温室作物叶-气系统水流阻力研究初探

温室作物叶-气系统水流阻力的确定对计算作物蒸腾量、制定温室作物灌溉制度以及调控温室小气候具有重要意义,但测量难度较大。该文通过对温室作物周围环境微气象条件的连续观测，计算分析了温室作物叶-气系统水流阻力各分项即叶片周围层流副层边界层阻力(r_b)、冠层上方湍流边界层阻力(r_g)、空气动力学阻力(r_e)和叶片气孔阻力(r_i)的变化规律。结果表明：温室内r_b比较稳定，平均约235 s/m，且与环境因素关系不甚密切；温室内黄瓜、西红柿类植物生殖生长期r_g<b，在计算r_e时，r_g的影响可忽略，取r_e≈r_b；利用基于能量平衡方程和空气动力学方程得出的叶-气温差计算公式计算得到r_i，符合其变化的一般规律；在此基础上计算了温室黄瓜的蒸腾速率，与实测值的一致性较好。     

基于Penman-Monteith方程的温室番茄蒸腾量估算模型

作物的蒸腾是作物生命过程中十分重要的组成部分。为寻求适合于温室栽培条件下番茄植株蒸腾量的计算模型,本文以Penman-Monteith方程为基础,针对温室特定的小气候环境,对番茄冠层整体气孔阻力、空气动力学阻力等参数进行合理修正,建立了包含气象数据、番茄叶面积指数和冠层高度为主要参数的温室番茄蒸腾量估算模型。分别采用2009年5月2-13日（开花坐果期）和2009年6月9-20日（成熟采摘期）2个时段内的实测蒸腾量对模型模拟结果进行验证,2个时段内模型模拟结果的平均相对误差分别为8.48%和9.20%,表明所建模型可以较好地的计算温室番茄的蒸腾量。本研究提出的蒸腾量估算模型对温室番茄作物水分关系的深入研究具有重要参考价值。     

塑料大棚气流场模拟及作物蒸腾量计算

为了分析塑料大棚内气流场的特征和计算与作物蒸腾量有关的通风参数,该文通过计算流体动力学模拟了塑料大棚内自然通风量,建立了华东地区常见塑料大棚内平均风速和外部风速之间的线性关系,根据能量平衡和紊流扩散模型建立了一个计算作物蒸腾量的数学模型,并利用棚外的常规气象资料和棚内的实测温度计算了棚内作物蒸腾量。通过将作物蒸腾量的计算值和实测值进行比较,结果发现作物蒸腾量的计算值与实测值比较一致,逐日蒸腾量间的决定系数为0.7756,累积蒸腾量间的决定系数为0.9983,模拟累计值与实测累计值之间标准误差为1.16 mm,最大绝对误差为4.82 mm;结果表明,所建立的计算方程参数较少,推求的风速参数比较适用于普通塑料大棚。该研究可满足大棚内作物水分管理、温室大棚设计规划和区域水资源管理等方面的需要。     

基于温室环境和作物生长的番茄基质栽培灌溉模型

为解决涵盖土壤蒸发和作物冠层蒸腾的土培作物蒸散模型不能直接应用于稻壳炭基质栽培番茄灌溉的问题,该研究首先通过修改Penman-Monteith模型的原始表达式来去除土壤蒸发部分,并引入TOMGRO模型来模拟番茄冠层生长,给出了阻抗参数的修正计算,得到了新的番茄基质栽培蒸腾模型。考虑到蒸腾模型中净辐射项削弱了室外太阳辐射对冠层及以下部整株植株的耗水影响,进而将新的蒸腾模型与太阳辐射线性比例供水模型结合建立蒸腾－辐射综合灌溉模型。结果表明,蒸腾－辐射综合灌溉模型对上海崇明A8温室番茄灌溉量的模拟结果与实际结果之间的相关系数高于0.95,平均相对误差小于20%。这说明蒸腾－辐射综合灌溉模型能够较好地估算温室稻壳炭基质栽培番茄的灌溉需水量,对深入研究温室灌溉实施具有参考价值。     

基于SIMDualKc模型估算非充分灌水条件下温室番茄蒸发蒸腾量

为了探讨SIMDual Kc模型在西北地区温室环境不同水分处理的适用性,以番茄为材料,于2013-2015年在陕西省杨凌区温室内进行亏水处理试验,设置全生育期充分灌水处理、仅发育期亏水50%处理、发育期中期连续亏水50%和全部亏水50%共4种水分处理,通过2013-2014年试验数据对SIMDual Kc模型进行率定,采用2014-2015年试验数据对模型进行验证,并通过模型将土壤蒸发量和番茄蒸腾量分开,利用模拟结果分析不同水分处理对土壤蒸发量和番茄蒸腾量的影响。结果表明:模型模拟不同水分处理蒸发蒸腾量与实测值有较好的一致性,其绝对误差为0.22~0.33 mm/d,均方根误差为0.26~0.48 mm/d、决定系数为0.51~0.81。该模型可以准确的将不同水分处理土壤蒸发量和作物蒸腾量分开,且土壤蒸发量模拟值与实测值有较好的一致性,其绝对误差为0.016~0.024 mm/d,均方根误差为0.013~0.034 mm/d和决定系数为0.63~0.84;通过模拟得到的番茄蒸腾量计算不同水分处理的水分亏缺系数,研究表明水分亏缺系数随亏水时间的增加而降低,复水后水分亏缺系数有不同程度的增加,且发育期、中期和后期连续亏水50%时,后期时水分亏缺系数降到最低,为0.63。因此该模型在西北地区温室环境下非充分灌溉条件下有一定的适用性。除此之外,研究通过模拟结果分析非充分灌水下番茄的响应及复水后的补偿机制,为非充分灌水条件下番茄栽培提供理论依据。     

温室封闭式栽培自适应灌溉方法

为了改进和提高温室封闭式栽培精细灌溉控制方法,针对利用Penman-Monteith(P-M)公式和传感器数据信息相结合进行灌溉控制中因为涉及参数较多而使用不便、需要近似计算导致建立的作物蒸腾模型精度不够等问题,该文根据封闭式栽培可以回收并循环利用多余灌溉水的特点,利用灌溉量与排出量的差值和温室小气候环境数据建立相对精确的作物蒸腾量计算模型,并在此基础上利用人工神经网络算法实现了温室封闭式栽培自适应灌溉控制,结果表明,在10 d内灌溉用水量为实际蒸腾量的97.8%,基本实现了按照作物需水量进行灌溉。研究对于实现按照作物蒸腾量进行准确的水分供给、节约灌溉用水量、提高水分利用效率具有一定的现实意义。     

大跨度保温型温室的热环境模拟

大跨度保温型温室为拱型钢骨架结构,南北走向,相邻温室间距仅2m,相比于传统日光温室土地利用率提高到91%,且仍具有日光温室节能的特点。为分析和评价该温室的蓄热保温性能,基于温室热传导、对流换热、太阳辐射、天空辐射、作物蒸腾、自然通风等热物理过程,构建了温室内热环境变化模型,并利用Matlab软件对其进行求解,模拟在冬季连续4个典型工作日无加温条件下,每10min的室内空气温度和作物根区温度,并将模拟值与实测值进行对比分析。结果表明,模型对大跨度温室内空气温度模拟的平均绝对误差在±1.3℃之内,模拟值与实测值间直线方程的决定系数（R2）为0.99（n=576）,回归估计标准误差（RMSE）和相对误差（RE）分别为1.6℃和16.4%;作物根区温度实测值与模拟值的绝对误差在±0.6℃之内,直线方程的R2为0.91（n=576）,RMSE和RE分别为0.76℃和6.7%。模型模拟值与实测值较为一致,可为温室环境精准调控和结构优化设计提供理论依据。     

温室内香蕉树蒸腾量预报的试验研究

在温室内研究了香蕉树蒸腾量和小气候的关系，用5种方法计算了温室内的参考作物腾发量，用20 cm蒸发皿测定温室内的水面蒸发力，并和测定的香蕉树蒸腾量进行对比。试验结果显示香蕉树蒸腾量和蒸发皿水面蒸发量的回归系数(R²)最高，为0.94，而和5种公式计算的参考作物腾发量的回归系数为0.47～0.60，以蒸发皿水面蒸发量计算温室内的作物蒸腾量要优于以参考作物腾发量计算作物蒸腾量的方法。温室内香蕉树的蒸腾量和20 cm蒸发皿蒸发量线性相关，可以此计算温室内作物的蒸腾量。     

长江中下游地区夏季温室黄瓜冠层温度模拟与分析研究

根据作物冠层能量平衡原理，建立了以温室内温度、湿度、冠层净辐射等为变量的温室作物冠层温度的模拟模型，并利用实测资料对模型的可靠性进行了检验，同时就温室内部温度、冠层净辐射、蒸腾速率对冠层温度的影响进行了敏感性分析。结果表明：模型能较好地预测长江中下游地区温室作物冠层温度，模型对该地区夏季(2002年6月24至7月12日，梅雨季节)温室内作物冠层温度预测值与实测值的决定系数(R²)和标准误(SE)分别为：0.8321，0.0037℃；建立的温室内部温度、相对湿度、净辐射和作物蒸腾速率的多元线性回归模型，其决定系数(R²)和标准误(SE)分别为：0.9996，0.8829℃；通过敏感性解释因子的分析表明，作物冠层温度对温室内部温度最为敏感，室内温度是预测冠层温度的主要因子。     

基于修正双作物系数模型估算温室黄瓜不同季节腾发量

为估算温室黄瓜植株蒸腾与土面蒸发,该研究基于FAO-56推荐的双作物系数模型,应用温室内实测微气象、叶面积指数(LAI)及土壤水分数据,对模型中基础作物系数(Kcb)和土面蒸发系数(Ke)进行修正,并基于修正后FAO-56Penman-Monteith(P-M)模型,确定温室参考作物蒸发蒸腾量(ET0),进而估算温室黄瓜蒸发蒸腾量(ETc)和植株蒸腾(Tr)。基于Venlo型温室内黄瓜不同种植季节(春夏季和秋冬季)Lysimeter和茎流计观测的黄瓜ETc和Tr,对修正后的双作物系数模型预测结果进行验证。结果表明,应用修正后的双作物系数模型估算的温室黄瓜ETc和Tr与实测值具有较好地一致性,春夏季温室黄瓜全生育期ETc估算值与实测值的日均值分别为3.05和2.94 mm/d,秋冬季分别为2.53和2.76 mm/d。修正后的双作物系数模型估算春夏季温室黄瓜日ETc的决定系数(R2)、均方根误差(RMSE)和模型效率系数(Ens)分别为0.95、0.41 mm/d和0.93;估算秋冬季ETc的误差计算结果依次为0.91(R2)、0.48 mm/d(RMSE)和0.90(Ens)。修正后的双作物系数模型估算春夏季日平均Tr与实测值分别为2.37和2.19mm/d,秋冬季分别为1.43和1.34 mm/d。研究结果还显示,不同种植季节温室黄瓜全生育期日平均Tr占ETc的比例分别为64.62%(春夏季)和68.59%(秋冬季)。该研究成果不仅为制定准确的温室黄瓜灌溉制度提供了理论依据,而且对实现温室环境智能化控制及减少温室内无效的土面蒸发具有重要意义。     

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.