60Co-γ辐射诱变处理对无芒雀麦种子萌发及幼苗期抗旱性的影响

为了解~(60)Co-γ射线辐射对无芒雀麦种子幼苗耐旱性的影响,试验利用聚乙二醇(PEG-6000)为渗透介质模拟水分胁迫,以无芒雀麦种子为材料,采用发芽盒滤纸萌发,研究不同剂量~(60)Co-γ射线辐射对无芒雀麦幼苗生长、细胞膜透性、渗透调节物质和保护酶活性的影响。结果表明:10%PEG为无芒雀麦种子萌发期的最佳胁迫浓度。低剂量~(60)Co-γ辐射提高种子的根系吸水能力,促进幼苗的含水量增加,从而促进种子的幼苗生长,高剂量辐射则具有抑制作用。相对电导率含量与辐射剂量呈正相关,随辐射剂量逐渐升高,对细胞膜的破坏性增强。脯氨酸、可溶性糖、可溶性蛋白含量变化均与辐射剂量呈负相关,低剂量辐射可以促进渗透调节物质含量的积累,进而维持正常的生理代谢。随着辐射剂量的增加,无芒雀麦幼苗的保护酶活性均呈现先升后降趋势,说明低剂量辐射促进无芒雀麦幼苗清除自由基的能力,而高剂量具有抑制作用。低剂量~(60)Co-γ射线辐射(50~100 Gy)促进无芒雀麦幼苗的生长,且通过相对电导率的降低对细胞膜起到保护作用。同时,无芒雀麦幼苗可通过体内渗透调节物质及抗氧化酶活性的增加来适应水分胁迫环境。     

温度对4种杂草种子萌发的影响

研究了20℃/15℃和25℃/20℃两种日波动温度对棒头草（Polypogon fugax Nees ex steud.）、大瓜草（Spergula arvensis L.）、红花月见草（Oenothera rosea L’Herit.ex Ait.）和紫茎泽兰（Eupatorium adenophorumSpreng.）种子的发芽率、发芽势和发芽指数的作用。结果表明,4种杂草种子萌发对两种波动温度的反应存在差异。前4 d高温有利于棒头草种子萌发,而3 d以后,种子在低温时的发芽率均高于高温处理。前3 d高温促进大瓜草种子的发芽势,而4 d后两种温度下种子的发芽率维持不变,且低温处理的发芽率比高温处理高10%左右。红花月见草和紫茎泽兰种子萌发对温度的反应很相似,即在种子萌发的早期高温和低温种子发芽率差异很大,随着发芽时间的进一步延长,两种温度处理的发芽率逐渐接近。     

三种高寒牧草种子萌发期耐镉性研究

为了解无芒披碱草(Elymus sinosubmuticus S. L. Chen)、麦薲草(Elymus tangutorum(Nevski) Hand.-Mazz.)和同德老芒麦(Elymus sibiricus L.)三种高寒牧草种子的耐镉性，设置0、5、10、20、40mg·L^-1镉胁迫液浓度探究它们的发芽和生长情况。结果表明：镉胁迫对无芒披碱草和同德老芒麦种子的发芽率、发芽势、发芽指数、株高、叶长与根长均具抑制作用，而麦薲草部分指标表现为“先促后抑”,在5mg·L^-1镉处理下，麦薲草种子发芽率、发芽指数株高和根长具促进作用。通过隶属函数指数法计算，三种牧草镉耐大小为无芒披碱草>同德老芒麦>麦薲草，无芒披碱草可优选作为镉污染土地种植材料。     

菠菜种子发芽试验

利用不同发芽处理研究菠菜种子的休眠和萌发特性，旨在解决菠菜种子发芽中的困难。结果表明：带果皮的菠菜种子在纸床和沙床上均难以萌发，在土床上的发芽率为85％；而去果皮的种子在纸床、砂床和土床上的发芽率为92％；完整菠菜种子的渗液显著抑制去果皮菠菜种子的萌发；低温处理可以打破休眠，提高种子的发芽率。菠菜果皮结构致密以及果皮内含有的抑制性物质是控制休眠的关键因素。     

不同储藏条件和高温处理对碎米荠种子萌发特性的影响

碎米荠为多功能野生草本植物,具有重要应用价值和生态影响。通过不同条件储藏、不同时间高温处理后的萌发试验研究碎米荠种子的萌发特性。结果表明,种子是碎米荠生活史的关键阶段,其种子多而小,靠角果弹裂进行散布。刚采集的种子需要较长时间完成萌发,低温和冷冻储藏后种子最早萌发日期相似,但萌发整齐度提高,表明碎米荠种子存在一定程度休眠。储藏导致发芽率不同程度降低(7.61%~100.00%),低温(5℃)和冷冻(-20℃)条件有利于碎米荠种子保存;-20℃保存种子的发芽率、发芽势和发芽指数均优于5℃条件,特别是储藏半年后(P0.05)。自然状态土壤埋藏的种子发芽率较高,室温密封保存会导致碎米荠种子活力丧失。高温处理显著降低了碎米荠种子的发芽率(P0.05),但不同高温和处理时间的种子萌发情况相近;与对照相比,高温处理后仍有超过50%的种子正常发芽。种子数量多、活力稳定及对不同温度较强的耐受性是碎米荠适应环境的重要特性。     

3种菊科入侵植物白花鬼针草、胜红蓟和假臭草的种子生物学特性比较研究

为探讨菊科入侵植物种子的繁殖特性,从种子的形态特征及种子萌发率等指标入手,对胜红蓟(Ageratum conyzoide)、白花鬼针草(Bidens alba)及假臭草(Eupatorium catarium)3种菊科入侵植物的种子特性进行比较研究。结果表明,白花鬼针草种子的冠毛芒最短及最少,沉降速度最大,种子的风媒传播能力最弱,但种子全身具长倒钩刺,主要通过人畜和货物等实现远距离散播。假臭草种子冠毛芒较胜红蓟的长和多,种子沉降速度较胜红蓟的小,其风媒传播能力较胜红蓟的强。白花鬼针草种子千粒质量、发芽指数、胚根、胚芽和胚轴均最大或最长,发芽率和发芽势也较高,其种子质量和种子活力为三者中最高。假臭草的千粒质量、胚根、胚芽和胚轴与胜红蓟无显著差异,但发芽势及发芽指数均显著高于胜红蓟,说明假臭草种子活力较胜红蓟的高。假臭草发芽率为三者中最小,这可能与其种子含水率(19%)高有关,高含水率隐含着种子在潮湿环境下易发生霉变。胜红蓟种子除了发芽率较高外,千粒质量、发芽势、发芽指数、胚根、胚芽和胚轴等指标均较小或大,反映其种子质量和活力较小。     

重金属铅锌镉对紫茎泽兰种子萌发及幼苗根长的影响

试验以紫茎泽兰(Eupatorium coelestinum L.)种子为材料,研究了重金属铅(Pb)、锌(Zn)、镉(Cd)单一及复合胁迫对种子萌发及幼苗根长的影响.结果表明,当Pb浓度在100～4 000 μmol/L时,紫茎泽兰种子的发芽率、发芽指数和发芽势都随着Pb浓度的增加而降低,但是当Pb浓度为100 ～200 μmol/L时,其发芽率、发芽指数及发芽势都比对照高,其中在100 μmol/L处理下其发芽率、发芽指数及发芽势都是最高的,分别为94.67％、42.25和89.67％;在Zn浓度为100 ～4 000 μmol/L范围内,紫茎泽兰种子的发芽率、发芽指数和发芽势随着Zn浓度的增加而降低;在Cd浓度为20～1 000 μmol/L范围内,紫茎泽兰种子的发芽率、发芽指数和发芽势都随着Cd浓度的增加而降低;在低浓度Pb(100 μmol/L)+Zn(100 μmol/L)复合胁迫下,其发芽率是最高的,为94.67％,之后随着复合浓度的增加,其发芽率、发芽指数和发芽势呈下降趋势;紫茎泽兰种子的发芽率、发芽指数和发芽势随着复合重金属Pb +Cd、Zn+ Cd、Pb+Zn+Cd浓度的增加而降低.无论是在单一还是复合重金属处理下,紫茎泽兰的幼苗根长与对照相比明显受到抑制.     

4种处理对龙葵种子萌发的影响

以龙葵种子为材料,研究了微波、超声波、酸度和Al3＋对龙葵种子萌发的影响。结果表明,在适宜的条件下,450 W微波处理20 s、超声波处理15 min、pH值5．0～6．5最利于龙葵种子萌发;Al3＋处理能降低龙葵种子的发芽率、发芽势和发芽指数。     

光照、温度和水分条件对沙地云杉种子萌发影响的研究

沙地云杉是内蒙古浑善达克沙地特有的常绿针叶树种。该研究对光照、温度和水分等环境因子对沙地云杉种子萌发的影响进行了测定 ,结果表明 :持续光照时沙地云杉种子萌发最适宜温度为 1 5℃ ,持续黑暗时沙地云杉种子萌发最适宜温度为 2 0℃ ,在 1 6h光照 /8h黑暗时沙地云杉种子萌发最适宜温度为 30℃ ;沙地云杉种子萌发最适宜土壤含水量为 1 5 %。     

影响丰花草种子萌发和幼苗生长的主要环境因子

运用培养皿滤纸法和盆栽法,分别研究温度、光照和水分条件对热带常见杂草丰花草种子萌发和幼苗生长的影响。结果表明:丰花草种子萌发温度范围广泛(5~40℃),随温度升高,丰花草幼苗的鲜质量和生长长度均呈现先升高后降低的趋势;恒温下30℃为其种子萌发的最适温度,其发芽率、发芽指数、活力指数均相对较高,而平均发芽时间最短;25℃时生长的幼苗最健壮,其芽长、根长和芽鲜质量、根鲜质量均显著高于其他温度时的对应值。而变温条件更有利于丰花草种子萌发,12 h D/12 h L、5℃/15℃时发芽率达55.63%,15℃/25℃时发芽率90%,25℃/35℃时的种子萌发率、幼苗长度、幼苗鲜质量均最大。光照不是影响丰花草种子萌发的关键因子,但光照可能有利于促进丰花草幼苗生物量向根部分配,光暗交替(12 h D/12 h L)条件下丰花草幼苗生长情况相对最好(长度根冠比为1.05∶1;鲜质量根冠比为0.51∶1)。水分是决定丰花草种子能否萌发的关键因素,25℃、12 h D/12 h L条件下,在土壤最大持水量60%时丰花草种子萌发和幼苗生长状况均最佳。     

不同光照和温度下白花鬼针草和金盏银盘种子萌发研究

通过在人工培养箱内模拟环境条件,探讨了不同光照和温度对白花鬼针草和金盏银盘种子萌发的影响,结果表明：光照和温度不是白花鬼针草种子萌发的必要条件,白花鬼针草种子萌发的温度适应范围比金盏银盘宽,在15＇12／10oc、20℃／15℃、25℃／20℃、30℃／25oC、35℃／30℃、40℃／35℃下均能萌发,在15％／10气、20％／15℃、25％／20℃、30~E／25℃时萌发率均达94％左右,金盏银盘种子在40％／35℃时不能萌发;温度影响白花鬼针草和金盏银盘种子萌发高峰的出现时间及峰值大小,而光照不影响。     

Germination characteristics and emergence time of annual Bromus species of differing weediness in Sweden

The germination ecology of four annual Bromus species, which differ in weediness on arable land in southern Sweden, was investigated. The most problematic species is Bromus sterilis , while Bromus hordeaceus frequently occurs on arable land. In contrast, Bromus arvensis is a rare weed, and Bromus tectorum is found infrequently in fields despite being a widespread ruderal species. Five experiments were conducted to identify germination characteristics that could explain differences in habitat and abundance: (i) intraspecific variation in dormancy level; (ii) germination response to different light conditions; (iii) light and temperature interactions at germination; (iv) timing of seedling emergence; and (v) seed persistence in soil. Bromus sterilis and B. tectorum behaved similarly in all tests. For both these species, there were large differences in dormancy level among populations and strong inhibition of germination by light. In addition, emergence from seeds sown on the soil surface was both delayed and reduced compared with buried seeds. In contrast, B. hordeaceus and B. arvensis showed generally weak dormancy, and germination was only slightly inhibited by light. It was concluded that germination characteristics alone do not explain the differences in weediness between these four species.     

Longevity of seeds of four annual grass and two dicotyledon weed species as related to placement in the soil and straw disposal technique

Persistence of seeds of the four winter annual grass species, Alopecurus myosuroides , Bromus sterilis , Bromus hordeaceus and Vulpia myuros , were studied under field conditions. The studies also included the two dicotyledon species, Tripleurospermum inodorum and Galium aparine . Seed samples were stored in the field at different depths in the plough layer for a year. Following germination, seedling emergence was taken as an indicator of field persistence. In a supplementary investigation, seed samples were placed on the soil surface or buried at 2 cm for a month and then tested for viability. Persistence of the two Bromus species was very short, irrespective of depth and duration of burial. Persistence of the other species was positively correlated with incorporation of seeds to a few centimetres depth. Increasing the depth of incorporation below 2 cm had a variable influence on persistence. Persistence of seeds placed directly on the soil surface was short, whether they were left there for a year or a month. Whether seeds at the soil surface were left uncovered or covered with chopped straw had limited influence on seed persistence. However, straw cover significantly increased persistence of A. myosuroides seeds and there was the same tendency with T. inodorum .     

芒果疮痂病菌生物学特性研究

 本文主要研究了温度、pH、光照、维生素对芒果疮痂病菌(Sphaceloma mangiferae Bit.&Jenk.)孢子萌发、营养生长及孢子形成的影响,在14种半固体、固体培养基上对产孢量作了比较,还对湿度和营养对孢子萌发的影响做了试验。湿病原菌分生孢子萌发的温度范围为12℃~37℃,最适28℃;pH值范围为3~9,最佳pH 5;以自由水或饱和湿度条件下萌发率最高;连续黑光灯光照促进萌发;1%的葡萄糖液在28℃或33℃下明显增加了萌发率。该菌营养生长的温度范围为4℃~37℃,22℃~33℃生长良好,最适为28℃,与Bitancourt的报道基本相似;pH值范围为2~11,最佳为pH 5;黑光灯连续光照有利生长,VB₂、VB₆及V A对生长均有促进作用,在试验的培养基中PDA是生长最好的。该菌孢子形成的温度范围为12℃~33℃,最适温度为28℃;pH值范围为5~9,最佳为pH 7;光暗12 h交替处理比连续光照更利于产孢;VB₁及VA可促进产孢,但只有VA (50μg/L)既促进生长,又促进产孢;所试验的培养基中以PDA₊牛肉浸膏及PDA的产孢量最多,胡萝卜块是固体培养基中较理想的。     

Mycelial growth rate and toxin production in the seed pathogen Pyrenophora semeniperda: resource trade‐offs and temporally varying selection

Pyrenophora semeniperda, an important pathogen in Bromus tectorum seed banks in semi‐arid western North America, exhibits >4‐fold variation in mycelial growth rate. Host seeds exhibit seasonal changes in dormancy that affect the risk of pathogen‐caused mortality. The hypothesis tested is that contrasting seed dormancy phenotypes select for contrasting strategies for increasing pathogen fitness, and that increased fitness on nondormant seeds involves a resource trade‐off between toxin production and growth. The strategy for successfully attacking rapidly germinating nondormant seeds at high inoculum loads in autumn involves increased post‐infection aggressiveness to prevent seed escape through germination. An earlier study demonstrated that slow‐growing strains caused higher mortality than faster‐growing strains on nondormant host seeds at high inoculum loads. In this study, production of the toxin cytochalasin B was significantly higher in slower‐growing strains, and was induced only in seeds or in seed‐constituent‐containing media. Its production was reduced in vivo by Bromus tectorum seeds, suggesting direct involvement in pathogenesis on seeds. Fast‐growing strains caused significantly higher mortality than slow‐growing strains at low inoculum loads on dormant seeds, which apparently have resistance that is overcome at high loads or through rapid mycelial proliferation. In a co‐inoculation study, the fast‐growing isolate produced 3 × more stromata than the slow‐growing isolate on dormant seeds, whereas the slow‐growing isolate was twice as successful on nondormant seeds. These results provide evidence that mycelial growth rate variation and associated variation in cytochalasin B production represent a trade‐off maintained through temporally varying selection resulting from seasonal variation in host seed dormancy status.     

长叶红砂和红砂种子萌发对光照、温度和水分的响应

长叶红砂(Reaumuria trigyna)和红砂(Reaumuria soongorica)均为荒漠地区超旱生小灌木,长叶红砂为红砂属珍稀种,而红砂为广布种。通过种子萌发对光、温和土壤水分需求的研究表明,长叶红砂对光照不敏感,而黑暗有利于红砂的萌发。种子萌发的适宜温度均为恒温20-25℃或15/25℃变温。25℃后,随着温度升高萌发率下降。土壤含水量在3%以上时,有利于两物种的萌发,萌发适宜的含水量都在12%。在各种条件下,珍稀种长叶红砂的萌发均高于广布种红砂,说明种子质量和萌发并没有造成长叶红砂的珍稀濒危。但长叶红砂高萌发率却不利于应对荒漠地区极端和不可预测的环境变化,增加了生存的风险性,可能是其濒危原因之一。     

向日葵锈菌夏孢子萌发条件的研究

以向日葵锈菌330生理小种为材料,研究了夏孢子萌发的适宜条件和培养载体。向日葵锈菌夏孢子萌发适宜温度范围10~25℃,最适温度15℃。15℃下在琼脂薄膜上1h即可萌发,12h达到萌发高峰,萌发率最高可达97%。孢子在无菌水中萌发最适浓度为20mg/L,萌发率随浓度增大而降低。光照在前5h均抑制夏孢子萌发,但7h后光照对夏孢子总萌发率基本无影响。新鲜夏孢子萌发率较高,在室温放置270d后基本丧失萌发能力。最适条件下,在供试的6种不同萌发载体上,夏孢子萌发率、芽管长度及萌发形态显著不同,琼脂薄膜载玻片、尼龙纱网、玻璃纸较适宜夏孢子萌发,萌发率超过90%;在PVDF膜和亲水滤膜上可观测到芽管内部黄色物质转移和特殊结构的形成。     

马唐生防真菌弯孢霉(Curvularia sp.)菌株QZ-200的生物学特性研究

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