科尔沁沙地黄柳和小叶锦鸡儿茎流及蒸腾特征

利用Dynamax茎流测量系统、Li-6400光合作用仪和自动气象站分别对科尔沁沙地两种灌木树种黄柳和小叶锦鸡儿的液流变化、蒸腾速率及其周围的环境因子进行检测.研究结果表明：（1）黄柳、小叶锦鸡儿茎干液流通量密度日变化趋势基本相同,呈多峰曲线;液流启动时间分别为4：30、5：30,在13：00左右到达各自液流峰值,峰值大小为81.2～91.7mg/h、17.3～27.1mg/h,20：30降为最低,晚间均具有明显的液流活动现象.（2）灌木的茎流日变化曲线与蒸腾速率日变化曲线并不吻合,实验测得的叶片蒸腾速率不能同步反映茎干液流的动态变化特征;黄柳的叶片蒸腾速率和单枝蒸腾耗水量均大于小叶锦鸡儿,耐旱性相对较低.（3）黄柳、小叶锦鸡儿白天液流通量密度变化趋势与环境因子变化趋势相吻合.相关性分析表明,影响灌木液流变化的主要因子依次是太阳有效辐射、相对湿度、大气温度、风速、10cm和20cm土壤温度.     

施用城市污泥对小叶黄杨光合特性和生长的影响

城市污泥作为有机肥料施用于园林植物已备受关注.本研究利用温室盆栽试验,分别设置不同用量城市污泥［低量（LC）、中量（MC）和高量（HC）］处理和无机肥（IF）处理,并以不施肥料和污泥为对照（CK）,研究不同用量城市污泥对小叶黄杨幼苗光合特性和生长的影响.结果表明：施用城市污泥可以提高小叶黄杨幼苗叶片叶绿素和氮素含量,但随污泥施用量的增加,叶片净光合速率（P_n）呈下降趋势.在生长季的8月,与IF处理和CK相比,LC、MC处理的叶片P_n均提高,而HC处理却较IF和CK分别降低了25.9%和8.9%;至10月,LC、MC和HC处理的叶片P_n均低于IF处理,但LC处理的P_n仍高于CK,而MC、HC处理的P_n均低于CK,其中HC处理的P_n较IF处理和CK分别降低了48.4%和29.2%.IF处理小叶黄杨植株的株高、地径和根长最大,LC处理次之,且地上生物量最大;MC处理除了株高和地上生物量高于CK外,根长和地径均低于CK;而HC处理则严重抑制了根系的生长.小叶黄杨幼苗的城市污泥施用量应限制在30 t·hm^-2以内.     

通过体内基因转染改变Meis1在围着床期小鼠子宫中的表达影响胚胎着床

通过宫腔内脂质体转染改变小鼠子宫内Meis1基因的表达水平,研究其对子宫内膜容 受性的影响,从而推测Meis1基因在胚胎着床中的作用.选择8～12周龄昆明小鼠,于妊娠 第2 ｄ,通过向小鼠宫腔内注入Meis1基因表达质粒和siRNA表达质粒及其各自的对照质粒 ,在妊娠第5ｄ, 提取小鼠子宫mRNA 和蛋白质行半定量RT-PCR 和免疫组化分析,观察各组小鼠子宫内膜Meis1和整合素β3的表达变化.在妊娠第9 ｄ,观察Meis1基因上调组及其对 照组、Meis1基因下调及其对照组妊娠率和胚胎着床数的差异.结果显示,Meis1基因下调组胚胎着床率明显低于对照组（P<0.05）,Meis1基因上调组胚胎着床率略高于对照组,但无统计学意义（P>0.05）;Meis1基因上调组其整合素β3的表达高于其对照组,Meis1基因下调组 整合素β3的表达低于其对照组,差异均有显著性（P<0.05）.以上观察结果表明,Meis1基因表达下降可明显减少胚胎着床率,影响整合素β3的表达.Meis1基因表达提高则可促进整合素β3的表达. 因此,Meis1可能作为1种子宫内膜容受分子,在胚胎着床中发挥重要作用.     

小叶锦鸡儿人工固沙区植被恢复生态过程的研究

主要研究了流动沙兵采用草方格固沙结合播种小叶锦鸡儿后,上锦鸡儿人工群落形成和发展过程,尤其对群落中物种侵入过程和群落组织结构在３５年间的变化情况做了详细分析。结果表明,人工小叶锦鸡儿群落不同发育阶段植物丰富度发生降有大的变化,从５种增加到２３种;在生活型组成结构上,一年生植物占约对优势,但所占比例随着时间的变化有８逐渐减少的趋势,地面芽植物和地下芽植物的种类数 和个体数所占比例均逐渐增加;物种多样     

小叶锦鸡儿灌丛群落蒸腾耗水量估算方法

为了确定沙地小叶锦鸡儿 (Caragana microphylla) 人工林的蒸腾速率, 于2006年6月运用热平衡茎流测量技术, 对科尔沁沙地一处15a生人工小叶锦鸡儿群落的分枝液流动态进行了监测。根据生物统计结果选取被测标准枝, 标准枝基径在0.4~1cm范围内。同时, 分别用基径总断面积推算法和叶片密度推算法对灌丛叶面积进行了估算。以叶面积为扩展纯量, 利用标准枝液流对灌丛群落耗水量进行尺度转换, 在转换过程中, 假设叶面积与蒸腾耗水量之间具有很强的相关性。该尺度转换方法经与大型称重式Lysimeter测值对比验证, 误差小于14.3%, 可望准确估算小叶锦鸡儿灌丛群落的蒸腾耗水量。     

长白山阔叶红松林不同深度土壤水分特征曲线

采用露点水势仪对长白山阔叶红松林不同深度（0～10 cm的壤土、20～30 cm的白浆土、50～60 cm的黄土）土壤水分特征曲线进行分析.结果表明：不同土层土壤水分特征曲线整体趋势均表现为快速下降-缓慢下降-基本平稳;用Gardner等提出的幂函数方程可较好地反映该区土壤含水量与土壤水势之间的数量关系,拟合方程的相关系数在0.9239～0.9400;不同土层土壤的持水能力大小依次为黄土>壤土>白浆土,土壤含水量随土壤水势降低而减小的速度依次为壤土>白浆土>黄土.不同土层脱湿过程的土壤水分特征曲线位于吸湿过程之下,说明土壤水分存在滞后现象,且滞后时效依次为壤土>黄土>白浆土.     

不同冬季覆盖作物对稻田甲烷和氧化亚氮排放的影响

采用静态箱-气相色谱法对不同冬季覆盖作物处理［免耕直播黑麦草-双季稻(T₁)、免耕直播紫云英 双季稻(T₂)、翻耕移栽油菜-双季稻(T₃)、免耕直播油菜-双季稻(T₄)和冬闲-双季稻(CK)］下稻田甲烷（CH₄）和氧化亚氮（N₂O）排放进行观测,分析了不同冬季覆盖作物对稻田CH₄和N₂O排放的影响.结果表明：在冬季作物生长期,不同冬季覆盖作物稻田CH₄和N₂O总排放量与对照（CK）的差异均达到极显著水平（P<0.01）;T₃和T₁处理的稻田CH₄和N₂O排放量最高,其CH₄排放量分别为0.88 和0.60g·m^-2,N₂O排放量分别为0.23 和0.20 g·m^-2;冬季作物还田后,各处理早、晚稻田CH4排放量均明显高于对照.早稻田CH₄排放量最高的为T₁和T₂处理,分别达21.70和20.75 g·m^-2;晚稻田CH₄排放量最高的为T₃和T₄处理,分别为58.90和54.51 g·m^-2.各处理早、晚稻田N₂O总排放量均显著高于对照,T₁、T₂、T₃和T₄处理的早稻田N₂O总排放量分别比对照增加53.7%、12.2%、46.3%和29.3%,晚稻田分别比对照增加28.6%、3.8%、34.3%和27.6%.     

Photosynthetic and morphological characters of Caragana microphylla in different slope aspects and positions

In order to find out how small scale topographical factors affect growth and physiological characters of Caragana microphylla, which is a widely distributed shrub species and has an important role in restoring degraded grassland in natural ecosystem, a natural population of C. microphylla was chosen in a typical steppe community in June, 2009. The population was 34 km to the southeast of Xilinhot City, China, and a total of 54 shrubs were selected from different slope aspects and positions. We investigated the photosynthetic and morphological characters of these shrubs and analyzed the relationship between plant traits of C. microphylla and soil nitrogen and phosphorus availability. Moreover, the relationship between plant traits of C. microphylla and herbaceous aboveground biomass was studied. (1) The maximum net photosynthetic rate (Pn_max) was significantly lower on shady slopes than that on sunny slopes and higher on upper slopes than that on lower slopes. Stomatal conductance (Gs), net photosynthetic rate/intercellular CO₂ concentration (Pn/Ci) and intercellular CO₂ concentration (Ci) under saturated irradiance showed similar trends with slope aspect and position. Likewise, the maximum photochemical efficiency of PSII (Fv/Fm), PSII potential activity (Fv/Fo) and the first-year shoot morphological characters of C. microphylla were also correlated with slope aspect and position. (2) Soil nitrogen availability showed no significant effect on photosynthetic or morphological traits of C. microphylla, however, there were several significant relationships between soil phosphorus availability and plant traits. Dry weight, shoot length, compound leaf size, and leaflet length of first-year shoots of C. microphylla were significantly negatively correlated with soil C:P ratio. Though not significant, photosynthetic parameters under saturated light and other morphological characters of first-year shoots were negatively correlated with soil C:P ratio, i.e., these traits increased with increasing soil phosphorus availability. These suggested that the difference of soil phosphorus availability played an important role in making C. microphylla having different photosynthetic and morphological characters on different slope aspects and positions. The individuals grown in relatively P-rich site had longer shoots and larger leaves and grew better. Low phosphorus content was thought to limit photosynthetic activity through several different mechanisms, including both stomatal and non-stomatal limitations, the latter being more likely in the present study. (3) Photosynthetic and morphological characters of C. microphylla were all negatively correlated with herbaceous aboveground biomass, though only Pn/Ci and length of first-year shoot were significantly correlated with it. This indicated that the difference in plant community was a factor making C. microphylla have different growth and physiological characters on different aspects and positions of slope. A number of studies showed that grazing of the herbaceous layer promoted the establishment and proliferation of woody species, and then led to grassland deterioration; but in arid and semi-arid ecosystems, some widely distributed shrub species like C. microphylla created resource islands and provide favorable microhabitat for grass species. In the present study, we found negative correlations between traits of C. microphylla and herbaceous aboveground biomass. We suggested that the removal of livestock grazing result in the decrease of the distribution C. microphylla and increase of grass coverage, and lead to the restoration of the typical steppe.     

六种藜科植物提取物对植物病原菌的抑制活性

研究了角果藜（ Ceratocarpus arenarius）、盐穗木（ Halostachys caspica）、里海盐爪爪（ Kalidium caspicum） 、叉毛蓬（ Petrosimonia sibirica ）、盐角草（ Salicornia europaea ）和小叶碱蓬 （ Suaeda microphylla ）等六种新疆藜科植物提取物及其不同极性萃取部分对根癌土壤杆菌（Agrobacterium tumefaciens ）、黄瓜角斑病菌（P Pseudomonas lachrymarts）、番茄疮痂病菌（ Xanthomonas vesicatoria ） 等植物病原细菌以及杨树溃疡病菌（ Botryosphaeria dothidea ）、棉花枯萎病菌（Fusarium oxysporum f. sp. vasinfectum ）、稻纹枯病菌（Rhizoctonia solani）等病原真菌的抑制活性。结果显示角果藜、叉毛蓬和盐角草乙醇粗提物表现出一定抗细菌活性,其中以叉毛蓬和盐角草提取物对黄瓜角斑病菌的抑制活性最强。多数植物提取物及其不同极性萃取部分对杨树溃疡病菌表现出强的抑制活性。抗真菌活性成分主要存在于供试植物的石油醚、氯仿和正丁醇萃取部分中,提示活性成分为极性中等的化合物。角果藜和盐角草乙醇粗提物及其不同极性萃取部分对供试真菌有较好的抑制活性。     

小菜蛾的耐热性

小菜蛾是世界范围内十字花科蔬菜上的重要害虫.临界高温(critical thermal maximum, CTMax)是昆虫耐热性的常用指标.采用动态加热方法,利用自行组装的装置测定了小菜蛾的临界高温,以此作为其耐热性指标,研究发育阶段、饲养温度、世代、性别和热激对小菜蛾耐热性的影响.结果表明： 25 ℃下饲养的小菜蛾4龄幼虫的CTMax 均值为50.31 ℃,显著高于1龄幼虫(43.03 ℃)、2龄幼虫(46.39 ℃)、3龄幼虫(49.67 ℃)以及雌性成虫(45.76 ℃)和雄性成虫(47.73 ℃);不同饲养温度(20、25和30 ℃)下成虫耐热性无显著差异;30 ℃下饲养1代、3代及6代的不同世代成虫CTMax也无显著变化;所有处理雌雄成虫的CTMax无显著差异;40 ℃下45 min热激可使5日龄雄成虫的CTMax值从45.51 ℃增加到46.49 ℃.