桉树人工林树液流动密度随边材径向深度的变化

树液流动密度(SFD)随边材径向深度的变化对于准确估测流经边材的树液通量是非常重要的,后者又制约着Heat Pulse的应用精度.但迄今为止,只有很少的研究估计了由于SFD随径向的梯度变化而带来的误差,SFD沿树干径向分布规律的获得往往依靠对少数几棵树的观测资料.基于在广东雷州半岛对两块3～4年生桉树(Eucalyptus urophylla S.T. Blake)人工林1年的Heat Pulse观测,探讨了对来自39株立木大量观测资料的综合处理方法,发现这两个样地(纪家和河头)的林分中SFD随边材径向深度的变化可以用如下回归方程来描述:纪家: y=3.667 5x3-7.295 5x2+3.682 6x+0.567 4 (R2=0.939 1, n=80, P=0.01)河头: y=5.006 2x3-9.116 1x2+4.454 4x+0.463 4 (R2=0.806 9, n=72, P=0.01)式中:y--某一树液感应器所测得的SFD与不同深度的4个感应器所测得的SFD的平均值之比;x-某一树液感应器在边材中的深度与边材厚度之比.从形成层到心材,SFD最初有所增加,随后持续减小,但由于树木年龄很小,最大的SFD只比最小的SFD大0.33～0.36倍.     

应用Granier热消散探针(TDP)法测定树木的木质部液流:理论与实践

Granier热消散探针法是目前研究树木生理生态和森林水文最常用的测定整树水分利用的方法之一.然而,已有的相关综述文献中,还没有专门介绍利用Granier热消散探针研究木质部液流的综述文章.本文重点介绍了Granier热消散探针测定系统的理论基础,对有关该探针的校准和改进的最新研究进展进行了综述,并还深入探讨了零液流信号值的确定、自然热梯度、损伤效应、液流的逆格型和将木质部液流密度外推至整树蒸腾耗水量等重要的实际问题.     

桉树人工林树液流动密度随边材径向深度的变化

树液流动密度 (SFD)随边材径向深度的变化对于准确估测流经边材的树液通量是非常重要的 ,后者又制约着HeatPulse的应用精度。但迄今为止 ,只有很少的研究估计了由于SFD随径向的梯度变化而带来的误差 ,SFD沿树干径向分布规律的获得往往依靠对少数几棵树的观测资料。基于在广东雷州半岛对两块 3～ 4年生桉树 (Euca lyptusurophyllaS .T .Blake)人工林 1年的HeatPulse观测 ,探讨了对来自 39株立木大量观测资料的综合处理方法 ,发现这两个样地 (纪家和河头 )的林分中SFD随边材径向深度的变化可以用如下回归方程来描述 :纪家 :y =3.6 6 75x3 - 7.2 95 5x2 3.6 82 6x 0 .5 6 74 (R2 =0 .9391,n =80 ,P =0 .0 1)河头 :y =5 .0 0 6 2x3 - 9.116 1x2 4.4 5 4 4x 0 .4 6 34(R2 =0 .80 6 9,n =72 ,P =0 .0 1)式中 :y———某一树液感应器所测得的SFD与不同深度的 4个感应器所测得的SFD的平均值之比 ;x—某一树液感应器在边材中的深度与边材厚度之比。从形成层到心材 ,SFD最初有所增加 ,随后持续减小 ,但由于树木年龄很小 ,最大的SFD只比最小的SFD大 0 .33～ 0 .36倍。     

Chitinase in Cucumber Xylem Sap

A chitinase activity was detected in fractions of xylem sap collected from the cut surface of cucumber stems. A 28-kDa acidic protein was purified from the active fractions and its N-terminal amino acids sequence was found to be identical to that of a chitinase gene. Cucumber roots produce and secrete an acidic chitinase, one of the PR proteins, into xylem sap and deliver it to aboveground organs.     

Relationships Between Climatic Variables and Sap Flow, Stem Water Potential and Maximum Daily Trunk Shrinkage in Lemon Trees

The feasibility of obtaining sap flow (SF), maximum daily trunk shrinkage (MDS) and midday stem water potential (Ψ_stem) baselines or reference values for use in irrigation scheduling was studied in adult Fino lemon trees (Citrus limon (L.) Burm. fil.) grafted on sour orange (C. aurantium L.) rootstocks. Plants were irrigated daily above their water requirements in order to obtain non-limiting soil water conditions. The results indicated that baselines for plant-based water status indicators (MDS, SF and Ψ_stem) can be obtained, even though there was a certain scattering of the data points representing the relations between the plant-based measurements and the environmental variables (reference evapotranspiration, solar radiation, vapour pressure deficit and temperature). SF was more closely associated with changes in the studied evaporative demand variables than were MDS and Ψ_stem. SF and Ψ_stem were more closely correlated with changes in reference evapotranspiration (ETo) (r ² = 0.93 and 0.79, respectively), while MDS behaviour was best correlated with mean daily air temperature (T _m) (r ² = 0.76). Increases in the evaporative demand induced more negative Ψ_stem values and, as a consequence, SF increased, which, in turn, was translated into an increase in MDS. This confirmed that SF and MDS were very good predictors of the plant water status during the observation period and their continuous recording offers the promising possibility of their use in automatic irrigation scheduling in lemon trees.     

The Role of Osmotic Potential in Spring Sap Flow of Mature Sugar Maple Trees (Acer saccharum Marsh)

Field measurements of xylem sap osmotic and pressure potentialwere made on sugar maple trecs (Acer saccharum Marsh) duringthe winter and spring of 3 years to determine whether the hydrostaticpressure was osmotically generated. Sap osmotic potential waslow enough to account for the hydrostatic pressure but the dynamicsof its diurnal behaviour indicated that osmotic potential wasnot directly responsible for hydrostatic pressure. The diurnalcourse of hydrostatic pressure showed definite peaks but osmoticpotential often did not. The magnitude of the diurnal changesin hydrostatic pressure was approximately 0·15 MPa whereasthe changes in osmotic potential were only 0·05 MPa.Because the sap osmoticum is primarily sucrose, and starch isstored in the xylem throughout the tree, the temperature dependenceof the sucrose-starch interconversion system was investigated.More active amylase was formed in maple twigs after incubationat 0°C and 4°C than at –3, 6 or 15°C. Therate of starch hydrolysis by maple amylase increased with temperature,reaching a maximum at approximately 45°C. There was somestarch hydrolysis at –3°C. The starch hydrolysis systemthus indicated no critical role for temperature fluctuationsabout 0°C. Starch was found to be densely stored in therays of the trunk and twigs and around the central pith in thetwigs. Key words: Acer succhmum Marsh, Osmotic potential, Xylem sap pressure     

转Bt基因抗虫棉(Gossyposium)伤流中Bt毒蛋白的运输

本文以常规棉品种‘石远321'和抗虫棉品种‘SGK321'与‘99B'为材料,通过考马斯亮蓝和ELISA方法分析了伤流中可溶性蛋白和Bt(苏云金芽孢杆菌)毒蛋白含量.结果发现,转基因抗虫棉伤流中可溶性蛋白含量显著高于常规棉,并在抗虫棉伤流中检测到了Bt毒蛋白,而常规棉伤流中没有Bt毒蛋白的存在.通过嫁接实验研究发现,将常规棉嫁接到转Bt基因抗虫棉砧木上,叶片中也有Bt毒蛋白的积累.这些结果说明,Bt毒蛋白可以通过木质部伤流液向地上部运输,并在叶片中积累,Bt毒蛋白由根系向地上部的运输对棉花的抗虫性是有益的.     

白桦树干液流的动态研究

应用热扩散原理,采用ICT－2000TE（Transpiration-Environment)自动监测系统,对东北东部山区的先锋树种白桦的树干液流及主要环境因子进行一个生长季的同步测定。结果表明,在整个生长季的晴天,白桦树干液流的日变化呈现明显的单峰曲线。液流速率的峰值出现在8月中旬,为84.72L/d。在白桦树叶脱落后,仍有较高的液流速率,而到10月中旬急剧下降,值为3.84L/d。在不同生长时期白桦每小时的液流速率与相应的环境因子逐步回归分析结果表明,影响白桦液流速率的主要环境因子是空气温度、空气相对湿度和辐射强度,在不同时期三者的作用是不同的。     

鼎湖山针阔叶混交林4种优势树种树干液流特征

运用Granier热消散式探针法,对鼎湖山自然保护区针阔叶混交林4种优势树种(马尾松、木荷、锥栗和广东润楠)的树干液流密度进行了长期连续观测,并同步监测林分的环境因子(光合有效辐射(PAR)、空气温度(T)、空气湿度(RH)、土壤含水量)。结果表明:(1)4种优势树种的边材面积(As)与胸径(DBH)均存在显著相关关系(P0.05);(2)各优势树种树干液流均呈现"昼高夜低"单峰曲线,且液流速率存在明显的季节性差异;(3)无论湿季还是干季,光合有效辐射(PAR)和水汽压亏缺(VPD)均为控制蒸腾的主要驱动因子;(4)4种优势树种湿季平均日蒸腾量高于干季,马尾松、木荷、锥栗、广东润楠湿季平均日蒸腾量分别为29.52、39.29、30.40、9.41 kg H2O/d,干季分别为20.91、24.84、24.26、8.43 kg H2O/d,干季和湿季的平均日蒸腾量(kg H2O/d)大小均为木荷锥栗马尾松广东润楠,这种种间差异是由边材面积大小和树种本身的生物学特性共同决定的。     

Sap salinity effects on xylem conductivity in two mangrove species

Xylem sap salinity and conductivity were examined in two mangrove ecosystem tree species . For Avicennia germinans , extracted xylem sap osmotic potentials ranged from −0.24 to −1.36 MPa versus −0.14 to −0.56 MPa for Conocarpus erectus. Xylem sap of Conocarpus did not vary in osmotic potential between sites nor between predawn and midday. In Avicennia , values were more negative at midday than predawn, and also more negative at hypersaline than hyposaline sites. After removing embolisms, specific conductivity ( K _s) was measured as a function of salinity of the artificial xylem sap perfusion. For both species the lowest K _s values, about 70% of the maximum K _s, were obtained when stems were perfused with deionized water (0 m m ; 0.0 MPa) or with a 557-m m saline solution (−2.4 MPa). Higher K _s values were obtained in the range from −0.3 to −1.2 MPa, with a peak at −0.82 ± 0.08 MPa for Avicennia and −0.75 ± 0.08 MPa for Conocarpus . The variations in K _s values with minima both at very low and very high salt concentrations were consistent with published results for swelling and shrinking of synthetic hydrogels, suggesting native hydrogels in pit membranes of vessels could help regulate conductivity.     

转基因林木研究进展

生物技术和基因工程为林木商用价值的提高开辟了广阔的前景。综述了最近几年转基因林木耐逆性提高、木质素的分子改造、植物体的繁殖不育以及转基因林木的安全性等研究进展。     

百合生长期茎流特征及其与环境因子的关系

以百合Oriental-Trumpet系列中的罗宾娜为实验材料,在监测环境因子的基础上,用包裹式茎流仪探头对其生长期茎流进行测定研究,明确百合生长期内的茎流和耗水量变化规律。结果表明:(1)百合158d生长期中,总茎流量为7 289.30g,平均日茎流量为46.13g,其中抽茎期、现蕾期、花期、果期和果后期的总茎流量分别为1 862.00、3 197.80、710.50、1 438.30和116.70g,日均茎流量分别为62.97、72.68、54.65、30.60和4.67g,不同生长时期百合日茎流速率有明显变化。(2)光辐射和大气温度是影响百合生长周期茎流量的主要环境因子,且光辐射、空气温度与茎流速率呈正相关,而与空气相对湿度呈负相关。(3)阴雨天茎流量和日茎流速率明显小于晴天。该研究为百合水分代谢模型的建立及现代化精准节水百合种植模式的研究奠定了理论基础,对于选择合适的百合节水栽培模式具有重要意义。     

种植密度对不同耐密性春玉米基部茎节维管束及根系伤流的影响

选用不同耐密性玉米品种‘郑单958’(密植品种)和‘辽单526’(稀植品种)为材料,设置4个不同的密度水平,分别在拔节期和乳熟期采用徒手切片显微观测基部茎秆内部维管束结构变化,采集茎基部伤流液测定其主要成份含量并计算伤流强度,以期为春玉米的密植高产提供理论依据.结果显示:(1)在拔节期,‘郑单958’维管束结构对密度变化反应相对敏感,而‘辽单526’维管束结构在各密度间并无显著差异;当密度最大时,‘辽单526’伤流强度的下降程度要大于‘郑单958’,但两品种伤流液成分对密度反应无明显变化.(2)在乳熟期,密度对‘郑单958’维管束结构无显著影响,而‘辽单526’在密度增加后维管束结构各指标明显下降且与对照(适宜密度)差异显著;各密度‘郑单958’的伤流强度均大于‘辽单526’,增加密度会提高两品种伤流液中可溶性糖的含量,尤其以‘辽单526’增加更显著.(3)在高于对照密度条件下,两品种的籽粒产量都不同程度低于对照,但‘辽单526’产量降低程度要大于‘郑单958’.研究表明,密植性玉米对密度压力的反应要早于稀植性玉米,其在高密度表现出的适应性也要优于稀植性玉米,这从茎基部的结构和功能上揭示了玉米品种耐密性差异的生理基础.     

新疆阿克苏干旱区富士苹果树干液流动态变化研究

选择新疆阿克苏干旱区富士苹果为研究对象,利用TDP茎流计连续测定苹果树干液流,并用自动气象站同步记录环境因子变化,探讨环境因子对树干液流的影响。结果显示:液流速率连日的变化过程是一个最大值不同的正弦曲线,夜间液流速率降低,白天液流速率上升;晴天液流速率呈明显的单峰曲线,阴天液流速率表现为多峰或双峰曲线,不论是晴天还是阴天,苹果在夜间仍然有微弱的活动,这种现象可能与新疆阿克苏地区的地理位置和气候有关;在苹果主要生长季内,树干液流速率(Fs)与大气温度(Ta)、太阳辐射(Rn)、相对湿度(RH)有较好的复相关关系(R2=0.93*),且影响苹果树液流速率Fs的最主要气象因子为大气温度Ta;苹果生长季内耗水总量为4 059.64L,并以7月耗水量最大(765.34L),占耗水总量的18.85%。研究表明,TDP径流计能够精确测定生长季内苹果茎干的液流速率与耗水量,且在干旱区影响苹果茎干液流变化的主要环境因子依次是大气温度、太阳辐射、相对湿度。     

南方果树在园林绿化中的应用

通过对我国南方果树的种类、特点及园林绿化应用特性进行初步调查研究,从应用种类、范围和方式等方面对其在园林绿化中的应用进行探讨。     

几种生理因素对玉米木质部汁液中蛋白质含量的影响

受干旱胁迫的玉米叶和茎木质部汁液中蛋白质含量降低,根中蛋白质含量升高.偏酸性营养液中的玉米各营养器官木质部汁液中蛋白质含量降低,中性或碱性营养液中的则升高.以100mmol·L-1的ABA营养液处理后的玉米根、茎和叶片的木质部汁液中蛋白质含量都升高;而用2 mmol·L-1EGTA、80 mmol·L-1三氟啦嗪或100mmol·L-1异博定处理后的木质部汁液中蛋白质含量变化不明显.