施氮及豆-禾混播对草地群落及土壤呼吸的影响

豆-禾混播是提高水土资源保持和利用效率、抑制土地退化和维持土壤健康的重要栽培措施。本实验以紫花苜蓿(Medicago sativa)、无芒雀麦(Bromus inermis)、羊草(Leymus chinensis)、紫花苜蓿+无芒雀麦、紫花苜蓿+羊草5种不同类型的人工草地为研究对象,以施氮水平为辅因素,通过对地上生物量、光合特性和土壤呼吸强度的比较研究,探明施氮条件下豆-禾混播草地群落动态及土壤呼吸日变化特征,以期为内蒙古东部地区人工草地合理建植与利用提供理论依据。结果表明:与苜蓿单播和羊草单播的生物量相比,混播对提高草地总体的生物量效果不显著;与苜蓿混播能在不同程度上提高禾本科牧草的净光合速率,其中无芒雀麦提升效果显著,3种牧草单播的净光合速率表现为紫花苜蓿无芒雀麦羊草;施氮提高了不同建植方式下人工草地的平均土壤呼吸强度;与苜蓿混播能显著提高禾草草地的土壤呼吸强度,且最高点一般出现在10:00—12:00。     

8种草坪禾草的抗逆性研究

选取８种不同的草坪禾草为材料,对其抗逆性进行了多指标的生理测定,并引种试验,结果表明,４种冷型草即草地早熟禾,瓦巴斯、苇状羊茅及匐茎剪股颖有较强的抗旱,耐热能力,所测的８种禾草均适合于在武汉地区推广,此外,还就所用方法与指标进行了比较和探讨。     

落叶松幼苗碳素和氮素的获取与分配对供氮水平的响应

落叶松(Larix gmelinii)是中国东北林区最重要的工业用材树种,而且在北温带森林中具有重要的生态学意义。落叶松的种植区域内气温低、冬季长,氮素矿化速度低,供氮不足常常成为落叶松生长的限制因素。为揭示落叶松生长与氮素营养的关系,采用沙培法设置了1、4、8和16 mmol·L^-1 4个供氮水平,研究了不同供氮条件下落叶松一年生幼苗对碳和氮的获取与分配的规律。结果显示,落叶松幼苗的生物量、全株氮浓度、氮含量、比氮吸收速率均随供氮水平的增加而升高,叶重比(LWR)、茎重比(SWR)及叶氮比(LNR)、茎氮比(SNR)亦随供氮水平的增加而增加,而根重比(RWR)和根氮比(RNR)则随供氮水平的增加而降低。当供氮水平从1 mmol·L^-1增加至8 mmol·L^-1时,落叶松幼苗相对生长速率呈线性增加,而全株氮生产力几乎未受供氮水平的影响;当供氮水平从8 mmol·L^-1增加至16 mmol·L^-1时,全株相对生长速率不再增加,全株氮生产力则显著下降。与全株氮生产力的变化不同,落叶松幼苗的叶氮生产力与供氮水平呈负相关。     

沙埋对无芒雀麦种子萌发和幼苗生长的影响

研究了沙埋对浑善达克沙地植物群落中多年生禾草无芒雀麦种子萌发、出苗和幼苗生长的影响.结果表明:无芒雀麦种子能在深度≤12cm的沙埋中萌发,≤8cm的沙埋中出苗.在此范围内,随着沙埋深度的增加,无芒雀麦种子的萌发率和出苗率逐渐降低.沙埋深度在植株高度的33%时,无芒雀麦1周龄和2周龄幼苗均全部存活,且总生物量≥对照(未沙埋幼苗);当沙埋深度增至植株高度的66%时,1周龄和2周龄幼苗的存活率分别降至70%和25%,生长也受到抑制;而遭受全部沙埋时,1周龄和2周龄幼苗均不能存活.遭受沙埋后,无芒雀麦幼苗分配较多的生物量用于地上部分的生长,其生物量分配模式改变可能是无芒雀麦幼苗对沙埋环境的重要适应对策.     

短期氮-水处理对刨花楠幼苗细根根序形态的影响

以种子来源于江西遂川的1年生刨花楠扦插苗为材料,设置田间持水量的80%、40% 2个水分水平,以及不添加(0 kg N·hm^-2)、低氮(50 kg N·hm^-2)、高氮(100 kg N·hm^-2) 3个氮添加水平共6种处理的氮-水交互受控试验,测定不同处理刨花楠幼苗3个根序细根比根长、比表面积、平均直径和根组织密度,分析短期氮添加、干旱胁迫及两者交互作用对刨花楠幼苗细根的影响.结果表明: 刨花楠幼苗细根平均直径、比根长在不同根序间差异显著.随根序的增加,刨花楠幼苗细根平均直径增加,其中3级根最大,为0.97 mm;而比根长降低,3级根最小,为238.99 cm·g^-1.氮添加对刨花楠细根的比表面积、平均直径、比根长和根组织密度无显著影响,而水分对刨花楠细根平均直径、比根长、根组织密度影响显著.干旱胁迫明显促进幼苗3级细根直径的增加,降低了1、2级细根根组织密度.干旱环境下幼苗3级根的比根长明显低于正常供水环境下幼苗.氮水交互作用对刨花楠细根形态影响不显著.     

水氮耦合对辣木幼苗根系形态特征的影响

辣木(Moringa oleifera)主要分布在热带地区，属落叶乔木，具有极高的经济价值和栽培用途。为探究12种水氮组合处理对辣木根系形态的影响，该研究设置3种土壤水分梯度，分别为40%(低水，W1)、60%(中水，W2)、80%(高水，W3)的田间饱和持水量，以及4种氮水平，分别为无氮(N0,0 g·plant^-1)、低氮(N1,0.6 g·plant^-1)、中氮(N2,1.8 g·plant^-1)、高氮(N3,3.6 g·plant^-1),比较不同水氮组合处理对辣木幼苗粗根和细根性状(根长度、根表面积、根体积、根平均直径、比根长、比表面积等)的影响。结果表明：(1)水处理对辣木幼苗粗根和细根的性状没均有显著影响。(2)氮处理对粗根的根长、根表面积、根体积、根平均直径和比表面积有显著影响，而仅对细根的平均直径和比表面积有显著影响。(3)双因素方差分析显示，水氮交互作用仅对细根根长有显著影响；在相同的水处理下，低氮促进而高氮抑制辣木粗根和细根根长、根表面积和根体积的增加，说明低氮中水处理和低氮高水...     

克隆整合对无芒雀麦在异质性盐分环境中存活和生长的影响

无芒雀麦是浑善达克沙地植物群落中占优势的多年生根茎禾草.研究了克隆整合特性对无芒雀麦在异质性盐分环境中存活和生长的影响.结果表明,克隆整合显著提高了无芒雀麦分株在高盐环境中的存活能力,耗-益分析表明无芒雀麦在高盐斑块中分株的生物量、分株数、根茎节数和根茎总长显著受益于克隆整合,而与之相连的非盐分斑块中的分株却没有产生显著的损耗.因而,克隆整合特性是无芒雀麦对异质性环境形成的重要适应对策,它使无芒雀麦能够扩展到不适合植物生长的高盐分斑块中,从而增加了无芒雀麦在浑善达克沙地中的存活和生长,提高了其在半干旱沙化地区的适合度.     

禾顶囊壳4个变种对禾本科牧草的致病性研究

采用人工接种法测定了禾顶囊壳小麦变种、燕麦变种、玉米变种和禾谷变种对4种禾本科牧草鸭茅、披碱草、苇状羊茅和无芒雀麦的致病性。结果表明,除禾顶囊壳玉米变种Ggm01菌株对披碱草没有致病性外,4个变种对供试的其它牧草都有致病性,且能产生全蚀病的典型症状。其中小麦变种和燕麦变种对供试牧草的致病性强于禾谷变种,玉米变种致病性最弱。各变种的菌株存在着致病性分化。小麦变种Ggt9813菌株对苇状羊茅和披碱草的致病性强于燕麦变种,发病严重度均达到50％以上。目前在我国尚未发现燕麦变种,小麦变种主要出现在北方地区,在牧草上的发生亦不广泛,因此二者具有检疫重要性。     

1973-2009年中国玉米品种演替过程中根系性状及其对氮的响应的变化

根系在氮素高效吸收过程中起重要作用,但人们对玉米育种过程中不同年代杂交种的根系生长特性及其对氮素供应的响应了解较少．选用中国1973．2009年育成的11个代表性玉米品种,在水培体系下研究了正常供氮（4retool／L）和低氮（0．04mmol／L）下根系与地上部生长差异．结果表明,与低氮处理相比,正常供氮降低根干重、根冠比和根系相对生长速率,但增加总根长和侧根长．对于20世纪90年代之前育成品种,供氮还降低总轴根长．氮处理不影响种子根数．随育种年代演进,地上部相对生长速率表现明显增加,不同氮水平下表现一致．但是,根系相对生长速率仅在正常供氮条件下表现出与育成年代线性相关．相应地,只在正常供氮条件下玉米总根长、侧根长、轴根长表现为随育成年代增加而明显增加．因此,在过去36年的玉米育种进程中,玉米地上部生长势在不同氮供应水平下均得到提高,而根系生长则只在正常供氮条件下得到提高．进一步改良根系在低氮环境下的生长能力可能提高现代玉米品种的氨吸收效率．     

天山北坡野生无芒雀麦的表型性状

为揭示新疆野生无芒雀麦的表型变异规律,采用变异系数、相关性、主成分分析等方法对采自天山北坡5个典型地区450株无芒雀麦的13个表型性状指标进行分析。结果表明:(1)天山北坡野生无芒雀麦存在变异,但变异系数较小,仅为0.294。(2)地区间无芒雀麦表型性状变异水平大于地区内变异水平,且天山北坡中段的变异程度与东段、西段相比差异较大;中段的变异程度随海拔的升高而增大,东段和西段则相反。(3) 13个性状指标在地区间变异范围广,最大的为分蘖数;性状指标与经度、纬度呈正相关,年均温度、年均降水量仅与穗长、根长等性状呈显著相关。(4)地区间表型性状的差异主要来源于生殖枝高度、穗长、叶长、叶宽等。(5)天山北坡中段的无芒雀麦株型较大,且大株型主要来自低海拔。综上所述,天山北坡中段气候更适宜野生无芒雀麦的生长,且低海拔的无芒雀麦生长情况优于其他两个海拔。     

Models analyses for allelopathic effects of chicory at equivalent coupling of nitrogen supply and pH level on F. arundinacea, T. repens and M. sativa

Alllelopathic potential of chicory was investigated by evaluating its effect on seed germination, soluble sugar, malondialdehyde (MDA) and the chlorophyll content of three target plants species (Festuca arundinacea, Trifolium repens and Medicago sativa). The secretion of allelochemicals was regulated by keeping the donor plant (chicory) separate from the three target plant species and using different pH and nitrogen levels. Leachates from donor pots with different pH levels and nitrogen concentrations continuously irrigated the target pots containing the seedlings. The allelopathic effects of the chicory at equivalent coupling of nitrogen supply and pH level on the three target plants species were explored via models analyses. The results suggested a positive effect of nitrogen supply and pH level on allelochemical secretion from chicory plants. The nitrogen supply and pH level were located at a rectangular area defined by 149 to 168 mg/l nitrogen supply combining 4.95 to 7.0 pH value and point located at nitrogen supply 177 mg/l, pH 6.33 when they were in equivalent coupling effects; whereas the inhibitory effects of equivalent coupling nitrogen supply and pH level were located at rectangular area defined by 125 to 131 mg/l nitrogen supply combining 6.71 to 6.88 pH value and two points respectively located at nitrogen supply 180 mg/l with pH 6.38 and nitrogen supply 166 mg/l with pH 7.59. Aqueous extracts of chicory fleshy roots and leaves accompanied by treatment at different sand pH values and nitrogen concentrations influenced germination, seedling growth, soluble sugar, MDA and chlorophyll of F. arundinacea, T. repens and M. sativa. Additionally, we determined the phenolics contents of root and leaf aqueous extracts, which were 0.104% and 0.044% on average, respectively.     

A simple method to determine leaf angles of grass species

There are several very accurate methods to determine leaf angles in closed canopies. However, these are generally very time-consuming or require special equipment. Average canopy leaf angles were derived from simple height and blade length measurements. An exponential relationship between the height/length ratio and the average blade leaf angle was used. The method was tested for two grass species, Dactylis glomerata and Festuca arundinacea, grown under different UV-B levels. The results clearly show that the method is reasonably accurate and able to identify UV-B induced changes in leaf angle. To get these results only 50 measurements of leaf blade height and length were necessary to calculate the allometric relationship, after which 10 length and height measurements from a canopy were used to calculate the average canopy leaf angle.     

外来杂草加拿大一枝黄花对入侵地植物的化感效应

采用人工气候箱培养试验,初步研究了入侵杂草加拿大一枝黄花对本地植物的化感作用.测定了根系和根状茎的不同浓度浸提液对白三叶发芽率和幼苗生长的影响;不同播种密度下根系1:60提取浓度对白三叶种子萌发和幼苗生长的影响;根状茎1:60提取浓度对白三叶、红三叶、天蓝苜蓿、黑麦草、北美车前、鸡眼草、苇状羊茅、胜红蓟、马齿苋、碱蓬和刺苋的种子萌发和幼苗生长的影响.结果表明,加拿大一枝黄花根系和根状茎的化感抑制作用均随浓度的升高而增强,且根状茎提取物的抑制效应高于根系提取物的效应;在1:60低浓度根系浸提液作用下,不同密度的白三叶幼苗萌发率和幼根、幼芽长度差异不显著;1:60低浓度根状茎提取物对11个物种的种子萌发均有显著抑制作用,但对不同物种的抑制程度有差异,对禾本科植物的抑制作用大于非禾本科和豆科;1:60低浓度根状茎提取物对10个物种的幼根影响与对萌发率的影响相似,但在对幼芽的影响上,仅对鸡眼草、刺苋和苇状羊茅起抑制作用,而对其他植物无显著抑制(黑麦草、北美车前、胜红蓟、马齿苋和刺苋)或起促进作用(白三叶、红三叶、天蓝苜蓿).     

保水剂对煤矸石基质上高羊茅生长及营养吸收的影响

为探索保水剂对煤矸石废弃地上高羊茅生长及营养特征的影响,按煤矸石与土壤质量比设3种基质梯度,每种基质分别添加3种质量的保水剂,设对照(CK),共10种处理。观测和分析不同处理下高羊茅的生长高度、生物量、营养特征及SPAD值(相对叶绿素含量),结果显示:保水剂主要影响高羊茅地上部分的生物量,而煤矸石与土壤的质量比主要影响地下部分的生物量;煤矸石与土壤质量比相同条件下,添加1 g/kg的保水剂即可促进高羊茅的生长,添加2 g/kg保水剂能使高羊茅尽快适应基质环境,使其日均生长率在出苗后第2周达到峰值。煤矸石基质中添加保水剂能促使高羊茅将煤矸石基质中的营养元素从植株地下部分向地上部分转移,供植株生长需要,基质中添加1 g/kg保水剂时高羊茅对磷的吸收效果最好。此外,添加保水剂能使叶片的SPAD值增加。综合比较不同处理下高羊茅的株高、生物量、营养特征及叶片的SPAD值认为,处理6(煤矸石与土壤质量比为750:250、基质中添加2 g保水剂)与处理8(煤矸石与土壤质量比为500:500、基质中添加1 g保水剂)是适合煤矸石废弃地上高羊茅生长的较好配比。     

<Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>-mediated transformation of <Emphasis Type="Italic">Festuca arundinacea</Emphasis> (Schreb.) and <Emphasis Type="Italic">Lolium multiflorum</Emphasis> (Lam.)

Agrobacterium tumefaciens strain LBA4404 carrying plasmid pTOK233 encoding the hygromycin resistance (hph) and beta-glucuronidase (uidA) genes has been used to transform two agronomic grass species: tall fescue (Festuca arundinacea) and Italian ryegrass (Lolium multiflorum). Embryogenic cell suspension colonies or young embryogenic calli were co-cultured with Agrobacterium in the presence of acetosyringone. Colonies were grown under hygromycin selection with cefotaxime and surviving colonies plated on embryogenesis media. Eight Lolium (six independent lines) and two Festuca plants (independent lines) were regenerated and established in soil. All plants were hygromycin-resistant, but histochemical determination of GUS activity showed that only one Festuca plant and one Lolium plant expressed GUS. Three GUS-negative transgenic L. multiflorum and the two F. arundinacea plants were vernalised and allowed to flower. All three Lolium plants were male- and female-fertile, but the Festuca plants failed to produce seed. Progeny analysis of L. multiflorum showed a 24-68% inheritance of the hph and uidA genes in the three lines with no significant difference between paternal and maternal gene transmission. However, significant differences were noted between the paternal and maternal expression of hygromycin resistance.     

Interaction between Some Pasture Species and 2

Possible control options are investigated for the introduced Hieracium weeds, particular problems in South Island high country, New Zealand. In a pot experiment regression of input to output ratios of above ground biomass over successive harvests, from binary mixtures was used to determine the competitive interaction between 13 pasture species and two Hieracium species, H. pilosella and H. praealtum, in a low fertility soil. Treatments also included a factorial of presence or absence of compartments separating root and shoots of species. Species differed in their mean growth rate, relative to Hieracium species. The ranking of mean growth rate relative to H. pilosella was Trifolium repens (best), Bromus inermis, Sanguisorba minor, Festuca novaezelandiae, F. rubra, Arrhenatherum elatius, Anthoxanthum odoratum, Lotus corniculatus, Hypochoeris radicata, Trifolium repens, T. hybridum, T. medium and Astragalus cicer. Shoot partitions decreased Hieracium's interaction with white clover while root partitions increased interaction with B. inermis. However, the rates were not related to the proportion of Hieracium in the mixtures, indicating a general lack of specific competitive effects against Hieracium.     

废橡胶颗粒浸提液物质释放及其浸种对草坪植物生长的影响

纯胶粒浸提液、胶粒与壤土混合的浸提液中重金属含量分析表明,纯胶粒浸提液中Zn含量最高,其次为Pb,而Cd与Cu最少;与纯胶粒浸提液相比,胶粒与壤土混合的浸提液中Zn含量显著降低.紫外吸收光谱图显示,胶粒粒径越小,浸提液中有机物越复杂.用4种不同粒径胶粒的浸提液对2种草坪植物种子浸种处理后进行培养,研究了草坪植物的生长效应.结果表明,胶粒浸提液浸种对2种草坪植物的种子萌发率影响不大,但对株高产生不同的影响.对黑麦草而言,以2～4 mm胶粒浸提液浸种的株高为最高,1～2和4～6 mm胶粒浸提液浸种株高与之差异较大,分别降低1.52和1.32 cm,但均与对照无显著差异.对于高羊茅,以粒径1～2 mm胶粒浸提液浸种的株高为最低,比对照降低了18.76%,其它处理间无明显差异.浸提液浸种对黑麦草地下生物量有明显的抑制作用,但对根长生长有促进作用.胶粒浸提液浸种对2种草坪植物的地上生物量无明显影响.从胶粒浸提液的物质释放及其浸种对草坪植物生长的影响来看,废胶粒可用于运动场草坪的基质组配.     

Co-existing grass species have distinctive arbuscular mycorrhizal communities

Arbuscular mycorrhizal (AM) fungi are biotrophic symbionts colonizing the majority of land plants, and are of major importance in plant nutrient supply. Their diversity is suggested to be an important determinant of plant community structure, but the influence of host-plant and environmental factors on AM fungal community in plant roots is poorly documented. Using the terminal restriction fragment length polymorphism (T-RFLP) strategy, the diversity of AM fungi was assessed in 89 roots of three grass species (Agrostis capillaris, Festuca rubra, Poa pratensis) that co-occurred in the same plots of a field experiment. The impact of different soil amendments (nitrogen, lime, nitrogen and lime) and insecticide application on AM fungal community was also studied. The level of diversity found in AM fungal communities using the T-RFLP strategy was consistent with previous studies based on clone libraries. Our results clearly confirm that an AM fungal host-plant preference exists, even between different grass species. AM communities colonizing A. capillaris were statistically different from the others (P < 0.05). Although grass species evenness changed in amended soils, AM fungal community composition in roots of a given grass species remained stable. Conversely, in plots where insecticide was applied, we found higher AM fungal diversity and, in F. rubra roots, a statistically different AM fungal community.     

Effects of soil temperature and phosphorus supply on an annual grass and clover grown in monoculture and in mixed culture

Summary This paper describes the effects of soil temperature and phosphorus supply on Bromus rigidum Roth. and Trifolium subterraneum L. grown either in monoculture or in mixed culture. The experiment was designed as a replacement series with plant density maintained at 0.3 plants cm^–2.The results show that increasing soil temperature increases the yield of both species, and increases the competitive ability of the clover with respect to the grass. The root length of the grass increased with increasing soil temperature, but that of clover remained constant. At any given temperature clover root length was greater in mixed culture than in monoculture.The ecological implications of these results are discussed.