Shengzuo Fang

Response of radiata pine forests to residue management and fertilisation across a fertility gradient in New Zealand

New Zealand law requires sustainable forest management. International definitions of sustainability typically include maintaining the productive capacity of forest soils, and decision tools are needed for managing harvesting and site preparation practices. Trials were established between 1986 and 1994 in different physiographic regions of New Zealand to determine the effects of management on the second-rotation performance of Pinus radiata. Main harvesting and residue treatments at three North Island sites include: whole-tree harvest plus forest floor removal, whole-tree harvest, and stem-only harvest retaining a single layer of slash. These treatments were installed in a random block split-plot design (with and without fertiliser). Additional treatments were added at specific sites (e.g., double slash addition at Woodhill; topsoil removal at Tarawera) to test hypotheses that harvesting intensity is negatively correlated with second-rotation growth, that inadequate nutrition is the reason for the negative correlation, and that fertiliser additions can compensate for the negative impact of harvesting on nutrition. Stands were thinned-to-waste to reduce stocking by 50% at Woodhill (age 7 years), Tarawera and Kinleith (age 5 years). On recent coastal sand dunes at Woodhill, foliar analyses suggest that nutrient availability to trees of N, P, K, B, Mn, and Zn were reduced during critical periods of stand establishment by forest floor removal, and improved by retention of thinning slash. Diameter at 5 years declined as forest floor C:N ratio increased. Diameter after 11 years was reduced by forest floor removal, and positively related with residue retention. On approximately 100-year-old basaltic tephra gravel at Tarawera, foliar concentrations of K and B were positively related with slash and soil nutrient retention, however, the effect of harvest removals on tree nutrition and growth was substantially less than observed on recent sand dunes due to greater native fertility of basaltic gravel. Forest floor C:N ratio at Tarawera explained less variation in tree growth than at Woodhill. On the N-rich Taupo sandy loam of Kinleith Forest, there was no correlation between forest floor C:N ratio and tree diameter to age 5 years. Fertiliser additions have increased tree diameter at all sites, and can ameliorate harvesting-related reductions in growth. However, fertiliser additions caused significant reductions in foliar concentrations of most nutrients studied except N. These trials have been useful for identifying the benefits of residue retention among sites with varying levels of native fertility. Based on the results of this study, we recommend organic matter retention during harvest and site preparation on N-deficient sites such as Pinaki Typic Sandy Recent Soil.

Integrated effects of light intensity and fertilization on growth and flavonoid accumulation in Cyclocarya paliurus.

Cyclocarya paliurus has been used for drug formulations and ingredients in functional foods in China. Field studies were conducted to examine the relationships between environmental factors and flavonoid accumulation. A split-plot randomized design was used to establish three shading treatments and three fertilization levels, and growth parameters and flavonoid contents were detected. The greatest biomass production was achieved in intermediate shade and fertilization treatment, and leaf production per seedling increased by 139.5% compared to the treatment without shade and fertilization. Overall, shade and fertilization had a significantly negative effect on contents of total flavonoid, kaempferol, quercetin, and isoquercitrin in leaves of C. paliurus. However, the greatest accumulation of total flavonoid in the leaves was observed in intermediate shade and fertilization treatment, achieving 364.4 g/plant. The results suggest that manipulating the field growing conditions and optimizing the silvicultural system would be important for obtaining the greatest yield of targeted health-promoting substances.

Tree species composition influences enzyme activities and microbial biomass in the rhizosphere: a rhizobox approach.

Monoculture causes nutrient losses and leads to declines in soil fertility and biomass production over successive cultivation. The rhizosphere, a zone of usually high microbial activities and clearly distinct from bulk soil, is defined as the volume of soil around living roots and influenced by root activities. Here we investigated enzyme activities and microbial biomass in the rhizosphere under different tree compositions. Six treatments with poplar, willow, and alder mono- or mixed seedlings were grown in rhizoboxes. Enzyme activities associated with nitrogen cycling and microbial biomass were measured in all rhizosphere and bulk soils. Both enzyme activities and microbial biomass in the rhizosphere differed significantly tree compositions. Microbial biomass contents were more sensitive to the changes of the rhizosphere environment than enzyme activities. Tree species coexistence did not consistently increase tested enzyme activities and microbial biomass, but varied depending on the complementarities of species traits. In general, impacts of tree species and coexistence were more pronounced on microbial composition than total biomass, evidenced by differences in microbial biomass C/N ratios stratified across the rhizosphere soils. Compared to poplar clone monoculture, other tree species addition obviously increased rhizosphere urease activity, but greatly reduced rhizosphere L-asparaginase activity. Poplar growth was enhanced only when coexisted with alder. Our results suggested that a highly productive or keystone plant species in a community had greater influence over soil functions than the contribution of diversity.

Effect of light regime and provenance on leaf characteristics, growth and flavonoid accumulation in Cyclocarya paliurus (Batal) Iljinskaja coppices

BackgroundAs a highly valued and multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medical use. However, limited information is available on its genotype selection and cultivation for growth and phytochemicals. Responses of growth and secondary metabolites to light regimes and genotypes are useful information to determine suitable habitat conditions for the cultivation of medicinal plants.ResultsBoth light regime and provenance significantly affected the leaf characteristics, leaf flavonoid contents, biomass production and flavonoid accumulation per plant. Leaf thickness, length of palisade cells and chlorophyll a/b decreased significantly under shading conditions, while leaf areas and total chlorophyll content increased obviously. In the full light condition, leaf flavonoid contents showed a bimodal temporal variation pattern with the maximum observed in August and the second peak in October, while shading treatment not only reduced the leaf content of flavonoids but also delayed the peak appearing of the flavonoid contents in the leaves of C. paliurus. Strong correlations were found between leaf thickness, palisade length, monthly light intensity and measured flavonoid contents in the leaves of C. paliurus. Muchuan provenance with full light achieved the highest leaf biomass and flavonoid accumulation per plant.ConclusionsCyclocarya paliurus genotypes show diverse responses to different light regimes in leaf characteristics, biomass production and flavonoid accumulation, highlighting the opportunity for extensive selection in the leaf flavonoid production.

Enzymatic activity and nutrient availability in the rhizosphere of poplar plantations treated with fresh grass mulch

Abstract Poplar plantations have been established in upland areas of southwestern China in recent years. However, poor site conditions limit the growth and ecological function of poplar plantations. In this experiment, poplar plantations were established in 2004 and circular areas were mulched around each tree at four rates: 0, 10,000, 20,000 and 30,000 kg ha−1 fresh grass (Imperata cylindrical var. major). The effects of varying amounts of fresh grass mulch on urease and acid phosphatase activities and nutrient availability (N, P and K) in the rhizosphere and bulk soil were assessed under field conditions. Additions of fresh grass mulch greatly improved urease and acid phosphatase activities as well as the concentrations of N, P and K in the rhizosphere and bulk soils, and all measured variables were enhanced as the mulching quantity increased, highlighting the importance of conducting effective residue management in poplar plantations growing on degraded agricultural soil. Enzymatic activity and nutrient availability were always higher in the rhizosphere than in the bulk soil, and rhizosphere effects were more pronounced in the mulch treatment. The results from the present study assume that reactions of enzymatic activity and available nutrients in rhizosphere soils are very sensitive to management practices and that the rhizosphere is an important indicator that reflects conditions and changes in soil fertility.

Seasonal and genotypic variation of water-soluble polysaccharide content in leaves of Cyclocarya paliurus

Cyclocarya paliurus (Batal) Iljinskaja is an important medicinal woody plant due to numerous bioactive natural products in its leaves. As an important bioactive natural product, water-soluble polysaccharides (WSP) in leaves of C. paliurus possess diverse biological activities, such as hypoglycemic, anticancer and free-radical-scavenging activities. To better understand accumulation patterns of WSP in C. paliurus leaves, seasonal, genotypic and positional variations of WSP content were investigated in this study. The results showed that the mean content of WSP in leaves from three crown positions (upper, middle and lower) within an individual was 38.5 mg g−1. ANOVA and Duncans multiple range test indicated that WSP content in leaves of the upper crown was significantly higher than that in the middle and lower crowns, whereas no significant difference was observed between the middle and the lower positions. Seasonal variation of WSP content in the leaves was revealed as a bimodal temporal pattern with the maximum (38.3 mg g−1) observed in April and the second peak (32.3 mg g−1) in October, whereas the lowest WSP content was observed in June (20.12 mg g−1) or in fallen leaves (17.71 mg g−1). Generally, higher contents of WSP accumulated in the maturity/senescence period (from September to mid-November) than during the rapid growth phase (from May to August). Moreover, WSP content varied significantly among 12 provenances, ranging from 22.09 to 34.56 mg g−1, in leaves sampled in October. Our results not only provide knowledge of the accumulative dynamics and genotypic variation of WSP, but also establish a basis for determining the optimal time for harvesting and for extensive selection and breeding programs to improve the content of beneficial compounds in the leaves of C. paliurus in the future.

Chemical Fingerprint and Multicomponent Quantitative Analysis for the Quality Evaluation of Cyclocarya paliurus Leaves by HPLC–Q–TOF–MS

Cyclocarya paliurus is an edible and medicinal plant containing various bioactive components with significant health benefits. A combinative method using high-performance liquid chromatography (HPLC) fingerprint and quantitative analysis was developed and successfully applied for characterization and quality evaluation of C. paliurus leaves collected from 18 geographical locations of China. For the fingerprint analysis, 21 common peaks were observed among the 18 samples, and these peaks were identified by high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC–Q–TOF–MS), while a simultaneous quantification of 16 markers was conducted to interpret the variations of contents of these bioactive compounds among the C. paliurus leaves from different geographical locations. Quantification results showed that the contents of these sixteen investigated compounds varied greatly among the leaves from different locations. The developed new method would be a valuable reference for further study and development of this bioactive plant.

Light quality affects flavonoid production and related gene expression in Cyclocarya paliurus

Understanding the responses of plant growth and secondary metabolites to differential light conditions is very important to optimize cultivation conditions of medicinal woody plants. As a highly valued and multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medical use. In this study, LED-based light including white light (WL), blue light (BL), red light (RL), and green light (GL) were used to affect leaf biomass production, flavonoid accumulation and related gene expression of one-year C. paliurus seedlings in controlled environments. After the treatments of 60 days, the highest leaf biomass appeared in the treatment of WL, while the lowest leaf biomass was found under GL. Compared to WL, the total flavonoid contents of C. paliurus leaves were significantly higher in BL, RL, and GL, but the highest values of selected flavonoids (kaempferol, isoquercitrin and quercetin) were observed under BL. Furthermore, the greatest yields of total and selected flavonoids in C. paliurus leaves per seedling were also achieved under BL, indicating that blue light was effective for inducing the production of flavonoids in C. paliurus leaves. Pearsons correlation analysis showed that there were significantly positive correlations between leaf flavonoid content and relative gene expression of key enzymes (phenylalanine ammonia lyase, PAL; 4-coumaroyl CoA-ligase, 4CL; and chalcone synthase, CHS) in the upstream, which converting phenylalanine into the flavonoid skeleton of tetrahydroxy chalcone. It is concluded that manipulating light quality may be potential mean to achieve the highest yields of flavonoids in C. paliurus cultivation, however this needs to be further verified by more field trials.

Antidiabetic Effect of Cyclocarya paliurus Leaves Depends on the Contents of Antihyperglycemic Flavonoids and Antihyperlipidemic Triterpenoids

Cyclocarya paliurus has been used commonly to treat diabetes in China. However, the effective components and the effect of plant origin remain unclear. In this study, C. paliurus leaves with different chemical compositions were selected from five geographical locations, and their effects on streptozotocin (STZ)-induced diabetic mice were evaluated with both ethanol and aqueous extracts. Glucose levels, lipid levels, and biomarkers of liver and kidney function were measured. The principal components of both C. paliurus ethanol and aqueous extracts from different geographical locations differed quantitatively and qualitatively. Results showed that C. paliurus extracts with better antihyperglycemic effects were characterized by higher contents of total flavonoids, especially quercetin-3-O-glucuronide and kaempferol-3-O-glucuronide. Furthermore, significantly negative correlations were found between triterpenoids contents and lipid levels. These results revealed the potential antihyperglycemic capacity of C. paliurus flavonoids and the antihyperlipidemic effect of C. paliurus triterpenoids. Thus, we suggest that the composition of C. paliurus compounds might help to design therapeutic alternatives for the treatment of diabetes mellitus. However, geographic origins and the extraction solvents can also affect the effectiveness of the treatment as these factors influence the chemical compositions and thereby the biological activities.

Influence of provenance and shade on biomass production and triterpenoid accumulation in Cyclocarya paliurus

Cyclocarya paliurus is a well-known multiple function tree species and has been used for ingredients in functional foods and drug formulations in China. A split-plot randomized design was used to grow three provenances at three different shade levels and effects of provenance and shading on growth and triterpenoid accumulation were assessed. Shading caused significant variation in photosynthetic photon flux density, air temperature and relative humidity, and moreover influenced total triterpenoid content in leaves. However, contents of cyclocaric acid B, cyclocarioside I, and arjunolic acid in the leaves were mainly affected by provenance. A significant seasonal variation of triterpenoid contents was observed in the leaves and the highest content appeared in September. Two-way analysis of variance revealed a significant provenance effect, shading effect and integrated effect between provenance and shading on biomass production. The highest accumulation of total triterpenoid and cyclocarioside I per plant was achieved in Muchuan provenance without shading, while the biggest accumulations of cyclocaric acid B and arjunolic acid were observed in Muchuan provenance with one-layer shading net. The data obtained suggest a complex relationship between environment, genotype and triterpenoid production but highlight that selecting suitable provenance of C. paliurus and optimizing cultivation system would be crucial for a high triterpenoid production.