脱落酸引发对夜香紫罗兰种子萌发的效应

研究脱落酸引发及其与植物生长调节剂的复合处理对夜香紫罗兰(Matthiola bicornis)种子萌发的效应.结果表明,将夜香紫罗兰种子于20℃下在2.5×10-5 mol/L脱落酸(ABA)溶液中引发7 d,能显著缩短种子平均萌发时间,增加种子萌发指数.在ABA溶液中加入吲哚乙酸(NAA)未能进一步改善夜香紫罗兰种子萌发,但其他复合处理均显著提高正常幼苗百分率.ABA和细胞分裂素(KT)及NAA复合处理进一步增加种子萌发指数,不仅比单独用ABA引发的效果好,而且也比用聚乙二醇(PEG)引发的效果好.ABA引发和PEG引发的夜香紫罗兰种子相对吸水量显著不同.对ABA引发机理和应用潜力进行了讨论.     

Stimulation of celery seed germination and seedling growth with combined ethephon,gibberellin and polyethylene glycol seed treatments

The upper-temperature limit for germination of cv. Celebrity celery seeds incubated in darkness in laboratory tests was slightly raised following a seed soak with a mixture of the gibberellins A₄ and A₇ + ethephon (G + E) but more so by osmotic priming with polyethylene glycol (PEG). However, the best effects were obtained with a combination of growth regulator and priming treatments. Incorporation of growth regulators into the PEG was more effective than soaking seeds in G + E solutions either before or after osmotic priming. In glasshouse tests, seedling emergence was more rapid, percentage emergence was higher and seedling weight was greater from seeds treated with PEG either alone or in combination with G + E than from untreated seeds, water-soaked seeds or seeds given G + E soaks before or after PEG treatment.     

Drought resistance in rice seedlings conferred by seed priming

Seed priming is a method by which seeds are subjected to different stress conditions to impart stress adaptation in seedlings germinating and growing under stressful situations. Drought stress is a major reason behind failure of crops. We studied the effects of hydropriming, dehydration priming (induced by PEG), and osmopriming (induced by NaCl and KH₂PO₄) on subsequent germination, growth and anti-oxidant defense mechanisms of 2-week-old rice seedlings under continuing dehydration stress. Unprimed seeds grown in PEG showed significantly lower germination and growth along with significantly higher reactive oxygen species (ROS) and lipid peroxidation levels. Among the priming methods, 5 % PEG priming was found to be the best in terms of germination and growth rate along with the lowest amount of ROS and lipid peroxidation (malondialdehyde [MDA]) values. MDA levels were reduced significantly by all of the priming methods. Hence, reduction of lipid peroxidation may be a key factor underlying the drought tolerance produced by the priming treatments. Glutathione peroxidase (GPX) activity seemed to bear an excellent correlation with oxidative stress resistance through seed priming. The PEG priming produced minimum peroxidative damage and superior germination and growth rate along with efficient GPX activity, overexpressed MnSOD and maintenance of HSP70 expression in normal as well as in drought condition. Therefore, in PEG-primed seeds the existence of robust protective mechanisms is definitely indicated.     

粗茎秦艽种子粗提物与破眠方法研究

为了探究影响粗茎秦艽（Gentiana crassicaulis Duthie ex Burk.）种子休眠的因素,破除休眠,寻找其种子快速萌发的方法,以干燥的粗茎秦艽种子为材料,测定种子吸水率及粗提物的活性,使用不同浓度的赤霉素（GA₃）、高锰酸钾（KMnO₄）、聚乙二醇（PEG6000）和过氧化氢（H₂O₂）溶液进行浸种处理,比较不同处理条件对粗茎秦艽种子萌发的影响。结果显示,粗茎秦艽种皮对种子吸水没有明显阻碍作用;不同浓度的种子粗提物对白菜、小麦的萌发和生长均表现出抑制作用;不同浓度的粗提物对粗茎秦艽种子自身的萌发也表现出一定的抑制作用,当粗提物浓度达到0.1 g/mL时,抑制作用最显著（P < 0.05）;高锰酸钾处理可提高粗茎秦艽种子的萌发率,浓度为1.5%时效果较显著（P < 0.05）,而过氧化氢处理对粗茎秦艽种子的萌发效果不如前者,此外,用500 mg/L的赤霉素浸种和300 mg/L的聚乙二醇预处理也可显著打破粗茎秦艽种子休眠（P < 0.01）。研究结果表明粗茎秦艽种子的内源抑制物是影响其休眠的因素之一;种皮的机械阻碍也在一定程度上影响了种子萌发;粗茎秦艽种子具有综合性休眠特性。高锰酸钾预处理、赤霉素浸种和聚乙二醇引发均可打破种子休眠、缩短种子出芽时间,提高种子的发芽能力。     

A comparison of two large-scale seed priming techniques

Leek seed lots of high (91%) and low (82%) viability were primed in aerated polyethylene glycol (PEG) solutions in Bubble-columns and by a non-osmotic priming technique in both 1987 and 1988 and the seeds were then sown in the field. Both methods of priming established a similar seed moisture content during treatment and, in the laboratory, produced seeds with more rapid and uniform germination than untreated seeds, with a greater advantage for Drum compared with Bubble-column priming in PEG. In the field, both priming techniques gave seedling emergence responses similar to those from priming in PEG by the laboratory-scale technique on filter paper. Both large-scale priming methods gave earlier and more uniform emergence than untreated seeds and gave similar or slightly higher levels of seedling emergence, except on one sowing occasion when seeds were stored before sowing followed by sowing into a drying seedbed.     

干旱胁迫对远志种子萌发及幼苗生长和生理特性的影响

以远志(Polygala tenuifolia Willd.)为研究对象,采用不同浓度(2.5%~25%)聚乙二醇(PEG-6000)模拟不同程度的干旱胁迫,探讨干旱胁迫对远志种子萌发及幼苗生理生化特性的影响。结果表明:(1)随着干旱胁迫强度的增加,远志种子的发芽启动时间推迟,发芽率、发芽势、发芽指数和活力指数降低,但种子发芽率在2.5%~15%PEG胁迫下与对照无显著性差异,而在20%PEG胁迫下均显著低于对照,在25%PEG胁迫下种子不能萌发;在干旱胁迫条件下,远志幼苗生物量降低,胚芽生长受到显著抑制,胚根长度则先伸长后缩短。(2)远志幼苗叶绿素含量在2.5%~10%PEG范围内随胁迫强度的增加和时间的延长而持续上升,在15%和20%PEG胁迫下则表现为先上升后下降,在10%PEG胁迫处理第15天时含量最高,为对照的1.34倍。(3)幼苗叶片的游离脯氨酸、可溶性糖和可溶性蛋白含量随PEG胁迫强度的增加和时间的延长而增加,各指标均在20%PEG胁迫处理第15天时含量最高,分别为对照的1.99倍、1.53倍和1.50倍。(4)随着PEG胁迫时间的延长,远志幼苗叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性先上升后下降,并在10%PEG胁迫处理第10天时活性最强;过氧化物酶(POD)活性随着胁迫时间的延长表现出先上升后下降又上升的特性,并在20%PEG胁迫处理第5天时活性最强;叶片丙二醛(MDA)含量在15%和20%PEG胁迫处理下持续上升,在2.5%~10%PEG胁迫范围内先上升后又有所下降。研究发现,远志种子在轻、中度干旱胁迫下仍可正常萌发,而且幼苗能通过调节自身生长、渗透调节物质含量和抗氧化酶活性主动适应干旱环境,对干旱环境表现出较好的适应能力。     

Control of macaw palm seed germination by the gibberellin/abscisic acid balance

The hormonal mechanisms involved in palm seed germination are not fully understood. To better understand how germination is regulated in Arecaceae, we used macaw palm (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.) seed as a model. Endogenous hormone concentrations, tocopherol and tocotrienol and lipid peroxidation during germination were studied separately in the embryo and endosperm. Evaluations were performed in dry (D), imbibed (I), germinated (G) and non‐germinated (NG) seeds treated (+GA₃) or not treated (control) with gibberellins (GA). With GA₃ treatment, seeds germinated faster and to a higher percentage than control seeds. The +GA₃ treatment increased total bioactive GA in the embryo during germination relative to the control. Abscisic acid (ABA) concentrations decreased gradually from D to G in both tissues. Embryos of G seeds had a lower ABA content than NG seeds in both treatments. The GA/ABA ratio in the embryo was significantly higher in G than NG seeds. The +GA₃ treatment did not significantly affect the GA/ABA ratio in either treatment. Cytokinin content increased from dry to germinated seeds. Jasmonic acid (JA) increased and 1‐aminocyclopropane‐1‐carboylic acid (ACC) decreased after imbibition. In addition, α‐tocopherol and α‐tocotrienol decreased, while lipid peroxidation increased in the embryo during germination. We conclude that germination in macaw palm seed involves reductions in ABA content and, consequently, increased GA/ABA in the embryo. Furthermore, the imbibition process generates oxidative stress (as observed by changes in vitamin E and MDA).     

Physiological and enzymatic activity of pepper seeds (Capsicum annuum) during priming

Pepper ( Capsicum annuum L. cv. Keystone Resistance Giant 3) seeds were monitored during priming to determine if seed treatments which accelerate the rate of germination could be correlated with specific physiological changes within the seeds. Pepper seeds primed with −0.90 and −1.35 MPa NaCl solutions at 23°C for 18 days did not completely equilibrate with the osmotic potential of the priming solution. Seed respiratory rates indicated that priming extends the lag phase of germination following imbibition. Soluble protein levels increased 115% in primed seeds, and the uptake and incorporation of [¹⁴C(U)] labelled amino acids into the acid insoluble fraction increased throughout the priming treatments. Alcohol dehydrogenase (EC 1.1.1.1, anaerobic metabolism), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44, pentose phosphate pathway) activities remained stable throughout the priming treatment, but were higher after 6 days. than the water-imbibed controls. Aldolase (EC 4.2.1.1. glycolysis) and isocitrate lyase (EC 4.1.3.1, glyoxylate cycle) activities increased with imbibition and were 61 and 56% (respectively) higher in primed seeds as compared to the water-imbibed controls after 12 days. Treatment with the −0.90 MPa NaCl solution was more effective than the −1.35 MPa solution in improving the rate of germination, yet there were no significant differences between the protein concentrations or enzyme activities of the two priming treatments. However, the incorporation of labelled amino acids into pepper seeds was significantly higher in the −0.90 MPa priming treatment.     

Improved germination in seeds of guayule (Parthenium argentatum Gray) following polyethylene glycol and gibberellic acid pretreatments

Suitable conditions for the pretreatment of seeds of guayule were determined with a view to improving germination. These included the addition of thiram (500 mg litre^-1), and applications of GA₄₊₇ alone, or in combination with polyethylene glycol. Significant improvements in the seed germination were seen following applications of PEG at -0.10 MPa. Simultaneous application of GA₄₊₇ with priming improved soil emergence and germination over a wide range of temperatures. No beneficial effects of PEG priming were evident on seed storage.     

Effects of combining priming and plant growth regulator treatments on the synchronisation of carrot seed germination

Osmotic priming of carrot seeds for 2 wk in polyethylene glycol (PEG, — 10 MPa) at 15 °C led to more rapid and synchronous germination at 20 °C compared to untreated seeds. These responses were enhanced by a 24 h pre-priming soak in water or a change of solution after the first 24 h of priming to remove leachate. The inclusion of 200 mg litre^-1N-substituted phthalimide in the pre-priming soak and/or in the PEG further enhanced the results of priming. Leachate removal combined with phthalimide inclusion gave 79% and 86% germination from seeds of two carrot cultivars during the first day in 20°C water following priming. In contrast, cumulative germination of untreated seeds of the same cultivars was 18% and 61% respectively after 3 days in 20°C water. Seeds primed in PEG containing 200 mg phthalimide litre^-1with the solution replaced after the first 24 h germinated earlier and more synchronously than untreated seeds over a range of germination temperatures (5, 10, 15, or 20°C), but the effects of priming were most marked at 5°C.     

Priming responses of leek (Allium porrum L.) seeds to different dissolved oxygen levels in the osmoticum

Leek seeds (Allium porrum L.) cv. Winterreuzen were treated for 5 days in stirred bioreactors containing a -1.0 MPa polyethylene glycol (PEG 6000) solution. The level of dissolved oxygen was controlled from zero to approximately two and a half times that of saturation with respect to atmospheric air by bubbling through 0₂/N₂ gas blends from 0% O₂ to 50% O₂. The treatment with 0% O₂ (i.e. bubbling with N₂) gave no reduction in germination time compared to untreated seeds after allowing for the time for water imbibition. As the proportion of oxygen was increased, a rapid reduction was observed until a concentration equivalent to air was used. Further increases to the maximum, produced only a marginal further improvement. The reduction in germination times for seeds that had been cabinet dried was longer for all treatments due to the time required for re-imbibition of water but the general response to priming was the same as with undried seeds. Only dried seeds treated with air or higher oxygen concentrations showed enhanced synchronicity of germination times. The percentage germination of seeds from all treatments was the same, including the treatment with nitrogen gas. These tests help to explain the recently reported advantages of using enriched air for seed priming and are one of the necessary protocols for ensuring satisfactory bulk priming.     

Comparative evaluation of hydro-, chemo- , and hormonal-priming methods for imparting salt and PEG stress tolerance in Indian mustard (<Emphasis Type="Italic">Brassica</Emphasis><Emphasis Type="Italic">juncea</Emphasis> L.)

The present study was aimed to evaluate the effect of different seed priming methods to enhance the sodium chloride (NaCl) and polyethylene glycol-8000 (PEG-8000) stress tolerance in Indian mustard (Brassica juncea L.). Seeds subjected to different priming treatments such as water (hydro-priming), calcium chloride (CaCl₂) (chemo-priming), and abscisic acid (ABA) (hormonal-priming) showed increased rate of germination as compared to non-primed seeds. The primed and non-primed seeds were grown for 15 days and then the seedlings were independently subjected to iso-osmotic salt (150 mM NaCl) or PEG-8000 (20%) stress. The different biochemical responses were studied 10 days after treatment. Under NaCl and PEG stress, the dry weight and total chlorophyll content were higher in primed sets as compared to non-primed treatment which was also evident by the phenotype of the seedlings. In general, the higher activities of superoxide dismutase and glutathione reductase resulted in lower oxidative damage, in terms of malondialdehyde content, under NaCl and PEG stress in hydro-primed set as compared to non-primed, ABA-, and CaCl₂-primed treatments. Besides, the level of total phenolics and accumulation of osmolytes such as free proline, glycine betaine, and total soluble sugars was also lower in hydro-primed set as compared to other primed and non-primed treatments. The study thus suggests the use of hydro-priming as a simple and cost-effective strategy to alleviate the NaCl and PEG induced stress in B. juncea.     

Effect of priming treatments on seed germination and seedling growth in bamboo [Dendrocalamus strictus (Roxb.) Nees]

Instances of flowering of bamboo species Dendrocalamus strictus are few and far between which are taken as opportunity by nurserymen to collect seeds for propagation. Germination of seeds is reported to be poor. Therefore, different seed priming treatments were applied to D. strictus seeds collected from Ranchi in order to obtain uniform and high germination. Under laboratory conditions, dehusking of seeds before sowing ensured cent percent germination. Seed priming with KNO₃ 1% solution resulted in 80.4% increase in germination followed by hydropriming by 16 h (73.1% increase). In field conditions, dehusked seeds gave 23.0% germination without any priming treatment. Priming treatment with KNO₃ 1% gave the highest rise in germination (39.1%) followed by hydropriming for 16 h (26.1%). Seeds with their seed coats intact could give germination of 9.5% when germinated without any treatment. A rise of 115.8% in germination was obtained by priming with KNO₃ 1% (final germination count 20.5%). The next best treatment was hydropriming for 16 h (final germination 18.5%, a rise of 94.7%). KNO₃ 1% also induced the earliest and the most rapid germination. When seedlings germinated in laboratory were transferred to soil, all seedlings from all treatments established successfully without any mortality whatsoever. Therefore, it is recommended that seeds should be primed for 8 h with 1% KNO₃ and germinated in laboratory or in farm house under normal atmospheric condition before transplanting the seedlings to soil.     

Hormonal Regulation of Dormancy in Developing Sorghum Seeds

The role of abscisic acid (ABA) and gibberellic acid (GA) in determining the dormancy level of developing sorghum (Sorghum bicolor [L.] Moench.) seeds from varieties presenting contrasting preharvest sprouting behavior (Redland B2, susceptible; IS 9530, resistant) was investigated. Panicles from both varieties were sprayed soon after pollination with fluridone or paclobutrazol to inhibit ABA and GA synthesis, respectively. Fluridone application to the panicles increased germinability of Redland B2 immature caryopses, whereas early treatment with paclobutrazol completely inhibited germination of this variety during most of the developmental period. Incubating caryopses in the presence of 100 [mu]M GA4+7 overcame the inhibitory effect of paclobutrazol, but also stimulated germination of seeds from other treatments. IS 9530 caryopses presented germination indices close to zero until physiological maturity (44 d after pollination) in control and paclobutrazol-treated particles. However, fluridone-treated caryopses were released from dormancy earlier than control and paclobutrazol-treated caryopses. Incubation in the presence of GA4+7 stimulated germination of caryopses from all treatments. Our results support the proposition that a low dormancy level (which is related to a high preharvest sprouting susceptibility) is determined not only by a low embryonic sensitivity to ABA, but also by a high GA content or sensitivity.     

种壳对大麦种子生理和成熟胚培养的影响及机理探讨Ⅱ

用30％PEG6000对大麦种子进行浸种等处理,并对其吸胀生理的多数指标进行了系统分析和检测,研究结果表明：种壳显著延缓种子的吸水进程;种壳对多数分子的渗漏有较大影响。N的渗漏主要来自胚乳,Mn^2 渗漏主要来自胚,种壳显著影响K^ 渗漏。去壳促使吸胀期间可溶性蛋白量和过氧化物酶同工酶的活性显著升高。吸胀使IAA、GA3含量提高,使胚乳中的ABA含量显著减少;去壳促进吸胀初期胚乳中的ABA、IAA、GA3含量,去壳减少吸胀后期胚中的ABA、IAA、GA3含量。种子去壳后吸胀24h有显著较高的萌发率、愈伤组织诱导率。     

The influence of aerated hydration seed treatment on seed longevity as assessed by the viability equations

Aerated hydration (AH) treatments of cauliflower seeds for 12 h (12AH) and 28 h (28AH) at 20 degrees C resulted in improved or reduced storage potential of low or high vigour seeds, respectively. Seeds were stored at their initial seed moisture content (mean 5.5% mc) or at 12% mc at 10 degrees C for 12 months and at 20 degrees C for 4 months. The improved longevity of low vigour seeds was associated with increased K(i) (initial seed viability) and a reduced rate of deterioration (1/sigma) whereas the K(i) of high vigour seeds fell after 28AH and the rate of deterioration increased such that the time to lose one probit of viability decreased from 28.7 to 5.3 months at 10 degrees C and from 10.4 to 1.2 months at 20 degrees C. The improved K(i) of low vigour seeds could be explained by the reduction in the extent of deterioration after AH, as indicated by the increase in germination after cotrolled deterioration (CD), and the possible activation of metabolic repair during treatment. In contrast the reduced germination after CD of AH-treated high vigour seeds was indicative of deterioration as a result of treatment. Both high and low vigour seeds contained constitutive levels of ss-tubulin which increased during AH treatment, the increase being greater in high vigour seeds. High vigour seeds also showed an increase in the proportion of nuclear DNA present as 4C DNA, from 3% (untreated seeds) to 26% (28AH), indicative of germination advancement from the G(1) to G(2) phase of the cell cycle during treatment. This higher proportion of 4C DNA is correlated with the increased sensitivity of seeds to drying and/or storage after AH, leading to their reduced K(i) and storage potential. In contrast, there was little change in %4C in low vigour seeds. Priming in polyethylene glycol (PEG, -1.0 MPa) for 5 d or 13 d also improved the longevity of low vigour seeds stored at their initial and 12% mc at 10 degrees C for 8 months, as reflected in their laboratory and CD germination. In this case, however, the improved longevity of the low vigour seeds following 13 d priming was associated with an increase in 4C DNA from 4% (dry control) to 56% after treatment. The germination of both untreated and primed high vigour seeds remained high throughout the storage period. Increases in the rate of germination (decreased mean germination time) observed after all AH and PEG treatments were not consistently associated with an increase in the proportion of nuclei containing 4C DNA.     

Protein Synthesis in the Axes of Polyethylene Glycol-Treated Pea Seed and during Subsequent Germination

Germination of Alaska pea seeds is inhibited by –0.3 MPapolyethylene glycol but upon subsequent transfer to water, germinationis completed rapidly and radicle emergence occurs more quicklythan in water-imbibed seeds. Protein synthesis is reduced inthe axes of seeds imbibed on PEG but increases upon their returnto water, though not to the level exhibited by axes germinatedon water. Mobilization of proteins in the axes is retarded bytheir failure to complete germination on PEG, although somedoes occur. The quantitative reduction in protein synthesisresulting from incubation in osmoticum is not accompanied bymarked qualitative changes. The block to germination is notobviously associated with a restriction in synthesis of anyparticular protein or set of proteins; conversely, no ‘water-stress’proteins are synthesized in the presence of PEG. The synthesisof growth-specific proteins is prevented by PEG, but these increaseupon relief from the osmoconditioning treatments. These observationsdispute earlier claims for accelerated protein synthesis resultingfrom PEG treatments. Key words: Osmotic priming, Pisum sativum, germination, protein synthesis     

Investigation of pulsed electromagnetic field as a novel organic pre-sowing method on germination and initial growth stages of cotton

Two different pre-sowing techniques have been investigated for their influence in an important industrial plant, namely cotton. Priming methods are very useful for agricultural practices because they improve crop seedling establishment, especially when environmental conditions are not optimum. Pulsed electromagnetic fields have been found to promote germination and improve early growth characteristics of cotton seedlings. Such priming techniques are especially valuable in organic cultivation, where chemical compounds are prohibited. PEG treatment showed an enhancement in some measurements, however in some cases the results were not statistically different compared to control plants. In addition, PEG treatment is a sophisticated method that is far from agricultural practices and farmers. In this research, two different ages of seeds were used (1- and 2-year-old) in order to investigate the promotory effects of priming techniques. Magnetic field treatment of 15 min was found to stimulate germination percentage and to promote seeds, resulting in 85% higher values than control seeds under real field conditions. Furthermore, seeds that were treated with magnetic field performed better in terms of early-stage measurements and root characteristics.     

Investigation of pulsed electromagnetic field as a novel organic pre-sowing method on germination and initial growth stages of cotton

Two different pre-sowing techniques have been investigated for their influence in an important industrial plant, namely cotton. Priming methods are very useful for agricultural practices because they improve crop seedling establishment, especially when environmental conditions are not optimum. Pulsed electromagnetic fields have been found to promote germination and improve early growth characteristics of cotton seedlings. Such priming techniques are especially valuable in organic cultivation, where chemical compounds are prohibited. PEG treatment showed an enhancement in some measurements, however in some cases the results were not statistically different compared to control plants. In addition, PEG treatment is a sophisticated method that is far from agricultural practices and farmers. In this research, two different ages of seeds were used (1- and 2-year-old) in order to investigate the promotory effects of priming techniques. Magnetic field treatment of 15?min was found to stimulate germination percentage and to promote seeds, resulting in 85% higher values than control seeds under real field conditions. Furthermore, seeds that were treated with magnetic field performed better in terms of early-stage measurements and root characteristics.