中华芦荟的离体快繁技术研究

[目的]探索芦荟的离体快繁技术,为芦荟的组织培养提供试验依据。[方法]以盆栽中华芦荟的嫩茎尖为外植体,MS为基本培养基,不同的增殖阶段添加不同的植物激素进行离体快繁试验。[结果]培养30 d后,3瓶被污染,4瓶不长愈伤组织,13瓶在芽基部产生圆球状浅黄色的愈伤组织。在诱导芽分化约20 d后,2瓶被污染,11瓶开始芽点分化。3.00 mg/L 6-BA的处理效果最佳。诱导生根11 d后,1瓶被污染,2瓶出现叶子干焦的现象,17瓶长势良好。中华芦荟愈伤组织诱导的适宜培养基为MS＋6-BA 2.50 mg/L＋NAA0.15 mg/L,诱导率为60%;丛生芽分化及继代的适宜培养基为MS＋6-BA 3.00 mg/L＋NAA 0.10 mg/L,诱导率为85%;生根的适宜培养基为MS＋6-BA 0.30～0.50 mg/L＋IBA 0.20 mg/L＋活性炭0.5%。[结论]该研究为芦荟的快繁提供了初步的理论依据。     

小花忍冬硬枝扦插影响因素分析

小花忍冬是观赏性和抗逆性兼具的优良树种之一。为了解决其种子繁殖子代分化变异大的问题,结合小花忍冬特性,通过不同基质、激素及不同浓度的处理,对其进行了硬枝扦插试验。结果表明：基质种类、激素种类、激素浓度都直接影响其扦插成活率,激素种类直接影响地下根系的生长量。其中,使用珍珠岩︰沙子=1︰2、NAA、100 mg/L组合,...     

镧对镉胁迫羽衣甘蓝的调节效应

[目的]为花卉植物用于cd污染土壤栽培提供依据。[方法]采用水培试验研究了镧（工丑）对羽衣甘蓝受到镉（Cd）胁迫的调节效应。[结果]低浓度的cd对羽衣甘蓝的出芽率、株高、根系、地上和地下鲜重与千重等指标均有一定的抑制作用，高浓度的cd对其有明显的抑制作用，而一定浓度的La可以缓解这种抑制作用。[结论]5mg／LLa缓解高浓度cd对羽衣甘蓝种子出芽以及生长等各项指标的抑制作用效果最好。     

细辛愈伤组织诱导条件的研究

[目的]筛选北细辛、汉城细辛愈伤组织诱导的适宜条件。[方法]选用北细辛、汉城细辛不同的外植体,在不同的培养基上加入不同浓度配比的外源激素进行诱导。[结果]北细辛、汉城细辛的根茎为最佳外植体。北细辛最适培养基为MS＋0.60 mg/L6-BA＋0.15 mg/LNAA,汉城细辛最适培养基为MS＋0.60 mg/L6-BA＋0.10 mg/LNAA。[结论]该研究为再生植株诱导、规模化生产、新品种的培育和推广提供理论依据。     

苏云金杆菌D—1(血清型H3ab)新菌株的研究

D—1菌株系从自然死亡的灯蛾虫尸分离的一株苏云金杆菌新菌株。经菌种鉴定与Bt.var.kurstaki相同,属血清Ⅲ型。其培养特性表现为:对培养基成分和培养温度适应范围较小,在温度28-30℃,培养基含固量为4.1-6.7％,C/N为5.7-6.2时发酵正常。32℃以上和浓培养基则影响其正常繁殖。这与HD-1菌株相吻合。对菜青虫、棉铃虫、玉米螟和松毛虫等4种昆虫毒力测定结果表明,D—1菌兼有H_5型青虫菌81—6和H_3型HD-1的杀虫特性。它对菜青虫和松毛虫的毒力与81—6相接近而高出HD—12.7—5.1倍。对棉铃虫和玉米螟的毒力则明显高于81—6也比HD—1强。     

不同水分状况对箭杆杨叶中输导组织及叶肉组织的影响

自然条件下水分状况对箭杆杨叶中输导组织及叶肉组织有一定的影响。水分状况好的叶中导管管腔直径大于水分状况差的，而管壁厚度却相反，水分状况差的导管管壁厚度大于水分状况好的。此点与试验条件下所得的结果略有差异，原因在于，试验条件下所用的材料为植物的幼茎或同化枝，而此项工作所用的材料为叶，在对干旱环境及水分状况变化的适应上，叶比茎或同化枝更为敏感。叶肉中栅栏组织在水分状况较差时发育程度比水分状况时高。无论     

New mite-borne virus isolates from rakkyo,shallot and wild leek species

Flexuous viruses were transmitted from rakkyo (Allium chinense) and wild leek species (especiallyA. commutatum) to plants of crow garlic (A. vineale), by transfer of dry bulb mites. By electron microscope decoration tests using three antisera and by inoculations onto test plants, it was concluded that from each of the two natural host species at least two viruses were isolated. The viruses from wild leeks are both pathogenic onAllium spp. and may be of economic importance. Decoration tests on a virus mixture from shallot obtained earlier, revealed another new mite-borne virus in this species. The mite-borne viruses ofAllium spp. appear to be very common; they are largely diverse and their identification remains difficult.     

Use of carbendazim and carbendazim-resistant yeasts to create different yeast densities on wheat leaves for field studies on biological control

Phyllosphere yeasts may play an important role in suppressing necrotrophic pathogens. In a randomized block design, yeast densities on flag leaves and second leaves of field-grown wheat were left unchanged (D), or were lowered by sprayings with carbendazim (A), or were raised by sprayings with a mixture ofSporobolomyces roseus, Cryptococcus laurentii var.flavescens and nutrients (B), or with carbendazim, carbendazim-resistantS. roseus andC. laurentii var.flavescens and nutrients (C). The application of carbendazim to plots A and C would avoid a biased interference of carbendazim due to other effects than reducing the natural yeast population. Prolonged differences in yeast density would be reflected in differences in severity of diseases caused by carbendazim-insensitive necrotrophic pathogens.Both treatments B and C enhanced the yeast density about 10-fold at the beginning of leaf colonization, 2 to 3 weeks after leaf emergence. Untreated leaves (D), however, were rapidly leaves. Initially, the yeasts were suppressed by carbendazim (A). However, progressively the yeast population consisted of carbendazim-resistant strains which made the carbendazim sprayings ineffective. Therefore, the substantial differences in yeast density were of limited duration. The effect of the treatments on naturally occurringMycosphaerella graminicola (anam.Septoria tritici), Puccinia recondita f. sp.tritici and the total necrotic leaf area (D-value) is discussed.Samenvatting Fyllosfeergisten kunnen misschien een belangrijke rol spelen in de onderdrukking van necrotrofe pathogenen. In een blokkenproef werd de dichtheid van gisten op vlagbladeren en tweede bladeren niet beïvvloed (D) of verlaagd door bespuitingen met carbendazim (A), of verhoogd door bespuitingen met een mengsel van gisten (Sporobolomyces roseus enCryptococcus laurentii var.flavescens en voedingsstoffen (B), of met een mengsel van carbendazim, carbendazim-resistenteS. roseus enC. laurentii var.flavescens en voedingsstoffen (C). De grootste verschillen in dichtheden van de gistpopulaties werden verwacht tussen de behandelingen A en B of C. Door alle veldjes A en C met carbendazim te behandelen wordt een eenzijdig effect van carbendazim, berustend op andere eigenschappen dan de onderdrukking van de natuurlijke gistpopulatie, voorkomen. Langdurige verschillen in de populatiedichtheden van de gisten zouden weerspiegeld kunnen worden in verschillen in aantasting door carbendazimongevoelige necrotrofe pathogenen.Aan het begin van de bladkolonisatie door gisten, 2 tot 3 weken na het verschijnen van het blad, leidde zowel behandeling B als C tot, een 10-voudige verhoging van de gistdichtheid. De onbehandelde bladeren (D) werden echter spoedig door de van nature voorkomende gisten gekoloniseerd en het verschil tussen de onbehandelde en met gist bespoten bladeren werd snel kleiner. Aanvankelijk werden de gisten door carbendazim (A) onderdrukt. Geleidelijk bestond de gistpopulatie echter uit carbendazim-resistente stammen, zodat de carbendazim bespuitingen nauwelijks meer effect hadden. Hierdoor werden grote verschillen in gistdichtheden niet langdurig gerealiseerd. Het effect van de behandelingen op de natuurlijke infectie doorMycosphaerella graminicola (anam.Septoria tritici), Puccina recondita f. sp.tritici en op het totale dode bladoppervlak (D-waarde) wordt besproken.     

Control of Phytophthora cryptogea in the hydroponic forcing of witloof chicory with the rhamnolipid-based biosurfactant formulation PRO1

Rhamnolipids, extracellular metabolites of Pseudomonas aeruginosa with surfactant properties, proved to be very effective in controlling the spread of brown root rot disease caused by Phytophthora cryptogea in the hydroponic forcing system of witloof chicory ( Cichorium intybus var. foliosum ). The biosurfactant was applied as the product PRO1, a formulation of 25% rhamnolipids in oil. Both an in vitro screening and in vivo experiments in a mini-hydroponic system demonstrated the ability of PRO1 to control brown root rot. A 25  µ g mL⁻¹ rhamnolipids nutrient solution was enough to obtain good control of an artificial infection with a zoospore suspension of P. cryptogea . The biosurfactant PRO1 performed well in a semicommercial system under growers' conditions. A treatment of 25  µ g mL⁻¹ rhamnolipids (100  µ g mL⁻¹ PRO1) reduced the disease incidence significantly in two independent experiments. However, PRO1 was not effective when a mycelial suspension was used as inoculum. Rhamnolipids have good potential to limit the spread of P. cryptogea in the hydroponic forcing system of witloof chicory, and can be used as a preventive measure against brown root rot.     

不同时期使用农抗120控制花生网斑病侵染源的试验研究

用农抗120防治花生网斑病,不同使用方法效果不一。用常规喷洒叶面方法控制再侵染源,防效为21.4％,相当于多菌灵(29.4％);用农抗120和杀菌剂(抗枯灵或多菌灵等)混合,在花生播种时喷洒地面一次,控制初侵染源,防效为48.6％,用农抗120同杀菌剂混合,播种时喷洒地面,以控制初侵染源,7月上旬再喷洒叶面,控制再侵染源,效果最佳,防效高达70％以上。