典型草原冷蒿小禾草群落实生苗动态的研究

从实生苗的出现和死亡情况研究了冷蒿 ( Artemisia communtata)小禾草群落的实生苗动态 ,发现实生苗出现时间和数量均受水分条件的制约。而不同植物的种子萌发特性不同是造成实生苗出现时间产生差异的主要原因。自然条件下由于水分的限制这种差异并不明显 ,浇水后显出规律性的变化 ,出现两个明显的高峰期。种子萌发后并不意味着完成了实生苗的补充 ,大部分实生苗会在各个阶段死亡。造成死亡的外因主要有三个 :干旱、竞争及家蓄和野生动物的采食、践踏。但在放牧条件下 ,实生苗死亡率的变化仍有较一致的趋势 ,即随着牧压增加实生苗死亡率增加。     

放牧制度对短花针茅草原主要植物种群繁殖特征的影响

本文对短花针茅荒漠草原划区轮牧与自由放牧条件下主要植物种群的繁殖特性进了比较分析。结果表明 ,划区轮牧与自由放牧相比有利于短花针茅生殖枝的形成 ,且能够产生较多的种子 ;划区轮牧有利于主要植物种群实生苗的存活 ,但禁牧条件下对实生苗的生长更有利 ;短花针茅草原主要植物种群以无性繁殖为主 ,有性繁殖机会较少 ,且受降雨量的影响较大     

荒漠草原地区不同载畜率对功能群特征及其多样性的影响

采用随机区组试验研究了内蒙古高原荒漠草原亚带短花针茅(Stipa breviflora)草原群落不同载畜率对草原功能群特征及其多样性的影响,结果表明:不同载畜率水平下,功能群组成结构没有改变,功能群内物种组成及其群落学特征随着载畜率的增加发生了相应的变化。灌木类和多年生禾草特性比较稳定,多年生杂类草随着载畜率的增加物种组成下降幅度较大,使得群落结构和组成随载畜率的增加趋于简单化。丰富度指数和多样性指数重牧区最低,均匀度变化有所不同,因为中度放牧提高草地群落的植物多样性,更主要地是通过改变群落物种均匀性来实现的。     

短花针茅荒漠草原建群种空间分布的多重分形研究

短花针茅荒漠草原建群种和优势种不仅具有相对较高的地上现存量,也具有特定且复杂的空间分布区域,其在维护草地植物群落结构和功能的稳定具有重要作用。为探讨建群种空间分布特点及其随放牧强度的变化规律,引入多重分形理论,揭示短花针茅荒漠草原主要植物种群空间分布形式、生态位变化和种内个体关系。结果表明:建群种短花针茅在各放牧强度处理的空间分布均存在特有的多重分形特征。短花针茅空间分布主要受低密度分布区影响,随放牧强度的增加,高密度分布区的作用在加强,其生态位宽度增加,空间分布均匀性增大,个体间的竞争强度增加。多重分形不仅可用于植物种群空间分布研究,其在揭示不同植物种空间分布特异性的同时,能够给出较为丰富的种群生态学信息。     

不同强度放牧后沙质草场土壤微生物的分布特征

本文通过对科尔沁沙质草场不同强度放牧后围栏封育过程中表层(0-5cm)和亚表层(5-15cm)土壤微生物及土壤因子的研究表明:不同放牧强度围栏内,土壤微生物总数表现出:轻牧区>中牧区>对照区>重牧区>自由放牧区,11年的围栏封育不能使不同放牧强度下的沙质草场恢复到相同水平;亚表层土壤的细菌、真菌和放线菌数量、pH、电导率和含水量均大于表层土壤。轻牧和中牧有利于微生物各类群的生长繁殖,过度放牧会抑制微生物的活动,一直自由放牧则会严重破坏沙质草场表层土壤,使其微生物数量和土壤含水量减少,土壤碱性增强。     

不同生境黑果枸杞实生苗生长及土壤养分空间差异的研究

研究不同生境黑果枸杞实生苗数量、生长状况、生物量分配及土壤养分空间差异,探讨环境因子对黑果枸杞实生苗生长的影响,为黑果枸杞种群恢复及持续经营提供理论依据。采用固定样地调查法,于2016年对张掖市甘州区、临泽县、肃南县及周边地区的农田地埂、水渠边、盐化沙地、盐碱荒地等各生境黑果枸杞进行调查。研究结果表明：不同生境均有黑果枸杞实生苗分布,农田地埂生境实生苗数量相对水渠边、盐化沙地、盐碱荒地分别增加66.67%、122.22%、215.79%。因环境条件差异,不同生境的黑果枸杞实生苗采取了不同的生存策略适应环境：农田地埂生境的黑果枸杞主要为增高生长,盐化沙地的黑果枸杞主要为冠幅的增长,而盐碱荒地的黑果枸杞主要为增粗生长。农田地埂生境0~20 cm土层有机质含量相对水渠边、盐化沙地、盐碱荒地分别增加28.50%、2.62%、10.13%;全氮含量分别增加44.08%、33.16%、72.41%;有效氮含量分别增加46.81%、0%、50%。空气湿度、土壤含水量对黑果枸杞幼苗数量及幼苗生长有显著影响。在今后的黑果枸杞栽培管理中,幼苗期应加强水分管理。     

荒漠草原群落及主要植物种群特征对放牧制度的响应

本文研究了短花针茅荒漠草原划区轮牧和自由放牧两种放牧制度群落及主要植物种群特征变化,结果表明:经过3年的轮牧试验后,划区轮牧区群落及主要植物种群的高度、盖度、密度均较自由放牧区有不同程度的提高。划区轮牧区与自由放牧区相比,草地基况有明显好转,而自由放牧区一些退化植物、一年生植物、杂类草在草群中的高度、盖度、密度有所增加。划区轮牧区现存量高于自由放牧区。     

培肥措施对植物线虫种群数量动态的影响

以华北高产粮区山东桓台县冬小麦-夏玉米轮作田为试验基地,研究培肥措施对植物线虫种群数量动态变化的影响。结果表明各施化肥(尿素)处理组线虫种群数量高于不施肥对照组。整个生长季,化肥使植物线虫种群数量增加;化肥+秸秆加剧植物线虫数量增加;化肥+秸秆+有机肥(猪粪)使植物线虫数量减少。化肥和秸秆还田增加植物线虫发生量,有机肥降低植物线虫增长数量,应提倡多施用有机肥。     

新疆野苹果(Malus sieversii)种群年龄结构及其动态特征

新疆野苹果（Malus sieversii）是我国珍贵的濒危野生植物。通过在伊犁河谷的那孜、大莫合沟、那拉提和交托海4个新疆野苹果分布区建立样地,绘制年龄结构图、编制静态生命表,采用生存分析探明种群的存在状况,应用时间序列分析预测种群发展趋势。结果表明：新疆野苹果年龄结构呈中部膨大,幼龄个体少,中老龄个体多,那孜种群年龄结构偏大,交托海种群偏小;与其他种群相比,大莫合沟V＇pi最小,随机干扰风险极大值（Pmax）接近0,对外界干扰较敏感;那拉提种群的区间寿命、总寿命和期望寿命低,消失率高,种群衰退早;不同种群的存活曲线趋于Deevey-Ⅱ型,表明各龄级的死亡率相近;随着龄级增加,种群死亡密度曲线先下降后上升,危险率函数在Ⅳ龄级后增加明显,说明环境压力对野苹果的影响在Ⅳ龄级后表现强烈;受虫害、旅游、放牧干扰影响,时间序列分析预测野苹果种群老龄个体数量增加,中、幼龄个体缺乏补充,呈现不同程度衰退。应采取人工促萌或补植幼苗,调控林地密度,控制虫害蔓延,加强野苹果种质资源保护。     

花粉和植物不同生长阶段对西花蓟马种群的影响

在凤仙花的Impulse Orange和Cajun Carmine品种上开展了花粉和植物不同生长阶段对西花蓟马种群的影响。结果表明:在植物未开花前,添加花粉和不添加花粉西花蓟马的种群数量差异显著,添加花粉能显著增加两个品种上西花蓟马的种群数量,其西花蓟马数量分别为174.50、43.67头,而未添加花粉时分别为138.33头和27.00头。在植物开花后,添加花粉对西花蓟马的种群数量虽有一定影响,但差异不显著。植物不同生长发育阶段对西花蓟马的种群数量影响很大,无论是添加花粉还是不添加花粉,在两个品种上均表现为开花后的数量显著大于开花前的数量,说明凤仙花植物本身的花对西花蓟马种群的迅速增长影响很大。     

Emergence patterns of weed seedlings in relation to cultivation and rainfall

In experiments over 4 years, separate field plots were cultivated once only at 2-week intervals and the weed seedlings recorded weekly. Soil disturbance resulted in a flush of seedlings of which 90% appeared within 10 weeks after cultivation in early spring and within 3 weeks after cultivation in summer. Weekly emergence then returned to the level prevailing on undisturbed soil. The species composition of the seedling populations varied with the time of year at which the soil was disturbed. In each year there was a spring flush of seedlings, probably associated with rising soil temperature; subsequent flushes were coincident on cultivated and undisturbed soil and were related to the rainfall pattern. In each year there were periods when lack of soil moisture restricted emergence, and this appeared to be the over-riding factor determining seedling numbers. When cultivations were followed by long dry periods which prevented germination, the numbers of seedlings appearing when rain ultimately fell were no different from those when the soil was disturbed just before the rainfall.     

36%噻虫啉水分散粒剂对番茄幼苗根系活力及生理生化指标的影响

为明确土壤中施用噻虫啉对番茄植株生长的影响,分别用36%噻虫啉水分散粒剂有效成分1.0、1.5、2.0、2.5、3.0和5.0 mg/株处理盆栽番茄植株,测定处理后30 d番茄幼苗的生长量、叶片保护酶活性及根系活力。结果表明:1.0~2.5 mg/株噻虫啉处理均可提高番茄幼苗展开叶片数、株高、主根长和鲜重等生理指标,3.0 mg/株处理与对照相比无显著差异,而5.0 mg/株处理则对番茄幼苗生长有显著的抑制作用。不同剂量的噻虫啉处理均可提高番茄幼苗叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)的活性及根系活力。PPO和SOD活性在2.0 mg/株噻虫啉处理时达到最大值,分别为47.9和14.2 U/(min·g FW),比对照高29.6%和49.5%;POD、CAT和PAL活性在2.5 mg/株剂量时达到最大值,分别为46.0、62.4和26.0 U/(min·g FW),比对照高47.0%、36.7%和35.3%。1.0~5.0 mg/株噻虫啉处理后番茄幼苗根系活力比对照提高2.7%~33.1%。研究表明,土壤施用适量的噻虫啉可显著促进番茄幼苗植株的生长。     

广州机场口岸进境植物种苗疫情分析及风险防控措施

本文对2012~2016年广州机场口岸进境植物种苗贸易情况以及截获疫情进行分析,重点分析各类疫情的构成及特点,并结合实际,探讨了口岸进境种苗传入有害生物的风险防控措施。     

Effect of Foliar Application of Urea on Rhizosphere and Rhizoplane Microflora of Wheat1)

The effect of urea leaf treatment on plant growth and rhizosphere microorganisms was studied under controlled environmental conditions with spring wheat at 2 growth stages, and at 2 inorganic nutrient levels of the soil. The increase in dry weight of shoots and roots was inhibited by the urea treatment. Treatment of seedlings also resulted in a delay in the formation of tillers and nodal roots, especially in low fertilized soil. A temporary increase of rhizoplane bacteria was demonstrated after 7–9 days due to a stimulation of fast growing strains. A quantitative effect on rhizoplane fungi was only apparent, on day 9 after treatment of seedlings, as a decrease in total numbers and coincided with the increase in numbers of bacteria and actinomycetes. At this time the numbers of fungi known to be early root colonizers like Penicillium spp. and Mortierella spp. decreased after initially being stimulated, while numbers of late colonizers like Fusarium spp. and Trichoderma spp. increased after 9 days after initially being reduced in comparison with the control. Investigation of the rhizosphere effect (R/S) of wheat by the soil dilution plate method and fluorescence microscopy showed a 200% increase in total numbers of micro-organisms in the rhizosphere soil when the former method was used, but a 10–30% reduction when fluorescence microscopy was employed.     

Phenotypic plasticity of Artemisia ordosica seedlings in response to different levels of calcium carbonate in soil

Plant phenotypic plasticity is a common feature that is crucial for explaining interspecific competition, dynamics and biological evolution of plant communities. In this study, we tested the effects of soil CaCO_3(calcium carbonate) on the phenotypic plasticity of a psammophyte, Artemisia ordosica, an important plant species on sandy lands in arid and semi-arid areas of China, by performing pot experiments under different CaCO_3 contents with a two-factor randomized block design and two orthogonal designs. We analyzed the growth responses(including plant height, root length, shoot-leaf biomass and root biomass) of A. ordosica seedlings to different soil CaCO_3 contents. The results revealed that, with a greater soil CaCO_3 content, A. ordosica seedlings gradually grew more slowly, with their relative growth rates of plant height, root length, shoot-leaf biomass and root biomass all decreasing significantly. Root N/P ratios showed significant negative correlations with the relative growth rates of plant height, shoot-leaf biomass and root length of A. ordosica seedlings; however, the relative growth rate of root length increased significantly with the root P concentration increased, showing a positive correlation. These results demonstrate that soil CaCO_3 reduces the local P availability in soil, which produces a non-adaptive phenotypic plasticity to A. ordosica seedlings. This study should prove useful for planning and promoting the restoration of damaged/degraded vegetation in arid and semi-arid areas of China.     

Variation in reproductive characteristics of Eupatorium adenophorum populations in different habitats

The invasive plant, Eupatorium adenophorum, produces large numbers of small seeds with a high germination rate. However, this investigation showed that E. adenophorum populations in an evergreen broad‐leaved forest had a high proportion of seedlings when compared with clonal plants. Whereas an opposite pattern was found in a deciduous broad‐leaved forest and in a roadside site. A seed addition experiment where E. adenophorum seeds were added to each of the three habitats did not increase the number of E. adenophorum seedlings at any of the three field sites. Field and greenhouse experiments demonstrated that a soil litter layer significantly reduced the number of E. adenophorum seedlings during the early seedling emergence period. However, at later periods, the litter cover did not affect survival and growth of individuals. The emergence of E. adenophorum seedlings was significantly increased in field experiments when there was no litter, and parental plants were removed. Finally, the growth of seedlings was significantly reduced when planted with their parental plants in a root box experiment. In the low‐resource environment of the evergreen broad‐leaved forest, E. adenophorum reproduced primarily by its abundant seed production. In the more open deciduous broad‐leaved forest and roadside site, the populations reproduce primarily by vegetative clones that can grow quickly, are better competitors and could take advantage of the high‐resource environment.     

5种药剂及鲫鱼放养对摇蚊防治效果比较

莼菜是一种经济价值较高的睡莲科作物,常因摇蚊幼虫的为害而遭受较大的经济损失。为了筛选出莼菜田中摇蚊的有效防治方法,本研究选取了5种杀虫剂(阿维菌素、灭蝇胺、敌百虫、噻虫嗪、毒死蜱)进行田间防治试验,同时与莼菜田中放养鲫鱼的防治方法进行效果比较。结果表明,所选取的5种药剂和放养鲫鱼均能有效抑制摇蚊幼虫。其中,90%敌百虫原药的速效性较强,1.8%阿维菌素乳油和40%毒死蜱乳油次之,但是50%灭蝇胺可湿性粉剂和鲫鱼放养法的持效性较好,在21 d时,防治效果仍在85%以上。结合莼菜的食用特性,建议在大田生产中采用放养鲫鱼控制摇蚊。     

协同增效型拮抗细菌组合CL-7和CL-8的稳定性及其对加工番茄的促生防病效果

将加工番茄根际土壤中筛选到的单一拮抗细菌进行复配，筛选获得两个具有促生拈抗作用的细菌组合CL-7和CL-8。经过20代转管连续培养检测细菌组合的稳定性，结果表明，这两个拮抗细菌组合从13代之后，其pH值基本稳定，组合内菌落种类及数目也基本稳定；且12代后抑菌活性基本保持不变。和单一拮抗菌株相比，CL-7和CL-8均能显著增加对番茄立枯病菌、辣椒疫霉病菌和枯萎病菌的抑菌效果。发芽和苗期灌根试验结果表明，拮抗细菌组合CL-7和CL-8可显著促进加工番茄幼芽及苗期的生长，苗期鲜重分别增加了147．620k和176．190k，干重分别增加了143．75％和143．75％。在温室和田间条件下，细菌组合CL-7和CL-8对加工番茄立枯病的防治效果都很显著，分别可达25．1％、40．1％和52．2％、55．5％。