锁阳种子休眠与萌发特性的初步研究

为了解锁阳（Cynomorium songaricum）寄生生长特性,使用物理方法和化学方法对其种子进行萌发诱导处理,观察萌发情况。结果表明：锁阳种子较小,成熟的种胚发育不完全,萌发前后处于球形原胚阶段。试验结果证明,锁阳种子萌发的启动,需有来自寄主根中的某种萌发刺激信号;外源赤霉素（GA3）及乙烯溶液对种子休眠的破除...     

根寄生杂草种子萌发剂概述

独脚金属（Striga spp.）及列当属（Orobanche spp.和Phelipanchce spp.）杂草是世界范围内对农业生产危害严重的根寄生杂草,主要依靠寄生茄科、豆科、谷类等作物获得水分和营养。根寄生杂草种子只有在合适的萌发诱导物（如独脚金内酯）刺激下才能萌发。文章从根寄生杂草的分类、分布及危害,种子萌发剂类型及适用范围,种子萌发剂独脚金内酯的生物合成及分离鉴定,根寄生杂草种子萌发诱导剂的作用机制以及种子萌发过程中激素间协同调控作用等方面进行了综述,并展望了种子萌发剂设计筛选及其在根寄生杂草化学防控中的潜在应用前景。     

116份藜麦种质资源萌发期抗旱性综合评价

采用不同浓度的PEG-6000模拟干旱胁迫,对黑藜（黑粒）、青海红（红粒）、柴达木红（红粒）、雪藜（白粒）和青藜1号（白粒）等3个类型的116份藜麦品种进行干旱胁迫试验,确定藜麦萌发期适宜抗旱性鉴定的浓度,并对不同类型藜麦种质资源进行萌发期抗旱鉴定。以发芽率、发芽势、发芽指数、活力指数、芽长、根长、鲜质量和萌发耐旱指数等8个萌发期相关指标为依据,采用主成分分析法、隶属函数法和聚类分析法对参试藜麦种质的抗旱性进行综合评价及分类。结果表明：20% PEG-6000可以作为胁迫试验的适宜浓度;采用此浓度对116份不同来源的藜麦种质资源进行萌发期抗旱性鉴定和各指标值的测定,再结合主成分分析和隶属函数法计算不同藜麦品种的加权隶属函数值,并以此进行抗旱性强弱排序;通过聚类分析将参试材料分为3大类群,其中第2大类群第1亚类群（Ⅱ₁）的29个藜麦品种抗旱性较好,可以作为后期抗旱品种培育的基础材料。     

NO和水孔蛋白在小麦种子萌发中的互作效应

为探究一氧化氮(NO)和水孔蛋白(AQP)在种子萌发过程中是否存在互作效应,以小麦品种陕合6号（耐旱型）和郑引1号（干旱敏感型）为材料,研究H₂O、HgCl₂（500 μM）、PEG（PEG-8000,-0.35 MPa）、SNP（0.5 mM）、SNP+PEG、SNP+HgCl₂溶液浸种对种子萌发的影响。结果表明：SNP(NO供体)促进了抗旱品种种子的萌发,而抑制了干旱敏感品种种子的萌发;AQP在干旱敏感品种种子萌发中的作用大于抗旱品种;NO能够 解除干旱和水孔蛋白抑制剂HgCl₂对种子萌发的抑制作用;处理对吸胀种子萌发的抑制效应小于直接在处理液中萌发的抑制效应;NO对AQP的活性具有调节作用且NO和AQP的作用主要存在于种子最初吸水萌动的12 h内。     

球孢白僵菌不同分离株的生物学特性的研究

为了明确不同白僵菌菌株的生物学特征,对15株白僵菌菌株的ITS片段进行测序分析,并对这些菌株的菌落生长速率、产孢量、孢子萌发率、单芽管孢子萌发比例、单芽管平均长度和长芽管平均长度等多项生物学指标进行测定。结果表明,单芽管孢子萌发比例变化范围在11．91％～96．03％;单芽管平均长度和双芽管平均长度分别为6．28-21．43μm和10．338～19．902μm;各菌株间孢子萌发率差异很大,变化范围22．09％-86．32％。对菌株的培养特性（孢子萌发率、产孢量和菌落生长速率）与孢子萌发特性（单芽管孢子萌发比例、芽管总平均长度和芽管整齐度）这两个主因子进行典型相关分析,两性状集团总体相关不显著（P=0．341）,而孢子萌发率与单芽管孢子萌发比例相关显著,菌落生长速率与芽管总平均长度呈显著相关。     

几种药用植物杀菌活性的初步研究

以茄链格孢（Alternaria solani）、尖孢镰刀菌（Fusarium oxysporum）、茄病镰刀菌（F. solani）、出芽短梗霉（Aureobasidium pullulans）、灰葡萄孢（Botrytis cinerea）为供试真菌,用生长速率法和孢子萌发法对8种药用植物提取物的离体活性进行测定。结果表明：在生药质量浓度为0.1 g/mL时,党参和黄芩对5种供试菌菌丝的抑制率达78%以上,苦参和地黄对5 种供试菌菌丝的抑制率达65%,苦参、党参和黄芩对5 种供试菌的孢子萌发抑制率大于70%。尤其是党参、黄芩和苦参的提取液对5 种供试菌的菌丝生长和孢子萌发抑制率均大于65%,值得进一步研究开发。     

莲子草假隔链格菌粗毒素生物活性研究

利用种子生测法,研究了莲子草假隔链格菌（Nimbya altermantherae）粗毒素对农田12种杂草的生物活性及6种作物的安全性。结果表明,该粗毒素对12种田间常见杂草种子萌发及根长、芽长均有抑制作用,且随粗毒素溶液浓度的提高抑制作用相应增强。在浓度为50μg／ml时,粗毒素对光头稗（Echinochloa colonum）、荠菜（Capsella bursa—pastoris）、升马唐（Digitaria ciliaris）的萌发表现出一定的抑制作用,在粗毒素浓度为400μg／ml时,对荠菜,千金子（Leptochloa chinensis）的萌发具有强烈的抑制作用,萌发率为0。在粗毒素浓度为50μg／ml时,对鳢肠（Eclipta prostrata）、光头稗Echinochloa colorbuln）、升马唐（Digitaria ciliaris）、蔺草（Beckmannia syzigachne）、看麦娘（Alopecurus aequalis）等杂草的根长、芽长也表现出一定的抑制作用。粗毒素对不同作物萌发的影响也有差异,对花生（Arachis hypogaea）、大豆（Glycine max）的萌发及根长的生长无抑制作用,其中对花生的根长还有一定的促进作用。粗毒素浓度小于或等于400μg／ml时,对油菜（Brassia campestris）的萌发及根长、芽长的生长无抑制作用。粗毒素对小麦（Triticum aestivum）不安全。     

假高粱籽实的萌发与颖壳的关系

对处于休眠期的假高粱籽实进行萌发试验，结果：（１）带颖壳的籽实不萌发，剥去颖壳的籽实有少量的萌发；经ＧＡ３处理，带颖壳的籽实仅个别萌发，剥去颖壳的籽实萌发率显著提高。表明颖壳具有机械阻力，限制籽实对水分和激素的吸收，降低萌发率；（２）剥去颖壳的籽实加入剥下的颖壳，籽实不萌发。经ＧＡ３处理，萌发率显著提高。表明颖壳对籽实的萌发具有化学抑制作用；（３）内颖基部的脉纹裂痕和上部的脉脊所形成的空隙，是适于籽实萌发的形态特征，有助于籽实的胚根由内颖基部突破颖壳和胚芽从顶部伸出颖壳。作者认为，假高梁的颖壳既有利于籽实休眠以度过不良环境条件，又具有适应籽实萌发的形态特征。     

外来有害植物土荆芥种子贮藏与萌发特性的研究

研究了不同光照和温度对外来有害植物土荆芥（Chenopodium ambrosioides L．）种子萌发率的影响及种子在不同贮藏时间和不同贮藏温度下萌发率的变化。结果表明，光照是土荆芥种子萌发的必要条件，全黑暗条件下萌发率仅为9．7％。种子在15～20℃恒温条件下萌发率均达到80％以上，25℃恒温和10℃恒温能显著抑制其萌发。零下低温（-20℃）和零上低温（4℃）贮藏3个月的土荆芥种子萌发率分别为86．3％和84．7％，与贮藏前萌发率（89．3％）相比无显著差异，而在室温和25℃条件下贮藏的种子，萌发率显著下降。     

蒲公英水提液对几种植物的化感作用

采用培养皿滤纸法,以反枝苋（Amaranthus retroflexus L．）、番茄（Lycopersicon esculentum Miller．）、生菜（Lactuca sativa L．var．ramosa Hort）、小白菜（Brassica rapa L．Chinensis Group）和小麦（Triticum aestivum L．）5种植物为受试植物,对蒲公英（Taraxacum mongolicum）水提液的化感作用进行了测定。结果表明,蒲公英水提液对5种植物种子的萌发均有一定的抑制作用。当浓度为0．1g／ml时,对5种植物种子萌发的抑制率均为100％,随着浓度降低,对种子萌发的抑制率减小。当浓度为0．1、0．05、0．025g／ml时,对5种植物根的生长、茎的生长均有一定抑制作用。当浓度为0．0125g／ml时,对反枝苋、番茄和生菜的幼苗茎生长有抑制作用,而对小白菜和小麦幼苗茎生长有促进作用。     

Effects of biological soil crusts and drought on emergence and survival of a Patagonian perennial grass in the Monte of Argentina

Biological soil crusts are widely distributed in arid and semiarid regions. They have an important eco- logical role, especially by modifying physical and chemical properties of soils. Biological crusts may also modify seed germination and seedling establishment. The effects vary widely according to the type of crust and the vas- cular plant species. The objective of this study was to determine the effect of moss-dominated biological soil crusts on the emergence, biomass and survival of Poa ligularis Nees ex Steud. under different irrigation regimes. We col- lected seeds of P. ligularis and biological soil crusts composed of two species of mosses： Syntrichia princeps （De Not.） Mitt and Ceratodon purpureus （Hedw.） Brid. from an area in the Monte of Argentina. The result showed that seedling emergence of P. ligularis was higher in treatments with bare soil than in soil covered by crusts, and also in those with watering to field capacity. Mean emergence time was higher in treatments with bare soil and watering to field capacity. Seedling biomass also showed significant differences between treatments. These results suggest that biological soil crusts dominated by mosses do not promote P. ligularis emergence, although they would not affect its survival.     

不同沙丘部位和不同结皮类型对土壤种子库的影响

采用萌发法对古尔班通古特沙漠沙垄不同部位生物结皮类型的种子库进行研究,发现不同沙丘部位和结皮类型种子分布特征有一定的规律性:藻类结皮的种子数量、丰富度和多样性均显著高于地衣和苔藓结皮。生物结皮从藻类到地衣和苔藓的演替,有降低种子数量和种子多样性的现象。在不同沙丘部位,沙丘顶部流沙的种子数量和多样性较低,与丘顶流沙相比沙丘底部的藻类结皮显示出较高的丰富度和多样性,但沙丘底部的地衣和苔藓结皮与丘顶流沙相比未表现出明显的差异。背风坡中部的藻类结皮种子多样性较高,显著高于迎风坡中部的藻类结皮。     

How to model the effects of farming practices on weed emergence

Early weed emergence models directly relate the weed seedbank to emerged seedlings, with constant emergence rates for each tillage tool. These models compare cropping systems at long term in a given region. Other models relate emergence to rain and air temperature. They are useful in no-till systems with seeds close to soil surface. Recently, other authors split emergence into germination and pre-emergence growth, depending on soil climate. But seed survival and dormancy as well as tillage were not yet integrated. Models advising farmers for strategic farming decisions in a large range of situations must split emergence into mechanistic relationships distinguishing the various underlying biological subprocesses in order to correctly quantify the effect of cropping system. The model Alomy Sys for Alopecurus myosuroides emergence follows this principle, based on submodels predicting (a) soil environment resulting from the cropping system, (b) vertical soil seed distribution after tillage, and (c) seed survival, germination and pre-emergence growth depending on soil environment, seed depth, characteristics and past history. This model can be used to determine the optimal tillage modes and sowing dates, depending on the preceding crop succession, the following crop and the work constraints of the farmer.     

Species composition, distribution patterns and ecological functions of biological soil crusts in the Gurbantunggut Desert

As one of the most important biological factors that maintain the stability of the largest fixed and semi-fixed desert in China,the Gurbantunggut Desert,the biological soil crusts (BSCs) develop well and play critical ecological roles in the desert ecosystem. In this paper,we briefly summarize our research findings since 2002 including species composition,distribution pattern and ecological functions of BSCs in the desert. Our results indicate abundant species diversity of BSCs in the Gurbantunggut Desert in comparison to other deserts in China. At the scales of sand dune or whole desert,the distribution patterns of BSCs are location-specific. The existence of BSCs in this desert could:(1) accelerate the formation of desert soil and the weathering of minerals; (2) accumulate organic matter in surface soil through related species in soil crusts; (3) enhance the abilities of sand surface to resist wind erosion; (4) influence seed germination of vascular plants; and (5) enhance the production of dew deposition on sandy soil surface.     

Effects of the seed weight and burial depth on the seed behavior of common ragweed (Ambrosia artemisiifolia)

Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8 cm. No germination or emergence was observed for the seeds that were buried at 10 and 12 cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10 cm, and not carrying out deep soil tillage the following year.     

Burial depth and cultivation influence emergence and persistence of Phalaris paradoxa seed in an Australian sub-tropical environment

Emergence and persistence characteristics of Phalaris paradoxa seeds in no- and minimum-till situations and at different burial depths were studied in a sub-tropical environment. Three experiments were carried out using naturally shed seeds. In the first experiment, seedlings emerged from May through to September each year, although the majority of seedlings emerged in July. In the second experiment with greater seed density, cultivation in March of each year stimulated seedling emergence, altered the periodicity of emergence and accelerated the decline of seeds in the seedbank compared with plots that received no cultivation. The majority of seedlings in the cultivated plots emerged in May whereas the majority of seedlings in the undisturbed plots emerged in July. Emergence accounted for only 4–19% of the seedbank in both experiments over 2 years. Seed persistence was short in both field experiments, with less than 1% remaining 2 years after seed shed. In the third experiment, burial depth and soil disturbance significantly influenced seedling emergence and persistence of seed. Seedlings emerged most from seed mixed in the top 10 cm when subjected to annual soil disturbance, and from seed buried at 2.5 and 5.0 cm depths in undisturbed soil. Emergence was least from seed on the soil surface, and buried at 10 and 15 cm depths in undisturbed soil. Seeds persisted longest when shed onto the soil surface and persisted least when the soil was tilled. These results suggest that strategic cultivation may be a useful management tool, as it will alter the periodicity of emergence allowing use of more effective control options and will deplete the soil seedbank more rapidly.     

古尔班通古特沙漠生物结皮影响下土壤水分的日变化

对新疆古尔班通古特沙漠生物结皮影响下土壤水分的日变化特征进行了定量研究,结果表明:①无论是结皮覆盖区还是无结皮覆盖区,其土壤含水量随深度的变化均表现出明显的层次性,其中以距地表 20 cm处的土壤含水量最高.②结皮覆盖区距地表5 cm和10 cm处的土壤含水量显著高于无结皮覆盖区(LSD检验, p ＜0.05);而45 cm和60 cm处的土壤含水量则表现为结皮覆盖区极显著低于无结皮区(LSD检验,p＜0.05),说明生物结皮具有较强的保持土壤表层水分的能力.③结皮覆盖区与无结皮覆盖区土壤水分的日变化特征明显不同于距地表5 cm处,而其他各土层的变化趋势则较为一致.无结皮覆盖区距地表5 cm处土壤水分的日变化呈先上升后下降的趋势,而结皮覆盖区的变化则恰恰相反.     

少花蒺藜草种子萌发与出苗特性

少花蒺藜草是我国重要外来入侵植物之一。研究了环境因子对少花蒺藜草种子萌发和出苗的影响。研究结果表明,光照会促进少花蒺藜草种子休眠,少花蒺藜草种子萌发温度范围为15～40℃,最适萌发温度为25℃,萌发的临界温度在10～15℃;临界水势在－12～－10 MPa,水势在－8～－4 MPa的环境适宜少花蒺藜草生长。少花蒺藜草出苗临界土壤含水量在1．0％～2．5％,生长临界含水量在2．5％～5．0％;少花蒺藜草在pH值为2～12的条件下均可萌发生长,但pH值为12的条件更适合生长;少花蒺藜草种子在沙土中0～15 cm深度均可出苗,1～9 cm深度出苗率最高,在壤土中1～7 cm深度出苗率最高,超过11 cm不能出苗。     

我国干旱沙漠地区不同类型土壤结皮的理化性质研究

本研究对我国干旱沙漠地区不同类型土壤结皮的理化性质特征进行了系统研究。研究结果表明:无论是不同地区还是同一地区不同发育程度的土壤结皮机械组成,它们的共同特征都是砂粒和粗粉粒含量相对较多,细粉粒和粘粒含量相对较少;从流沙到土壤结皮的形成过程中,粗粉粒是土壤结皮形成的关键基础。通过对同一地区不同发育程度的结皮机械组成比较说明结皮形成初期对颗粒组成有一定的要求,组成达到一定范围才能形成结皮,结皮一旦形成,随时间的增加,结皮厚度在不断增加,但质地基本不变。土壤结皮的形成过程是土壤养分和有机质不断富积的过程。各研究区的土壤结皮pH值相差不大,均在8左右,呈弱碱性;碱化度均≥5,处于碱化发育过程中。由于各地降水量和土壤母质发育的不同,不同地区以及同一地区不同发育程度的土壤结皮之间的CaCO3含量差异较大;同一地区土壤结皮的全盐量差异不大;不同地区土壤结皮的阴阳离子交换量差异较大,同一地区之间差异不大。该文对进一步研究土壤结皮的形成有一定的参考价值。     

黄土高原藓结皮覆盖土壤导水性能和水流特征

生物结皮具有特殊的水文物理性质,为探究其对土壤水分渗透性和水流特征的影响,以黄土高原风沙土和黄绵土上3种典型地表覆盖类型(裸地、藓结皮、藓结皮-草本植物混合)为对象,采用环刀法和染色示踪法对其导水性质与水流特征进行探究。结果表明:藓结皮对2种土壤类型0~5 cm土层土壤理化性质影响较大,与裸地相比土壤容重降低了9.85%~10.00%,土壤黏粒含量增加了1.01~1.29倍,表层有机质含量提高了2.73~3.02倍;藓结皮使0~5 cm土层土壤饱和导水率降低了61.32%~88.89%,而在5~10 cm土层饱和导水率则有明显上升。另外,由于草本植物的影响,藓结皮-草本植物0~5 cm土层与藓结皮土壤相比土壤饱和导水率提高了1.32~6.43倍;黄绵土藓结皮与藓结皮-草本植物的染色面积比均高于裸地,且水分下渗深度增加了10 cm,而风沙土藓结皮与风沙土裸地的染色面积比差异不明显。综上所述,藓结皮和藓结皮-草本植物的存在改变了表层土壤水分渗透性以及水流运动特征和水分下渗深度,影响着黄土高原土壤水分保持和生态恢复。