不同施肥水平对扁穗雀麦种子产量的影响

采用二次回归旋转组合设计,研究了N肥、P肥、K肥和有机肥4因子对扁穗雀麦种子产量的影响,建立了相应的数学模型,结果表明:N肥用量在15.98~19.02 kg/667m2、P肥用量在22.83~27.17 kg/667m2、K肥用量在9.23~10.69 kg/667m2、有机肥用量在2 350.77~2 497.04 kg/667m2时,扁穗雀麦种子产量大于192.5 kg/667m2,是较适宜的处理组合。     

Use of hummocks and hollows by trees in tidal freshwater forested wetlands along the Savannah River

Tidal freshwater forested wetlands occupy a relatively narrow range, occurring where wind and lunar tides interact with coastal river systems, causing freshwater flooding onto the floodplain. A prominent component of this wetland type is hummock and hollow microtopography. Tidal freshwater forested wetlands along the Savannah River were differentiated into backswamp and streamside areas, and the degree to which trees occupied hummocks and hollows were compared at three scales: landscape (backswamp vs. streamside), tree community, and species (within community). The community- and species-level analyses were extended to determine whether trees were using either hummocks or hollows in a nonrandom manner. Trees in the backswamp setting were found to use hummocks more than trees in the streamside setting. At the community scale, three of the five treatment groups investigated differed based on the degree to which trees on hummocks outnumber trees in hollows. Further examination of microtopography usage confirmed that hummocks are used significantly more than hollows in two communities, both of which are located in the backswamp setting. Though no tree community used hollows significantly more than hummocks, species-level analyses confirmed that, within a specific tree community in the streamside setting, alder (Alnus serrulata [Ait.] Willd.) is found more in hollows than on hummocks. Fourteen different species between the two communities in the backswamp setting are found on hummocks more than in hollows, and only one species, sweetgum (Liquidambar styraciflua L.), is found more on hummocks than in hollows in the tree community in the streamside setting.     

Pedobiochemical indicators for eutrophication and the development of ”︁black spots” in tidal flat soils on the North Sea coast

The increasing eutrophication of tidal flat soils on the North Sea coast and the appearance of ”︁black spots” gave rise to this study. The aim was to find pedobiochemical indicators for the development of ”︁black spots”. Artificially eutrophicated soils were compared with untreated soils in the field and laboratory. The pH values of the artificially eutrophicated and natural soils often differed by nearly one unit. The treated soils mostly showed lower redox potentials (˜ —300 mV) than the untreated samples (˜ —250 mV). The mean sulfate concentrations were 2.2 mM in the eutrophicated laboratory soils and 13.1 mM in the eutrophicated field soils, compared with 12.5 mM and 20.2 mM in the untreated ones. Consequently, the SO₄^2—:Cl^— ratios and SO₄^2— differences were lower in the treated soils. Non‐eutrophicated soils showed methane concentrations of < 5 nmol cm^—3, whereas the eutrophicated soils showed up to 217.0 nmol cm^—3 in the field and 479.1 nmol cm^—3 in the laboratory. Differences between field and laboratory data were mainly due to a continuous sulfate supply and reoxidation process only possible in the field. Although all parameters showed differences between the eutrophicated and untreated soils, only the methane data did not overlap with their interquartile ranges. Those of the untreated soils were 2—7 nmol cm^—3 and those of the treated were 12—360 nmol cm^—3. Thus, threshold values can be defined. Methane concentrations of approximately > 10 nmol cm^—3 refer to the beginning eutrophication process and those in the range of > 100 nmol cm^—3 to advanced processes, phenologically forming ”︁black spots”.     

江苏海涂气候研究

利用江苏海涂区域22个代表站1971～2006年年平均降水资料和年平均气温资料,用EOF展开分析时空变化的差异;再用方差分析、气候趋势系数和线性回归等方法,得到海涂区域降水和温度空间分布的主要形态和特征。结果表明：整个海涂区域年平均气温周期性明显,36年来气温有明显的上升趋势;整个区域降水呈东南向西北递增的分布,高荷载主要位于连云港到盐城的北部区域;一致增加的分布类型的次数增加对海涂区域年平均气温的升高贡献较大,是气温持续上升的主要原因。此外,海涂区域降水和温度在纬向和经向之间也存在分布差异。     

贵州扁形茶杀青工艺比较

为了探索茶叶加工过程中现代杀青方式对茶叶品质的影响,从而为贵州扁形茶加工提供参考,促进贵州茶产业的优质化发展,设计了滚筒杀青、微波杀青、滚筒+微波杀青3种杀青方式,以杀青前后叶绿素含量的变化和样品茶感官审评结果为判断依据,对比3种杀青方式对贵州扁形茶品质的影响。结果表明,滚筒+微波杀青效果较好,茶样感官品质优于滚筒杀青和微波杀青处理,微波杀青的样品在外形形状上明显优于滚筒杀青和滚筒+微波杀青处理。     

牧草干燥太阳能折射式线聚焦平板聚光镜设计与试验

针对目前太阳能干燥设备生产率低、太阳能空气集热器热效率低的问题,设计了太阳能折射式线聚焦平板聚光镜.对聚光镜进行三维模型设计,通过数值计算建立聚光镜能效模型,进而分析光线入射角、焦距误差、系统跟踪精度和聚光面加工误差对聚光比和聚焦光带能量分布的影响.分析得出,当聚光镜采用东西方位跟踪太阳、方位角跟踪误差保持在±1.1°...     

毯状秧苗切块受力影响因素试验研究

通过用锯条对毯状秧苗在不同秧苗根系密度、秧苗土壤含水率、切割角度和切割速度水平下的切割试验,经回归分析,得出切割时切刀的加载速度对切割力影响不明显;而秧苗根系密度、秧苗土壤含水率和切割角度对切割力的影响明显,为对毯状秧苗切块提供了实验依据.     

三个类型桃及其杂种后代糖酸含量的差异

 以早星×早露蟠桃和94-1-40×早红2号两个杂种后代群体为试材,研究了果实糖、酸性状遗传与果形（扁平/圆形）、果皮毛有无（普通桃/油桃）、果肉颜色（白肉/黄肉）等质量性状的关系。桃果实的可溶性糖主要是蔗糖,占总可溶性糖的60%以上,其次是葡萄糖、果糖和山梨糖醇。桃果实的有机酸主要是苹果酸、柠檬酸和奎宁酸,莽草酸含量很低,仅占总酸含量的约0.3 %。在蟠桃群体中蔗糖、总糖、可溶性固形物的含量均显著高于普通桃群体,而葡萄糖、果糖、柠檬酸和莽草酸含量在蟠桃和普通桃后代间不存在显著差异。不同年份间苹果酸和奎宁酸含量在蟠桃和普通桃后代间存在差异。油桃后代的苹果酸、总酸平均含量显著高于普通桃后代,其柠檬酸、奎宁酸、莽草酸平均含量与普通桃后代间不存在显著差异。2005年油桃后代总糖、可溶性固形物及各可溶性糖组分含量均显著高于普通桃,2004年仅山梨醇含量显著高于普通桃后代。两年的结果均表明,总糖、可溶性固形物、总酸及各种糖酸组分在黄肉桃和白肉桃之间不存在显著差异,与吴本宏2003年的报道一致。     

珠三角滩涂围垦农田土壤和农作物重金属污染

为了研究珠三角滩涂围垦农田土壤和农作物重金属污染状况,采集了广州南沙、中山一带围垦农田农作物及其根际土壤样品,测定重金属的质量分数。结果表明,围垦农田土壤样品中Cu、Ph、Cd、Ni、Cr和Zn含量均大于广东省相应土壤环境背景值,其中Cu（56．06mg·kg^-1）、Pb（48．30mg·kg^-1）、Cd（0．72mg·kg^-1）、Ni（41．15mg·kg^-1）、Cr（115．1mg·kg^-1）和Zn（200．1mg·kg^-1）分别为背景值的3．30、1．34、12．82、2．26、2．28和4．23倍。与《土壤环境质量标准》（GB15618-1995）中Ⅱ级标准（pH〈6．5）比较,土壤样品中Cu、Cd、Ni和Zn的超标率分别为73．7％、88．6％、59．6％和28．9％。以GB15618-1995中Ⅱ级标准为评价标准,采用Nemerow指数法进行评价,土壤重金属平均综合污染指数为1．86,属3级轻污染。与《食品中污染物限量》（GB2762-2005）等相关标准比较,农作物中Cu、Pb、Cd、Ni、Cr和Zn含量的样品超标率分别为0、28．9％、2．6％、48．3％、12．3％和6．1％。由此可见,珠三角滩涂围垦农田土壤和农作物重金属污染问题已经比较突出,土壤污染以Cd为主,而农作物污染则以Ni、Ph、Cr为主。     

基于GIS的海涂围垦区土地资源多目标适宜性评价研究

海涂土地资源适宜性评价是合理开发海涂的基础。选择浙江沿海典型海涂围垦区,基于GIS建立空间和属性数据库,采用栅格运算与评价模型相结合的方法,对研究区的土地资源进行多目标适宜性评价研究;根据优先用地规划方案,应用评价结果,初步实现了研究区土地利用结构的空间配置。结果表明:研究区的土地资源具有多宜性特点,不同利用类型的适宜等级间存在"重叠"现象;基于土地多目标适宜性评价结果进行土地利用结构的空间配置时,不同的用地规划方案会产生不同的配置结果。