F. benjamina and F. altissima had medium-sized figs and large seeds, so they not only had high seed germination rate, but also the growth of roots and stems was fast. The fig size and seed number of F. concinna were small, so its seed germination rate was the lowest among four Ficus species, and the growth of root and stem was the slowest too. Ficus species living in warm, humid and better environment had smaller-sized seeds and relatively worse germination ability and speed compared to those living in barren environment, because of few limits on water, heat, and sunlight. Therefore, these suggested that different Ficus species in different habitats had already evolved variant mechanisms of reproduction allocation and strategies of resource utilization to adapt their environments.

Abstract:In order to reveal the function of homeobox (KNOX) gene in the stem development of Dendrocalamus latiflorus, a homologous gene of KNOX, named as DlKNOX, was cloned from the bamboo young stem using RT-PCR and RACE. The cDNA was 1511 bp in full length, including 5' UTR 196 bp, 3' UTR 238 bp and an ORF 1077 bp, which encoded a protein with 358 amino acids. The conserved domain analysis demonstrated that the protein contained KNOX1, KNOX2, ELK and Homeobox KN domains, which was in line with the characteristics of KNOX family, belonging to the class I protein. The bioinformatics analysis indicated that DlKNOX had the highest identities with OSH1 from rice for 86%. The expression analysis showed that DlKNOX expressed in knob with the highest level, next in stem, and the lowest in root. DlKNOX was expressed in Escherichia coli, and a recombinant protein about 82 kDa was obtained, which was consistent with the expected molecular weight of the recombinant protein composed of MBP (42.5 kDa) and DlKNOX (39.5 kDa). The optimum conditions for the expression of DlKNOX in E. coli were induced by 0.3 mmol L^-1 IPTG for 2 h at 28℃. These lay the foundation for further research on the function of DlKNOX in stem development of D. latiflorus.

Abstract:In order to understand the genetic relationship of Phyllostachys edulis, seven newly published infra-species, including‘Mira’,‘Porphyrosticta’,‘Anjiensis’,‘Exaurita’,‘Holochrysa’,‘Lücaoguijiazhu’, and‘Purpureosulcata’, were studied using AFLP molecular marker. The results showed that there were 1728 bands amplified by selected 8 pairs of primer with 98.77% polymorphic bands and 881 polymorphic loci. The Nei's genetic diversity index was 0.2736 and Shannon information index was 0.4291. These supplied the molecular research data of all 23 infra-species of P.edulis.

Abstract:In order to understand the effect of light quality on growth of Bletilla striata seedlings in vitro, the growth characters, activities of antioxidant enzymes and enzyme gene expression of B. striata seedlings under different light qualities were studied. The results showed that there were significant promoting effect on growth of B. striata under blue light and red light, but the effect of green light was not obvious. Except of CAT, the activities of APX, POD and SOD increased under different light qualities, in which the activities of APX and SOD were the highest under yellow light, and that of POD did under red light. The activities of antioxidant enzyme under green light were the lowest. The expression of antioxidant enzyme genes increased under blue light for 35-45 days. Therefore, red and yellow light could promote the height and rooting of B. striata, the activities of antioxidant enzyme increased overall under different light qualities, and the expression of antioxidant enzyme genes were the highest under blue light.

Abstract:In order to reveal the function of MYB52 in wood development of Hevea brasiliensis, a G21 subgroup gene member of MYB transcription factor, named HbMYB52, was cloned from its transcriptom. The ORF of HbMYB5 was 2726 bp, encoding a protein with 242 amino acids. HbMYB5 had high expression in xylem. Overexpression of HbMYB52 in Arabidopsis thaliana had no significant difference in phenotype between transgenic and wild type plants, but it led to significant thickening of cell wall in interfascicular fiber, and inhibition of secondary wall formation in vessels and xylem fiber. The contents of lignin and cellulose decreased in transgenic lines 3 and 6, and the expressions of key enzyme genes involving the corresponding components biosynthesis were significantly descended in transgenic lines. However, the lignin deposition in transgenic line 8 was ectopic, and the expressions of genes related to lignin biosynthesis were active. Therefore, it was suggested that HbMYB52 might play dual roles in the regulation of secondary wall formation, which negatively regulated secondary wall formation of vascular and promoted cell wall thickening of interfascicular fibers in A. thaliana.

Abstract:To reveal the defense mechanism of anthocyanins under salt stress, the physiological responses to NaCl stress in three Arabidopsis mutants (tt3, tt4 and tt3tt4) deficient in anthocyanin biosynthesis and wild type (WT) plants were studied. The mutants tt3, tt4 and tt3tt4 are deficient in dihydroflavonol 4-reductase gene (DFR), chalcone synthase gene (CHS) and both DFR and CHS, respectively, these genes encode enzymes that act in the anthocyanin biosynthesis pathway. The results showed that, under salinity stress, the three mutants with lower anthocyanin accumulation exhibited greater reductions in PSII maximum quantum yield (Fv/Fm), effective quantum yield (Yield), electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (NPQ) and greater increases in lipid peroxidation, than the WT. Histochemical stains with nitroblue tetrazolium (NBT) showed that superoxide anion free radical (O₂·^-) in tt3tt4 was the highest, followed by tt3 or tt4, and then by WT. These suggest that anthocyanins play an important role in plant adaptations to salinity stress, possibly via serving as a kind of osmo-regulator and antioxidant. Therefore, anthocyanin contents can be used as an indicator for screening of salt-tolerant crops.

Abstract:In order to understand the effect of low temperature on growth of Ilex verticillata, the photosynthetic pigment contents, antioxidant enzymes activities and antioxidant ability of 2-year-old seedlings under -6℃ were studied. The results showed that the chlorophyll, carotenoids contents in leaves decreased, while the ratio of chlorophyll/carotenoids and chlorophyll b content increased under low temperature. The REC (relative electrical conductivity) and H₂O₂ content significantly increased under low temperature. There was no significant difference in superoxide dismutase (SOD) activity, but the catalase (CAT) activity significantly reduced. Under low temperature, the peroxidase (POD) activity significantly increased, and reached the peak treated for 48 h. The ascorbate peroxidase (APX) activity enhanced treated for 12 h, and then decreased. The AsA (ascorbic acid) and GSH (glutathione) contents increased at first 24 h then decreased from 48 to 72 h. Therefore, Ilex verticillata seedlings could endure low temperature stress for short term (12-24 h), and antioxidant system could play key role in cold stress at early stage, but it might suffer damage with time extension under low temperature.

Abstract:In order to understand the effects of exogenous proline and phosphate fertilizer under salt stress, the growth and physiology index of Populus cathayana seedlings were studied with different treatment. The results showed that the growth and biochemical substances contents in female and male seedlings were affected under salt stress, while the application of proline and phosphate fertilizer could improve the salt tolerance of male seedlings to a certain extent, but it was not obvious on female seedlings. Therefore, it is better to choose male seedlings with strong stress resistance in the improvement of saline alkali land, and at the same time, it is considered to choose phosphate fertilizer for enhance salt tolerance of plants because of affordable and easy to use.

Abstract:Delphinium angustipaniculatum W. T. Wang described from southern Gansu, China, is found to be conspecific with D. sutchuenense Franch., a species previously recorded to occur in southern Gansu and northern Sichuan. Therefore, the former is reduced to the synonymy of the latter. Morphological differences between D. sutchuenense and its two putative close allies, D. giraldii Diels and D. sparsiflorum Maxim., are discussed.