果园防霜机模糊控制系统设计及防霜效果试验

为预防果树霜冻害,提高果园管理水平,该文设计了一台基于模糊控制策略的果园防霜机。利用STM32微控制器和触摸屏开发了防霜自动化控制系统,通过无线射频网络进行环境信息采集,设计了回转平台的摆头速度变频控制系统,实现不同摆头速度的360°往复运动。防霜机有效工作半径为5～48m,最大保护面积约7150m2。试验结果表明,防霜机摆头速度和防霜机的距离对温度和风速有交互作用,在模糊控制条件下,平均温度和风速的下降量小于常规控制条件的下降量。在试验期间,应用模糊控制和常规控制的平均温升均分别是3.1和2.8℃,模糊控制和常规控制下的苹果树芽孢受冻率分别是5.6%和11.6%,模糊控制的防霜机运行时间节省21.1%。结果说明该防霜机可以实现防霜智能控制,运行模糊控制策略后,防霜效果好于常规控制,并且运行时间相对较短。     

天水蜜桃开花期不同措施防霜效果试验初报

试验设地面覆膜和树冠盖膜防霜措施,并将其与灌水、喷药、烟熏等传统防霜措施进行有机结合,形成共9个防霜措施试验设计,以无防霜措施为对照,通过2013年4月6日(最低气温-4.7℃)、10日(最低气温-3.1℃)两次霜冻天气过程进行防霜试验。结果表明,各种防霜措施均有一定保温防霜效果,其中以树冠盖膜、地表覆膜烟熏和无膜桃园喷药(碧护)烟熏3种措施的防霜效果最佳,桃树冠层1m处平均最低温度较对照偏高1.7~3.0℃,0℃以下低温持续时间减少6~7h,桃花受冻率降低25.3~68.7个百分点。各试验处理两次霜冻过程花蕾均未受冻,但对照桃园蕾苞有明显受冻现象,受冻率分别达33.3%和50.0%。利用试验及相关调查资料,分析蜜桃花期霜冻灾害指标,并建立统计模型对不同低温及其持续时间下的桃花受冻率进行测算,测算结果与实况调查基本一致。因此,根据桃树春季花蕾期不同发育进程和霜冻强度,选择适宜的防霜措施,对有效防御花期霜冻灾害,减轻冻害损失具有一定指导意义和推广前景。     

化学调控技术的防霜应用研究

应用不同类型化学制剂促进作物早熟缩短生育期、防霜减灾试验表明 ,利用化学制剂调节作物发育速度 ,有一定的促早熟避霜冻作用 ,且有一定矮化植株和提高产量的作用     

环青海湖地区草地近地层气象要素变化特征

利用青海湖北岸海北牧业气象试验站2006年5月-12月观测的天然草地近地面层气象要素梯度资料，分析了该地区近地层温度、湿度和风速的日变化规律及其廓线特征。结果表明：青海湖北岸草地近地层0．3—10．0m高度范围内温度、相对湿度和风速都呈现出明显的以24h为周期的日变化规律；各层温度最高和最低时的位相随高度增加而滞后，相对湿度和风速最大与最小时的位相随高度增加而提前；14时温度随高度的增加而降低，20时的温度随高度增加先增后降，温度廓线在4．0m高度存在一拐点，随后逐渐进入逆温状态，至8时逆温程度达到最大；不论白天还是夜间，相对湿度随高度的增加而减小；风速随高度的增加而增大。     

乌兰布和沙漠东北缘近地层风速和降尘量特征

选择乌兰布和沙漠东北缘荒漠-绿洲过渡带和绿洲为定位监测点,基于磴口生态站近地层(0~50 m)风沙监测塔2013年全年的风速和降尘数据,分析了沙漠东北缘近地层风沙时空变化规律。研究结果如下:1)过渡带和绿洲内近地层的风速均随着高度增加而增大,风速廓线特征可用幂函数表示;过渡带风速显著高于绿洲内风速。2)过渡带和绿洲内近地层沙尘水平通量和降尘量均随着高度增加而减少,其分布特征遵循幂函数关系;过渡带沙尘水平通量显著高于绿洲内,说明绿洲防护体系对沙尘具有明显的削弱作用;过渡带沙尘水平通量与降尘量之间为线性关系,而绿洲内二者之间为指数函数关系。3)在春、夏、秋、冬季,过渡带和绿洲内近地层沙尘水平通量和降尘量均随着高度增加而减小;春季是沙尘水平通量和降尘量集中的季节,其次为夏季,秋季和冬季相对较低;一年四季中,过渡带沙尘水平通量和降尘量均高于绿洲内。     

山西省冬小麦种植区霜冻气候指标的时空特征分析

利用山西省冬小麦种植区80个站点1961-2010年地面0cm日温度资料和冬小麦霜冻灾情资料,以地面0cm日最低温度界定霜冻过程,以霜冻过程为尺度构建霜冻的气候指标即过程积霜,分析该气候指标的年际变化及空间分布。结果表明,用年历次霜冻过程积霜和的相对值区分霜冻可能年份与其它年份有较好的效果。轻、中、重霜冻以及全部霜冻过程积霜和多年均值具有良好的空间一致性。对于同一区域,重霜冻积霜和多年均值最大,中霜冻次之,轻霜冻最小。根据地面0cm温度构建的霜冻气候指标,是进行霜冻实时评估和霜冻风险区划的基础。     

塔克拉干沙漠腹地沙尘暴天气下风速脉动特征

利用塔克拉玛干沙漠2次沙尘暴天气条件下人工绿地近地层80 m风速观测资料,探讨近地层风速脉动特征及其与能见度、PM_(10),PM_(2.5)的关系,为进一步研究湍流情况下风蚀和风扬粉尘释放奠定基础。结果表明:(1)不同高度风速脉动值在随高度的变化上近似符合高斯分布且在时间序列上波动性均具有一致性,脉动频率不稳定,无明显周期性,相邻高度间均具有显著相关性。(2)风速脉动强度随风速增大而增强,随距离地表高度的降低呈先增大后降低的趋势。湍流度均与高度成反比关系,整体上均随着高度的降低而增大,因为地表植被的存在增大了湍流度。(3)沙尘暴过程中地面风速的大小对水平能见度,PM_(10),PM_(2.5)具有直接影响,风速脉动变化与水平能见度呈现反比关系,与PM_(10),PM_(2.5)呈现正比关系。     

基于Logistic回归建立霜自动判识模型

利用安徽省23个典型气象站2003?2017年观测数据,根据无霜日的气象要素阈值条件进行质量控制,在此基础上,构建各气象站基于Logistic回归的霜自动判识模型,并对模型的霜判识效果进行评估。结果表明：（1）通过气温、风速和降水量等气象要素阈值,能够有效判定出安徽各站当日无霜现象;（2）各气象站的霜判识模型均入选了温度、湿度和风速等相关要素作为判识因子,入选要素的时次多集中在4：00?8：00区间;（3）独立样本检验表明,基于Logistic回归的霜判识模型对安徽地区霜的平均判识准确率、命中率、漏判率、空判率和TS评分分别为89.0%、91.6%、8.4%、15.8%和78.2%,表明模型对安徽地区的霜具有较好的判识能力;（4）与Bayes判别模型对比发现,基于Logistic回归的霜判识模型在准确率、空判率和TS评分方面表现更优,可以使用Logistic回归模型实现霜的自动化判识。     

不同防冻措施茶园茶汤滋味差异的电子舌检测

为探讨轻度“倒春寒”对不同防护措施下3种茶园蒸青茶样的茶汤滋味影响,遂选品种和管理措施一致的安装防霜扇的茶园、松树林围绕的茶园以及未设防护措施的普通茶园,用电子舌综合评价3种茶园茶汤滋味、高效液相色谱检测茶汤游离氨基酸组分及含量。结果表明：基于电子舌检测数据的主成分分析、软独立建模分析和聚类分析结果揭示了普通茶园的茶汤滋味与防霜扇茶园和林间茶园的差异显著（P<0.05）;从9种茶样中皆检测出18种氨基酸,游离氨基酸质量分数介于19.691～30.947 mg/g 之间,茶氨酸含量占游离氨基酸含量的55.1%～70.5%;随着3种茶园气温的降低,游离氨基酸含量和茶氨酸含量呈升高趋势,3种鲜味氨基酸（天冬氨酸、谷氨酸、茶氨酸）、5种甜味氨基酸（脯氨酸、丙氨酸、甘氨酸、苏氨酸、丝氨酸）和5种苦味氨基酸（异亮氨酸、亮氨酸、苯丙氨酸、酪氨酸、缬氨酸）共占游离氨基酸含量在防霜扇茶园和林间茶园中分别出现升高、降低和降低趋势,而在普通茶园中变化与之不同。分析认为：轻度“倒春寒”可导致无防护措施的普通茶园茶叶滋味劣变,林间茶园能够减轻冻害,防霜扇作为防护手段不仅可以减免冻害,还可避免茶叶滋味品质下降。该研究结果为后续深入研究不同防护措施茶园茶叶品质提供参考。     

农田休闲期垄作地形对近地表风场的影响

垄作是旱作农田常用的保护性耕作技术,而其防风抗蚀的机制尚需研究。通过野外试验,对垄脊高25cm,垄沟宽1.5m的垄作田上风向、垄间及下风向地带0～4m的风流场进行了同步观测,对不同观测位置的时均风速、空气动力学粗糙度、摩阻速度和风速脉动进行了对比分析。结果表明,土垄间和下风向近地表0～1m内时均风速比上风向平坦地表明显降低,其中高0.3m处降低幅度最大。水平方向上风速降低幅度、空气动力学粗糙度和摩阻速度均随观测点与垄作地表距离的增大而减小。受风速递增的影响,风速的绝对脉动强度随高度呈对数关系递增。风速的相对脉动强度在0～1m内随高度增大而降低,1m以上基本无变化。高0.05m处风速的相对脉动强度在水平方向上随与垄作田距离的减小而增大,其中垄间最大,时均风速相同时对地面剪切力最大。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.