蔬菜穴盘苗自动精确移栽组合式取苗机构设计与测试

Precision planting is one key point of precision agriculture.A doorframe type swing seedling pick-up device for the automatic precise field transplanter was designed and tested in a laboratory.The seedling device could automatically extract seedlings from growing trays, transfer them, and release them into the planting unit where they were to be precisely transplanted into the ground.It consisted of a path manipulator and two grippers.The path manipulator for seedling extraction was constructed with creative design of Ⅱ-type mechanism combination in series.It consisted of an oscillating guide linkage mechanism and a grooved globoidal cam mechanism.According to the planned seedling pick-up trajectory, the design of the path manipulator for seedling extraction was finished with a set of the closed loop vector equation.The gripper was a pincette-type mechanism using the pick-up pins to penetrate into the root mass for seedling extraction.It consisted of multiple pick-up pins, U-type pull rod, shaft, stop block, compression spring and frame.The mechanical dimensions of the gripper were determined by the tray size and plant characteristic with a set of rectangular equations and the boundary constraint conditions.The final gripper was developed on the basis of cultural practice for vegetable seedling in China.A prototype of the seedling pick-up device was constructed to examine whether its working efficacy was satisfactory or not.According to the analysis on the work process, the seedling pick-up device could precisely complete a work cycle of approaching, penetrating, extracting, transferring, erecting and discharging a seedling.Taking pepper seedlings, tomato seedlings and cucumber seedlings as the transplanting objects, the performance tests were conducted to evaluate the practicality and adaptability of the pick-up device.The laboratory evaluation showed that the pick-up device equipped with two grippers could extract 70 seedlings per minute with an average success ratio of 90.49%.The quality of extracting seedlings was satisfactory.     

一种模拟土壤养分提取及及植物吸收的装置研究

In situ evaluating the availability of soil nutrients has been a challenge. In this study, a new type of Device for Simulating Soil Nutrient Extraction and Plant Uptake (DSSNEPU) and its operating procedures were introduced. The device consists of a sampling tube, a fluid supply system, a low pressure system, a tube sheath and an elution cylinder. The sampling tube was firstly soaked in the solution of 0.5 mol L 1 NaHCO 3 and then buried into soils. The fluid supply system was connected to the sampling tube and the deionized water was supplied. During the period, low pressure system started a vacuum for 3 min every 10 min interval. After extraction, the sampling tube was removed and the nutrients on the sampling tube were eluted with 0.5 mol L 1 HCl. The elution solution was used for nutrient measurement. The amounts of P and K extracted by DSSNEPU reached the maximal values after 4 h. No significant increases of P and K were observed for longer extraction duration. The optimal temperature for extracting P and K was 30 C in this experiment. Extracted P and K were increased by 83.3% and 84.6% with the employment of low pressure system in comparison to those without employing low pressure system. Correlation analysis indicated that P and K extracted by DSSNEPU were highly correlated with those by conventional chemical extraction and by plant uptake. The above results suggest that this device is applicable to assess the availability of nutrients in soils.     

伊朗一些石灰性土壤中锌解吸动态研究

Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants. Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran. Soils were equilibrated with 0.005 mol L-1 DTPA solutions for 0.25 to 192 h. The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment. Desorption kinetic data was fitted to pseudo-first-order kinetic model. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h. The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn: a labile fraction (Q1 ), quickly extracted with a rate constant k1 , and a slowly labile fraction (Q2 ), more slowly extracted with a rate constant k2 . The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.     

化学萃取修复尾渣土壤的金属形态变化特征

The efficiency of EDTA, HNO3 and CaCl2 as extractants to remove Pb, Zn and Cu from tailing soils without varying soil pH was investigated with distributions of Pb, Zn and Cu being determined before and after extraction using the sequential extraction procedure of the optimized European Community Bureau of Reference （BCR）. Results indicated that EDTA and HNO3 were both effective extracting agents.The extractability of extractants for Pb and Zn was in the order EDTA 〉 HNO3 〉 CaCl2, while for Cu it was HNO3 〉 EDTA 〉 CaCl2. After EDTA extraction, the proportion of Pb, Zn and Cu in the four fractions varied greatly, which was related to the strong extraction and complexation ability. Before and after extraction with HNO3 and CaCl2, the percentages of Pb, Zn and Cu in the reducible, oxidizable and residual fractions changed little compared to the acid-extractable fraction. The lability of metal in the soil and the kinds of extractants were the factors controlling the effects of metal extraction.     

PESA对污泥中铬的萃取研究

An environmentally benign biodegradable chelant,polyepoxysuccinic acid(PESA),was used to separate heavy metals from sewage sludge from the Shanghai Taopu Wastewater Treatment Plant,China,based on chemical extraction technology.The extraction of chromium(Cr) from sewage sludge with an aqueous solution of PESA was studied under various conditions.It was found that the extraction of Cr using PESA was more efficient than that using ethylenediaminetetraacetic acid(EDTA) and S,S-ethylenediaminedisuccinic acid(EDDS) under similar conditions.PESA was capable of extracting Cr from the sewage sludge,and the extraction efficiency was obviously dependent on both the pH and the concentration of the chelating reagent.The extraction efficiency decreased gradually with increasing pH,and the dependence on pH decreased as the concentration of PESA increased.The extraction efficiency reached 58% under conditions of pH = 4 and a ratio of PESA to total heavy metals of 10:1.The extraction efficiency was maintained above 40% within the pH range from 1 to 7 at the high ratio of PESA to total heavy metals of 10:1.Comparing the contents of heavy metals in the sewage sludge before and after the extraction,it was found that the extracted Cr came mainly from the reducible and oxidizable fractions.     

中甸泥炭中胡敏酸的分离及其吸附特征

The Zhongdian swamp meadow in Zhongdian, China is well known as “Shangri-la”, where the peat has never been studied for its potential to interact with pollutants. Humic acid (HA) was extracted from Zhongdian peat using two methods, namely sodium pyrophosphate extraction (SPE) and dilute base extraction (DBE), and characterized for its functional groups and sorption property. The HAs extracted by both methods contained several active functional groups and had large external specific surface areas. The adsorption mechanism of methylene blue onto HAs was interpreted as Langmuir sorption. SPE-HA showed higher sorption capacity because of its larger specific surface area, whereas the extraction yield of DBE-HA was twice that of SPE-HA. Kinetics modeling indicated that the sorption of methylene blue was a two-component first order reaction. The component with the higher rate constant also showed higher sorption capacity. No pH effect was observed for methylene blue sorption on HA in our experimental design, and the sorption decreased as the temperature increased.     

土壤中有机磷农药的提取纯化和气相色谱-氮磷检测器测定

The objectives of this study were to optimize instrumental parameters and conditions for analysis of selected organophosphorus pesticides (OPPs) by gas chromatography (GG) with nitrogen-phosphorus detection (NPD) (GG-NPD); to select an appropriate solvent system; to conduct a comparison of sonication and shaking extractions; and to select an appropriate procedure for extracting organophosphorus pesticides from soils. Procedure Ⅰ consisted of n-hexane or petroleum ether together with acetone used as solvents, while Procedure II contained several solvents including acetone,methanol, dichloromethane, and n-hexane or petroleum ether. Experimental results indicated that a mixture of petroleum ether/acetone (2:1, v/v) could be used in place of n-hexane/acetone (2:1, v/v) as it was a less expensive solvent system.In addition, shaking under a water bath at 20℃ was more effective than sonication. Also, Procedure Ⅰ was more effective,safer, and more timesaving than Procedure Ⅱ. Procedure Ⅰ was applied to three soil types of different organic matter content, with recoveries of the OPPs from the yellow-brown soils, which had a higher organic matter content, being lower than those from the yellow and red soils.     

基于遥感的区域生态安全综合评价研究——以三峡库区忠县为例

Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response (DPSER) model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed: 1) scale conversion of ecological security regime results from pixel to small watershed; and 2) scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.     

Integrated Evaluation of Ecological Security at Different Scales Using Remote Sensing： A Case Study of Zhongxian County,the Three Gorges Area, China

Based on related literature and this research, an ecological security evaluation from the pixel scale to the small watershed or county scale was presented using remote sensing data and related models. With the driver-pressure, state and exposure to pollution-response （DPSER） model as a basis, a conceptual framework of regional ecological evaluation and an index system were established. The extraction and standardization of evaluation indices were carried out with GIS techniques, an information extraction model and a data standardization model. The conversion of regional ecological security results from the pixel scale to a small watershed or county scale was obtained with an evaluation model and a scaling model. Two conceptual scale conversion models of regional ecological security from the pixel scale to the county scale were proposed： 1） scale conversion of ecological security regime results from plxel to small watershed; and 2） scale conversion from pixel to county. These research results could provide useful ideas for regional ecological security evaluation as well as ecological and environmental management.     

土壤侵蚀磁性示踪剂的研制及其示踪效果研究

Soil erosion, which includes soil detachment, transport, and deposition, is one of the important dynamic land surface processes. The magnetic tracer method is a useful method for studying soil erosion processes. In this study, five types of magnetic tracers were made with fine soil, fly ash, cement, bentonite, and magnetic powder (reduced iron powder) using the method of disk granulation. The tracers were uniformly mixed with soil and tested in the laboratory using simulated rainfall and inflow experiments to simulate the interrill and rill components of soil erosion, in order to select one or more tracers which could be used to study detachment and deposition by the erosive forces of raindrops and surface flow of water on a slope. The results showed that the five types of magnetic tracers with high magnetic susceptibility and a wide range of sizes had a range of 0.99-1.29 g cm?3 in bulk density. In the interrill and rill experiments, the tracers FC1 and FC2 which consisted of ?y ash and cement at ratios of 1:1 and 2:1, respectively, were transported in phase with soil particles since the magnetic susceptibility of sediment approximated that of the soil which was uneroded and the slopes of the regression equations between the detachment of sediment and magnetic tracers FC1 and FC2 were very close to the expected value of 20, which was the original soil/tracer ratio. The detachment and deposition on slopes could be accurately reffected by the magnetic susceptibility differences. The change in magnetic susceptibility depended on whether deposition or detachment occurred. However, the tracer FS which consisted of fine soil and the tracers FB1 and FB2 which consisted of fly ash and bentonite at ratios of 1:1 and 2:1, respectively, were all unsuitable for soil erosion study since there was no consistent relationship between sediment and tracer detachment for increasing amounts of runo?. Therefore, the tracers FC1 and FC2 could be used to study soil erosion by water.     

污泥加石灰后作为肥料用于玉米生长中施肥研究

The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, as an agricultural fertilizer. The agricultural soil amended with 250 g kg^-1 sewage sludge with or without lime treatment was used for the growth of the common local grain crop, maize （Zea maize）. The mobility of the trace and toxic metals in the sludge samples was assessed by applying a modified BCR sequential extraction procedure. The single extraction procedure was comprised of the application of a mild extractant （CaCl2） and water, for the estimation of the proportion of easily soluble metal fractions. To check the precision of the analytical results, the concentrations of trace and toxic metals in every step of the sequential extraction procedure were summed up and compared with total metal concentrations. The plant-available metal contents, as indicated by the deionized water and 0.01 mol L^-1 CaCl2 solution extraction fractions and the exchangeable fraction of the sequential extraction, decreased significantly （P 〈 0.05） with lime application because of the reduced metal availability at a higher pH, except in the cases of Cd and Cu, whose mobility was slightly increased. Sludge amendment enhanced the dry weight yield of maize and the increase was more obvious for the soil with lime treatment. Liming the sewage sludge reduced the trace and toxic metal contents in the grain tissues, except Cu and Cd, which were below the permissible limits of these metals. The present experiment demonstrates that liming was an important factor in facilitating the growth of maize in sludge-amended soil.     

二氧化碳施肥对番茄幼苗生长与养分吸收利用的影响

Exposing tomato seedlings to elevated CO2 concentrations may have potentially profound impacts on the tomato yield and quality. A growth chamber experiment was designed to estimate how different nutrient concentrations influenced the effect of elevated CO2 on the growth and nutrient uptake of tomato seedlings. Tomato (Hezuo 906) was grown in pots placed in controlled growth chambers and was subjected to ambient or elevated CO2 (360 or 720 μL L-1), and four nutrient solutions of different strengths (1/2-, 1/4-, 1/8-, and 1/16-strength Japan Yamazaki nutrient solutions) in a completely randomized design. The results indicated that some agricultural characteristics of the tomato seedlings such as the plant height, stem thickness, total dry and fresh weights of the leaves, stems and roots, the G value (G value = total plant dry weight/seedling age),and the seedling vigor index (seedling vigor index = stem thickness/(plant height × total plant dry weight) increased with the elevated CO2, and the increases were strongly dependent on the nutrient solution concentrations, being greater with higher nutrient solution concentrations. The elevated CO2 did not alter the ratio of root to shoot. The total N, P, K, and C absorbed from all the solutions except P in the 1/8- and 1/16-strength nutrient solutions increased in the elevated CO2 treatment. These results demonstrate that the nutrient demands of the tomato seedlings increased at elevated CO2 concentrations.     

土壤非交换态钾与结构态钾能够区分吗?（英文）

Nonexchangeable K(NEK) is the major portion of the reserve of available K in soil and a primary factor in determining soil K fertility.The questions of how much NEK is in soils and how to quantify total NEK in soils are so far still unclear due to the complicated effects of various minerals on K fixation.In this study,the NEK in 9 soils was extracted with sodium tetraphenylboron(NaBPh_4) for various time periods longer than 1 d.The results showed that the NEK extracted by NaBPh4 gradually increased with time,but showed no more increase after the duration of extraction exceeded 10-20 d.As the temperature increased from 25 to 45 ℃,the duration to obtain the maximum extraction of NEK was reduced from 20 to 10 d,and the maximum values of NEK released at both temperatures was almost the same for each soil.The maximum NEK(MNEK) of the 9 soils extracted by NaBPh.4 varied from3074 to 10081 mg kg~(-1),accounting for 21%-56%of the total soil K.There was no significant correlation between MNEK released by NaBPh4 and other forms of K,such as NH_4OAc-extracted K,HNOg-extracted K and total K in soils,which indicates that NEK is a special form of K that has no inevitable relationship to the other forms of K in soils.The MNEK extraction by NaBPh4 in this study indicated that the total NEK in the soils could be differentiated from soil structural K and quantified with the modified NaBPlu method.The high MNEK in soils made NEK much more important in the role of the plant-available K pool.How to fractionate NEK into different fractions and establish the methods to quantify each NEK fraction according to their bioavailability is of great importance for future research.     

Kinetic Characteristics of Nitrate Uptake by Wheat and Rape and Their Determination

15－day old seedlings of wheat and rape were grown in a series of solutions with different concentrations of KNO3 for a definite period of time.The changes in NO3^- concentration of the solutions were determined by the double ion-selective electrode method,and then the amount of NO3^- taken up by the plants was estimated and values of Km and Imax of the Michealis-Mentan equation were calculated.Results show that both the method and conditions of determination affected the values of Km and Imax.For example,the Km value was appreciably reduced when the volume of culture solution was increased or when the duration of nutrient uptake was shortened;the Km value obtained with short-term depletion method was higher than that obtained with long-term one.Similar Variations were found for the values of Imax.There was a considerable difference in the characteristics of uptake kinetics between wheat and rape when determined under the same conditions of determination.The isotherm of NO3^- uptake by wheat could be separated into saturated and unsaturated parts,and when the concentration of NO3^- exceeded 180μM,the relationship between the rate of NO3^- uptake and NO3^- concentration tended to be linear.However,the isotherm of NO3^- uptake by rape was found to fit the Michealis-Menten equation and no linear relationship could be found.     

磷酸铁盐涂层: 控制黄铁矿氧化的新手段

A novel coating technique was develped for controlling pyrite oxidation .The technique involved leaching pyrite particles with a solution containing low concentrations of phosphate and hydrogen peroxide.During the leaching rpocess,the iron released from pyrite by hydrogen proxide was precipitated by phosphate as a ferric phosphate coating .This coating was shown to be able to effectively prevent pyirte from oxidation and it could be established at the expense of only surface portions of pyrite.The emergence of this technique could provide a unique potential route for abating acid mine draingage and reclaiming sulfide-containing degraded mining land.     

聚环氧琥珀酸对污泥中镉的萃取作用

Polyepoxysuccinic acid (PESA), as an environmental benign biodegradable chelant, was used to remove heavy metals from the sewage sludge of Shanghai Taopu Wastewater Treatment Plant. The extraction of cadmium (Cd) from sewage sludge using aqueous solution of PESA was studied. It was found that PESA was capable of extracting Cd from the sludge, and the extraction efficiency was dependent on both pH and the concentration of the chelating reagent. The extraction efficiency decreased gradually with increasing of pH, whereas the dependency on pH decreased as the concentration of PESA increased. In the case of the high PESA to total metal ratio, e.g., 10:1, the extraction efficiency reached above 70% within the pH range from 1 to 7. The highest extraction efficiency obtained in the experiment was 78％. By comparing the contents of the heavy metals in sewage sludge before and after the extraction, it was found that the extracted Cd came mainly from the four fractions: acid-soluble, reducible, oxidizable, and water-soluble fractions.     

阳离子交换膜技术的评估及钾临界值的估测

Soil and tissue analyses are usually used in identifying potassium(K) deficiencies and predicting K fertilizer requirements of crops.The critical levels of both soil and fresh leaf tissue at seventh leaf stage were developed and assessed for canola,chickpea and sunflower grown on two saskatchewan,soils,with six rates of K fertilizer supply.in a growth chamber experiment.The available potassium in soils was detemined by two methods:1)resin strip extraction,and 2)NH4OAC extraction.The potassium in fresh leaves was determined at seventh leaf stage by a simple procedure using a common garlic press and injector to extract the plant sap and testing the sap with a handheld ion selection electrode meter,The results showed significant relationships between the resin strip extractable K and NH4OAC extractable K,and between the plant uptake of total K and the supple of available K in the soils determined by the two methods.Good relationships were also found between the potassium in fresh leaves and the plant uptake of totak K for canola,chickpea and sunflower.The resin strip extraction for K was calibrated using common NH4OAC extraction,and recommended for routine analyses because of its simplicity and sensitivity.     

热带土壤上连续9年施入污水污泥后重金属Zn, Cd和Pb的分离研究

A long-term field experiment was carried out in the experiment farm of the Sao Paulo State University, Brazil, to evaluate the phytoavailability of Zn, Cd and Pb in a Typic Eutrorthox soil treated with sewage sludge for nine consecutive years, using the sequential extraction and organic matter fractionation methods. During 2005-2006, maize (Zea mays L.) was used as test plants and the experimental design was in randomized complete blocks with four treatments and five replicates. The treatments consisted of four sewage sludge rates (in a dry basis) : 0.0 (control, with mineral fertilization), 45.0, 90.0 and 127.5 t ha^-1, annually for nine years. Before maize sowing, the sewage sludge was manually applied to the soil and incorporated at 10 cm depth. Soil samples (0-20 cm layer) for Zn, Cd and Pb analysis were collected 60 days after sowing. The successive applications of sewage sludge to the soil did not affect heavy metal (Cd and Pb) fractions in the soil, with exception of Zn fractions. The Zn, Cd and Pb distributions in the soil were strongly associated with humin and residual fractions, which are characterized by stable chemical bonds. Zinc, Cd and Pb in the soil showed low phytoavailability after nine-year successive applications of sewage sludge to the soil.     

藻(Ziziphus spina-christi)体内外无性繁殖的方法

Christ‘s thorn (Ziziphus spina-christi L. Desf.) is ecologically and economically important in Iran. Since it is a crosspollinated plant with a wide range of genetic variability, an investigation was carried out to determine the best method for mass and clonal propagation. Three vegetative methods were examined, including 1) cutting, where shoots with a 22-25 cm length and three shoot diameters were treated with two culture media; 2) layering, where air layering and trench layering treatments consisted of three growth regulators at three levels of concentration; and 3) tissue culture with nodal segments bearing axillary buds that were removed from shoots of mature trees at different seasons. Several experiments were carried out to determine the best disinfectant chemical, the best culture method, the best season, the appropriate explant characteristics and media type. Rooting was successful only on the sandy beds for cuttings with more than 8.0 mm diameter. For the trench layering method, only one specimen in one replicate rooted a very small root, while for the air layering method, only seedlings with growth regulator treatments rooted successfully. The best season for explant harvesting was determined as mid summer, and among the disinfecting treatments, Ca(OCI)2 at a concentration of 0.5g kg^-1 for 20 minutes was the best. There were no significant differences for shoot weight and length with a Murashige and Skoog (MS) medium with and without a hormone.     

Difference in selenium accumulation in shoots of two rice cultivars

Two japonica rice （Oryza sativa L.） cultivars, Xiushui 48 and S. Andrea, differing in their ability to accumulate Se in the grain （as high as a three-fold difference）, were compared for selenium （Se） accumulation in their shoots when their growth media was supplied with different forms of Se. Results indicated that when treated with 0.25μmol L^-1 Na2SeO3, Xiushui 48 accumulation of Se in the shoots was significantly more rapid （P〈0.05） than S. Andrea, probably because of greater Se uptake and transport in Xiushui 48. Xiushui 48 rice seedlings had a higher shoot-Se accumulation rate and absorbed selenocysteine （Se-Cys） more rapidly than S. Andrea seedlings. However, when treated with Se as 0.25μmol L^-1 selenomethionine （Se-Met）, the S. Andrea seedlings＇ accumulation rate was significantly greater （P〈0.05） than that of Xiushui 48. Possibly, the high Se accumulation rate of Xiushui 48 seedling shoots compared to S. Andrea shoots was the result of a higher capacity of Xiushui 48 to transform selenite to organic Se compounds and a higher selenite uptake rate.