Germination characteristics of some plant species from calcareous fens in southern Germany and their implications for the seed bank

Seeds of 25 plant species from calcareous fen hay meadows were exposed to different experimental conditions and their germination was characterised. Constant temperature inhibited germination especially in Cyperaceae . Both gibberellic acid and potassium nitrate failed to terminate dormancy. Increased germination rates were found in dicot species after treatment with gibberellic acid. Temperature fluctuations increased germination of Cyperaceae as well as dicotyledons. Treatment with gibberellic acid removed the chilling requirement in some of the species. Dormancy of small seeds with thin seed coats was broken by the application of gibberellic acid or fluctuating temperature; large thick-coated seeds were unaffected by gibberellic acid. No obligatory darkness requirement was found in any species; three species germinated irrespective of light treatments. All other species achieved higher percentage germination in daylight or in red (670 nm) light. Permanent darkness and far-red light (730 nm) reduced germination drastically. The results indicate that germination characteristics of the species investigated can be related to their seed bank types.     

The physiological basis of seed dormancy in Avena fatua. VIII. Action of malonic acid

Adkins, S. W., Symons, S. J. and Simpson, G. M. 1988. The physiological basis of seed dormancy in Avena fatua . VIII. Action of malonic acid - Physiol. Plant, 72: 477–482.
A low concentration of malonic acid (50 m M ) induced germination in four genetically pure dormant lines of Avena fatua L. Sensitivity to this treatment was poor immediately after harvest but increased markedly during after-ripening, indicating that the mode of action of malonic acid (50 m M ) was similar to that of another organic acid, citric acid. Over the concentration range (10–50 m M ) where malonic acid promoted germination, oxygen uptake was also stimulated, and this was before the first visible signs of germination. At higher concentrations (100–300 m M ) where there was no promotion of germination, malonic acid strongly inhibited oxygen uptake. These results show that malonic acid has a dual effect on oxygen uptake and subsequent germination. Low concentrations (10–50 m M ) act by stimulating the Krebs cycle and germination through an acidification reaction like citric acid, and high concentrations (100–300 m M ) act by inhibiting germination through enzymatic restraint of the Krebs cycle.
The stimulation of both oxygen uptake and germination by three established germination promoters (sodium nitrate, citric acid and ethanol) was inhibited by a high concentration of malonic acid (200 m M ) but unaffected by a low concentration (50 m M ). These results show that oxygen uptake, and hence the activity of the Krebs cycle, are important processes involved in the dormancy breaking mechanism of these three promotors.     

模拟酸雨对茄科3种蔬菜种子萌发的影响

采用pH 2.0、3.0、4.0、5.0的模拟酸雨和pH 6.5的中性溶液(ck)处理番茄、茄子、辣椒3种蔬菜种子,研究酸雨胁迫强度对3种蔬菜种子萌发的影响。结果表明：从发芽率、发芽势、发芽指数3个萌发指标来看,番茄种子在pH 2.0～3.0的强酸雨胁迫下,萌发受到轻微抑制;茄子种子在pH 2.0～5.0的酸雨胁迫下,萌发一直受到抑制,尤其是在pH 2.0的强酸雨胁迫时表现出萌发几乎完全受到抑制,而辣椒种子在酸雨胁迫下,萌发几乎没有受到抑制。3个萌发指标均随着酸雨pH值的减小而减少。pH 2.0～5.0酸雨胁迫下,辣椒吸水值的变幅（13.75）﹤番茄（19.91）﹤茄子（20.58）,同等酸雨胁迫强度下,根长抑制指数、蛋白质含量降幅、丙二醛增幅辣椒﹤番茄﹤茄子。这表明抗酸雨胁迫能力：辣椒>番茄>茄子。     

Actions of gibberellic Acid and phytochrome on the germination of grand rapids lettuce seeds

Red light and gibberellic acid were about equally effective in promoting germination of Grand Rapids lettuce (Lactuca sativa L.) seeds. With initial far red light treatment more than 80% remained dormant in subsequent dark storage. After 2 days of dark storage, red light effectively promoted germination, while gibberellic acid action was weak. With between 2 and 10 days of dark storage, gibberellic acid had little effect, while promotion by red light decreased slowly and finally disappeared. After 10 days of dark storage, both gibberellic acid and red light were required for germination. The dark storage treatment interferes with phytochrome-independent germination processes and cannot be overcome by added gibberellic acid. However, storage may also decrease the effectiveness of endogenous gibberellins. Phytochrome-dependent germination seems to require only low levels of endogenous gibberellin activity or the addition of gibberellic acid. Gibberellins and red light appear to act on germination by regulation of sequential sites of a branched-looped pathway.     

The physiological basis of seed dormancy in Avena fatua. VII. Action of organic acids and pH

Citric, succinic, fumaric, malic, pyruvic and lactic acids induced germination in two genetically pure dormant lines of Avena fatua L. The sensitivity to these acids was low immediately after harvest and increased markedly after a period of dry after-ripening. Because the acids could only overcome dormancy in partly after-ripened caryopses, the mode of their action in these caryopses differed from that of another germination promotor, ethanol, and was similar to that of the germination promoter, sodium nitrate. The mode of action of the organic acids on the partly after-ripened caryopses through lowering pH was indicated by the observation that other non-metabolic weak acids could also break dormancy while neutral pH value salt solutions of some of the tested acids were inactive. The dose-response curves of citric acid for the stimulation of germination and for oxygen uptake were similar, indicating that this organic acid may stimulate germination by promoting oxygen uptake. A time sequence study showed that citric acid stimulated oxygen uptake before the first visible signs of germination. Stimulation of germination and oxygen uptake over a range of pH values showed that those values of pH which stimulated germination also stimulated oxygen uptake, indicating that the ability to stimulate oxygen uptake was not confined to organic acids. The stimulation of both germination and oxygen uptake by citric acid was not inhibited by salicylhydroxamic acid, an inhibitor of alternative respiration, therefore stimulation of both germination and oxygen uptake by citric acid does not require the operation of the alternative pathway of respiration. The function of weak acids as promoters of oxygen uptake is discussed with reference to the breakage of dormancy in partly after-ripened caryopses and the involvement of various respiratory pathways is indicated.     

加快棕种子萌发和幼苗生长的研究

棕种子萌发和幼苗生长十分缓慢 ,为了探索加快种子萌发和幼苗生长的方法 ,对棕种子进行不同处理、不同时间催芽和催芽后不同处理等试验 ,结果表明 :(1)生长调节剂 3号 ABT生根粉、吲哚丁酸和 2 ,4 - D可提高种子萌发率 ,促进幼苗生长。 (2 )播种前催芽可促使种子提前萌发 ,延长幼苗生长期 ,使当年生苗更粗壮 ;贮藏 3个月后催芽可提高 10 %～ 15%的发芽率。 (3)催芽后用 50 mg/ L和 10 0 mg/ L的 3号 ABT生根粉、或者 10 0 mg/ L的萘乙酸浸泡都可以提高幼苗出土率 ,但对幼苗生长没有明显影响。     

Effects of simulated acid rain on the pollen germination and pollen tube growth of apple (Malus sylvestris Miller cv. Golden)

The pollens of apple flowers have been treated with simulated acid rain solutions in range of pHs 2.9 to 5.0 in order to determine the threshold proportion values that lead the observed symptoms of detriments of acid rain. Compared to controls (pH 6.5), pollen germination decreased by 41.75% at pH 3.3 and pollen tube elongation decreased by 24.3% at pH 3.4. Acid rain threshold proportion value was around pH 3.3 and 3.4 for apple pollen germination and pollen tube elongation, respectively. Furthermore, pollen tube elongation was determined to be more sensitive to acid rain than pollen germination. The pH values below 3.1 resulted in complete destruction of pollen tubes. Pollen germination entirely stopped at around pH 3.0. Finally, it has been shown that the acid rain has a blocking effect on pollen germination and pollen tube elongation in apple. The conclusion is that not only pH value but also the quantity of acid rain is important factor in germination. The results were found statistically significant through the LSD test at levels of p < 0.05 and p < 0.01.     

Delayed germination of Bacillus cereus T spores after treatment with trichloroacetic acid and their reactivation by heating

Treatment of Bacillus cereus T spores with trichloroacetic acid delayed their germination. The extent of retardation depended on the concentration of trichloroacetic acid, and the temperature, pH and duration of treatment. The effect was completely reversed by subsequent heating, and this restoration of germination also depended on the temperature and duration of heat treatment. Fourteen compounds were examined for their ability to suppress germination of spores. The halogenated fatty acids tested, such as trifluoro-, tribromo-, and dichloroacetic acid, caused suppression of germination, whereas other compounds, i.e., free fatty acids and amino acids, did not. It is concluded that the charge distribution of fatty acid molecules is important for their effect in suppressing germination of spores.     

Physiology of Oil Seeds: II. Dormancy Release in Virginia-type Peanut Seeds by Plant Growth Regulators

Germination, ethylene production, and carbon dioxide production by dormant Virginia-type peanuts were determined during treatments with plant growth regulators. Kinetin, benzylaminopurine, and 2-chloroethylphosphonic acid induced extensive germination above the water controls. Benzylaminopurine and 2-chloroethylphosphonic acid increased the germination of the more dormant basal seeds to a larger extent above the controls than the less dormant apical seeds. Coumarin induced a slight stimulation of germination while abscisic acid, 2,4-dichlorophenoxyacetic acid, and succinic acid 2,2-dimethylhydrazide did not stimulate germination above the controls. In addition to stimulating germination, the cytokinins also stimulated ethylene production by the seeds. In the case of benzylaminopurine, where the more dormant basal seeds were stimulated to germinate above the control to a larger extent than the less dormant apical seeds, correspondingly more ethylene production was induced in the basal seeds. However, the opposite was true of kinetin for both germination and ethylene production. When germination was extensively stimulated by the cytokinins, maximal ethylene and carbon dioxide evolution occurred at 24 and 72 hours, respectively. Abscisic acid inhibited ethylene production and germinaton of the seeds while carbon dioxide evolution was comparatively high. The crucial physiological event for germination of dormant peanut seeds was enhancement of ethylene production by the seeds.     

TRANS-CINNAMIC ACID AND SOME RELATED COMPOUND EFFECTS ON ORNITHOGALUM CAUDATUM POLLEN

Fresh pollen of Ornithogalum caudatum was germinated in the absence or presence of trans-cinnamic acid (t-CA), trans-cinnamaldehyde (t-CAld) and related compounds, and germination percentage studied. Hydrocinnamic acid, t-CA, and t-CAld reduced germination to 50% of the control at 20–40 mg/liter. Hydrocinnamaldehyde, 3-phenyl-1-propanol and phenylacetic acid gave 50% reduction at 70–80 mg/liter, and caffeic acid, ferulic acid, phenethyl alcohol, coumarin, styrene, phenylalanine or ethyl cinnamate required 200 mg/liter or more for similar reduction in germination percentage. The inhibition of germination by t-CA could not be overcome by indole acetic acid and vice versa, indicating a lack of antiauxin activity.     

植酸对杂交水稻V20B种子萌发及生理特性的影响

以杂交水稻V20B 为材料,研究外源植酸对种子萌发的影响。结果表明,外源植酸浓度为10 mmol/L 时能明显抑制种子萌发。生理生化检测表明,植酸对杂交水稻种子萌发过程中α-淀粉酶活性、可溶性糖和内源植酸含量变化有不同程度的影响。     

萌发前处理和种子大小对瓜拉那(Paullinia cupana var.sorbilis)种子萌发的影响

为了增加对瓜拉那(Paullinia cupana var.sorbilis)种子萌发特性的了解,寻求提高瓜拉那种子萌发的最佳条件,本研究用控制实验,研究了瓜拉那种子去/不去假种皮、不同种子大小和酸处理下的萌发行为.结果表明,去假种皮且酸处理的大种子发芽率最高,为100%;不去假种皮且无酸处理的小种子基本不萌发;去假种皮种子发芽率显著高于未去假种皮种子;种子大小对萌发率有显著影响,大种子比小种子趋于有更高的萌发率;酸处理能进一步提高去假种皮种子萌发率.     

The Effects of Gibberellic Acid and Scarification on the Seed Dormancy and Germination in Luzula spicata

Luzula spicata L. seeds are completely dormant at maturity. A germination inhibitor is present at the micropylar end. Normally, the only effective means of eliciting germination is a precise scarification of the micropylar end which inactivates the inhibitor. Exogenous application of gibberellic acid, kinetin, KNO₃, and thiourea have no affect on the dormancy of unscarified seeds. Scarification of the hilar end of the seed does not elicit germination, but when gibberellic acid is applied to the hilar scarified seeds moderate germination results. Presumably, these seeds are dormant due to a deficit of endogenous gibberellin; a condition which can be overcome by the application of gibberellic acid to seeds scarified at a site in itself ineffective in producing germination. Apparently the gibberellic acid serves to initiate amylase activity in the endosperm, overcoming the inhibitor block. Luzula spicata seed dormancy is apparently unique in that a germination inhibitor is operative in conjunction with the commonly recognized gibberellin-amylase mechanism.     

Inhibition of cottonseed germination with abscisic Acid and its reversal

Germination of cottonseed (Gossypium hirsutum L.) was inhibited by abscisic acid. Inhibition was greater when seeds were soaked in abscisic acid for 5 hours and dried prior to germination than when abscisic acid was applied in the germination medium. (2-Chloroethyl)phosphonic acid, gibberellic acid, and kinetin partially overcame the inhibitory action of abscisic acid. Combinations of (2-chloroethyl)phosphonic acid with gibberellic acid or kinetin were more effective than the individual substances. Germination also was partially restored by removal of seed coats. Fusicoccin completely restored germination of abscisic acidtreated seeds.     

Endogenous abscisic Acid levels in germinating and nongerminating lettuce seed

The concentrations of abscisic acid in Grand Rapids lettuce (Lactuca sativa L.) seeds imbibed under conditions which promote or inhibit germination were determined by electron capture-gas chromatography. The concentration of abscisic acid in dry seeds was 12 to 14 nanograms per 100 milligrams. During 24-hour imbibition, the abscisic acid content diminished more rapidly during conditions which allow germination (25 C in light) than in conditions which inhibited germination (35 C in light or darkness at 25 C). A decrease in endogenous levels of abscisic acid was not always correlated with germination.     

Increased Germination Rates of Baldcypress and Pondcypress Seed Following Treatments Affecting the Seed Coat

The effects of seed-coat removal, warm-water soaking, cold stratification, dry-cold storage and acid treatment on the germination of baldcypress (Taxodium distichum (L.) Rich.) and pondcypress (Taxodium distichum var. nutans (Ait.) Sweet) seed were studied. Removal of the hard seed coat resulted in a prompt and high percent germination, indicating that there was no physiological embryo dormancy. Cold stratification, warm-water soaking and acid treatment did not increase percent germination over the control after a 60-day germination period. They did promote the rate of germination however, having a significantly higher germination at 30 days. Dry-cold storage promoted the initial rate of germination, but resulted in a decreased percent germination below the control after 60 days. The above results suggest that moisture, and not cold, was the crucial component of stratification. The improved germination rate following acid treatment further suggests that any treatment which rendered the seed coat more permeable or softened it was more effective in increasing the rate of germination of baldcypress and pondcypress seed.     

-aminobutyric acid as a required germinant for mutant spores of Bacillus megaterium

Germinated spores of Bacillus megaterium QM B1551 were irradiated with ultraviolet light, and spore-forming survivors were screened for germination requirements. Spore strains which failed to germinate in a variety of defined solutions germinative for spores of the parent strain were obtained. Mutant spores germinated readily in solutions containing yeast extract or one of numerous complex preparations. gamma-Aminobutyric acid, obtained from yeast extract by column chromatography, was shown to be required for germination by the mutant spores. gamma-Aminobutyric acid and l-alanine at final concentrations of 1 mm each, in solutions of KI (40 mm), equaled the potency of yeast extract (1 mg/ml) in the germination of the mutant spores. One of several other amino acids could be substituted, though less effectively, for l-alanine. alpha-Aminobutyric acid, beta-aminobutyric acid, beta-alanine, and 5-aminovaleric acid were ineffective substitutes for gamma-aminobutyric acid in mutant spore germination.     

Effect of jasmonic acid, ACC and ethephon on pollen germination in strawberry

The effects of jasmonic acid (JA), I-aminocyclopropane carboxylic acid(ACC) and 2-cholorethyl phosphonic acid (ethephon) on pollen germination wereinvestigated in strawberry cv. Tufts. ACC and ethephon stimulated pollengermination while JA was inhibitory. Pollen germination was decreased by 0.5mM JA from 42.5 to 5.8% compared with the control after4 h of incubation. On the other hand, ACC and ethephon (0.5mM) increased the pollen germination percentage to 55.6 and 60.7%,respectively. In addition, both ethephon and ACC relieved the inhibition ofpollen germination by JA.     

Biochemical changes during germination and seedling growth in Cuscuta campestris

Changes in the contents of starch, protein, DNA, RNA, total phosphorus, acid soluble phosphorus and inorganic phosphorus, and in the activities of some enzymes of carbohydrate, amino acid, nucleic acid and phosphate metabolism were studied during the germination of Cuscuta campestris seeds. The results are expressed on per seed basis.
Starch content in Cuscuta seeds showed a steady decline with most of it depleted by the end of the eighth day of germination. Protein content increased with germination up to 48 h and then decreased. RNA and DNA contents increased to a maximal level on the fourth day of germination and then decreased. Total phosphorus in the seeds remained almost unchanged during the period of study. Both trichloroacetic acid soluble and inorganic phosphorus increased until the third day and then decreased. Phytin was rapidly hydrolyzed with little being detectable by the seventh day of germination. Glucose-6-phosphate dehydrogenase increased with germination, while fructose bisphosphate aldolase which is indispensable for glycolysis, decreased with germination. Ribonuclease and deoxyribonuclease increased till the third and fourth day, respectively, and then decreased. Aspartate and alanine aminotransferases showed a maximum on the second day and then decreased. Activities of alkaline fructose-1,6-bisphosphatase and phytase were absent in the dry seeds and appeared only on the second day of germination. Both α- and β-amylase activities were present in the dry seed.     

茄子根系分泌物中香草醛和肉桂酸对黄萎菌的化感效应

采用室内培养和生物测定的试验方法,研究了不同浓度的香草醛和肉桂酸对黄萎菌（Verticillium dahliae）及茄子种子萌发、幼苗生长的化感效应.结果表明,香草醛和肉桂酸对茄子黄萎菌的化感效应存在差异,表现为所有浓度的肉桂酸都抑制了黄萎菌孢子萌发,当浓度为0.5mmol/L时抑制作用最大;香草醛在浓度为0.1mmol/L时抑制孢子萌发,其余浓度则表现出促进作用.对香草醛和肉桂酸的生物测定结果显示,当浓度为0.1mmol/L时,肉桂酸促进茄子种子萌发和幼苗生长,其余浓度则表现为抑制作用,并且随着浓度的加大抑制作用增强;香草醛在各浓度水平下都促进了茄子种子萌发和幼苗生长,当浓度为0.5mmol/L时促进作用最大.