龙葵果实汁液的除草活性初探

以龙葵(Solanum nigrum L.)、反枝苋(Amaranthus retroflexus L.)为试材,用种子萌发法检测了龙葵果实汁液对其萌发的抑制作用.试验结果证明,龙葵果实汁液中含有除草活性物质,而且活性较高,热稳定性较好,在150 ℃下加热0.5 h依然保持除草活性.龙葵果实汁液对龙葵种子萌发的抑制作用高于对反枝苋的抑制作用.水培14 d,龙葵果实汁液含量为1%时,只能推迟龙葵种子的萌发时间,对最终的发芽率没有影响;含量为5%时,龙葵种子的发芽率仅为的21.5%;含量为10%时能够完全抑制龙葵种子的萌发.含量低于5%时,对反枝苋种子萌没有影响;含量为10%、15%、20%时,反枝苋的发芽率分别为60.00%、43.75%、22.50%.     

龙葵种子休眠解除方法研究

龙葵种子具有休眠习性,采用合适的化学药剂能够打破龙葵种子休眠。H2O2、NaOH、HCl、KNO3、GA浸泡24 h,均能明显提高龙葵种子的萌发率。以2.25～36.00 g/L HCl浸种的萌发率最高,萌发率超过90.00%;40.00 g/L KNO3与200.00 mg/L GA浸种后,萌发率超过80.00%,已达到打破龙葵种子的休眠的目的。     

不同萌发期龙葵的生长和繁殖特性比较

龙葵为我国农田常见杂草之一,了解其生活史可以为其有效防除提供理论依据。2015年利用盆栽试验,设置了4、5、6、7、8、9月份共6个不同的杂草萌发期处理,研究不同萌发时期对龙葵生长和繁殖的影响。结果表明,龙葵的萌发期显著影响其各项生长和繁殖指标。4月份萌发的龙葵始终保持生长优势,株高和茎直径在整个生长季节均高于晚萌发的植株,且植株干重也随着萌发时期的推迟而降低,与7—8月份萌发的植株相比,4—5月份萌发的龙葵所产的球果较大,且单个球果内的种子数也较多,然而其种子千粒重却较小。因此,在进行龙葵防除时,应及时铲除早期萌发的个体,以有效减少杂草种子形成,从而避免来年杂草的进一步蔓延。     

不同贮藏条件下龙葵种子的季节性休眠特性

龙葵是农田恶性杂草?为明确龙葵种子休眠与季节温度的关系, 研究了室内和室外不同贮藏条件下其种子萌发对温度的响应规律?结果表明, 室外贮藏条件下的龙葵种子萌发呈季节性变化, 从10月到翌年5月, 龙葵种子萌发率均在95%以上, 随着夏季温度的升高, 萌发率从6月开始下降, 9月达到最低值(25.4%), 由此进行年际间休眠和非休眠周期的循环?夏季6月-9月的高温可诱导龙葵种子进入休眠状态, 而秋冬季的相对低温有利于解除种子休眠, 使种子恢复萌发状态?龙葵种子休眠和非休眠状态之间的切换受季节性温度变化的影响?室内贮藏的种子, 由于环境温度较为稳定, 其萌发率年际变化较小, 在20%~50%之间?本文明确了龙葵种子休眠的周期性变化规律, 有助于精准预测其出苗时间, 研究结果可为阐明龙葵种子休眠萌发机制和制订基于萌发调控的绿色防控策略提供依据?     

引发对黄芪种子萌发及幼苗抗旱性的影响

本研究目的在于分析种子引发处理后黄芪发芽特性及幼苗抗旱性,探索提高黄芪种子萌发率的方法,为人工栽培黄芪提供技术支撑。采用20％ PEG-6000、0．25％ KNO3、100 mg·L-1 GA3、12．5 mg·L-16-BA及H2 O （对照）5种化学物质引发处理黄芪种子,进行萌发试验及干旱胁迫,测定种子萌发特性及有关抗旱生理指标。结果表明：各处理发芽势、发芽率的一致顺序为12．5 mg·L-16-BA＞100 mg·L-1 GA3＞0．25％ KNO3＞20％ PEG-6000＞H2 O。幼苗丙二醛（MDA ）含量、可溶性蛋白含量、脯氨酸含量、叶绿素含量、超氧化物歧化酶活性（SOD ）、过氧化物酶活性（POD ）和过氧化氢酶活性（CAT ）与CK之间存在显著差异。比较各处理黄芪幼苗的隶属函数平均值可看出,不同引发处理黄芪种子,幼苗的抗旱性顺序为H2O＞20％ PEG-6000＞0．25％ KNO3≈12．5 mg·L-16-BA＞CK＞100 mg·L-1 GA3。结论：采用20％ PEG-6000或0．25％ KNO3作为引发剂处理黄芪种子,可有效促进黄芪种子萌发和提高幼苗抗旱性。     

刺萼龙葵种子中适宜内参基因的筛选

入侵杂草刺萼龙葵Solanum rostratum Dunal传播扩散的主要载体是种子,研究其种子休眠萌发基因的激素调控对于其防除具有重要意义,而选择合适的内参基因可以提高相关基因表达分析的准确性。本研究以赤霉素、脱落酸和水处理的刺萼龙葵种子为材料,利用geNorm、NormFinder、BestKeeper和RefFinder 4种软件对15个候选内参基因进行表达稳定性评价,并通过检测ABI5(abscisic acid-insensitive 5)的表达验证所筛选的内参基因的适用性。结果表明,对于赤霉素、脱落酸和水处理过的种子,最稳定的内参基因分别为eIF(eukaryotic initiation factor)、SAND(SAND protein family)和ACT(β-actin);对所有种子样本而言,PP2Acs(a catalytic subunit of protein phosphatase 2A)是最稳定的内参基因。研究结果将为刺萼龙葵种子休眠萌发的遗传调控研究提供重要参考。     

龙葵提取物对不同作物幼苗的化感效应

将龙葵(Solanum nigrum L.)整株干燥粉碎后,用甲醇、乙酸乙酯、二氯甲烷和石油醚依次提取,通过测定这4种浸提物对水稻、玉米和萝卜种子萌发率、植株根数量、根长、根鲜质量、茎长及茎鲜质量的影响,明确龙葵不同浸提物对不同作物幼苗的化感效应。结果表明,龙葵的甲醇和乙酸乙酯浸提物对萝卜种子萌发率及根长表现为促进作用;相反,龙葵的二氯甲烷和石油醚浸提物对水稻和玉米种子萌发率、植株根数量、根长、根鲜质量、茎长及茎鲜质量主要表现为抑制作用,抑制率范围在9.52%~90.37%之间;其中250倍稀释倍数下,龙葵的石油醚浸提物对玉米植株茎鲜质量抑制率高达90.37%。研究表明,龙葵提取物对作物幼苗化感效应明显,具体化学成分及机制有待进一步研究。     

刺萼龙葵种子休眠和萌发特性研究进展

刺萼龙葵是一种外来恶性杂草,在我国境内的传播对现有的生态系统构成严重威胁。刺萼龙葵对环境条件的广泛适应能力增强了其竞争优势,使其发展成为一种高度危险的外来入侵杂草,控制刺萼龙葵的危害和扩散蔓延已变得越来越重要。文章综述了刺萼龙葵种子的形态特征和休眠机制,总结了种子萌发特性和打破种子休眠的一些方法,为制订其综合防控策略提供科学依据。     

利用凝胶扩散法测定刺萼龙葵种子中β-甘露聚糖酶的活性

β-甘露聚糖酶是种子萌发过程中降解胚乳细胞壁的关键酶,明确其活性的动态变化可为揭示杂草种子的休眠萌发机制提供重要依据。以外来杂草刺萼龙葵Solanum rostratum Dunal种子为材料,建立了种子中β-甘露聚糖酶活性的检测方法—凝胶扩散法。利用凝胶扩散法对不同贮存时间及贮存条件下刺萼龙葵种子中β-甘露聚糖酶的活性进行了检测,发现贮存3年以上的种子中该酶的活性为0.03 nmol/(min·mg),显著低于贮存3年以下的种子中的酶活性0.15 nmol/(min·mg),而湿润冷藏的种子中β-甘露聚糖酶的活性为0.12 nmol/(min·mg),显著高于干燥冷藏的种子的酶活性0.02 nmol/(min·mg)。实际应用结果表明,凝胶扩散法综合了传统方法的优势,检测特异性强、灵敏度高、重复性好,可同时检测大量种子样品,具有良好的实用性。     

野榆钱菠菜的果实多型性及其萌发对策

野榆钱菠菜有3种形态的果实和种子,这3种果实在形状、大小、颜色、着生方式及包被其苞片的大小上均有差异.以野榆钱菠菜的3种果实(种子)为材料,在暗/光为5 ℃/25 ℃,5 ℃/15 ℃,15 ℃/25 ℃,暗周期和光周期同为12 h的条件下,进行萌发实验.结果表明:新采收的C型种子成熟后具有一定的萌发能力,并且在5 ℃/25 ℃下的萌发率最高(＞90%);A型和B型种子存在休眠现象.划破种皮后,A型和B型种子在3个温变处理下的萌发率显著提高,12 星期的低温层积处理也能有效地加速和提高A型和B型种子的萌发率,表明A型和B型种子的休眠属于非深度生理休眠.     

Seasonal changes in seed dormancy of Solanum nigrum and Solanum physalifolium

The seed dormancy cycle in Solanum nigrum and Solanum physalifolium was studied in relation to seasonal temperature. Seed lots of both species were buried in pots outdoors in a randomised complete block design with four replicates from November 2004 to November 2006. At regular intervals, samples of the seeds were randomly exhumed and tested for germination in incubators at three temperatures and light/darkness regimes. For both species, low winter temperature weakened dormancy and high temperature strengthened it. Dormancy induction mainly occurred from August to October in both species after experiencing warm temperatures. An exception from the general pattern of seed dormancy was however observed; seed germination percentages were temporarily reduced in early spring, followed by a peak in germination, before the main period of strong dormancy in S. nigrum . The same phenomenon was observed in S. physalifolium during June in the first year. This short-lived dormancy induction might explain the late emergence of the species. Seed dormancy enables the species to maximise its chance of survival by regulating germination timing to favourable conditions. Therefore, information on the dormancy cycle can be used to predict seedling emergence and optimise weed control operations.     

黄花刺茄浸提液对番茄种子萌发及幼苗生长的影响

为明确入侵植物黄花刺茄对当地主栽经济作物番茄种子萌发和幼苗生长的影响,本文采用培养皿滤纸法,在智能光照培养箱的变温控制条件下,分别研究了黄花刺茄根、茎、叶浸提液对番茄种子发芽率、发芽指数及幼苗根长和苗高的影响。结果表明:(1)黄花刺茄不同器官的浸提液对番茄种子发芽率、发芽指数、幼苗根长和苗高的影响不同,其茎、叶浸提液的化感作用较为显著(P<0.01)。(2)黄花刺茄同部位浸提液对番茄种子发芽率、发芽指数、幼苗根长和苗高不同指标的影响也不同。根浸提液对种子发芽率、幼苗根长影响不显著(P>0.05),但对种子发芽指数的影响极显著(P<0.01)。茎和叶浸提液各浓度对种子发芽指数的影响比种子发芽率、幼苗根长和苗高的影响显著(P<0.01)。     

苍耳等14种植物对植物病原菌的抑菌活性

以番茄灰霉菌、辣椒丝核菌、黄瓜枯萎菌、黄瓜黑星菌和番茄早疫菌为供试菌,用生长速率法和孢子萌发法对14种植物提取物的离体生物活性进行了测定。结果表明:在供试质量浓度为0.1 g/mL时,苍耳茎叶、百部根、龙葵对辣椒丝核菌和黄瓜枯萎菌的抑制率达到100%;黄花蒿、苦参根、狼毒根对5种供试菌的抑制率均在60%以上。苍耳根、苍耳茎叶、泽漆、苦参根、龙葵、黄花蒿、蒲公英提取物至少对1种供试菌孢子萌发抑制率大于90%。本试验中,苍耳茎叶和根提取物对供试菌的菌丝生长和孢子萌发均显示了很高的抑制作用。     

Seed dormancy dynamics and germination characteristics of Solanum nigrum

Four experiments were conducted to study seed dormancy and germination requirements in Solanum nigrum . In Expt 1, seeds were stratified at different constant and stepwise rising temperatures and their germinability was tested at three germination regimes at weekly intervals. In Expts 2–4, seeds dry stored at 4°C and stratified at 5 and 15°C were tested at constant temperatures, as well as fluctuating temperatures with constant and increasing amplitudes. Results suggest that the rate of dormancy release increased with increasing temperatures ranging from 4.5 to 18.6°C. However, prolonged stratification at higher temperatures caused subsequent induction of dormancy. When tested at constant temperatures, stratified seeds germinated between 18 and 34°C, with the optimum between 26 and 30°C, while dry-stored seeds showed no germination. Fluctuating temperatures, with amplitudes ranging from 5 to 15°C, promoted germination of seeds from all treatments. The dormancy dynamics and germination characteristics of the species will have implications for its survival and establishment. This information can be used to predict time of emergence and, thus, improve control of the species in weed management systems.     

The potential value of British wild Solanum spp. as trap crops for potato cyst–nematodes, Globodera rostochiensis and G. pallida

Two forms of Solanum nigrum subsp. nigrum, two forms of S. nigrum subsp. schultesii, S. americanum, S. chenopodioides, S. sarrachoides, S. scabrum, S. villosum subsp. villosum and S. villosum subsp. puniceum were grown in pots for over 4 months to measure their effect on numbers of potato cyst–nematodes, Globodera rostochiensis and G. pallida, in the soil. No Solanum tested significantly reduced numbers of G. rostochiensis or G. pallida. Solanum americanum, S. sarrachoides and S. villosum puniceum increased numbers of G. pallida slightly.     

外来刺萼龙葵与本地龙葵的比较

外来入侵植物刺萼龙葵与我国本地龙葵在分类学上同属茄科（Solanaceae）茄属（Solanum）,但在形态特征、发生分布、生物学特性、化学成分及生物活性、重要性及利用价值方面却存在差异。本文主要从以上几个方面对刺萼龙葵和龙葵进行论述比较,以期为这2种茄属植物的深入研究提供参考。     

Chemical and environmental factors driving germination of Solanum americanum seeds

Solanum americanum Mill. is a weed that occurs with a number of crops, and it is known for its high seed production and its staggered germination. The objective of this work was to evaluate the germination behavior of S. americanum seeds under the influence of chemical and environmental factors. In the laboratory, we tested the effect on germination of (i) constant and alternating temperatures, (ii) seed washing, (iii) exposure time and concentration of chemical treatments and (iv) seeding depth and soil covered with plant residue on seedling emergence. The variables analyzed were germination percentage, germination rate index, seedling emergence and length of the seedlings. The results indicated that alternating temperatures are the main way to promote germination of S. americanum; however, chemical treatments can help to increase the germination percentage and rate index. There was no increase in germination with seed washing, with the exception of KNO₃ application. A GA₃ concentration of 0.84 g L^?1 and an exposure time of 21.22 h in 0.2% of KNO₃ promoted the highest germination of S. americanum. Germination occurs when seeds remain on the soil surface and are not covered by crop residue.     

番茄细菌性斑点病病原菌鉴定

 1998~1999年在吉林省、辽宁省、黑龙江省等地的大棚番茄上发现一种番茄病害,并从其病叶、病茎杆上分离得到了23个细菌菌株。接种番茄幼苗上,发病症状与自然发病症状完全一致,并从接种病株上重新分离到此病原细菌。各菌株致病力无明显的差异。经革兰氏染色反应、菌体形态、培养性状、生理生化反应、G+C mol%等鉴定,确认该病原菌为丁香假单胞杆菌番茄致病变种(Pseudomonas syringae pv.tomato(Okabe)Young,Dye&Wilkie)。该病菌引起番茄细菌性斑点病(又称叶斑病)。病菌除侵染番茄外,尚能侵染茄子、辣椒、龙葵、白花曼陀罗和毛曼陀罗。该病害尚属我国大陆首次报道。     

外源水杨酸对野生龙葵幼苗干旱胁迫的缓解效应

利用20%的PEG6000模拟干旱胁迫,同时用不同浓度（0、0.5、1.0、1.5、2.0 mmol·L^-1）的水杨酸(SA)喷施幼苗,研究了不同浓度水杨酸处理对干旱胁迫下野生龙葵幼苗生长的影响。结果表明：干旱胁迫下,龙葵幼苗植株变矮、鲜重降低、根长缩短,叶绿素和可溶性蛋白含量减少,抗氧化酶活性、游离脯氨酸和丙二醛含量增加;经SA处理干旱胁迫下龙葵幼苗株高、根长和鲜重都有明显增加,特别是1.5 mmol·L^-1 SA处理组分别增加20.8%、28.0%和29.7%,1.5 mmol·L^-1 SA处理组龙葵幼苗叶绿素含量提高31.9%、脯氨酸含量提高65.4%,可溶性蛋白含量提高42.8%,超氧化物歧化酶（SOD）、过氧化物酶（POD）与过氧化氢酶（CAT）活性达到最高,与对照相比分别增加了30.2%、87.8%和50.3%;SA处理使丙二醛（MDA）含量降低了37.8%。综合来看,适当浓度的SA可以缓解干旱对龙葵幼苗造成的伤害,并以1.5 mmol·L^-1外源SA缓解效果最好。