几种草坪草的引种栽培试验研究

通过对引种栽培的8种草坪草的物候期、覆盖度、再生速度、品质特性及抗逆性等方面进行分析研究和综合评价,筛选出适合北方温带环境条件下栽培的几种优良草坪草品种——新哥来德(Poa pratensis cv．Nugtade)、枪手股(P.pratensis cv．BlueChip)、午夜(P．pratensis cv．Midnight)、帕特(Agrostis tenuis cv．Putter)、贝克(碧西)(Festuca arundinacea cv．Plxie)等。对陕西关中草坪草的引种和适地栽植提供一定的理论依据。     

9种蕨类植物丛枝菌根真菌侵染的结构观察

蕨类植物普遍能与丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)形成稳定的共生关系,并显著增强其获取养分和抵抗环境胁迫的能力,为了明晰AMF在不同蕨类植物体内的侵染特征,该研究对广东封开黑石顶自然保护区内的蕨类植物进行野外调查取样,并利用光镜和透射电镜对蕨类植物—AMF共生体的显微和亚显微结构进行观察分析,以明确不同蕨类植物与AMF的共生特征,从而进一步保护和开发利用华南地区蕨类植物资源。结果表明:(1)研究区的AMF对不同蕨类植物的侵染形式均以菌丝为主,而丛枝侵染率最低;不同蕨类植物之间的AMF总侵染率存在显著差异,其中团叶鳞始蕨(56.03%)均显著高于其他物种(P<0.05)。(2)显微观察显示,菌丝是AMF定殖于各种蕨类植物根系中最常见的形式,在9种蕨类植物根皮层细胞中均有发现,但不存在于中柱细胞。(3)观察发现,AMF菌丝主要由2~3层厚薄不一的薄壁细胞组成,多呈椭圆形和扁平形状。(4)AMF菌丝及泡囊中包含许多小液泡和脂质类物质,这可能是菌根结构储存能量的重要方式。研究认为,陆地生态系统中AMF对蕨类植物普遍具有侵染的能力,但其在不同蕨类植物根系中的赋存形式具有显著差异,这可能归因于植物自身生理特征以及生境条件的相互作用。     

草坪草总RNA几种提取方法的比较

分别采用DEPC水法、TRIzol法、CTAB-LiCl沉淀法、SDS-酚法、SDS提取液抽提法以及异硫氰酸胍法等6种方法提取草坪草总RNA,通过检测对各种方法的提取效果进行比较分析。结果表明,DEPC水法是最经济、操作最简单的一种方法,并且提取的RNA质量较好、可靠性高、易于大量制备,是提取草坪草RNA比较理想的方法之一,建议使用该方法。利用TRIzol法提取到的28S rRNA亮度约为18S rRNA的两倍,效果较好,操作简单,符合分子生物学实验要求。CTAB-LiCl沉淀法、SDS-酚法、SDS提取液抽提法也获得较高质量的RNA,但存在不同程度的DNA污染。异硫氰酸胍法提取RNA有明显的蛋白质污染,且RNA部分降解,此种方法不予采用。     

三裂叶豚草锈菌侵染寄主叶片的显微和超微观察

【背景】三裂叶豚草是我国重要的外来入侵植物之一,其传播速度快,已给我国造成巨大的经济损失。近年来发现的三裂叶豚草锈菌是一种对其具有生物防治潜力的病原菌。【方法】本文利用显微技术研究了三裂叶豚草锈菌的侵染过程及其对寄主结构的影响。【结果】三裂叶豚草锈菌菌丝可从多处侵入同一个叶肉细胞,胞间菌丝与叶肉细胞相接触可使部分细胞壁增厚。锈菌侵染使三裂叶豚草叶脉末梢导管分枝增多,造成三裂叶豚草水分代谢失调;叶片细胞内膜系统破碎化,细胞器结构受到不同程度的破坏,导致细胞内膜系统紊乱,细胞器结构稳定性降低。【结论与意义】豚草锈菌侵染破坏了三裂叶豚草叶片的细胞结构。本研究为深入研究豚草锈菌的致病机理奠定了基础。     

鸡眼草水浸提液对4种草坪草的化感作用

为探讨鸡眼草(Kummerowia striata)不同部位、不同浓度水浸提液对高羊茅(Festuca arundinacea)、黑麦草(Lolium perenne)、狗牙根(Cynodon dactylon)、白三叶(Trifolium repens)等4种草坪草的化感效应和作用规律,采用培养皿纸床法,以蒸馏水为对照,研究鸡眼草剪碎的植株、未剪碎的植株、叶、茎、根、地上部分0.012 5、0.025、0.05 g/mL 3个不同浓度的水浸提液对高羊茅、黑麦草、狗牙根、白三叶的种子发芽率、发芽速率、幼根长、幼苗高的化感作用。结果表明,鸡眼草水浸提液对高羊茅、黑麦草、狗牙根、白三叶4种受体植物种子的萌发及幼苗生长均有较强的化感抑制作用,且对种子发芽率作用强弱顺序为:狗牙根白三叶黑麦草高羊茅,对种子发芽速率作用强弱顺序为:黑麦草高羊茅狗牙根白三叶,对幼苗苗高作用强弱顺序为:黑麦草白三叶狗牙根高羊茅,对幼苗根长作用强弱顺序为:白三叶黑麦草狗牙根高羊茅。对4种受体植物的综合化感效应以高羊茅最弱,黑麦草、狗牙根、白三叶较为相近。4种受体植物所受到的抑制作用均随着水浸提液浓度的增加而增强,在同一浓度不同部位水浸提液处理下,叶、整株(剪碎)水浸提液对4种受体植物抑制作用比根、茎、整株(未剪碎)及地上部分水浸提液强。高羊茅、黑麦草、狗牙根3种草坪草受0.05 g/mL鸡眼草叶水浸提液的化感抑制作用最强,白三叶则受0.05 g/mL鸡眼草整株(剪碎)水浸提液的化感抑制作用最强。     

三种暖季型草坪草对二氧化硫抗性的比较

二氧化硫(SO_2)是城市大气污染的重要污染物之一,这已经越来越成为国家迫在眉睫须彻底解决的环境问题,解决SO_2污染问题仍是一个重要的生态与环保课题。草坪植物现已成为城市绿化的主要造景材料,依据植物对大气污染的反应特性来选择城市草坪草种,使之在发挥景观效果的同时,发挥其更好的生态效果。采用人工模拟熏气法,以CK(自然状态)、S1(4.29mg/m~3)、S2(6.44mg/m~3)、S3(8.58mg/m~3)、S4(10.73mg/m~3)5个SO_2浓度水平,对城市常用的3种暖季型草坪草:结缕草(Zoysiajaponica)、百喜草(Paspalum notatum)、狗牙根(Cynodon dactylon)进行SO_2胁迫处理,并测定3种草坪草生理生化指标,最终比较3种草坪草对SO_2的抗性。结果表明:随SO_2浓度增加,3种草坪草的可溶性糖含量(SS)、脯氨酸含量(Pro)、丙二醛(MDA)含量呈增加趋势;结缕草可溶性蛋白(SP)呈先降后升趋势,百喜草则呈先升后降趋势,狗牙根各胁迫处理下其SP含量均低于CK;结缕草和狗牙根过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性呈增加趋势,百喜草SOD和CAT活性呈先升后降趋势,同时其POD活性在各SO_2胁迫处理下均低于CK。将所有测定指标采用模糊数学隶属度公式进行综合相关分析,得出3种草坪草对SO_2的抗性由强到弱的排序为:结缕草狗牙根百喜草。结缕草在SO_2胁迫下与其它两种草坪草相比,表现出了更好的抗性能力,因此,在城市空气不断遭受污染的今天,结缕草可以作为热带和亚热带城市绿化草坪植物的优选草种之一。     

外源养分和激素对AM真菌侵染和产孢的影响

在温室30%强度Hoagland营养液半水培条件下,对寄主植物玉米Zea mays接种丛枝菌根(Arbuscular myeorrhizae,AM)真菌Glomus mosseae后施加不同浓度的葡萄糖、蔗糖、脯氨酸(Pro)、吲哚-3-乙酸(IAA)、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)。结果表明:除低浓度GA3处理外,其他处理尤其是高浓度处理抑制了玉米植株的生长。中浓度蔗糖、脯氨酸(Pro)和吲哚-3-乙酸(IAA)处理显著提高玉米菌根侵染率,其中以中浓度蔗糖的处理最高,达92.3%。葡萄糖、赤霉素(GA3)和6-苄基腺嘌呤(6-BA)处理则降低菌根侵染率。施加不同有机养分和植物生长物质并未提高AM真菌产孢数量,相反,却减少了孢子的形成。高浓度氨基乙酸(Gly)和低浓度6-BA处理的产孢量分别为50和48个/管,高于其他处理,但低于对照(78个/管);可溶性糖处理的产孢数量最少,平均仅18个/管。本试验条件下菌根侵染率与产孢数量不具有相关性,而产孢数与根外菌丝量具相关性。认为通过外界不同的化学调控,对植物生长、菌根侵染、根外菌丝量和孢子发育产生了一定的影响,具有一定的调节作用。     

高温胁迫对两种冷季型草坪草生理生化特性的影响

为研究高温胁迫对冷季型草坪草生理生化指标的影响,通过盆栽试验测定了昼夜(38/28℃)两种温度下两种冷季型草坪草的5种生理生化指标(质膜透性、脯氨酸含量、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量)。结果表明:随着胁迫时间的延长,各品种叶片的相对电导率、丙二醛含量和游离脯氨酸含量均呈递增趋势,其增加幅度与胁迫时间呈正相关,胁迫后各指标相对于对照均有了显著的增加(P<0.05);过氧化物酶和超氧化物歧化酶活性则呈先上升后下降的趋势。高羊茅属3个品种的耐热性大于早熟禾属各品种的耐热性,其中高羊茅属的RebleⅣ和早熟禾属的Blue Sap-phire的耐热性优于种间其他品种。     

入侵植物野胡萝卜浸提液对4种草坪草的化感效应

【目的】明确入侵植物野胡萝卜水浸提液对4种草坪草的化感效应。【方法】采用培养皿滤纸法,观察记录不同浓度(0、10、20、30、40 g·L^-1)的野胡萝卜根、茎、叶水浸提液对4种草坪草种子萌发的影响,根据化感综合效应指数分析野胡萝卜水浸提液的化感作用。【结果】野胡萝卜不同部位浸提液对受体种子的发芽率、发芽势、发芽指数、活力指数、根长和芽长均有一定的影响。化感综合效应指数表明,随着野胡萝卜浸提液浓度的增加,对白三叶、黑麦草、翦股颖的化感抑制作用均增强,对高羊茅的化感作用表现为“低促高抑”的双重效应。4种草坪草的耐受强弱顺序为:高羊茅＞黑麦草＞翦股颖＞白三叶;野胡萝卜叶浸提液对4种草坪草的化感作用强于根和茎。【结论】入侵植物野胡萝卜浸提液对4种草坪草的化感效应较为显著,在入侵严重地区,可选用耐受力强的草坪草建坪。     

三种阔叶草坪草对斜纹夜蛾生长发育及营养利用的作用

为了探讨斜纹夜蛾Spodoptera litura对草坪的为害,提供综合治理该虫的理论依据,室内利用白三叶草Trifolium repens、红三叶草T. pratense和马蹄金Dichondra repens 3种阔叶草坪草,分别饲喂斜纹夜蛾幼虫;应用编制实验种群生命表的方法,分析斜纹夜蛾种群生长发育的趋势;同时研究该幼虫对3种草坪草的趋性及营养利用。结果表明：斜纹夜蛾幼虫的趋性表现为白三叶草＞红三叶草＞马蹄金。该虫在3种草坪草上都能够完成生活史;2种三叶草饲喂的该虫幼虫存活率、化蛹率、成蛾率显著高于马蹄金,幼虫期和蛹期则显著短于马蹄金;3种草坪草饲喂的该虫产卵期和平均产卵量相互之间差异不显著,而马蹄金饲喂的产卵前期和雌成虫寿命则显著短于2种三叶草。3种草坪草饲喂的该虫净生长率（Ro）、世代平均周期（T）、内禀生长率（r_m）、周限生长率（λ）、种群加倍时间（DT）及种群增长参数（I）都有差异,其中2种三叶草的各种群增长参数较接近。对5龄幼虫取食3种阔叶草坪草的营养指标测定结果显示：取食马蹄金的相对生长率显著高于取食红三叶草的;取食马蹄金的相对取食量和近似消化率显著高于取食三叶草的;取食马蹄金的食物利用率和食物转化率显著低于取食三叶草的;2种三叶草间无显著差异。综合分析认为,斜纹夜蛾最喜食三叶草,最容易在三叶草草坪上猖獗为害。     

The propagules of vesicular-arbuscular mycorrhizal (VAM) fungi capable of initiating VAM infection after topsoil disturbance

Summary The removal and storage of topsoil decreases the infectivity of vesicular-arbuscular mycorrhizal (VAM) fungi. The propagules of VAM fungi include spores, root fragments containing hyphae and vesicles, and soil hyphae. The viability of each type of propagule after disturbance will determine the initiation of VAM associations with plants recolonizing the disturbed site. This study aimed to examine which of the propagules of VAM fungi are capable of initiating VAM infection after soil disturbance. Soil from an open woodland site of low soil fertility, in southeastern Australia was wetsieved through a tier of three sieves (1 mm, 250 m and 106 m), and the following fractions were extracted: (i) root fragments, (ii) fungal hyphae, and (iii) VAM spores. Each fraction was tested to determine its potential to initiate VAM. Hyphae of VAM fungi grew from root fragments within 14 days. The VAM spore fraction initiated VAM infection after 28 days. VAM hyphal fragments did not produce any VAM infection even after 42 days.     

金银花根系VAM真菌侵染过程观察

在金银花生长季节,从西北农林科技大学北校区药用植物园采集金银花根系及根际土壤,采用形态学方法观察研究了VAM真菌侵染其根系的过程,并对其孢子进行了初步的形态学分类。结果表明:(1)VAM真菌侵染金银花根系时,先形成附着胞,然后入侵到皮层细胞,在根内形成线性菌丝、圈状菌丝;菌丝末端产生泡囊;在较粗的菌丝上产生丛枝状菌丝,而且VAM胞内菌丝主干可以穿越相邻的2个皮层细胞,在皮层中连续形成丛枝;VAM菌丝形成丛枝时,首先是胞内菌丝上膨大产生乳状突起,而后在乳状突起上产生较粗的丛枝柄,最后在这些丛枝柄上产生极细的丛枝状菌丝形成成熟的丛枝结构。(2)VAM真菌菌丝在金银花皮层细胞中,有伸展状态、菌丝圈及丛枝状态,所以金银花与VAM真菌形成的菌根是混合型菌根。(3)金银花根际土壤中至少存在3种类型的VAM真菌孢子,因此认为金银花至少可与3种VAM真菌共生。(4)金银花种植地土壤有效磷含量(6.6mg/kg)显著高于对照空地土壤有效磷含量(3.5mg/kg);金银花生长旺盛季(4月下旬到5月中旬)VAM真菌对其根系的侵染率高达81%。     

An instrumental modification of Gerdemann and Nicolson's method for extracting VAM fungal spores from soil samples

An easily constructed apparatus for extraction of VAM fungal spores from soil samples by a modification of Gerdemann and Nicolson's wet sieving and decanting method is described. For the soils employed in this study, it proved considerably more effective and more precise than either the original wet sieving and decanting method or differential water/sucrose centrifugation. The apparatus gave results that were less subject to interference from extraneous particles than the wet sieving and decanting method. The effect of prior soil dispersion is also reported.     

Characteristic responses of three tropical legumes to the inoculation of two species of VAM fungi in Andosol soils with different fertilities

The growth and mineral nutrition responses were evaluated of three tropical legumes, cowpea (Vigna unguiculata L. cv Kuromame), pigeonpea [Cajanus cajan L. (Millsp.) cv ICPL 86009] and groundnut (Arachis hypogaea cv Nakateyutaka) inoculated with two different species of VAM fungi, Glomus sp. (Glomus etunicatum-like species) and Gigaspora margarita, and grown in Andosols with different fertilities [Bray II-P: topsoil (72 ppm), subsoil (<0.1 ppm)]. Percent fungal root colonization was high in cowpea and groundnut but relatively low in pigeonpea in both soil types. Despite the low rate of root infection, significant growth responses were produced, especially in the inoculated pigeonpea plant. In all legumes, shoot dry matter production was favoured by the inoculations. Increases in shoot biomass due to mycorrhizae were greater in the subsoil than in the topsoil. Mycorrhization raised shoot concentrations of P and Ca (in cowpea and groundnut) and P and K (in pigeonpea) in the topsoil. Whereas the P concentration in shoots in the subsoil was not positively affected by VAM fungi, particularly in cowpea and pigeonpea, the concentration of K in such plants was significantly increased by VAM treatment. The results also showed that mycorrhizal enhancement of shoot micronutrient concentrations was very rare in all plants, with negative effects observed in certain cases. Cu concentration, in particular, was not affected by VAM formation in any of the plants, and Mn and Fe in pigeonpea and groundnut, respectively, remained the same whether plants were mycorrhizal or not. In both soils the three legumes responded to Glomus sp. better than to Gigaspora margarita, and the effects of the VAM fungi on each of the crops relative to the controls were greater in the subsoil than in the topsoil. However, shoot growth of groundnut was not affected as much as cowpea and pigeonpea by the type of soil used. In spite of the relatively low infection of its root, pigeonpea was generally the most responsive of the three legume species in terms of mycorrhizal/nonmycorrhizal ratios.     

Survival of the external mycelium of a VAM fungus in frozen soil over winter

The present investigation examines (1) whether the external VAM mycelium survives winter freezing to act as a source of inoculum in the spring, and (2) whether soil disturbance reduces the infectivity of the external VAM mycelium following freezing of the soil. Sealed pouches of fine nylon mesh were placed in pots containing soil inoculated with a Glomus species. The mesh was impervious to roots but not to hyphae. Following two 3-week growth cycles of maize in the pots, the pouches were transplanted to the field. Pouches were removed from the field once during the 4 months when the soil was frozen, and once after spring thaw. Measurements were made of VAM spore density, hyphal length and viability in the pouches. Bioassays for infectivity were conducted on all pouches. Some VAM hyphae survived freezing and remained infective following winter freezing, in the absence of plant roots. Soil disturbance did not reduce the infectivity of hyphae following exposure to freezing temperatures. We observed a change in the distribution of viable cytoplasm within hyphae over winter, which we hypothesize represents an adaptation allowing hyphae to survive freezing temperatures. We suggest that the effect of disturbance on hyphal infectivity may be related to this seasonal change in the distribution of hyphal viability.     

Effect of VAM inoculum carry-over on the successive cropping of maize and mungbean

A field study to determine the endomycorrhizal inoculum carry-over effect of the first crop [maize inoculated with Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe] on the succeeding crop (mungbean) was carried out in fumigated and nonfumigated acidic soil (pH 5.3) with moderate extractable P (Olsen 23 ppm). G. mosseae inoculation increased maize dry matter and grain yield over the uninoculated control in the nonfumigated soil. The maize inoculation failed to carry the effective inoculum over to the mungbean crop planted immediately after maize harvest and thus did not increase root colonization and grain yield of the succeeding crop. Fresh inoculation of the mungbean with G. mosseae increased grain yield over the uninoculated control.     

Effect of tillage and farming system upon VAM fungus populations and mycorrhizas and nutrient uptake of maize

Low-input agricultural systems that do not rely on fertilizers may be more dependent on vesicular-arbuscular mycorrhizal [VAM] fungi than conventionally managed systems. We studied populations of spores of VAM fungi, mycorrhiza formation and nutrient utilization of maize (Zea mays L.) grown in moldboard plowed, chisel-disked or no-tilled soil under conventional and low-input agricultural systems. Maize shoots and roots were collected at four growth stages. Soils under low-input management had higher VAM fungus spore populations than soils under conventional management. Spore populations and colonization of maize roots by VAM fungi were higher in no-tilled than in moldboard plowed or chisel-disked soil. The inoculum potential of soil collected in the autumn was greater for no-till and chisel-disked soils than for moldboard plowed soils and greater for low-input than conventionally farmed soil. The effects of tillage and farming system on N uptake and utilization varied with growth stage of the maize plants. The effect of farming system on P use efficiency was significant at the vegetative stages only, with higher efficiencies in plants under low-input management. The effect of tillage was consistent through all growth stages, with higher P use efficiencies in plants under moldboard plow and chisel-disk than under no-till. Plants grown in no-tilled soils had the highest shoot P concentrations throughout the experiment. This benefit of enhanced VAM fungus colonization, particularly in the low-input system in the absence of effective weed control and with likely lower soil temperatures, did not translate into enhanced growth and yield.     

The enhancement of root colonisation of legumes by vesicular-arbuscular mycorrhizal (VAM) fungi through the inoculation of the legume seed with commercial yeast (Saccharomyces cerevisiae)

Nodule number, dry weight of shoot and root biomass of legumes (Leucaena leucocephala, Glycine max, Cajanus cajan, Phaseolus mungo, Phaseolus aureus, Vigna unguiculata) were enhanced by inoculation with live yeast cells (Saccharomyces cerevisiae). Root infection (native VAM) and the formation of vesicles, arbuscules and spores were also increased with yeast inoculation. The increase in the parameters varied with legume and the type of yeast culture. Perceptable differences in the effectiveness of yeast culture (live and dead), were also observed.     

Soil microflora of the rhizosphere of plants from several habitats in the botanical garden in Poznań.

The abundance and activity of certain groups of soil microorganisms were estimated in the rhizosphere of 13 plants from four different habitats at several dates. An additional study was made of the rhizosphere microflora of Ledum palustre from a peat-bog. Numbers of proteolytic, nitrate assimilating, denitrifying, and cellulolytic bacteria were estimated. The intensity of ammonification, nitrification and Clostridium growth was estimated. The studies have revealed that the abundance and the activity of all the groups of bacteria studied depended on the habitat. Within one habitat, however, the influence of the plant was sometimes more pronounced than that of the habitat itself, particularly on the abundance of proteolytic bacteria (Fig. 1). The date of sampling had very little effect on the abundance of all the bacterial groups studied except the cellulolytic bacteria.