Soil biochemical responses to nitrogen addition in a bamboo forest.[Pubmed: 25029346]

Many vital ecosystem processes take place in the soils and are greatly affected by the increasing active nitrogen (N) deposition observed globally. Nitrogen deposition generally affects ecosystem processes through the changes in soil biochemical properties such as soil nutrient availability, microbial properties and enzyme activities. In order to evaluate the soil biochemical responses to elevated atmospheric N deposition in bamboo forest ecosystems, a two-year field N addition experiment in a hybrid bamboo (Bambusa pervariabilis × Dendrocalamopsis daii) plantation was conducted. Four levels of N treatment were applied: (1) control (CK, without N added), (2) low-nitrogen (LN, 50 kg N ha(-1) year(-1)), (3) medium-nitrogen (MN, 150 kg N ha(-1) year(-1)), and (4) high-nitrogen (HN, 300 kg N ha(-1) year(-1)). Results indicated that N addition significantly increased the concentrations of NH4(+), NO3(-), microbial biomass carbon, microbial biomass N, the rates of nitrification and denitrification; significantly decreased soil pH and the concentration of available phosphorus, and had no effect on the total organic carbon and total N concentration in the 0-20 cm soil depth. Nitrogen addition significantly stimulated activities of hydrolytic enzyme that acquiring N (urease) and phosphorus (acid phosphatase) and depressed the oxidative enzymes (phenol oxidase, peroxidase and catalase) activities. Results suggest that (1) this bamboo forest ecosystem is moving towards being limited by P or co-limited by P under elevated N deposition, (2) the expected progressive increases in N deposition may have a potential important effect on forest litter decomposition due to the interaction of inorganic N and oxidative enzyme activities, in such bamboo forests under high levels of ambient N deposition.

Simultaneous determination of 12 coumarins in bamboo leaves by HPLC.[Pubmed: 24282929]

A simple, rapid, and sensitive HPLC-UV method was developed for qualitative and quantitative analysis of 12 coumarin compounds (skimin, scopolin, scopoletin, umbelliferone, 6,7-dimethoxycoumarin, coumarin, psoralen, xanthotoxin, 5,7-dimethoxycoumarin, pimpinellin, imperatorin, and osthole) in bamboo leaves. The samples were extracted with ethanol-water (70 + 30, v/v) by ultrasonication and purified by Florisil SPE. The method was validated for linearity, LOD, LOQ, accuracy, precision, and recovery. The standard curves in the corresponding ranges had good linearity. LOD was at the range of 0.19 to 0.85 mglkg and LOQ 0.64 to 2.82 mg/kg. The values of RSD for accuracy and intraday and interday precision were less than 3%, except for 6,7-dimethoxycoumarin. Recoveries from spiked samples at 30, 20, and 10 mg/kg in Dendrocalamus giganteus Munro were higher than 70%, except for scopoletin, 6,7-dimethoxycoumarin, and coumarin. The method was validated using field-collected samples taken from Beijing and Changning Counties, SiChuan, China. Six coumarins, namely, skimin, scopolin, scopoletin, umbelliferone, coumarin, and pimpinellin, were found in the extracts of 11 species of bamboo leaves. The concentrations of total coumarins were in the range of 8.67 to 99.2 mg/kg. The maximum concentration of total coumarins was found in Bambusa pervariabilis, and the minimum was in.

Purification of protein AP-toxin from Arthrinium phaeospermum causing blight in Bambusa pervariabilis × Dendrocalamopisis grandis and its metabolic effects on four bamboo varieties.[Pubmed: 23095467]

Bambusa pervariabilis × Dendrocalamopisis grandis blight is caused by a toxin produced by the fungus Arthrinium phaeospermum. In this study, a toxin fraction (P1-2-2) with an estimated molecular mass of 31 kDa was purified from a culture filtrate of this fungus by ammonium sulfate precipitation, Sephadex G-50 gel chromatography, Q Sepharose Fast Flow anion exchange resin, and Sephadex G-75 chromatography. The N-terminal amino acid sequence (i.e., H(2)N-Gln-Val-Arg-Asp-Arg-Leu-Glu-Ser-Thr) determined by Edman degradation showed homology to known serine alkaline proteases. The purified protein was named AP-toxin. Effects of the purified protein toxin on total phenol, flavonoid, total nucleic acid, DNA, RNA, soluble protein, and soluble sugar content, as well as DNase and RNase activities and disease index, were analyzed in different bamboo varieties by the impregnation method. The toxin had a significant effect on each parameter tested. In addition, a significant correlation was observed among the metabolic index, treatment time, bamboo resistance, and disease index. These data suggest that AP-toxin plays an important role in mediating the phytotoxic activities of A. phaeospermum. This study also indicates that metabolic indices could reflect the resistance indices of hybrid bamboo to blight.

[Effects of simulated nitrogen deposition on soil respiration in a Bambusa pervariabilis x Dendrocala mopsi plantation in rainy area of West China].[Pubmed: 21774300]

From January 2008 to February 2009, a field experiment was conducted in Rainy Area of West China to understand the effects of nitrogen (N) deposition on the soil respiration in a Bambusa pervariabilis x Dendrocala mopsi plantation. Four treatments were installed, i. e., no N added (control), 5 g N m(-2) a(-1) (low-N), 15 g N m(-2) a(-1) (medium-N), and 30 g N m(-2) a(-1) (high-N), and soil respiration rate was determined by infra-red CO2 analyzer. In the plantation, soil respiration rate had an obvious seasonal change, with the maximum in July and the minimum in January. In control plot, the annual cumulative soil respiration was (389 +/- 34) g m(-2) a(-1). Soil respiration rate had significant positive exponential relationships with soil temperature at 10 cm depth and air temperature, and significant positive linear relationships with soil microbial biomass carbon (MBC) and nitrogen (MBN). Simulated N deposition promoted soil respiration significantly, with significant differences between the low- and medium-N and the control but no significant difference between high-N and the control. In control plot, surface soil (0-20 cm) MBC and MBN were 0.460 and 0.020 mg g(-1), respectively. In N-added plots, both the MBC and the MBN had significant increase. The fine root density in surface soil was 388 g m(-2), which was less affected by simulated N deposition. The soil respiration Q10 value calculated from soil temperature at 10 cm depth and air temperature was 2.66 and 1.87, respectively, and short-term N deposition had lesser effects on the Q10 value. The variation of soil respiration in the plantation was mainly controlled by temperature and soil microbial biomass, and simulated N deposition could increase the CO2 emission via increasing soil microbial biomass.

[Fractal features of soil aggregate structure in slope farmland with different de-farming patterns in South Sichuan Province of China].[Pubmed: 20873614]

By using fractal model, this paper studied the fractal dimension of soil aggregate structure (D) in the slope farmland (CK), its 5-year de-farmed Neosinocalamus affinis plantation (NAP), Bambusa pervariabilis x Dendrocalamopsis oldhami plantation (BDP), Alnus crenastogyne + Neosinocalamus affinis plantation (ANP), and abandoned farmland (AFL) in south Sichuan Province of China, and analyzed the relationships between the D and soil physical and chemical properties. In the de-farmed plantations and abandoned farmland, the contents of > 0.25 mm soil aggregates and water-stable aggregates were increased significantly, compared with those in the slope farmland. The D was 1.377-2.826, being in the order of NAP < BDP < ANP < AFL < CK, and decreased with the increasing contents of > 0.25 mm soil aggregates and water-stable aggregates. Comparing with CK, de-farming increased the soil natural water content, capillary porosity, and contents of soil organic matter, total N, alkali-hydrolysable N, total P, and total K, and decreased soil bulk density, non-capillary porosity, and aeration porosity. There were close relationships between the fractal dimension of soil aggregate structure and the soil physical and chemical properties. All the results suggested that the de-farming of slope farmland was beneficial to the increase of the contents of > 0.25 mm soil aggregates and water-stable aggregates, and the enhancement of soil structure stability. The D could be used as an ideal index to evaluate soil fertility, and planting Neosinocalamus affinis on the de-farming slope farmland was a good measure for the improvement of soil fertility in the research area.

Coumarins from the leaves of Bambusa pervariabilis McClure.[Pubmed: 20390773]

A new pyrone-coumarin, 7,8-dihydroxy-3-(3-hydroxy-4-oxo-4H-pyran-2-yl)-2H-chromen-2-one (1), along with two known coumarins, scopoletin (2) and scopolin (3), was isolated from the 95% EtOH extract of the leaves of Bambusa pervariabilis McClure. Their structures were determined on the basis of spectroscopic techniques and chemical methods.