白首乌地上部分多糖的微波提取技术研究

[目的]提取白首乌地上部分多糖并测定含量。[方法]采用微波技术,通过正交试验探讨白首乌(Cynanchum auriculatum Aerial Parts)地上部分多糖提取的最佳工艺,用苯酚-硫酸法在波长490 nm处测定吸光度。[结果]结果表明,用苯酚-硫酸法在波长490 nm处测定吸光度,得白首乌地上部分粗多糖含量为2.57%。微波提取白首乌地上部分多糖的最佳工艺参数为料液比1∶25、微波强度80%、提取时间80 s。[结论]该研究为白首乌地上部分资源的开发提供依据。     

Forty years of lowland monsoon rainforest expansion in Kakadu National Park, Northern Australia

Monsoon rainforest is a key habitat in sustaining the natural and cultural values for which Kakadu National Park is World Heritage listed. The integrity of monsoon rainforest boundaries was thought to have been threatened by an increase in fire and feral animal disturbance over the last few decades. However, as no broad-scale assessment of rainforest boundary change had been undertaken, the rate and even direction of boundary change remained uncertain. In this study changes to the boundaries of 50 monsoon rainforest patches were assessed using temporal sequences of digitised aerial photography, with a view to understanding the relative importance of the drivers of change. Boundaries were compared for each of the years 1964, 1984, 1991 and 2004. Vegetation types were manually classified for each year with a 20 × 20 m point lattice, based primarily on the distance between tree crowns. Transition matrices, size-class distributions and fragmentation indices were calculated. Field samples of a subset of 30 rainforest patches supported the accuracy of the GIS-based mapping of rainforest boundaries. Rainforest patches increased in size between 1964 and 2004 by an average of 28.8%, with an average area increase of 4.0 ha. The expansion is likely to have been primarily driven by increases in variables such as rainfall and atmospheric CO₂, but has been strongly mediated by fire regime. This project has provided land managers with an appreciation of the extent and causes of landscape-scale changes to rainforest boundaries. This will contribute to ‘adaptive management’ programs, especially with respect to fire management.     

秋水仙素注射大蒜花苞诱导四倍体的研究

为获得染色体加倍的大蒜植株,用0.05%、0.10%、0.15% 和0.20% 的秋水仙素注射苍山糙蒜和金蒜3 号的花苞,并在不同生长调节剂组合的MS 培养基上培养花苞内形成的气生鳞茎,当再生体系建立后,对根尖进行倍性鉴定。结果表明,MS 基本培养基添加0.05 mg·L-1 NAA 和2.0 mg·L-1 KT 能诱导较多的气生鳞茎萌发,直径4～5 mm 的气生鳞茎萌发率最高,且苍山糙蒜气生鳞茎的萌发率整体比金蒜3 号高。秋水仙素注射花苞后,金蒜3 号的花苞死亡率远远高于苍山糙蒜。随着秋水仙素浓度增大,花苞内形成气生鳞茎数不断降低,染色体加倍率升高。苍山糙蒜以0.20% 秋水仙素浓度处理下四倍体诱导率最高,为7.69%;金蒜3 号以0.15% 秋水仙素浓度处理下四倍体诱导率最高,为11.76%。     

Variograms of Ancillary Data to Aid Sampling for Soil Surveys

To provide reliable estimates for mapping soil properties for precision agriculture requires intensive sampling and costly laboratory analyses. If the spatial structure of ancillary data, such as yield, digital information from aerial photographs, and soil electrical conductivity (EC) measurements, relates to that of soil properties they could be used to guide the sampling intensity for soil surveys. Variograms of permanent soil properties at two study sites on different parent materials were compared with each other and with those for ancillary data. The ranges of spatial dependence identified by the variograms of both sets of properties are of similar orders of magnitude for each study site. Maps of the ancillary data appear to show similar patterns of variation and these seem to relate to those of the permanent properties of the soil. Correlation analysis has confirmed these relations. Maps of kriged estimates from sub-sampled data and the original variograms showed that the main patterns of variation were preserved when a sampling interval of less than half the average variogram range of ancillary data was used. Digital data from aerial photographs for different years and EC appear to show a more consistent relation with the soil properties than does yield. Aerial photographs, in particular those of bare soil, seem to be the most useful ancillary data and they are often cheaper to obtain than yield and EC data.     

A comparison of different survey methods for assessing gap parameters in old-growth forests

Examining the actual state of canopy gaps in forests is critically important for evaluating forest community structure and dynamics, and for comparing gap disturbance regimes in different forests. We, therefore, re-examined our own previously published data from three studies of three different gap survey methods - the Belt transect method, the canopy coverage census method, and an aerial photography method - in order to ascertain how gap parameters (area, size and density of gaps, and related gap characteristics) obtained from these methods differ from each other. We found that the Belt transect method is easy to apply and practical in the field, and the method used for gap measurement is simple. Mean gap size and size distribution obtained using the Belt transect method were not different statistically from those of the other gap survey methods, and quantified gap parameters were in the range recorded for other forests of the world. For preliminary studies of gap dynamics in different forest types, an easy, speedy and workable gap survey method is needed. In addition, surveying a large number of gaps and a large area improve the accuracy of the method. We conclude that the Belt transect method is most suitable method for preliminary gap surveys in the field.     

Soil carbon mapping using on-the-go near infrared spectroscopy, topography and aerial photographs

Efficient tools for accurate soil carbon (SC) mapping are imperative for large scale assessment of total SC stocks and their changes in time as well as for site-specific tailoring of agricultural management practices. On-the-go near infrared (NIR) reflectance spectroscopy has been used recently in aid to the conventional, laborious and expensive soil analyses, since NIR measurements are taken in-situ quickly and non-destructively. However, NIR spectrum data need to be effectively calibrated with conventionally measured SC. Our objectives are to compare calibration approaches, including pre-processing transformations (Savitzky-Golay derivatives, standard normal variate and mean centering) and multivariate statistical methods (principal component regression, partial least squares, partial least squares leaving one-outlier-out) for using NIR spectra data as SC predictor, to evaluate NIR reliability in predicting SC under low carbon contents typical for Midwest Alfisols; and finally to compare predictions of SC by using three sources of auxiliary information (NIR spectral data, visible-NIR reflectance obtained from aerial photographs and topographical features). No improvements in calibration accuracy were observed when using pre-processing transformations. Partial least squares (RMSE = 1.90) tended to perform better than principal component regression (RMSE = 1.96); especially when spectral-NIR outliers are dropped (RMSE = 1.68). Our results suggested that visible-NIR data from aerial photographs used along with topographical attributes outperformed on-the-go spectral NIR data. Topographical data improved prediction in the models with aerial photograph visible-NIR data; however no improvement was noticed when used with spectral-NIR data. Though, NIR spectral data is frequently used as a proxy for SC prediction, we notice that this auxiliary information is not well suited under all scenarios. Particularly, when SC levels are low and the range of SC data is narrow, as in this study, NIR was only moderately successful in predicting SC.     

我国农业无人机航空植保技术现状与发展趋势分析

无人机航空植保技术是一种现代化的施药方式,适合复杂地形和小面积作业,在我国南方水田、丘陵山地等地有着较好应用前景。但目前,我国无人航空植保技术的研究还处于初级阶段。本文在介绍国外无人机航空植保技术现状的基础上,分析了我国无人机航空植保技术的发展水平及存在的问题,并提出无人机植保施药技术的发展方向与技术需求,仅供参考。     

Trends in Decision Support Systems for Cropping Systems Analysis: Examples from Nebraska

SUMMARY

Over the past 20 years, decision support systems (DSS) have been applied to a number of important problems in cropping systems analysis. Seven interrelated information technologies are currently driving new opportunities for decision support systems: global positioning systems (GPS), sensors for direct field measurements, variable rate application technology, remote sensing, data communication systems, geographic information systems (GIS), and personal computers. These technologies were used in three modeling examples designed to develop DSS at three different levels: competition between individual plants in an uneven stand (modeled at hourly time steps and sub-meter resolution), historical analysis of county-level yields (100 year sequence at multi-kilometer resolution), and yield map modeling (daily time step for a 64 ha field). In each case, a sequential analysis of model predictions helped identify additional data or algorithms needed to model the system at its appropriate scale. Continued progress in system modeling combined with projected growth in computer power, near-term improvements in remote sensing and precision farming equipment, and new developments in the automation of data exchanges over the Internet should all contribute to expanded use of DSS for cropping systems analysis in the future.     

Monitoring conidial density of <Emphasis Type="Italic">Monilinia fructigena</Emphasis> in the air in relation to brown rot development in integrated and organic apple orchards

In a three-year Hungarian study, conidial density of Monilinia fructigena in the air determined from mid-May until harvest was related to brown rot disease progress in integrated and organic apple orchards. Conidia of M. fructigena were first trapped in late May in both orchards in all years. Number of conidial density greatly increased after the appearance of first infected fruit, from early July in the organic and from early August in the integrated orchard. Conidial number continuously increased until harvest in both orchards. Final brown rot incidence reached 4.3–6.6% and 19.8–24.5% in the integrated and organic orchards, respectively. Disease incidence showed a significant relationship with corresponding cumulative numbers of trapped conidia both in integrated and organic orchards, and was described by separate three-parameter Gompertz functions for the two orchards. Time series analyses, using autoregressive integrated moving average (ARIMA) models, revealed that the temporal patterns of the number of airborne conidia was similar in all years in both integrated and organic orchards. Conidia caught over a 24-h period showed distinct diurnal periodicity, with peak spore density occurring in the afternoon between 13.00 and 18.00. Percent viability of M. fructigena conidia ranged from 48.8 to 70.1% with lower viability in dry compared to wet days in both orchards and all years. Temperature and relative humidity correlated best with mean hourly conidial catches in both integrated and organic apple orchards in each year. Correlations between aerial spore density and wind speed were significant only in the organic orchard over the 3-year period. Mean hourly rainfall was negatively but poorly correlated with mean hourly conidial catches. Results were compared and discussed with previous observations.     

飞机超低量喷洒生物农药防治兴安落叶松鞘蛾的效果

利用飞机超低量喷雾法防治兴安落叶松鞘蛾.经室内试验和田间试验,选择出1%苦参碱液剂3000倍液及2010年生产的0.2%的阿维菌素油剂作为飞机防治用药.结果表明:喷药后15d时,1%苦参碱液剂375g hm-2以上喷洒量防治效果可达到95%以上,0.2%阿维菌素油剂2500 g·hm-2以上喷洒量防治效果可达96%以上...