牛心朴子种子萌发特性及对干旱胁迫的响应

试验设置了不同温度、光照和PEG等梯度处理,以发芽率、发芽势和发芽指数等作为测定指标,筛选牛心朴子种子的最优发芽条件并确定种子对干旱胁迫的忍耐能力。结果表明:1)牛心朴子种子不存在休眠现象,最适的萌发恒温范围为20~30℃,且萌发的起始温度较低,为10℃。光照条件不是限制种子萌发的关键条件,但黑暗条件会影响种子的活力;2)低浓度(5%)的PEG对牛心朴子种子胚根的伸长有一定的促进作用,但对胚芽则表现为抑制作用;随着PEG浓度的增加,胚根/胚芽比值亦增大,而发芽率、相对发芽率、发芽势、发芽指数、种子萌发胁迫指数以及种子萌发抗旱指数则呈明显的下降趋势;3)牛心朴子种子对干旱胁迫具有一定的忍耐能力,在15%浓度的PEG溶液胁迫下,种子可正常萌发;4)牛心朴子种子发芽较快,在置床后的第3天便有超过70%的种子萌发,故推荐该种子萌发的初次计数时间为置种后的第3天,末次计数时间为第8天。     

植物激素及水盐胁迫对橡胶草种子萌发的影响

本研究以橡胶草种子为实验材料,通过不同植物激素及水盐胁迫处理,对橡胶草种子在处理条件下种子发芽率进行比较分析,探讨橡胶草种子萌发特性。研究结果表明:1)生长调节物质对橡胶草种子萌发影响作用主要表现在萌发第1~3天,不同激素处理,对橡胶草种子萌发影响不显著。2)种子萌发第1~3天,随着PEG浓度的逐渐增加,橡胶草种子的萌发率发芽率较对照略有降低,自第4天起,各处理的种子萌发时间与萌发率与对照无显著差异。3)橡胶草种子萌发对盐胁迫响应较敏感,自0.20%Na Cl处理浓度起,各处理种子发芽率与对照差值均高于10%,橡胶草种子发芽率与盐胁迫处理浓度呈负相关。     

射干种子萌发特性及对干旱胁迫的响应

对射干(Iris Belancanda chinensis (L.) DC.)种子进行纸上发芽试验,以发芽势、发芽率、发芽指数等作为发芽指标,旨在摸清射干种子萌发特性,筛选出该种子萌发的最适组合条件,探讨聚乙二醇(PEG)模拟水分胁迫对射干种子萌发的影响。结果表明: 1)种子最适的温度条件为恒温20 ℃,且对光照较为敏感,可归为需光种子;2)随着PEG浓度的升高,发芽率、发芽势、发芽指数、相对发对率、萌发胁迫指数、胚芽长均呈现先升高后降低的趋势,且在5% PEG处理下达到最大值,即低干旱水平可促进种子萌发及抗旱能力,高干旱水平会起抑制作用;随着PEG浓度的升高,萌发抗旱指数、胚根长明显降低,即该2种指标与PEG浓度呈负相关关系;胚根/胚芽亦会随着PEG浓度升高而增大,说明干旱胁迫对胚根的抑制作用显著高于对胚芽的抑制作用。用一元线性回归拟合种子发芽率和PEG浓度,预测出射干种子所能抵御的水分渗透势临界值为-0.2 MPa,极限值为-0.4 MPa;3)综合考虑发芽率、发芽整齐度及速度等因素,推荐射干种子在发芽检测时初次计数时间为置床后第8天,末次计数时间为置床后的第15天。     

高山龙胆种子萌发特性研究

为了解高山龙胆种子萌发的适宜条件,[方法]研究了不同温度、不同光照条件和不同赤霉素浓度处理对种子萌发的影响。研究结果表明,不同温度对高山龙胆种子的发芽率影响明显,低温(5 ℃)和高温(35 ℃)严重抑制种子萌发,25 ℃是高山龙胆种子萌发的最理想温度,发芽率达到68.9%。光照条件对高山龙胆种子萌发具有显著的影响,黑暗条件不利于种子萌发。赤霉素处理对高山龙胆种子的发芽势和发芽率均有促进作用,但过高的浓度会阻碍种子萌发,以300-400 mg/L的赤霉素处理种子最为适宜,发芽率可达85%以上。 [结论]因此,高山龙胆种子发芽最适温度为25 ℃,且种子需光萌发,300-400 mg/L的赤霉素处理可以明显提高种子发芽率。     

狼尾草种子萌发条件的研究

以采自河南、湖北、湖南和江西4个不同地区的狼尾草种子为试验材料,设20、25、30℃和35℃4个恒温处理,研究狼尾草种子萌发的适宜温度.结果表明,25℃和30 ℃处理下,种子萌发时间较其它处理早1 ～2d,发芽率和发芽指数显著高于20℃和30℃,综合考虑,狼尾草种子的最适宜萌发温度为恒温25 ～ 30℃,初次计数时间为第5天.     

赤霉素对猕猴桃种子萌发的影响

为了明确赤霉素对猕猴桃种子萌发的影响,采用上海同瑞科技有限公司生产的75%的赤霉素结晶粉对猕猴桃种子进行处理,在猕猴桃种子萌发的适宜条件下实验,结果表明,用赤霉素处理的种子的发芽势和发芽率明显高于对照,尤其是发芽势明显增强,两次实验4次重复平均发芽数在播后第20天(发芽势记载日期)比对照高38.3%~80.1%,在播后第19天高67.2%~140.4%,同时萌发的时间缩短,比对照早2~4d;不同浓度处理之间的发芽率随着浓度的增加也有增效作用,浓度越大,发芽率越高,在播后第19天的发芽率在39.3%~56.5%之间,第24天的发芽率在94.3%~99%之间.     

温度、光照和水分对珍稀濒危树种崖柏种子萌发的影响

以崖柏种子为试验材料,研究不同温度条件、光照和持续黑暗、不同浸种时间等对种子萌发的影响,探讨适宜崖柏种子萌发的环境条件。结果表明:适宜崖柏种子萌发的温度为25℃,种子发芽率为88%,20℃和30℃条件下的种子发芽率分别为77%和33%。种子萌发进程在20℃和30℃条件下比在25℃条件下开始的时间晚,萌发持续的时间长。高温会显著提高种子霉变率,30℃条件下的种子霉变率高达40%;光照不是崖柏种子萌发的必要条件。在连续黑暗条件下种子仍可萌发,且种子发芽率、发芽指数、发芽势、霉变率等无明显差别。但在光照下种子持续发芽的时间短,种子霉变率低;浸种72 h、96 h和120 h对崖柏的种子萌发没有显著影响,但浸种120 h的种子发芽率低,霉变率高。浸种72 h即可以满足崖柏种子萌发对水分的基本需求。     

含羞草种子萌发特性研究

采用浓硫酸酸蚀、烫种、砂磨等不同处理方法对含羞草种子进行萌发试验,测定其发芽率、发芽势及在不同温度下的生长势,探讨含羞草种子的萌发特性。结果表明:未经处理的含羞草种子发芽率为13.6%,硬实率达60.6%;种皮是影响其萌发的主要因素,95℃1min烫种对含羞草种子萌发作用明显,发芽率、发芽势最高,分别为94.3%、92.0%;浓硫酸处理50min也可提高含羞草种子萌发,发芽率、发芽势分别为84.0%,79.7%;砂磨处理发芽率为16.3%,效果不明显;含羞草种子萌发最适温度为30℃。     

不同温度和浸种时长对紫苏种子萌发的影响

为了解紫苏生长生理机制,采用不同温度和浸种时长处理紫苏种子,以探究贵州紫苏种子发芽特性。结果表明:紫苏种子萌发的最适温度为20℃、25℃和30℃,发芽率均高达90%以上;25℃萌发条件下,低温处理紫苏种子24h、48h和72h的发芽率分别为90%、93%、90%;紫苏种子最适浸种时长为48h,发芽率最高为97%。     

干旱胁迫对北苍术种子萌发及幼苗生理特性的影响

用聚乙二醇（PEG-6000）模拟干旱胁迫,探究其对北苍术种子萌发及幼苗生理特性的影响。分别以 5%、10%、15%、20%、25% 浓度的 PEG-6000 溶液对内蒙古赤峰和河北承德的北苍术种子进行处理,分析种子的萌发时间、发芽势、发芽率、根长、茎长和呼吸速率指标变化;发芽后模拟自然干旱,探究其对幼苗光合速率的影响。结果表明,河北种子的萌发时间比内蒙古种子短;内蒙古种子和河北种子的发芽率随着干旱胁迫的加剧先升高后降低,在 10% 干旱胁迫下,种子的发芽率最高,内蒙古种子为 49.97%,河北种子为 80.00%;在 25% 干旱胁迫下,种子的发芽率最低,内蒙古种子的发芽率为 6.67%,河北种子的发芽率为 31.07%。2 种种子的发芽势、根长、茎长和呼吸速率均随着干旱胁迫的加剧逐渐降低,但整体上河北种子的降低程度小于内蒙古种子。自然干旱胁迫 6d 后,北苍术幼苗的光合速率降低。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Pollen and pollination experiments. III. The viability of apple and pear pollen as affected by irradiation and storage

Summary Apple and pear pollen was irradiated with doses of 0, 50, 100, 250 and 500 krad (gamma rays) and stored at 4°C and 0–10% r.h. From the in-vitro germination percentages an average LD 50 dose of about 220 krad was estimated. For both irradiated and untreated pollen a close and corresponding lineair relationship existed between germination percentage and pollen tube growth.Irradiated pollen was much more sensitive to dry storage conditions than untreated pollen, resulting in less germination and more bursting. Apparently, irradiation caused the pollen cell membrane to lose its flexibility faster than normal. Rehydration of dry-stored, irradiated pollen in water-saturated air restored germination percentages up to their initial levels. The importance of this procedure in germination trials is stressed.     

Optimization of Extraction Technology and Determination of Content of Total Phenols of Leaves in Acanthopanax giraldii Harms

[Objectives] To determine the optimum extraction technology for total phenols of leaves in Acanthopanax giraldii Harms.[Methods]The single factor test and ortho...     

Cytoplasmic male sterility,resistance to gall mite and mildew,and season of leafing out in black currants

Summary Cytoplasmic male sterility (cms) is described in the F₁ hybrids Ribes × carrierei (R. glutinosum albidum × R. nigrum) and R. sanguineum × R. nigrum. In backcrosses to R. nigrum, progenies with R. glutinosum cytoplasm were either all male sterile, or segregated for full male fertility (F) and complete (S) and partial (I) male sterility. Ratios of F:I+S suggested that two linked genes controlled cms, F plants being dominant for one (Rf ₁) and recessive for the other (Rf ₂).Segregation for cms in relation to three linded genes, Ce (resistance to the gall mite, Cecidophyopsis ribes), Sph ₃(resistance to American gooseberry mildew, Sphaerotheca mors-uvae) and Lf ₁(one of two dominant additive genes controlling early season leafing out) indicated that Rf ₁and Rf ₂were in this linkage group. The gene order and approximate crossover values appeared to be: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqef0uAJj3BZ9Mz0bYu% H52CGmvzYLMzaerbd9wDYLwzYbItLDharqqr1ngBPrgifHhDYfgasa% acOqpw0xe9v8qqaqFD0xXdHaVhbbf9v8qqaqFr0xc9pk0xbba9q8Wq% Ffea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8frFve9Fve9Ff0dme% aabaqaciGacaGaamqadaabaeaafaaakeaacaWGdbGaamyzamaamaaa% baGaaiiiaiaacccacaGGWaGaaiOlaiaacgdacaGG0aGaaiiiaiaacc% caaaGaaiiiaiaacccacaGGGaGaamOuaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaaccdacaGGUaGaaiOmaiaacs% dacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaaaacaWGsbGaamOzaSGa% aGOmaOWaaWaaaeaacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccaaaGaamitaiaadAgaliaaigdakmaamaaa% baGaaiiiaiaacccacaGGGaGaaiiiaiaacccacaGGGaGaaiiiaiaacc% cacaGGGaGaaiiiaiaacccacaGGGaaaaiaadofacaWGWbGaamiAaSGa% aG4maaaa!6E4D!\[Ce\underline { 0.14 } Rf1\underline { 0.24 } Rf2\underline { } Lf1\underline { } Sph3\]. Crossover values of 0.36 for Ce-Lf ₁, and 0.15 for Lf ₁-Sph ₃were estimated from the relative mean differences in season of leafing out between seedlings dominant and recessive for Ce and Sph ₃.It is suggested that competitive disadvantage of lf ₁-carrying gametes and/or zygotes at low temperatures may be implicated in the almost invariable deficit of plants dominant for the closely linked mildew resistance allele Sph ₃. Poor performance of lf ₁- (and possibly lf ₂-) carrying gametes and young zygotes during periods of low temperature at flowering might also account for the liability of some late season cultivars and selections to premature fruit drop (running off).     

Screening techniques and sources of resistance to parasitic angiosperms

Parasitic angiosperms cause great losses in many important crops under different climatic conditions and soil types. The most widespread and important parasitic angiosperms belong to the genera Orobanche, Striga, and Cuscuta. The most important economical hosts belong to the Poaceae, Asteraceae, Solanaceae, Cucurbitaceae, and Fabaceae. Although some resistant cultivars have been identified in several crops, great gaps exist in our knowledge of the parasites and the genetic basis of the resistance, as well as the availability of in vitro screening techniques. Screening techniques are based on reactions of the host root or foliage. In vitro or greenhouse screening methods based on the reaction of root and/or foliar tissues are usually superior to field screenings and can be used with many species. To utilize them in plant breeding, it is necessary to demonstrate a strong correlation between in vitro and field data. The correlation should be calculated for every environment in which selection is practiced. Using biochemical analysis as a screening technique has had limited success. The reason seems to be the complex host-parasite interactions which lead to germination, rhizotropism, infection, and growth of the parasite. Germination results from chemicals produced by the host. Resistance is only available in a small group of crops. Resistance has been found in cultivated, primitive and wild forms, depending on the specific host-parasite system. An additional problem is the existence of pathotypes in the parasites. Inheritance of host resistance is usually polygenic and its transfer is slow and tedious. Molecular techniques have yet to be used to locate resistance to parasitic angiosperms. While intensifying the search for genes that control resistance to specific parasitic angiosperms, the best strategy to screen for resistance is to improve the already existing in vitro or greenhouse screening techniques.