乳突果种子生物学特性研究

通过发芽实验研究了温度、光照、pH值、贮藏时间等因素对乳突果种子萌发的影响.结果表明,乳突果种子无后熟休眠特性;其最适萌发温度为25℃;光照条件和黑暗条件发芽率没有差异;其对pH具有广泛的适应性,在pH值为2～10范围内均可萌发,但在pH值为6～8范围内可获得较高的发芽率.最适贮藏时间为12个月.     

繁缕(Stellaria media(L.)Vill.)种子萌发特性的研究

对繁缕进行温度、光照、低温贮藏、赤霉素和破种皮处理实验,研究不同条件对种子萌发的影响。结果表明,繁缕种子萌发对温度敏感,对光照不敏感,最适宜的萌发温度为12℃,最适光照条件为8 h。低温贮藏处理可有效促进种子萌发,-70℃贮藏后种子萌发率达到93.25%。赤霉素对种子萌芽影响较显著,最适浓度为500 mg/L。破种皮处理后种子萌发效果最好,萌发率达到96.75%,并于5 d萌发完毕。     

西南紫薇种子贮藏与萌发特性的研究

本文就温度、光照、土壤水分对西南紫薇（Lagestroemia intermedia Koehne）种子萌发的影响及种子贮藏进行了研究，结果表明，西南紫薇种子具有明显的光促进萌发特性，并表现出温度对光照的补偿表明；在周期性光照条件下，最适宜萌发温度为25℃～30℃；在全黑暗条件下，则为30℃；土壤水分条件以15%～60%为佳；其种子耐脱水、耐低温、耐贮藏，可以用种子库常规的种子保存技术实现长期保存。研究认为，目前西南紫薇的濒危状态主要是由于其生境遭受破坏造成的，该物种宜采取就地保护、迁地保护和种子保存相结合的方法进行种质资源保存。     

大叶千斤拔种子萌发特性研究

探讨大叶千斤拔种子发芽最佳基本条件和种子的寿命,为栽培生产提供科学依据。测定种子的吸水率;通过磨破种皮、热水处理和浓硫酸处理等找到破除种子硬实的最佳方法;考察不同温度和光照、发芽床、贮藏对种子萌发的影响。结果表明,大叶千斤拔种子吸水率为31.26%,种皮透水性差是影响种子发芽的关键因素。种子适宜萌发的温度范围为25～30℃,发芽前用磨擦种皮+80℃热水浸种4 h的方法可使种子的发芽率提高到66.67%;光照和发芽床对种子萌发无显著影响。种子在4℃低温条件下贮藏3年发芽率仍有61%,贮藏4年发芽率降至32%。综上,大叶千斤拔种子为硬实性种子,发芽前需要预处理;种子为高温萌发型、光中性种子;种子寿命在4年以上。     

西藏色季拉山沙棘萌发特性研究

以西藏色季拉山沙棘种子为对象,研究不同光照和温度对种子萌发进程、萌发速率的影响,为该品种的种质资源开发利用提供理论基础。结果表明,种子在光照和黑暗条件下均能发芽。在光照条件下的最适萌发温度是5℃/1℃,萌发率为98.7%;在黑暗条件下的最适萌发温度是20℃/5℃,萌发率为95.0%。光照能有效促进种子萌发进程,播种时应选择有光地段。沙棘种子萌发温幅较宽,在5℃/1℃～20℃/5℃范围内均有较高的发芽率,而高温(30℃/15℃)抑制了种子的萌发。     

不同环境条件对车桑子萌发的影响

以车桑子(Dodonaea viscose(L.)Jacq)种子为实验材料,置入光照气候箱实培养,研究不同浸种方式(40℃温水、0.3%高锰酸钾溶液、不浸种)、温度处理(15、20、25、30℃恒温和18～25℃变温)和贮藏时间(11、15、19个月和23个月)对车桑子种子萌发的影响,结果表明:3种浸种方式下的萌发率差异不显著;在贮藏时间实验中,萌发率先升后降,在贮藏19个月时达到最高,与其他3次实验均呈现显著性差异;温度处理中,18～25℃变温处理萌发率比其他4次实验显著提高,20℃以上适合车桑子种子萌发。     

光照和温度对红果小檗种子萌发的影响

研究了温度和光照条件对红果小檗种子萌发的影响,结果表明:光照对红果小檗种子的萌发无显著影响.恒温条件下,红果小檗种子萌发适宜温度为10℃,最适温度为20～25℃,低于或高于此温度,种子萌发率降低或萌发期延长；变温条件下,10℃/20℃、10 ℃/25℃和15 ℃/25℃为种子萌发适宜温度,萌发率均达到94％以上.     

甘草种子萌发特性的研究

通过研究温度、光照、覆土厚度、水分、pH值、赤霉素和贮藏时间等条件对甘草种子萌发的影响,探讨甘草种子的萌发特性。结果表明,甘草种子最合适的萌发温度为25℃;在适宜的温度下,全光照比无光照的发芽势和发芽率都高;覆土厚度在0.5~1.5cm之间甘草种子出苗较齐;土壤含水量为15%最利于甘草种子发芽;甘草种子对pH值的适应范围较宽,pH值在6~10之间时甘草种子发芽率较高;50~200mg/L的赤霉素处理显著提高了甘草种子的发芽势,发芽时滞缩短;甘草种子最适贮藏时间为12个月,生产中建议使用新采收种子进行播种。     

雪上一枝蒿种子发芽特性研究

研究了温度、光照及不同贮藏期对雪上一枝蒿种子发芽力的影响.结果表明:雪上一枝蒿种子萌发需要温度较低,大于22℃时萌发则受到抑制,达30℃时则完全抑制其萌发;光照对其影响不明显.常温储藏的种子较0～5℃低温湿沙中贮藏的种子萌发力显著减弱.     

贮藏方式和培养温度对药用植物假马鞭种子萌发的影响

为探查药用植物假马鞭(Stachytarpheta jamaicensis)种子破除休眠的贮藏方法以及萌发的最佳温度条件,将假马鞭种子分别进行30 天的室温干燥贮藏、15℃湿润贮藏、4℃低温层积和0℃冰冻贮藏后,测定其萌发率;种子在6 个温度梯度(15、20、25、30、35、40℃)、12 h 光照/12 h 黑暗条件下培养,观测其萌发率和萌发进程。结果表明：假马鞭种子具有较高活性(92%),初始萌发率为10%~49.3%;经过室温干燥贮藏、15℃、4℃湿润贮藏的种子,在变温(25℃/15℃)培养下其萌发率分别达到55.3%、70%和56.7%,经0℃冰冻贮藏后萌发率降低至9.3%;假马鞭种子对6 种培养温度显示出不同的响应,在30℃和35℃培养下,萌发开始时间较早（1~7 天）,累积萌发率不足20%;在20℃和25℃培养下,萌发开始时间较晚（7~11天）,累积萌发率分别达到72.7%和56%。假马鞭种子具有中度生理休眠,经过室内干燥贮藏、15℃湿润贮藏和4℃层积可以破除种子部分休眠,获得较高萌发率,种子达到最高萌发率(70%)的最佳贮藏条件是15℃湿润贮藏、变温培养(25℃/15℃);未经贮藏处理的种子达到最高萌发率(72.7%)的培养温度是20℃。     

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...     

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.     

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.     

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.