[Uptake and Accumulation of Cadmium and Zinc by Two Energy Grasses: A Field Experiment].

The remediation potential of large biomass energy grasses in cadmium-contaminated soil remains ambiguous. A field experiment was carried out in a cadmium-contaminated farmland using two energy grasses and two control plants. The two energy grasses were hybrid pennisetum (Pennisetum americanum×P. purpureum, PAP) and purple elephant grass (P. purpureum 'Purple', PPP), and the two control plants were Iris lactea var. chinensis (ILC) and a cadmium hyperaccumulator, Noccaea caerulescens (NC). The results showed that the aboveground biomass of PAP was the largest among the four plants, and 126 and 36 times that of NC and ILC, respectively, but no significant difference with that of PPP. The concentrations of cadmium and zinc in the shoots and roots of NC were significantly higher than in the other plants. Zinc concentrations in the shoots and roots of ILC were lower than in the other plants, while cadmium concentrations were significantly higher than in PAP and PPP (P<0.05). The amounts of cadmium and zinc accumulated in the shoots of PPP were the highest among the four plants, while cadmium concentrations in the shoots and roots of PPP were significantly lower than in ILC and NC (P<0.05). Cadmium amounts accumulated in PPP shoots were 7.0 and 4.1 times that of ILC and NC, respectively. Zinc amounts accumulated in PPP shoots were 41 and 11 times that of ILC and NC, respectively (P<0.05). Cadmium accumulation in the shoots of PAP was 19.4% lower than in PPP, and zinc accumulation had no significant difference with that of PPP. NC, having a bioconcentration factor of shoot (BCFS) and a translocation factor (TF) for cadmium and zinc both larger than 1, is usable for phytoextraction of soils contaminated by cadmium and zinc. ILC, having a bioconcentration factor of root (BCFR) larger than 1 and a TF lower than 1 for cadmium, is usable for the phytostabilization of soils contaminated by cadmium. PPP, having a BCFR larger than 1 and a TF lower than 1 for zinc, can be used in the phytostabilization of soils contaminated by zinc. Under field conditions, PPP and PAP showed great potential for the extraction and removal of cadmium and zinc from soil due to their large biomass and ability to produce economic benefits, have good application prospects.

[Prediction of Cellulose, Hemicellulose, Lignin and Ash Content of Four Miscanthus Bio-Energy Crops Using Near-Infrared Spectroscopy].

Biomass energy is being industrialized rapidly in China in recent years, whereas, research on energy grass is still in primary stage. Only if near-infrared spectroscopy mode was constructed which was used to predict the lignin, cellulose and hemicellulose contents in energy crop, the varieties screening, performance evaluation and on-line control of industrialization would be facilitated. In this study, the prediction model for quality indices (cellulose, hemicellulose, lignin and ash) of four energy grass (Miscanthus) was built using Fourier transform near-infrared (FT-NIR) spectroscopy combined with partial least squares regression (PLSR), and the impacts exerted by particle size on the model were also revealed. The results showed that (1) the root mean error of cross validation (RMSECV) of cellulose, hemicelluloses and lignin contents were 1.35% (R = 0.88), 0.39% (R = 0.91) and 0.35 (R2 = 0.80), respectively in stalk and 0.72% (R = 0.88), 0.85% (R2 = 0.85) and 0.44 (R2 = 0.87), respectively in leaf. The model showed good performance in prediction of corresponding contents in unknown samples, however, no satisfying performance in ash content. (2) Both 2 mm and 0.5 mm grades of particle size can meet accuracy requirements of the model. But considering the time and labor cost, 2 mm grade was suggested for model building.

[Impacts of salt stress on the growth and physiological characteristics of Panicum virgatum seedlings].

An experiment was conducted in an artificial climate chamber to study the growth and physiological characteristics of switchgrass (Panicum virgatum) seedlings exposed to 0, 50, 100, 150, and 200 mmol x L(-1) of NaCl solutions. With the increasing concentration of the NaCl, the seedling growth was obviously inhibited. The plant height decreased, leaves became smaller, photosynthetic leaf area and net photosynthetic rate reduced, and dry matter accumulation decreased significantly, presenting the general traits of glycophyte. Meanwhile, the seedlings also showed relatively high salt tolerance. After exposed to 200 mmol x L(-1) of NaCl for 30 days, the seedlings still survived, with the green leaf area per plant and net photosynthetic rate being 491.9 cm2 and 0.93 micromol CO2 x m(-2) x s(-1), respectively. In this experiment, the salt tolerance threshold for P. virgatum was 178.6 mmol L(-1) when taking 50% drop in biomass as the standard.

[Study on the determination of total nitrogen (TN) in different types of soil by near-infrared spectroscopy (NIS)].

In the present paper, the feasibility of determination of total nitrogen (TN) content in different types of soil based on NIS technology was studied. Some surface and subsurface soil samples were collected from Jiangsu, Henan, Shanxi, Hebei and Jilin province in China, on behalf of paddy, calcareous, loess, coastal alluvial and black soil types separately. After being air-dried, milled and screened, the scanned spectra were obtained by near-infrared spectrometer using the sample with diameter below 1 millimeter, meantime the content of TN was measured with the traditional Kelvin method. A model between TN content and spectrum was established and also it was modified through some spectrum pretreatment using the OPUS software. Then a best model was chosen with root mean squares of crosscheck (RMSECV) being the lowest. Finally the stability and application of the model was discussed through quantitative analysis. The results showed that a good model can be separately established in each province using the surface soil from the same area on behalf of the same soil type, whose RMSECV were within 0.01% on average, and the correlation efficient was above 0.85 basically. The model established using the surface soil can be well used for analysis of TN content in other surface and subsurface soil from the same area whose TN was within the range of the model. The root mean squares of prediction (RMSEP) and correlation efficient of the quantitative analysis were at about 0.01% and 0.80 separately. However, maybe affected by soil types, the model established in one area had certain limitations in the application to other areas even as its TN content was within the range of the model. Whenas, choosing some data from each area randomly to form a new sample group can establish a good new integrated model with RMSECV and correlation efficient being 0.010 2% and 0.985 6 respectively and that can be well used to predict TN content in soil from each area.

[Growth vitality and pollutants-removal ability of plants in constructed wetland in Beijing region].

Nine aquatic plant species commonly found in northern China were transplanted in a horizontal subsurface flow constructed wetland in Beijing region to study their growth vitality in the wetland and their removal ability to the pollutants in domestic sewage. The results showed that the wetland's front unit had greater contribution to the COD, TN and TP removal than the rear ones, and all test plant species could grow well in the wetland. After growing for 112 days, different plant species had significant differences in their N and P contents and total biomass (P <0.05). For most species, the N and P contents were higher in underground than in aboveground part, and the biomass ratio of under-/aboveground part (U/A) was close to or exceeded 1. The accumulated N and P in the plants ranged from 1.36 to 7.89 g m(-2) and from 0.19 to 1.07 g m(-2), respectively, and the N and P accumulation in plants were more affected by plant biomass than by its N and P contents. Among the test plant species, Iris pseudacorus ranked the first in setting up the constructed wetland, followed by Typha angustifolia, Acorus calamus, and Triarrhena sacchariflora, whereas Alisma plantago-aquatica and Arundo donax were not recommended due to their sensitivity in cold winter in northern China.

[Index system and fuzzy synthetic assessment in landscape evaluation of ornamental grasses].

A composite index system for landscape evaluation of ornamental grasses was built from the aspects of ecological constraints, resources requirement and aesthetic values, and the ornamental grass landscapes in Beijing Botanical Garden and in Nanzhongzhou public green spaces were evaluated by fuzzy synthetic assessment (FSA) method. The results showed that the scores of "very apt" for the ornamental grasses in Beijing Botanical Garden and in Nanzhongzhou public green spaces were 0.459 and 0.413, respectively, while those of "apt" for the two landscapes were 0.302 and 0.301, respectively. The evaluation results were consistent with the public feedbacks, suggesting that the composite index system and FSA method were applicable for the landscape evaluation of ornamental grasses.