Zu Yuangang

Influences of addition of different krilium in saline-sodic soil on the seed germination and growth of cabbage

Abstract China is one of the largest countries with huge amount of saline-sodic soil. How to ameliorate these lands is a hotspot in China. Through measurement of soil salinity, pH value and seed germination and growth status of cabbage seedlings, 17 kinds of krilium were added to experimented soil to evaluate their effects on amelioration of heavy saline-sodic soil. Firstly, among these 17 kinds of krilium, 11 (HPMA, gypsum, HEDP, T225, PAPEMP, MA-AA, ATMP, AA/AMPS, PAA, charcoal and BHMTPMPA) were effective agents and could effectively induce seed germination without any germination phenomena in the control saline-sodic soil. HPMA was the best one in ameliorating saline-sodic soil, which has been manifested by various indices of seed germination. Secondly, addition of gypsum together with other organic agents could strongly increase the ameliorative effectiveness if compared with relatively weak agents, while decrease seed germination if compared with the stronger agent of the 2 mixed agents, showing that the synergetic effect between gypsum and other kinds of tested krilium was not evident. Thirdly, optimum dosages for separate addition of HPMA and gypsum were 42.8 L m−3 and 25 kg m−3, while mixed-addition of these 2 agents at the same dosages did not cause plus effect in soil improvement. Finally, field application of HPMA could enhance the growth of cabbage seedlings at the first month, but began to wilt thereafter. Thus, instead of one-time addition, several-time addition of HPMA at the suitable dosage in field practice could strengthen the effectiveness of soil amelioration.

Influences of forest floor cleaning on the soil respiration and soil physical property of a larch plantation in Northeast China

Abstract Aimed to estimate how forest floor cleaning affected the carbon budget and soil physical feature, a 2-yr (2005–2006) measurement on soil respiration, soil bulk density, capillary porosity, soil temperature and soil volumetric moisture was carried out in a larch plantation. Firstly, forest floor cleaning evidently decreased soil respiration. Annual cumulative soil CO2 efflux decreased from 44.2 μmol·m−2 a−1 to 22.4 μmol·m−2 a−1. Secondly, cleaning practice slightly increased soil temperature at the growing season, but reduced it at the dominant winter season. It also made soil moisture higher in summer, but lower in spring and autumn. Moreover, the cleaning practice induced more compact soil compared with the uncleaned control. Thirdly, forest floor cleaning of litters and understory shrubs could cause non-respiratory carbon loss of about 175.0 mol·m−2. This loss decreased from 175.0 mol·m−2 to 137.4 mol·m−2 when soil respiratory carbon loss decreased. However, the alteration of soil physical characters in the cleaned plots should be carefully considered since this alteration was not favorable to the growth of larch plantation in a long run.

Dynamic feature of flavonoids content in different organs of larch (Larix gmelinii)

Flavonoids in plants is very important in its ecological role and economic value. The dynamic features of flavonoids content in different organs of larch (Larix gmelinii) at different light and temperature conditions were investigated in this study. Results showed that the order of flavonoids content in different organs from high to low was 7.78% (stem bark)>2.79% (leaves) >1.72% (branches) >1.19% (stem xylem)and different organs had a great seasonal variation in flavonoids content, but the change of flavonoids content at different temperature was not obvious in different organs., The content of flavonoids in barck had, a positive correlation with temperature (R2=0.75), but that in other organs had slight variation with the change of temperature. For all the tested organs, the flavonoids content in summer and autumn was approximately 3–4 times higher than in spring and winter. This is attributed to the great stress from environmental physical variables such as UV radiation, high temperature that induce the accumulation of flavonoids. The flavonoid content of sun leaves was evidently higher than that of shade leaves, and leaves at upper part of canopy had a higher flavonoids content compared with that at other parts. This result indicates that sun radiation could improve flavonoids production in leaves (R2=0.76). The flavonoids may actively evolve in plant defenses to environmental stress, protecting larch from the damage of high temperature and radiation, and its main function is different in different organs.

Alkaloid variations in Catharanthus roseus seedlings treated by different temperatures in short term and long term

A study was conducted to investigate the effects of high temperature on variations of alkaloid metabolism in C. roseus seedlings in Key Laboratory of Forest Plant Ecology, Northeast Forestry University, Heilongiang, China. 60-day-old C. roseus seedlings with 3–4 pairs of leaves were incubated in chambers with temperature of 30°C and 40°C for short-term heat shock experiment and 20°C, 25°C and 35°C for long-term experiment. The contents of vindoline, catharanthine, vinblastine and vincristine in C. roseus leaves and root were checked at different temperatures in short term (1–6 h) and long term (1–16 d). Results showed that under short-term heat shock, the contents of vindoline, catharanthine and vinblastine in leaves of the seedlings were higher at 40°C than at 30°C, but after 6 h treatment, the contents of vindoline and catharanthine under the two temperatures came to the same level. Catharanthine was exclusively distributed in C. roseus roots and its content was increased by 40% after two hours incubation at 40°C, while increased slowly at 30°C incubation and reached the highest value at 6 h. In the Long-term experiment, concentrations of monomeric alkaloids catharanthine and vindoline were higher at 20°C than at 25°C and had a sharp increase under the condition of 35°C. While for dimeric alkaloid, it showed that the higher the temperature, the earlier the peak value of vinblastine content appears. Vincristine had a continuous enhancement and attained 0.027 mg·g−1 at 16th day under 35°C condition which was higher than those in the other conditions. It was concluded that high temperature could promote the accumulation of different alkaloids in C. roseus and the accumulation characteristic is highly related to treatment time.

Antimicrobial activities of essential oil from Artemisiae argyi leaves

A study was conducted to determine the antimicrobial activities of essential oil from Artemisiae argyi leaves. The sample of the essential oil was analyzed by GC-MS. From 18 compounds representing the oils, Eucalyptole (18.42%), Spathulenol (14.32), 4-Methyl-1-(1-methylethyl)-3-cyclohexen-1-ol (3.10%), 3-Carene (2.64%) appeared as the main components. The screening of antimicrobial activity of the essential oil was evaluated using agar diffusion and broth microdilution methods. Gram-positive bacterial were more sensitive than gram-negative bacterial of the 8 microorganisms, and Staphylococcus aureus ATCC 6538 showed the lowest MIC (0.3125%) and MBC (0.625%). In the disc diffusion assay, Staphylococcus epidermidis ATCC 49134 and Bacillus subtilis ATCC 6633 showed obvious inhibitory activity. Survival curve showed that, 2MIC of Artemisiae argyi essential oil had a lethal effect on Candida albicans within the first 1 h. Results presented here suggest that the essential oil of Artemisiae argyi leaves possesses antimicrobial properties, and provides scientific foundations for exploition of Artemisiae argyi.

Notes on the forest soil respiration measurement by a Li-6400 system

The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to efficiently reduce the influence of CO2 spring-out. Moreover, collar insertion depth substantially affected soil respiration measurement, i.e., when collar was shallowly inserted into soil, transversal gas diffusion and the CO2 re-spring-out caused by unstable collars in the measurement could lead to overestimating soil respiration rate; however, when collar was deeply inserted into soil, root respiration decline caused by root-cut and the most active respiratory of the surface soil separated by the inserted collars could lead to underestimating soil respiration rate. Furthermore, an error less than 5% could be guaranteed in typical sunny day if the target [CO2] was set to the mean value of ambient [CO2] in most time of the day, but it should be carefully set in early morning and late afternoon according to changing ambient [CO2]. This protocol of measurement is useful in real measurement.

Distribution of solanesol in Nicotiana tabacum

Solanesol is an important secondary metabolite in Nicotiana tabacum. Distribution of solanesol in Nicotiana tabacum was investigated by High Performance Liquid Chromatography (HPLC) method. The quantitative distribution of solanesol in various organs and tissues of N. tabacum showed that solanesol content, obviously different in all organs, was 6.8, 18.3, 27.5, 45.8, and 68.0 times higher in leaves than that in the stalks, flowers, seeds, fruits and roots, respectively. The contents of solanesol in various parts of leaf, stalk and flower were determined. The content of solanesol in top leaf, middle leaf and bottom leaf gradually decreased (6.124, 5.813 and 5.687 mg·g−1, respectively) and the content of solanesol in various leaf-parts (leaf apex, leaf middle and leaf base) also gradually decreased. The content of solanesol in top stalk was 1.19 times and 1.92 times higher than that in the middle stalk and the bottom stalk, respectively. The content of solanesol in various tissues of stalk (epidermis, cortex and stele) dramatically decreased. The sepal contained higher concentration of solanesol (1.192 mg·g−1) compared to any other parts in flower. The study will provide the base data for the regulation and control of solanesol, moreover, it will provide the scientific evidences for the rational development and utilization of N. tabacum resources.

Characteristics of the temperature coefficient, Q10, for the respiration of non-photosynthetic organs and soils of forest ecosystems

The temperature coefficient, Q10 (fractional change in rate with a 10°C increase in temperature) describes the temperature sensitivity of soils, roots, and stems, as well as their possible performance in global warming processes. It is also a necessary parameter for the estimation of total CO2 efflux from each element. A number of studies have focused on Q10 values to date; however, their conclusions are not universal and do not always agree. A review of these reported Q10 values therefore becomes necessary and important for a global understanding of the temperature sensitivity of different forest types and elements. The aims of our present paper are, first, to find the frequency distribution pattern of soils, roots, and stems (branches) and compare their temperature sensitivity; then, to find the Q10 differences between conifer and deciduous tree species and the effect of methodology on Q10 values; finally we want to give a perspective on future Q10-related studies. We found that most Q10 values of each element were concentrated in a relatively narrow range despite a total data distribution over quite a wide range. For soil respiration, the median Q10 value was 2.74 and the center of the frequency distribution was between 2.0 and 2.5 with a percentage of 23%. Most of the data (>80%) were within the range from 1.0 to 4.0. The median Q10 value for root respiration was 2.40 and the center of the frequency distribution was from 2.5 to 3.0 with a percentage of 33%. Most of the results (>80%) ranged from 1.0 to 3.0. For stem respiration, the median Q10 value was 1.91 and the frequency distribution was concentrated between 1.5 and 2.0. Over 90% of the data ranged from 1.0 to 3.0. Obvious differences in Q10 value were found between different elements, stem < root < soil including root < soil excluding root. The differences between woody organisms of stems, roots, and soils excluding roots were statistically significant (p<0.05), indicating that heterotrophic respiration from microorganism activity may be more sensitive to global warming. The duration of the period with leaves slightly affects the temperature sensitivity of woody organisms since the Q10 values for root and stem of coniferous evergreen trees did not differ significantly from deciduous trees (p>0.10). CO2 analytical methods (soda lime absorption method, IRGA (Infra-read gas analysis), and chromatograph analysis) and root separation methods (excised root and trenched box) slightly affected the Q10 values of soil and root respiration (p>0.10), but an in vitro measurement of stem respiration yielded a significantly higher Q10 value than an in vivo method (p<0.05). In general, although the Q10 values of non-photosynthetic organisms stayed within a relatively conservative range, considerable variation between and within elements were still detectable. Accordingly, attention should be paid to the quantitative estimation of total CO2 efflux by Q10-related models. In future studies, the biochemical factors and the environmental and biological factors controlling respiration should be emphasized for precise estimation of total CO2 efflux. The difficulty is how to clarify the underlying mechanism for fluctuations of Q10 values for one specific habitat and element (e.g. temperature acclimation or adaptation of Q10 values) and then allow the Q10 values to be more conservative for representation of temperature sensitivity in global warming processes.

Characteristics of the microbial community in rhizosphere of Camptotheca acuminata cultured with exotic invasive plant Eupatorium adenophorum

The traditional culture-dependent plate counting and culture-independent small-subunit-ribosomal RNA gene-targeted molecular techniques, Single-Strand Conformation Polymorphism (SSCP) and terminal Restriction Fragment Length Polymorphism (tRFLP) combined with 16S rDNA clone library were adopted to investigate the impacts of secretion from Camptotheca acuminata (abbreviated to Ca) roots on the quantities and structure of eukaryotic microbes and bacteria in the rhizosphere, and the possibility that Ca controls exotic invasive plant Eupatorium adenophorum (Ea). The counting results indicated that the number of bacteria increased in turn in rhizospheres of Ea, Ca-Ea mixed culture and Ca, while that of eukaryotic microbes decreased. PCR-SSCP profiles showed eukaryotic microbial bands (corresponding to biodiversity) in rhizosphere of Ea were more complex than those of Ca and CE. Meristolohmannia sp., Termitomyces sp. and Rhodophyllus sp. were the dominant populations in the rhizosphere of Ca. Bacterial terminal restriction fragments (TRFs) profiles showed no difference among three kinds of rhizospheres, and the sequences of the 16S rDNA clone library from Ca rhizospheres were distributed in 10 known phyla, in which phylum Proteobacteria were the absolute dominant group and accounted for 24.71% of the cloned sequences (δ-Proteobacteria accounted for up to 17.65%), and phyla Acidobacteria and Bacteroidetes accounted for 16.47% and 10.59% of the cloned sequences, respectively. In addition, high performance liquid chromatography detected a trace amount of camptothecin and hydroxycamptothecin in the rhizospheric soil of Ca and CE, but examined neither camptothecin nor hydroxycamptothecin in rhizospheric soil of Ea. Therefore, invasion and diffusion of Ea evidently depended on distinguishing the eukaryotic community structure, but not on that of the bacterial pattern. Ca was able to alter the eukaryotic community structure of invasive Ea by secreting camptothecin and hydroxycamptothecin into rhizospheres, and may benefit the control of overspread of Ea. This study provided theoretical evidence for rhizospheric microbial aspects on substituting Ca for Ea.

Effect of priming on the germination ofPeltophorum dubium seeds under water stress

Peltophorum dubium seeds provided by Anhembi, SP were scarified in 98% H2SO4 for 15 min to overcome mechanical dormancy. Seeds were primed in solutions of 0.2% Captan at 10 °C and 27°C, PEG 6000 −1.0 MPa at 10°C and 27°C, 0.5 mol KNO3, 0.75 Mol KNO3, 1.0 Mol KNO3. Eight treatments including the primed seeds and nonprimed seeds, five replicates with 100 seeds for each treatment, were set to 15-cm-Petri dish with double filter paper moistened with testing solution PEG in refrigerator at 27°C. For the experiments of all the groups, osmotic potential were 0.0, −0.2, −0.4, −0.6, −0.8, −1.0, −1.2, and −1.4 MPa.P. dubium seeds were also set to water stress experiment in rolled paper with PEG solutions from 0.0 to −1.0 M Pa. Germination percentage decreased with the increase of PEG concentration. Control group had a better germination percentage than other groups. Germination hardly occurred in PEG −1.4 MPa.