Effects of Bamboo (Phyllostachys praecox) Cultivation on Soil Nitrogen Fractions and Mineralization

The mineralization of soil organic nitrogen (N) is the key process in the cycling of N in terrestrial ecosystems. Land-use change to bamboo (Phyllostachys praecox) cultivation that later entails organic material mulching combined with chemical fertilizer application will inevitably influence soil N mineralization (Nmin) and availability dynamics. However, the soil Nmin rates associated with various N fractions of P. praecox in response to land-use change and mulching are not well understood. The present study aimed to understand the effects of land-use change to P. praecox bamboo cultivation and organic material mulching on soil Nmin and availability. Soil properties and organic N fractions were measured in a P. praecox field planted on former paddy fields, a mulched P. praecox field, and a rice (Oryza sativa L.) field. Soil Nmin was determined using a batch incubation method, with mathematical models used to predict soil Nmin kinetics and potential. The conversion from a paddy field to P. praecox plantation decreased the soil pH, soil total N, and soil organic matter (SOM) content significantly (p < 0.05); the mulching method induced further soil acidification. The mulching treatment significantly augmented the SOM content by 7.08% compared with the no-mulching treatment (p < 0.05), but it decreased soil hydrolyzable N and increased the nonhydrolyzable N (NHN) content. Both the Nmin rate and cumulative mineralized N were lowest in the mulched bamboo field. The kinetics of Nmin was best described by the ‘two-pool model’ and ‘special model’. The Pearson’s correlation analysis and the Mantel test suggested soil pH was the dominant factor controlling the soil cumulative mineralized N and mineralization potential in the bamboo fields. These findings could help us better understand the N cycling and N availability under mulching conditions for shifts in land use, and provide a scientific basis for the sustainable management of bamboo plantations.

Exogenously Applied Spermidine Alleviates Hypoxia Stress in Phyllostachys Praecox Seedlings Via Changes in Endogenous Hormones and Gene Expression

PurposeHypoxia stress is thought to be one of the major abiotic stresses that inhibits the growth and development of higher plants. Phyllostachys pracecox is sensitive to oxygen and suffers soil hypoxia during cultivation; however, the corresponding measures to mitigate this stress are still limited in practice. In this study, a simulated hypoxia stress with flooding was conducted to investigate the regulatory effect of Spermidine (Spd) on P. praecox seedlings. MethodsIndicators including growth, membrane lipid peroxidation, S-adenosylmethionine decarboxylase (SAMDC), ACC oxidase (ACO) and ACC synthetase (ACS) activities, indole-3-acetic acid (IAA) and abscisic acid (ABA) content, and expression of hormone-related genes in P. praecox were measured. ResultsApplication of 1 mM and 2 mM Spd could alleviate plant growth inhibition and reduce oxidative damage from hypoxia stress. Exogenous Spd significantly (P<0.05) increased SAMDC activity, enhanced ABA and IAA content, and reduced ACO and ACS activities to protect membranes from lipid peroxidation. Moreover, exogenous Spd up-regulated the expression of auxin-related genes auxin responsive factor1 (ARF1), auxin1 protein (AUX1), auxin2 protein (AUX2), auxin3 protein (AUX3) and auxin4 protein (AUX4), and down-regulated the expression of ethylene-related ACO and ACS genes during flooding. ConclusionThe results indicated that exogenous Spd altered hormone concentrations and the expression of hormone-related genes, thereby protecting the bamboo growth. Our data suggest that Spd can be used to reduce hypoxia-induced cell damage and improve the adaptability of P. praecox to flooding stress.

Using the Major Components (Cellulose, Hemicellulose, and Lignin) of Phyllostachys praecox Bamboo Shoot as Dietary Fiber

Bamboo shoots are a renewable and abundant biomass containing cellulose, hemicellulose, and lignin. Although many studies have explored the applications of each of these components in the preparation of biochemicals and biopolymers, few studies have evaluated the utility of these components as a dietary fiber supplement. In this study, a powder consisting of the main components of bamboo shoots (cellulose, hemicellulose, and lignin) was prepared from fresh Phyllostachys praecox shoots and characterized by scanning electron microscopy, infrared spectroscopy, and X-ray diffraction. To evaluate the potential utility of these components as a dietary fiber supplement, we conducted an experiment in which this powder was supplemented in the diet of mice for 7 weeks. The experiment included three diet groups (n = 10/group): a low-fat control diet (LFC), high-fat diet (HFD), and high-fat diet with bamboo shoot powder (HFBSP). Compared with HFD mice, the body weights of LFC and HFBSP mice were lower, indicating that the addition of bamboo shoot powder could reduce the weight gain associated with the HFD. Bamboo shoot powder supplementation could also reduce the levels of triglycerides (TG), blood glucose (GLU), total cholesterol (CHOL), high-density lipoprotein (HDL-C), and low-density lipoprotein (LDL-C) in HFD mice. The fat histology images indicated that obesity was alleviated in HFBSP mice, and the liver histology images indicated that the addition of bamboo shoot powder to the HFD could reduce the risk of fatty liver disease. The addition of bamboo shoot powder to the HFD might also improve the gut microbiota of mice. Thus, the major components of bamboo shoot powder (cellulose, hemicellulose, and lignin) could be used as beneficial natural additives in the food industry.

Effects of Chicken Farming on Soil Phosphorus Availability and Associated Microbial Properties in Lei Bamboo (Phyllostachys praecox) Forest Ecosystems

Background: Bamboo-chicken farming (BCF) is a popular bamboo complex management model in Southeast Asia owing to its high economic benefits. However, the effects of BCF on phosphorus (P) availability and the associated microbial communities in soil remain poorly understood. In this study, we compared the soil properties, P fractions, phosphatase activities, and bacterial community compositions in the surface soil (0–20 cm) of a typical bamboo (Phyllostachys praecox)-chicken farming system under different grazing densities (represented as distances of 5, 15, 25, and 35 m from the henhouse, respectively). The variables were also compared with the soil measurements from an adjacent pure bamboo forest without chicken framing (control site).Results: We observed a significant increase in soil pH, cation exchange capacity (CEC), total N (TN), total P (TP), and available potassium (AK) with increasing grazing density, while soil organic carbon (SOC) showed no significant difference between the sites. The total P accumulation of the soil was also more rapid than that of SOC and TN with increasing grazing density. Labile P and moderately labile P dominated the soil P accumulation under BCF. In particular, Resin-Pi (labile P), NaHCO3-Pi (labile P), and 1 M HCl-Pi (moderately labile P) increased by 100–233%, 83–183% and 414–1314%, respectively, compared with the control values. In contrast, the contribution of labile or moderately labile organic phosphorus to the total phosphorus (Pt) content decreased significantly with increasing grazing density from 38.54% (control) to 17.65% (5-m site). Phosphatase activity also increased with increasing grazing density, which suggests that BCF effectively promoted the mineralization of soil Po. A redundancy analysis showed that the changes in bacterial community structure were closely related to Resin-Pi and 1 M HCl-Pi (r2 = 0.938 and 0.958, respectively). The relative abundances of the phosphobacteria Flavobacterium, Pseudomonas, Streptomyces, and Arthobacter increased with increasing grazing density, while the abundance of Burkholderia decreased at the 5-m site. Inorganic P (Resin-Pi, NaHCO3-Pi, and 1 M HCl-Pi) was positively correlated with the abundances of Flavobacterium, Pseudomonas, and Arthrobacter but negatively correlated with the abundance of Burkholderia; this highlights the different functional bacteria involved in P cycling. Conclusions: We conclude that BCF generally increases soil P availability and supply, and the changes in the P forms were closely related to the changes in soil bacterial community composition. However, excessive grazing density or long-term BCF practices can cause soil nutrient imbalance, labile and moderately labile P accumulation, and P leaching. Therefore, appropriate grazing densities and/or an interval of no grazing are required under the BCF model for effective and sustainable bamboo forest management.