江西兴国水土流失治理区土壤有机质动态变化

在ArcGIS8.1软件系统平台上,用普通克立格和概率克立格等多种方法研究潋水河流域土壤有机质含量的动态变化特征。结果表明,潋水河流域106个样点的土壤有机质平均含量增加,由1981年的18.16±7.23g/kg增加到2002年的19.14±11.25g/kg;2002年土壤有机质含量为(30.0～40.0g/kg)、(20.0～30.0g/kg)级地的面积扩大,所占流域面积比分别较1981年增加11.38%和28.54%。近20年来该流域内水田、旱地和林地的土壤有机质平均增加量分别为2.3g/kg、3.5g/kg和3.1g/kg,坡度≤2°、2～6°、6～15°、15～25°和>25°的土壤有机质平均增加量分别为1.8g/kg、2.6g/kg、3.3g/kg、3.6g/kg和4.0g/kg。结合概率克立格法和加权平均法探讨了<10.0g/kg含量水平下区域土壤有机质的概率分布特征,其几何平均概率由1981年的0.2008下降到2002年的0.1503。     

Estimation of soil organic matter by geostatistical methods: Use of auxiliary information in agricultural and environmental assessment

Mapping soil properties such as soil organic matter (SOM), or soil organic carbon (SOC) content represent a problem often arising in agronomic and environmental surveys, since point data must be spatialized with the best interpolation. Deterministic methods (Inverse Distance Weighting, Splines, ecc.) do not account for the error, thus probabilistic methods as geostatistics (e.g. Ordinary Kriging, OK) have been successfully applied for many years. Maps derived from this kind of stochastic interpolation, based only on a recognized autocorrelation among measured points, could not be suitable in representing the reality, since they usually show a smoothed pattern. Hybrid interpolation methods, such as Regression Kriging (RK), combine an interpolation based only on point data and an interpolation based on a regression of the target variable with other continuous variables, spatially related, well known on the whole area.In the Teramo province, central Italy, a set of 250 soil samples, collected from the surface horizon of agricultural soils is available. From these samples the estimation of soil texture, SOC, SOM related to texture and C/N both by OK and RK was performed. The following predictors were used for RK: (i) indexes derived from Landsat TM imagery, (ii) morphometric parameters derived from DEM, (iii) soil subsystems map 1:250,000. The maps obtained by both OK and RK in this survey show substantial agreement, without significant improvement in map accuracy using auxiliary information.     

基于神经网络模型和地统计学方法的土壤养分空间分布预测

采用径向基函数神经网络模型与普通克里格法相结合的方法,预测川中丘陵区县域尺度土壤养分(有机质和全氮)的空间分布,并与普通克里格法和回归克里格法进行比较.结果表明：各方法对研究区土壤养分的预测结果相似.与多元回归模型相比,神经网络模型对验证样点土壤有机质和全氮的预测值与样点实测值的相关系数分别提高了12.3%和16.5%,表明神经网络模型能更准确地捕捉土壤养分与定量环境因子间的复杂关系.对469个验证样点预测结果的误差分析表明,神经网络模型与普通克里格法相结合的方法对土壤有机质和全氮预测结果的平均绝对误差、平均相对误差、均方根误差较普通克里格法分别降低了6.9%、7.4%、5.1%和4.9%、6.1%、4.6%,降低幅度达到极显著水平(P<0.01);与回归克里格法相比则分别降低了2.4%、2.6%、1.8%和2.1%、2.8%、2.2%,降低幅度达显著水平(P<0.05).     

Transgenic maize hybrids as a tool to control Sesamia cretica Led. compared by conventional method of control on normal hybrids

This study was conducted on Bt and normal maize hybrids during two successive sowing dates, early and late summer plantation. The Sesamia cretica larvae were observed for the first time on first week of April on different commercial maize hybrids. While there was no larva/plant on transgenic maize hybrids, YieldGard and Ageeb-YG, while larvae were found on last week of July by a very little number on maize hybrids for late one. In Early summer planting date showed highly significant differences in reduction percent, between tested compounds and control one, in the pink corn borer population. The bio-residual activity of the NeemAzal-T/S 0.5% on TWC310 was significantly less pronounced, i.e. 75.5%, than other tested ones; the highest percentage of reduction, 86.6%, was achieved by Chlorophan 0.005% on SC2031, followed by NeemAzal-T/S 0.5% on SC2031 83.5% and Chlorophan 0.005% on SC2030 83.4%, respectively. Also the average reduction percentage of S. cretica larvae differed significantly from 69.6%, on NeemAzal-T/S SC2031, to 83.0%, on Chlorophan SC2031, in the late summer planting. The different treatments had positive effects on maize yield in the two planting dates. In the first plantation date, the increased rate of control ranged from 1.04 to 1.24, when NeemAzal-T/S acted on TWC310 and transgenic IYG, respectively. And in the second plantation date, rate of control obtained was 1.06–1.30, when NeemAzal-T/S acted on SC 2031 and transgenic IYG, respectively. The tested compounds played an important role in controlling the pink corn borer insect, S. cretica, and this study suggests that Cry 1Ab-expressing corn hybrids would provide a great value as a component of corn IPM in Egypt.     

Spatial analysis of marine categorical information using indicator kriging applied to georeferenced video mosaics of the deep-sea Håkon Mosby Mud Volcano

The exact area calculation of irregularly distributed data is in the focus of all territorial geochemical balancing methods or definition of protection zones. Especially in the deep-sea environment the interpolation of measurements into surfaces represents an important gain of information, because of cost- and time-intensive data acquisition. The geostatistical interpolation method indicator kriging therefore is applied for an accurate mapping of the spatial distribution of benthic communities following a categorical classification scheme at the deep-sea submarine Håkon Mosby Mud Volcano. Georeferenced video mosaics were obtained during several dives by the Remotely Operated Vehicle Victor6000 in a water depth of 1260 m. Mud volcanoes are considered as significant source locations for methane indicated by unique chemoautotrophic communities as Beggiatoa mats and pogonophoran tube worms. For the detection and quantification of their spatial distribution 2840 georeferenced video mosaics were analysed by visual inspection. Polygons, digitised on the georeferenced images within a GIS, build the data basis for geostatistically interpolated mono-parametric surface maps. Indicator kriging is applied to the centroids of the polygons calculating surface maps. The quality assessment of the surface maps is conducted by leave-one-out cross-validation evaluating the fit of the indicator kriging variograms by using statistical mean values. Furthermore, the estimate was evaluated by a validation dataset of the visual inspection of 530 video mosaics not included within the interpolation, thus, proving the interpolated surfaces independently. With regard to both validating mechanisms, we attained satisfying results and we provided each category applied for the identification of biogeochemical habitats with a percentage probability value of occurrence.     

Responses of transgenic maize hybrids to variant western corn rootworm larval injury

Abstract:  In 2005 and 2006, transgenic insecticidal maize hybrids (YieldGard Rootworm, MON 863, Cry3Bb1, Vector ZMIR 13L) were evaluated for their ability to limit root injury caused by western corn rootworm ( Diabrotica virgifera virgifera LeConte) larval feeding. Hybrids in each year of the experiment were planted in plots that had been devoted to a trap crop (late-planted maize interplanted with pumpkins) the previous growing season. All maize hybrids were provided by Monsanto Company and the genetic backgrounds remain unknown to the investigators. In 2005, the experiment was conducted in Urbana, Illinois. Urbana is located in east central Illinois, an area of the state in which a variant of the western corn rootworm has overcome the pest management benefits of crop rotation. Variation in root injury was noted across the maize hybrids in 2005 and the level of pruning increased from 20 July to 9 August for most hybrids. In 2006, the experiment was conducted in two locations, Monmouth and Urbana, Illinois. Monmouth is located in north-western Illinois and is within an area of the state in which densities of the variant of the western corn rootworm are lower than in east-central Illinois. In 2006, variation in root protection was again observed across the maize hybrids. Root injury differences among the hybrids were more prominent at the Urbana site. Similar to the previous year, root injury increased from the third week in July to the first week of August at both locations with this increase most noticeable at the Urbana location. We hypothesize that the variant western corn rootworm may be able to inflict more root injury to these transgenic insecticidal maize hybrids than the non-variant population of this species.     

Spatial variability of agricultural soil parameters in southern Spain

Spatial patterns for seven soil chemical properties and textures were examined in two fields in southern Spain (Monclova and Caracol, province of Seville, Andalusia) in order to identify their spatial distribution for the implementation of a site-specific fertilization practice. Two sampling grids of 35×20 and 35×35 m were established in Caracol and Monclova, respectively. Fourteen and eight georeferenced soil samples per hectare were collected at two depths (0–0.1 and 0.25–0.35 m) in early November 1998 before fertilizing and planting the winter crop. Data were analyzed both statistically and geostatistically on the basis of the semivariogram. The spatial distribution model and spatial dependence level varied both between and within locations. Some of the soil properties showed lack of spatial dependence at both depths and at the chosen interval (lag h). Such was the case for clay, organic matter and NH₄ at Monclova; and clay and NH₄ at Caracol. Bray P and exchangeable K showed a strong patchy distribution at any field and depth. It is important to know the spatial dependence of soil parameters, as management parameters with strong spatial dependence (patchy distribution) will be more readily managed and an accurate site-specific fertilization scheme for precision farming more easily developed.     

横断山北部生态脆弱区土壤磷素空间分布特征

根据90个样点表层(0~20cm)土壤磷素的化验数据,在A rcG IS8.1平台上运用地统计学方法研究了横断山北部土壤磷素的空间分布特征及其影响因素。结果表明,该区土壤全磷和速效磷含量均属中上水平,全磷含量达1.20±0.66 g k-g 1,速效磷含量达13.7±12.6m g k-g 1。土壤全磷空间分布总体上呈团状或块状,高值区(1.8~2.8g k-g 1)主要分布于雅砻江流域西岸甘孜、新龙段和金沙江白玉、巴塘段之间的区域,并向西北和东南方向逐渐减少,低值区(<0.7g k-g 1)则主要分布于稻城县南部以及莫拉山以南德格以北的一个狭长区域;速效磷空间分布总体上呈小团块状,高值区(28~55m g k-g 1)主要分布于雅砻江中游的甘孜县东部和西部,并向西北和正南方向逐渐减少,低值区(<12m g kg-1)则主要分布于研究区东南部和南部边缘。成土母质本身含磷量和风化程度的不同使得磷素空间分布存在一定的水平、垂直分布特征。土地利用方式、海拔和坡度通过气候差异或土壤侵蚀程度来影响磷素含量。     

利用分子标记技术检测玉米杂种纯度研究

以12份玉米自交系及其组配的8个杂交种为材料,利用分子标记技术进行杂种纯度检测研究。有用RAPD标记方法,从300个随机引物中,筛选确定了8个杂交种种子纯度检测引物,制定了检测标准标记图谱。建立了海禾3纯度分析的SCAR标记,该SCAR标记与RAPD标记在种子纯度检测上结果完全一致。     

用地统计学方法对落叶松人工纯林表层细根生物量的估计

 采用地统计学的变异函数分析方法定量研究了落叶松（Larix olgensis）纯林表层（0～10 cm）细根的空 间异质性特征,利用地统计学的克里格内插法结合定积分,对落叶松纯林表层细根（<2 mm）的生物量进 行了估测。结果表明：1）6种林龄（14～40 年）的落叶松人工纯林表层细根的变异函数曲线理论模型均 为球状模型,空间变异主要是由结构性因素引起,且空间自相关程度均属中等以上（空间结构比>25%）。 14、19、22、26、32、40年生的落叶松纯林表层细根的空间变异尺度分别为1.76、3.40、1.02、4.12、 3.37和5.58 m。在所研究的林龄范围内,随林龄的增长,落叶松纯林表层细根的空间变异尺度近似呈直线 增长（p =0.074 4）。2）非参数统计的成对样本符号检验结果表明,变异函数分析结果基础上的克里格 内插法适用于落叶松纯林表层细根生物量的估计。利用此估计值,拟合其与位置坐标值之间的多元回归关 系均为二元十次余弦级数多项式。利用此多项式,通过定积分的方法（积分区间为整块样地的大小）,估 计出14、19、22、26、32、40年生的落叶松纯林表层细根生物量分别为1.097 3、1.434 0、1.185 4、 0.974 3、1.682 6、1.255 6 Mg• hm-2。3）在本次调查的林龄范围内（14～40年）,落叶松纯林表层细 根的现存量近似相等（α=0.037 3）,土壤表层单株细根生物量与林龄之间呈极显著的指数增长关系（α =0.002）。4）采用地统计学的克里格空间插值,结合多元回归和定积分的方法,可以实现落叶松人工林 表层细根生物量的准确估计。     

Peat carbon stocks in the southern Mackenzie River Basin: uncertainties revealed in a high-resolution case study

The organic carbon (C) stocks contained in peat were estimated for a wetland‐rich boreal region of the Mackenzie River Basin, Canada, using high‐resolution wetland map data, available peat C characteristic and peat depth datasets, and geostatistics. Peatlands cover 32% of the 25 119 km² study area, and consist mainly of surface‐ and/or groundwater‐fed treed peatlands. The thickness of peat deposits measured at 203 sites was 2.5 m on average but as deep as 6 m, and highly variable between sites. Peat depths showed little relationship with terrain data within 1 and 5 km, but were spatially autocorrelated, and were generalized using ordinary kriging. Polygon‐scale calculations and Monte Carlo simulations yielded a total peat C stock of 982–1025 × 10¹² g C that varied in C mass per unit area between 53 and 165 kg m^?2. This geostatistical approach showed as much as 10% more peat C than calculations using mean depths. We compared this estimate with an overlapping 7868 km² portion of an independent peat C stock estimate for western Canada, which revealed similar values for total peatland area, total C stock, and total peat C mass per unit area. However, agreement was poor within ～875 km² grids owing to inconsistencies in peatland cover and little relationship in peat depth between estimates. The greatest disagreement in mean peat C mass per unit area occurred in grids with the largest peatland cover, owing to the spatial coincidence of large cover and deep peat in our high‐resolution assessment. We conclude that total peat C stock estimates in the southern Mackenzie Basin and perhaps in boreal western Canada are likely of reasonable accuracy. However, owing to uncertainties particularly in peat depth, the quality of information regarding the location of these large stocks at scales as wide as several hundreds of square kilometers is presently much more limited.     

Relationship between root elongation rate and diameter and duration of growth of lateral roots of maize

The objective of this work was to describe the relationship between elongation rate and diameter of maize roots and to estimate the length and growth duration of lateral roots of maize. Diameters and elongation rates of roots were measuredin situ on plants grown 5 weeks in small rhizotrons under greenhouse conditions. At the end of the experimental period the roots were harvested and diameters of axile and lateral roots were measured. The frequency distribution of diameters of harvested roots was bimodal with a minimum at 0.6 mm; 97% of axile roots were larger than this value and 98% of the lateral roots were smaller. Root elongation per day increased as diameter increased but the slope of the relationship with lateral roots was about 2.5 times that with axile roots when separate linear regressions were fitted to the two populations. The length of lateral roots found on axillary roots between the base and about 30 cm from the apex was approximately 2.2 cm. All of the data was consistent with the hypothesis that the lateral roots grew for about 2.5 days and then ceased growing. The axillary roots continued to grow throughout the experimental period at a rate of about 3 cm day⁻¹. Contribution from the Department of Agronomy, New York State College of Agriculture and Life Sciences, Cornell University, Ithaca, NY 14853. Agronomy paper No. 1661. This research is part of the program of the Center for Root-Soil Research.     

Sieve size effects on root length and biomass measurements of maize (Zea mays) and Grevillea robusta

The purpose of this study was to investigate the effects of different mesh sizes on the recovery of root length and biomass and to determine whether the degree of recovery was influenced by plant species and sample location. Sieves of 2.0, 1.0, 0.5 and 0.25 mm (4.0, 1.0, 0.25 and 0.06 mm2) mesh sizes were used to recover and measure the root length and biomass of Zea mays L. (maize) at 0–15 cm and 30–45 cm depths and of Grevillea robusta A. Cunn. ex R. Br. (grevillea) at the same depths 1.0 m and 4.5 m from a line of grevillea trees. At 0–15 cm, the coarser sieves (sum collected with 2.0 and 1.0 mm sieves) recovered approximately 80% of the total root biomass measured, but only 60% of the root length. The proportion of total maize root length and biomass recovered by the coarser sieves decreased with soil depth. The proportion of total grevillea root length recovered by the coarser sieves was similar at the two soil depths, but increased slightly with distance from the tree line. The ≥ 0.5 mm sieves recovered between 93 and 96% of grevillea and maize root biomass and between 73 and 98% of their root length, depending on the sample location. Roots passing through the 0.5 mm sieve, but recovered by the 0.25 mm sieve were about 20% of total maize root length and grevillea root length at 1.0 m from the tree line but < 5% of the total grevillea root length at 4.5 m from the tree. Roots passing through the 0.5 mm sieve but recovered by the 0.25 mm sieve contributed only slightly to root biomass. Although the ≥ 0.5 mm sieves provided adequate measurements of root biomass, the ≥ 0.25 mm sieves were required for accurate measurement of fine root length. There was no universal correction for root length and biomass underestimation when large sieve sizes were used because the proportions of length and biomass recovered depended on the plant species and on soil depth and distance from the plant. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geometrical properties of simulated maize root systems: consequences for length density and intersection density

The spatial distribution of root length density (RLD) is important because it affects water and nutrient uptake. It is difficult to obtain reliable estimates of RLD because root systems are very variable and heterogeneous. We identified systematic trends, clustering, and anisotropy as geometrical properties of root systems, and studied their consequences for the sampling and observation of roots. We determined the degree of clustering by comparing the coefficient of variation of a simulated root system with that of a Boolean model. We also present an alternative theoretical derivation of the relation between RLD and root intersection density (RID) based on the theory of random processes of fibres. We show how systematic trends, clustering and anisotropy affect the theoretical relation between RLD and RID, and the consequences this has for measurement of RID in the field. We simulated the root systems of one hundred maize crops grown for a thermal time of 600 K d, and analysed the distribution of RLD and root intersection density RID on regular grids of locations throughout the simulated root systems. Systematic trends were most important in the surface layers, decreasing with depth. Clustering and anisotropy both increased with depth. Roots at depth had a bimodal distribution of root orientation, causing changes in the ratio of RLD/RID. The close proximity of the emerging lateral roots and the parent axis caused clustering which increased the coefficient of variation.     

荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响

植物的根系分泌物是植物根系与周围环境之间的化学媒介,通过传递特定的信息,调节根际微环境,影响周围植物的生长。玉米(Zea mays L.)和荞麦(Fagopyrum esculentum Moench)是农作物间套作体系中典型的不能搭配的组合,其障碍因素尚不清楚。以玉米为受体植物,采用根悬空培养的方法,研究了荞麦、高粱(Sorghum bicolor(L.) Moench)根系分泌物对玉米根边缘细胞和根生长的影响。结果发现,玉米根边缘细胞离体培养条件下,用荞麦根系分泌物中的小分子物质处理4、8 h显著诱导边缘细胞凋亡、死亡,细胞活率分别比对照降低了71.6%和72.3%;荞麦根系分泌物中的小分子物质对玉米根产生氧化胁迫,诱导根SOD、POD和CAT活性分别比对照高22.6%、33.9%和107.2%,根中超氧阴离子(O₂^-·)和脯氨酸含量分别比对照高33.9%和49.8%;荞麦根系分泌物中小分子物质的胁迫使根细胞膜透性增大,与对照相比升高80.0%,丙二醛(MDA)含量比对照升高31.5%;荞麦根系分泌物中小分子物质诱导根内源激素(IAA)含...