紫茎泽兰水浸液对威宁球茎草芦种子萌发及幼苗生长的影响

通过研究紫茎泽兰对优良牧草威宁球茎草芦的化感作用,以期为威宁球茎草芦替代控制紫茎泽兰利用提供科学依据,试验用不同浓度的紫茎泽兰肉质根和根状茎的浸提液、粉碎液及紫茎泽兰根际土壤水浸液处理威宁球茎草芦种子,研究粉碎波及水浸提液对威宁球茎草芦萌发及幼苗生长的影响,结果表明:低浓度紫茎泽兰肉质根和根状茎及根际土壤水浸液对威宁球茎草芦种子的萌发及幼苗生长具有一定的促进作用,高浓度紫茎泽兰水浸波及所浓度粉碎液对威宁球茎草芦种子的萌发及幼苗生长则具有明显的抑制作用,而紫茎泽兰根际土壤水浸液对威宁球茎草芦种子萌发及幼苗生长影响不大,表明威宁球茎草芦可作为紫茎泽兰替代种植的优良牧草品种推广种植.     

三种植物在不同肥力下对紫茎泽兰的生态控制效果

以狗尾草、黑麦草、白三叶为材料研究了混栽其中的紫茎泽兰在不同肥力条件下的生长状况。结果表明,黑麦草和白三叶在高肥力的条件下对紫茎泽兰的控制效果最好,中肥力次之,低肥力最差;而狗尾草在三种肥力条件下最终控制效果基本相同,基本上消灭了紫茎泽兰。因此可以建议,在土壤肥力较差时,可以通过施肥等措施来加强黑麦草和白三叶的竞争力,从而达到控制紫茎泽兰的作用。     

几种植物对紫茎泽兰种子萌发抑制作用的研究

紫茎泽兰是我国外来入侵物种中危害最为严重的植物之一.为探讨贵州本地植物的化感作用与紫茎泽兰种子萌发之间的关系,采用培养皿滤纸法,研究了10种供体植物的叶片浸提液对紫茎泽兰种子萌发的影响.结果表明:10种供体植物的化感物质对紫茎泽兰种子萌发均存在化感作用,并且随着浓度的升高,化感作用逐步增强,紫茎泽兰种子发芽速度指数比发芽率更为敏感.其中,油茶、板栗、花椒、月月青4中植物的化感抑制效果最为显著,构树、苣荬菜、狗尾草的化感作用不明显.     

紫茎泽兰叶片水提液对鸭茅种子发芽、幼苗生长及保护酶的影响

对紫茎泽兰(Ageratina adenophora Sprengel)化感作用的研究有很多,但化感物质以土壤为媒介对与之竞争的本地植物的影响以及本地植物自身的反应机理还知之甚少。以具有较强竞争力的优质牧草鸭茅(Dactlis gloerata L.)为材料,利用改进的培养皿滤纸法测定了紫茎泽兰叶片水提液对鸭茅种子相对发芽率、发芽时间的影响,研究了幼苗株高、生物量及保护酶（SOD、POD和CAT）活性的时间动态。紫茎泽兰叶片水提液对鸭茅种子发芽和幼苗生长均有化感作用,不同浓度的水提液对受体植物的化感作用强度不同。在5%高浓度处理下鸭茅种子发芽率显著降低;2.5%和5%两个浓度处理则使种子的发芽时间明显滞后。处理初期,高浓度水提液处理下的幼苗高度和生物量较低,但随着时间延长,各处理间逐渐差异减小,第20天时,各浓度处理间无显著性差异。水提液对鸭茅体内保护酶活性影响显著。其中在低浓度处理下,随着处理时间的延长POD活性波动较小,CAT活性则波动较大;相反,高浓度处理下POD活性波动较大,CAT活性则波动较小;在处理初期,各处理间的SOD活性差异较为显著,第20天时,各浓度处理间无显著性差异,与株高和生物量变化趋势相符。以土壤为媒介时,鸭茅幼苗表现为对紫茎泽兰的水提液的化感作用不敏感,说明其潜在的替代控制紫茎泽兰的能力,对于紫茎泽兰的替代控制提供了一定的指导。     

药用植物灯盏花与玉米轮作效应的初步研究

为了研究药用植物根际土壤对轮作农作物的化感作用并探究它们间的轮作效应,采用水浸法制备不同浓度的灯盏花根际土壤水浸提液,测定其对玉米种子萌发、幼苗生长的化感效应、玉米幼苗的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性的影响变化。结果表明,灯盏花根际土壤水浸提液对玉米种子发芽率具有抑制作用,当处理浓度为从0.16 g/mL (C)上升到0.50 g/mL (A)时,种子萌发率从62%降低到58%,发芽率化感效应指数随着浓度上升而加大,水浸提液使玉米幼苗的SOD活性和POD活性随着水浸提液浓度的增加而加强。灯盏花根际土壤含有化感物质对玉米具有明显的化感作用,从而对玉米种子发芽及幼苗生长表现出抑制作用,玉米不宜与灯盏花轮作栽培。     

紫茎泽兰对三叶鬼针草的化感作用研究

为了探索紫茎泽兰对三叶鬼针草的化感作用,研究了紫茎泽兰叶片水浸液和枯落物对三叶鬼针草种子萌发及幼苗生长的影响。结果表明,紫茎泽兰叶片水浸液对三叶鬼针草种子萌发有一定的抑制作用,随着浓度的增加,种子发芽率逐渐降低,3%浓度时,种子已不能萌发,对胚根的抑制作用强于胚芽,对幼苗的生长有微弱的促进作用;枯落物水浸液对种子的萌发抑制作用弱于叶片水浸液,随着枯落物添加量的增加,三叶鬼针草长势越好,能够促进植株体内物质的积累。说明三叶鬼针草能够在紫茎泽兰入侵地上生长良好,可以采用三叶鬼针草代替紫茎泽兰,为紫茎泽兰的防控发挥作用。     

紫茎泽兰对蓝桉种子萌发及苗生长的化感作用

紫茎泽兰为桉树林下革本层的优势种,为探讨紫茎泽对蓝桉种子萌发及苗生长的化感作用,采用盆栽试验,用其叶不同浓度水提液(0,0.005,0.01,0.02,0.04 g/mL)对蓝桉种子进行处理.结果表明:不同浓度水提液对蓝桉种子萌发(发芽速率、发芽势、发芽率)、苗生长(地径、高度)及生物量(根重、茎重、叶重、总重)均有显著的影响;随着处理浓度的增加,种子萌发、苗生长、生物量受抑制作用增强;种子萌发、苗生长、生物量与处理浓度之间均呈极显著负相关.处理60 d比处理30 d对苗生长的化感抑制作用加大,说明蓝桉幼苗生长受抑制作用随处理时间延长而增大.在林下及林缘广泛分布的紫茎泽兰,可通过化感作用影响蓝桉的天然更新和生长.     

马尾松和青冈凋落物对紫茎泽兰生长的影响

为了探究紫茎泽兰在马尾松林下较多,青冈林下很少的原因。笔者以种子萌发性状参数（发芽率、芽长、根长和鲜重）和幼苗生长性状参数（株高、最大叶面积）为评价指标,野外模拟与室内盆栽研究了2 种林下凋落物覆盖及水浸液对紫茎泽兰种子萌发及幼苗生长的影响。结果表明：（1）马尾松林下覆盖,紫茎泽兰种子发芽和幼苗生长优于无覆盖但不显著;（2）青冈林下覆盖严重抑制种子发芽和幼苗生长;无覆盖对种子发芽率无影响,但对芽后生长和幼苗生长有明显抑制作用;（3）马尾松水浸液对种子发芽和幼苗生长基本无影响,青冈水浸液除种子发芽率外对其他指标都具有极显著抑制作用。紫茎泽兰密度差异显著的原因：马尾松林下松针凋落物覆盖保湿效果好、透气性好,凋落物分解提供了适宜的紫茎泽兰生长的土壤养分,青冈阔叶凋落物覆盖透气性差,凋落物分解释放出抑制紫茎泽兰生长的化感物质。     

几种多花黑麦草与紫花苜蓿品种的化感作用研究

本文对三个多花黑麦草与两个紫花苜蓿品种的茎、叶和根的水浸提液化感作用进行了研究分析。结果表明：三种花黑麦草与两种紫花苜蓿品种对受体赛迪7有一定的化感影响,对赛迪7的种子发芽都有抑制作用;多花黑麦草 Barextra和Barmega两个品种的根、茎、叶水浸提液对赛迪7的苗高、根长及生物量的积累都存在低促高抑的化感作用;供体不同部位化感作用不同;紫花苜蓿两个品种茎的水浸提液在三种浓度下均对赛迪7的根长有促进作用,对苗高有抑制作用。     

四种菊科入侵植物茎水浸提液对狗牙根种子萌发的影响

为探讨不同菊科入侵植物对替代植物狗牙根种子萌发的化感作用,采用培养皿滤纸法,比较研究紫茎泽兰、小飞蓬、飞机草和肿柄菊等四种入侵植物茎水浸提液不同浓度处理(0(ck)、0.25 g/L、0.50 g/L、1.00 g/L和2.00 g/L)对狗牙根种子的发芽率、发芽势和化感效应指数的影响。结果表明,四种入侵植物茎水浸提液对狗牙根种子发芽均产生显著抑制效应,且随着浓度的升高抑制效应呈递增趋势;在中高浓度(0.50 g/L、1.00 g/L和2.00 g/L)时,其水浸提液对狗牙根种子发芽率抑制作用和化感指数大小顺序为：紫茎泽兰<飞机草<小飞蓬<肿柄菊;在低浓度(0.25 g/L)时,紫茎泽兰对狗牙根种子发芽率抑制强度最小,而其他三种入侵植物对狗牙根种子发芽率抑制效应无显著差异;四种入侵植物茎水浸提液对狗牙根种子发芽势的影响随浓度的增大而增强,但呈现不同的变化规律。研究表明,四种菊科入侵植物茎水浸提液对狗牙根种子萌发具有较强的化感作用,应用狗牙根抵御或进行生态修复需采取适当措施应对化感作用的不利影响。     

Establishment, Development and Yield of Forage Legumes and Grasses as Cover Crops in Grain Corn in Eastern Canada

Interseeded cover crops can minimize soil erosion, increase organic matter and nutrient levels and the yield of subsequent crops. However, their performance is very sensitive to local conditions. Field experiments were conducted at two Quebec locations in 1993 and 1994 in order to evaluate the potential use of forage legumes and grasses as interseeds in corn in eastern Canada. Twelve forage species were evaluated. Fall rye ( Secale cereal L.), hairy vetch ( Vicia villosa Roth), a mixture of red clover ( Trifolium pratense L.) and ryegrass ( Lolium multiflorum Lam), a mixture of white clover ( Trifolium repens L.) and ryegrass, subterranean clover ( Trifolium subterraneum L.), yellow sweet clover ( Melilotus officinalis Lam.), black medic ( Medicago lupulina L.), Persian clover ( Trifolium resupinatum L.), strawberry clover ( Trifolium fragiferum L.), crimson clover ( Trifolium incarnatum L.), annual alfalfa ( Medicago saliva L.) and berseem clover ( Trifolium alexandrinum L.) were seeded at two planting dates (10 and 20 days after corn emergence). The control treatments were: hand weeding, chemical weeding and non-weeded. Early seeded forages established better and had higher biomass accumulation than the late seeded ones. In the presence of larger weed populations, the interseeded forages did not develop well due to competition with the weeds. At Macdonald crimson clover provided good soil cover while Persian clover, fall rye and alfalfa provided relatively little cover. Strawberry clover and hairy vetch did not provide early ground cover due to their late development. Forage mixtures of red or white clover and rye grass established well and achieved high populations at the end of the growing season. Fall rye provided good early ground cover but senesced by the middle of the season. The better establishment and early germination of crimson clover caused a 19% reduction in corn grain yield in 1993. In 1994 none of the cover crops caused a reduction in corn yield.     

Allelopathic Potential of Parthenium hysterophorus L.

Allelopathic influences of aqueous extracts of congress grass ( Parthenium hysterophorus L.) were investigated on germination and seedling vigour of cereals (rice and wheat) and pulses (black gram and chick pea).
The observations on germinations of crop seeds were recorded daily while linear growth of plumules and radicles were measured 2, 4 and 6 days after initiation of study. Aqueous extract of this weed exhibited allelopathic effects on germination and seedling vigour of both cereals and pulses. With increase in concentrations of aqueous extract there was decline in percentage of germination in both cereals and pulses but germination of pulses were more adversely affected than cereals.
It was also observed that aerial portion of plant part was found to be more potent than sub-aerial portion in reducing germination and length of roots and shoots of both cereals and pulses under test. The aqueous extract of 10 % concentration obtained from aerial/sub-aerial portion of plant brought about maximum reduction in length of roots and shoots.     

Cover crops and interrow tillage for weed control in short season maize (Zea mays)

Weed competition can cause substantial maize (Zea mays L.) yield reductions. Interseeding maize with cover crops or a combination of interrow cultivation and interseeded cover crops are possible alternative methods of weed control. This study was conducted to examine the potential of interrow cultivation plus cover crops to reduce weed density in maize without reducing the grain yield. Field experiments were conducted in 1993 and 1994 at two sites in Québec to determine the effects of planting 12 cover crops with maize on weed control. Fall rye (Secale cereal L.), hairy vetch (Vicia villosa Roth), a mixture of red clover (Trifolium pratense L.) and ryegrass (Lolium multiflorum Lam), a mixture of white clover (Trifolium repens L.) and ryegrass, subterranean clover (Trifolium subterraneum L.), yellow sweet clover (Meliotus officinalis Lam), black medic (Medicago lupulina L.), Persian clover (Trifolium resupinatum L.), strawberry clover (Trifolium fragiferum L.), crimson clover (Trifolium incarnatum L.), alfalfa (Medicago sativa L.), and berseem clover (Trifolium alexandrinum L.) were seeded at two planting dates, 10 and 20 days after maize emergence. Interrow cultivation was carried out weekly until forage seeding, with a final cultivation being conducted just prior to cover crop seeding. Cover crop planting date did not affect maize yields or the ability of interrow tillage plus cover crops to suppress the development of weed populations. Maize yield was less affected by the interseeded cover crops under conditions of adequate rainfall. Corn planted in fields heavily infested with weeds resulted in substantial yield reductions even when rainfall was adequate. Except for 1993 at l'Assomption interrow tillage plus cover crop treatments had consistently lower weed biomass when compared to the weedy control. Most of the weed control was due to the interrow cultivation performed prior to seeding of the cover crops. The lowest weed density occurred in the herbicide treated plots. The ability of interrow tillage plus cover crops to suppress the development of weeds was affected by the level of weed infestation, the growing conditions and location. The cover crops provide additional weed control but the interrrow tillage or some herbicide application may still be necessary.     

鳢肠水提液对棉花和棉田常见杂草的化感作用

采用培养皿滤纸法研究鳢肠水提液对棉花和棉田常见杂草种子萌发和幼苗生长的化感作用。结果表明:当鳢肠水提液质量浓度为0.01~0.08 g·m L-1时,对中棉所49和中棉所79种子萌发影响不大,而对杂草种子的萌发表现为抑制作用;其中,对禾本科杂草种子萌发的抑制强度表现为牛筋草马唐稗草,对阔叶杂草种子萌发的抑制强度表现为反枝苋马齿苋苘麻。鳢肠水提液对棉花和杂草幼苗生长的影响表现为,低浓度促进,高浓度抑制,并随着质量浓度增加抑制作用提高,其中0.04~0.08 g·m L-1的鳢肠水提液对反枝苋胚根和胚芽长的抑制率均达到100%。     

Weed Control of Four Higher Plant Species in Paddy Rice Fields in Southeast Asia

Four higher plants, namely glory bowers (Clerodendrum trichotomum L.), jimsonweed (Datura stramonium L.), beggarweed (Desmodium triflorum L.) and Chinaberry (Melia azedarach L.), with the strong allelopathic potential among 19 allelopathic species from Southeast Asia, were tested for their effects on weed emergence in paddy soil and field. In a greenhouse experiment, D. stramonium, D. triflorumand M. azedarach exhibited similar inhibitory magnitude at 1 t ha^?1 achieving more than 90 % weed control. C. trichotomum achieved about 70 % weed reduction at 2 t ha^?1. In paddy fields, D. triflorum was the most promising material for weed control and attained the highest rice yield among treatments, at the concentration of 2 t ha^?1, whereas the inhibition of D. stramonium and M. azedarach was weakened in the greenhouse. No injury of rice plants was observed. These plants might be used as natural herbicides to reduce the dependence on synthetic herbicides.     

Allelopathic Effect of Three Serious Weeds of Nigerian Savanna on Germination and Seedling Vigour of Soybean and Maize

Allelopathic effects of aqueous extract of three weeds, Ageratum conyzoides L., Imperata cylindrica (L.) Beauv and Commelina benghalensis L. of Nigerian savanna were investigated on the germination and seedling vigour of soybean ( Glycine max [L.] Merr.) and maize ( Zea mays L.). Aqueous extracts of these weeds exhibited allelopathic phenomenon on seed germination and seedling vigour. Aqueous extracts of I. cylindrica and C. benghalensis at 1 % and 5 % concentration (w/v) had stimulatory effect on soybean germination as against inhibitory effect of 10 % aqueous extract of all weeds on the germination of both soybean and maize seeds. Seedling vigour-length of roots and shoots and fresh weight of seedlings were promoted by aqueous extract of A. conyzoides up to 5 % concentration in soybean whereas all concentrations of extract stimulated the seedling vigour of maize. Aqueous extract of I. cylindrica up to 5 % also caused stimulatory effect on the seedling vigour of both crops but such effects were lesser in magnitude than that observed in case of A. conyzoides. On the contrary, the aqueous extract of C. benghalensis at all concentrations resulted in deleterious effect on the seedling vigour of both soybean and maize.     

膜荚黄芪根水浸液对4种作物种子萌发及幼苗生长的影响

通过室内生物测定法,研究了黄芪根水浸液对4种作物种子萌发及幼苗生长的化感影响。结果表明,黄芪根水浸液对4种作物种子萌发及幼苗生长均有明显的化感作用,其中根受到的化感抑制大于地上部分,种子萌发阶段受到的化感抑制大于幼苗生长阶段。不同受体的发芽势、最长根长和根冠比受到的化感抑制最强。4种作物的化感敏感性为小麦>板蓝根>大麦>大豆。因此,选择与黄芪轮作、套作的作物时,优先选择大豆和大麦,其次为板蓝根。     

Effects of water deficit and plant interaction on morphological growth parameters and yield of white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.) mixtures

The effects of soil water deficit and interspecific plant interaction were studied on the dry matter (DM) yield of white clover and ryegrass and on the morphogenesis of white clover. Plants were grown either: (1) individually (no interaction); or in a mixture of equal plant numbers with either (2) just shoot interaction, or (3) both shoot+root interaction. Plants were subjected to soil water deficits corresponding to no (0 MPa), moderate (−0.5 MPa) or severe (−1.0 MPa) water deficit. Ryegrass had higher above- and below-ground DM yields than white clover. The above- and below-ground DM yield for ryegrass, and the above-ground DM yield, stolon growth and relative growth rate (RGR), and leaf appearance rate (LAR) for white clover decreased as soil water deficit increased. In shoot+root interaction at no and moderate soil water deficit levels, white clover had the highest proportion of above-ground growth in the leaf form (69%) and had, respectively, 11% and 32% more above-ground DM yield than when grown in just shoot interaction; ryegrass had, respectively, 20% and 25% more above-ground DM yield than ryegrass grown in just shoot interaction. In shoot+root interaction at severe soil water deficit, ryegrass had twice as much above-ground DM yield as white clover (3.50 g per plant versus 1.59 g per plant, respectively) and white clover had 60% less above-ground DM yield than when grown in just shoot interaction. In a soil column of restricted depth (30 cm) at no and moderate soil water deficit levels, remarkable increases in shoot biomass yield were observed for both white clover and ryegrass grown in shoot+root interaction. The increased shoot biomass yield of ryegrass can be attributed to benefits from white clover's N fixing ability, whereas the causes for increased white clover biomass yield need to be studied further. However, at severe soil water deficit, ryegrass had a competitive advantage over white clover when grown in shoot+root interaction. This was due to the larger root system of ryegrass and its ability to control transpirational losses more efficiently, thus prolonging its growth period compared with white clover.     

生草栽培对柑桔丛枝菌根形成及果实品质的影响

试验以枳砧锦橙(CitrussinensisOsbeck.)初结果树为试材。试验设4个处理,分别为柑桔园间作百喜草(Bahiagrass)(PaspalumnotaturnFlugge)、白三叶草(Whiteclover)(TrifoliumrepensL.)、紫花苜蓿(Alfalfa)(MedicagosativaL.)和多年生黑麦草(Perennialryegrass)(LoliumperenneL.),以清耕为对照。单行小区,随机区组排列,3次重复。结果表明,在干旱季节,所有生草处理区都显著改善了根际土壤水分和温度状况,而百喜草和白三叶草生草区土壤丛枝菌根真菌孢子数和柑桔根系菌根侵染率显著高于清耕区和其它生草区。表明在干旱季节,百喜草和白三叶草生草栽培促进了果园土壤丛枝菌根真菌的生长和柑桔根系菌根的形成,从而促进了柑桔根系对水分和磷素营养的吸收利用。试验结果表明果园管理中宜选择菌根侵染率高的草种如百喜草、白三叶草在柑桔园进行生草栽培,促进柑桔根系菌根形成,改善植株生理代谢,提高果品质量。