Allelopathic Potentials of Some Crop Residues on the Germination and Growth of Bidens pilosa. L.

The allelopathic potentials of the aqueous extracts of rice husk and sorghum stem were examined on the germination and growth ofBidens pilosa. L. The extracts inhibited the germination ofB. pilosa seeds and the growth lengths of its radicle and plumule. In both extracts, the severity of the inhibition increased with the increase in the concentrations of the extracts, indicating that the effects of the extracts were concentration dependent. The results obtained also showed that the degree of retardation appeared to be more pronounced in the rice husks extract-treated seeds than those of sorghum extract-treated seeds. However there were no significant differences （at 5% level） in the comparison of the degree of inhibitions of radicle and plumule growths at the varying extract concentrations as well as those of the control in both extracts treated seeds.     

小偃22秸秆对作物种子的化感作用

以种子萌发法测定了小偃22秸秆水提液及有机溶剂萃取物溶液对黄瓜、小麦、油菜、高粱、玉米、大豆、番茄、绿豆、苜蓿、莴苣、青菜、萝卜等12种作物种子幼苗生长的化感作用。结果表明小偃22秸秆水提液对小麦、番茄、萝卜、苜蓿、玉米和大豆幼根生长有显著抑制作用,对油菜幼根生长表现出显著促进作用,而对黄瓜、绿豆、高粱、青菜和莴苣幼根生长无显著影响。小偃22秸秆水提液对小麦、番茄、萝卜、苜蓿、玉米5种种子幼芽生长有显著抑制作用,对黄瓜、莴苣幼芽生长有显著促进作用。小偃22化感物质为强极性和中等极性化合物。     

黄瓜叶片水浸提液对黄瓜、 黑籽南瓜种子萌发的影响

以黄瓜、 黑籽南瓜种子为试材, 研究不同浓度黄瓜叶片水浸提液对其种子萌发及生理特性的影响。 结果表明, 随着黄瓜叶片水浸提液浓度的增加, 黄瓜发芽率、 发芽指数、 α-淀粉酶活性及脱氢酶活性等均降低, 抑制了黄瓜根系、 胚轴的生长; 而一定浓度的黄瓜叶片水浸提液提高了黑籽南瓜 α-淀粉酶和脱氢酶活性, 促进黑籽南瓜种子萌发, 高浓度浸提液抑制黑籽南瓜种子萌发。 通过化感效应值可以得出, 黄瓜叶片水浸提液对黄瓜种子萌发的化感效应为负效应, 而对黑籽南瓜则一定浓度范围为正效应, 高浓度为负效应。 黄瓜叶片水浸提液抑制黄瓜种子萌发, 而对黑籽南瓜种子萌发表现为 “低促高抑”。     

醉马草内生真菌对3种草坪草种子与种苗的化感效应

于2008年通过种子萌发法和盆栽法研究了醉马草(Achnatherum inebrians Keng.)内生真菌(Neotyphodium gansuense Li & Nan)对多年生黑麦草(Lolium perenne L.)、高羊茅(Festuca arundinacea Schreb.)和草地早熟禾(Poa pratensis L.)3种草坪草化感作用的影响。结果表明:在种子萌发试验中,醉马草草粉对3种草坪草的生长均有一定的抑制作用,而且内生真菌显著增强了醉马草草粉对多年生黑麦草发芽率和对草地早熟禾发芽率、芽长的抑制作用(P<0.05);显著降低了醉马草对多年生黑麦草的胚根长、芽长、芽重和对高羊茅的发芽率、芽长的抑制作用(P<0.05)。在盆栽试验中,醉马草草粉对3种草坪草的生长均有一定的促进作用,而且内生真菌显著增强了醉马草对多年生黑麦草的初期出苗率,对高羊茅的初期出苗率、苗长和对草地早熟禾的出苗率的促进作用(P<0.05)。因此,内生真菌增强了醉马草对3种草坪草的化感效应。     

草原2号杂花苜蓿浸提液对4种牧草种子萌发的影响

通过研究草原2号杂花苜蓿(Medicago varia cv. caoyuan No.2)浸提液对4种牧草种子萌发的影响,探索利用生物检测法初步确定其与自身及其他3种牧草间化感作用。用草原2号杂花苜蓿根、茎、叶水浸提液处理草原2号杂花苜蓿、蒙古冰草(Agropyron mongolicum Keng)、扁穗冰草(Agropyron cristatum (L.) Gaertn.)和红豆草(Onobrychis viciaefolia Scop.)的种子,测定其发芽率、苗高、根长,利用生物检测法确定草原2号杂花苜蓿对受体植物的化感效应。结果表明:草原2号杂花苜蓿的自毒性及化感作用存在浓度效应,即不同浓度的根、茎、叶浸提液对不同受体植物种子萌发、幼苗高度、根长影响效果不同,其叶浸提液对扁穗冰草和蒙古冰草种子发芽的抑制效应小于草原2号杂花苜蓿和红豆草;其叶、茎、根浸提液对蒙古冰草、扁穗冰草的苗高、根长的促进作用大于红豆草和草原2号杂花苜蓿;根据试验结果,初步认为草原2号杂花苜蓿与蒙古冰草、扁穗冰草混、间播效果要比与红豆草混、间播和单一连播杂花苜蓿效果好。     

Allelopathy Importance,Field Application and Potential Role in Pest Management： A Review

Allelopathy importance and its application under field conditions are reviewed. Recent achievements in the field of plant protection are mainly considered and presented. Natural chemicals of potential use as pesticides, commercialized natural products of pesticidal properties are included. Reported plants of pest control properties, their targeted agricultural pests, formulations, methods of application and activity under field conditions are presented. Allelopathic plant species and implications on their use in the field, positive and negative impacts on cultivated crop species and agricultural pests are discussed. Some research difficulties and experimental methodology problems are mentioned. Prospects of allelopathy as a future strategy for pest management, development of eco-friendly biopesticides and importance for sustainable agriculture and recent developments in allelopathy research are discussed.     

白三叶腐解液对5种草坪草的化感作用研究

为明确白三叶(Trifolium repens L.)入侵禾本科草坪的原因,采用室内生物测定法研究了白三叶腐解液对多年生黑麦草(Lolium perenne L.)、紫羊茅(Festuca rubra L.)、高羊茅(Festuca arundinacea Schreb.)、草地早熟禾(Poa pratensis L.)和匍匐翦股颖(Agrostis stolonifera L.)种子的发芽率、发芽势、发芽指数、活力指数、苗高、根长、干重、鲜重以及综合效应的影响。结果表明:白三叶残体腐解液对5种受体种子萌发以及初期生长有双重浓度效应,即低浓度(0.011 g·mL^-1)有一定促进作用,高浓度(0.090 g·mL^-1)抑制作用显著(P<0.05)。加入腐解液降低了5种受体种子的发芽率,并抑制其幼苗生长。白三叶腐解液对5种受体植物均表现出不同程度的化感作用,其化感作用敏感性的强弱顺序为草地早熟禾>紫羊茅>匍匐翦股颖>高羊茅>黑麦草;化感物质定性鉴定表明,白三叶腐解液中含带邻、间位羟基的酚类化感物质。综上所述,白三叶腐解液具有化感作用,能够影响5种草坪草正常生长,是白三叶入侵5种禾本科草坪的原因之一。     

烤烟顶杈腐解液对烟草生长和相关生理指标的影响

以烤烟品种K326烟株为材料,采用漂浮育苗试验方法,研究了烤烟顶杈腐解液（腐解液浓度梯度为0.00,0.25,0.50,0.75,1.00 g/mL）对其生长的影响。结果表明：顶杈腐解液对烟草生物性状上表现为＂高抑低促＂的作用,0.25 g/mL的腐解液能促进烟草生长,而其他浓度的处理则对烟草生长产生一定程度的抑制作用,并随着浓度增大而增强;在生理生化指标上,腐解液对总叶绿素含量、烟草根系活力与硝酸还原酶活性都能产生抑制作用,抑制作用也随着浓度的增大而加强;烟草过氧化物酶活性和丙二醛含量两项抗逆性指标数据均高于对照组。     

两种本地植物种子和幼苗对紫茎泽兰化感作用的响应

采用生物测定方法,研究了两种本地植物苣荬菜、月月青种子萌发及幼苗生长对紫茎泽兰地上部分水浸液化感作用的响应情况。结果表明：紫茎泽兰水浸液对两种本地植物种子发芽势、发芽率都有一定低浓度促进、高浓度抑制的现象,但促进效应不显著;在死亡率、败育率上,只有高浓度水浸液表现出显著的促进作用;二者胚根生长状况比其他指标（包括胚轴生长）对紫茎泽兰水浸液化感物质表现更为敏感,普遍受到显著抑制。引入化感作用抑制率进行对比研究显示,月月青比苣荬菜对于来自紫茎泽兰的化感作用更具忍耐力。     

Weed control in sunn hemp and its ability to suppress weed growth

Sunn hemp is a tropical, herbaceous annual legume that has potential as a cover crop during the summer in temperate climates. Due to the recent increased interest in sunn hemp breeding and seed production for temperate climates, there is a need for weed control in sunn hemp production. No herbicide product currently on the market specifically identifies sunn hemp as a tolerant crop. The aims of this research were 1) to evaluate herbicides with the intent of identifying a herbicide program that can assure near weed free sunn hemp intended for seed harvest and 2) to demonstrate and quantify sunn hemp-weed suppression. Pre-emergence applied treatments consisted of pendimethalin alone, imazethapyr alone, and pendimethalin plus imazethapyr. Pendimethalin alone provided consistent effective weed control and maximum sunn hemp biomass, but when yellow nutsedge was present, imazethapyr was required for effective control and greater sunn hemp biomass. The combination of pendimethalin and imazethapyr was detrimental to sunn hemp biomass yield. Results also established that sunn hemp is tolerant of 2,4-DB applied post-emergence, but was not necessary for weed control in these studies because of the lack of broadleaf weed pressure. In a separate study with variable sunn hemp densities, weed biomass reductions of ≥50% were obtained with sunn hemp densities of only 20 to 50 plants m⁻². This degree of weed suppression obtained from relatively modest sunn hemp densities is likely indicative of the ability of sunn hemp to grow faster and taller than other plants.