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1.
Nondormant A. caudatus seeds germinated in the darkat temperatures between 20 and 35° but not at 45 °C.Incubation at this temperature for at least 10 h inhibited seedgermination over the temperature range 20 to 35 °C,temperatures previously suitable for germination. Thus incubation at 45°C induced secondary dormancy. Mechanical or chemicalscarification or exposure to pure oxygen caused complete or almost completegermination of dormant seeds although more slowly in comparison to nondormantseeds. Secondary dormant scarified seeds required a lower concentration of ABAthan nondormant seeds to inhibit germination. The high temperature, whichinduced dormancy, 45 °C, caused the seed coat to be partiallyresponsible for secondary dormancy. Involvement of ABA (synthesis orsensitivity) in the induction and/or maintenance of this dormancy should beconsidered. 相似文献
2.
J. GIRARD 《Plant, cell & environment》1990,13(8):827-832
Abstract. The germination behaviour of two Petunia hybrida lines. M30 and Th7 , and their reciprocal hybrids was studied. Two sets of experimental conditions appeared helped to distinguish between dormant and non-dormant parental lines: (1) 25 and 35 °C in the dark, in the latter case after 2 months of dry storage at 20 °C; (2) 35 and 40 °C in the light. Photosensitivity was tested in the first case and sensitivity to GA3 in the second case. The predominance of paternal control over dormancy was evident. A maternal or tegumentary control of photosensitivity and of sensitivity to GA3 was also shown. Transferring the seeds, originally imbibed in conditions expressing primary dormancy, to conditions which previously supported their germination, allowed us to show that secondary dormancy could be easily induced when a deeper primary dormancy had already developed in the seeds. 相似文献
3.
Abstract. The effects of diurnally alternating temperatures and of prolonged burial in the soil on germination response of redroot pigweed ( Amaranthus retroflexus L.) seeds to ethylene were investigated. Percentage germination in a 12 h/12 h, 23° C/35° C temperature regime roughly equalled that observed at constant 35° C, and greatly exceeded that observed at 30°C. Preincubation for 61 d in alternating temperatures, which were gradually increased to simulate soil warming in spring, caused little germination in the absence of ethylene, but considerably enhanced sensitivity to ethylene. Seeds kept in soil in the same temperature regime failed to show the response to ethylene, and the soil itself removed ethylene from the soil atmosphere.
After burial in a field plot either over winter or during the summer, seeds had a very low ethylene response threshold (0.01−0.05 cm3 m−3 ) and strong response to ethylene (70–95% germination at 51 cm3 m−3 compared to 1–20% without ethylene). Germinability of seeds buried overwinter declined between 10 May (85%) and 24 May (7%), and 90% of those recovered on or after 24 May had a visible rupture in the seed coat. Apparently, germination had begun during burial, but was arrested by unknown causes in an early phase and was followed by seed deterioration.
Although the role of ethylene in germination of buried seeds remains uncertain, the greatly enhanced sensitivity to ethylene observed in pigweed seeds after burial deserves further investigation. 相似文献
After burial in a field plot either over winter or during the summer, seeds had a very low ethylene response threshold (0.01−0.05 cm
Although the role of ethylene in germination of buried seeds remains uncertain, the greatly enhanced sensitivity to ethylene observed in pigweed seeds after burial deserves further investigation. 相似文献
4.
Methyl jasmonate (JA-Me) inhibited or retarded germination of Amaranthus caudatus seeds in darkness at 24°C, Ethephon, ACC and gibberellins (GA3 or GA4+7) partially or completely reversed this inhibition depending on the concentration of JA-Me applied. Both ethephon and the gibberellins were more effective than ACC. Both GA3 and GA4+7 enhanced the stimulatory effect of ethephon or ACC on germination of seeds inhibited by JA-Me.Abbreviations ACC
1-aminocyclopropane-1-carboxylic acid
- JA
jasmonic acid
- JA-Me
methyl jasmonate 相似文献
5.
Antagonistic effects of abscisic acid and gibberellic acid on the breaking of dormancy of Fagus sylvatica seeds 总被引:1,自引:1,他引:0
Study of the factors involved in the dormancy of Fagus sylvatica seeds shows that such dormancy is due partly to the seed coats and partly to endogenous factors. Seed coat removal accelerates both the release from dormancy and the effects of the other treatments that abolish it. The dormancy of these seeds is eliminated by cold treatment at 4°C over a period longer than 8 weeks, and exogenous application of abscisic acid (ABA) reverses the effects of low temperature, the seeds remaining in an ungerminated state. Additionally, ABA reduces protein synthesis but slightly increases RNA synthesis, which suggests its involvement in the synthesis of RNAs related to this process. In vitro translation of the RNAs isolated from these seeds shows that ABA delays the disappearance of at least 2 polypeptides (of ca 22 and 24 kDa), which are abundant in dormant seeds and under conditions that prevent the release from dormancy, but which disappear under treatments that abolish it. Exogenous application of gibberellic acid (GA3 ) proved to be efficient in breaking the dormancy of these seeds and in substituting for cold treatment as well as in antagonizing the effects of ABA on the synthesis of both DNA and proteins. GA3 also accelerates the disappearance of the two polypeptides abundant in dormant seeds and in ABA-treated seeds. These findings suggest that both ABA and GA3 could be involved in the regulation of nucleic acid and protein metabolism during dormancy, acting antagonistically in these processes and, specifically, in the regulation of the synthesis of the two proteins that appear to play a role in the maintenance of dormancy in these seeds. 相似文献
6.
The germination of Amaranthus paniculatus seeds was inhibited by applying paclobutrazol, a specific inhibitor of gibberellin biosynthesis. This inhibition was markedly counteracted by gibberellin A3 (GA3), suggesting that endogenous gibberellins are required for germination in this species. The inhibitory effect of paclobutrazol was also overcome by ethephon (2-chloroethylphosphonic acid) or the precursor of ethylene biosynthesis, ACC (1-aminocyclopropane-l-carboxylic acid). Thus the physiological effect of gibberellin can be mimicked by ethylene released from ethephon or synthesised from exogenous ACC. It is suggested, that endogenous gibberellins are involved in germination of Amaranthus paniculatus seeds and that action of GA3 can be substituted by ethylene.Abbreviations ACC
1-aminocyclopropane-l-carboxylic acid
- AMO-1618
(2-isopropyl-5methyl-4-trimethylammoniumchloride)-phenyl-l-piperidinium-carboxylate
- ancymidol
-cyclopropyl--(4-methoxyphenyl)-5-pyrimidine methanol
- chloromequat chloride
(2-chloroethyl)trimethylammoniumchloride
- ethephon
2-chloroethylphosphonic acid
- GA
gibberellin A3
- paclobutrazol
(2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-lyl)pentan-3-ol
- Phosphon D
2,4,dichlorobenzyl-tributhylphosphoniumchloride
- tetcyclacis
5,(4-chlorophenyl)-3,4,5,9,10-pentaaza-tetracyclo)5,4,1,0,Z,6,08,11 dodeca-3,9-diene 相似文献
7.
Hassan Karimmojeni Amir Hossein Bazrafshan Mohammad Mehdi Majidi Shahram Torabian Behzad Rashidi 《Plant Species Biology》2014,29(3):E1-E8
Amaranthus retroflexus L. is an importunate annual weed in many cropping systems of different countries. The main aim of this study was to investigate the effects of maternal nitrogen and drought stress on the seed dormancy and germinability of A. retroflexus. Field experiment was carried out in a factorial based on randomized complete block design, with four potential levels of soil water (–2, ?6, ?8 and ?10 bar) and three levels of nitrogen (0, 100 and 200 kg/ha). The germination characteristics of the seeds were measured at three different times (1 month, 6 months and 1 year after harvesting). Results showed that drought stress had positive effects on breaking of A. retroflexus seed dormancy until 6 months after seed harvesting. Seeds that were developed under severe water stress exhibited the highest germination percentage and germination rate. The results obtained from this study revealed that application of 100 kg/ha nitrogen during seed development increases germinability of A. retroflexus, whereas application of 200 kg/ha nitrogen induced seed dormancy. Furthermore, 100 kg/ha nitrogen application in the field along with 200 ppm gibberellic‐acid treatment during seed after‐ripening showed the highest germination percentage and germination rate for seeds after 6 months harvesting. Results also indicated that after‐ripening significantly increased seed germination and germination rate of A. retroflexus. These findings indicate that long‐term management of the soil seed bank in this species requires more stringent control due to the changes in germination timing, as detected in this study. 相似文献
8.
Conversion of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene was studied in sunflower (Helianthus annuus L., cv. Mirasol) seeds in relation to germinability. Ethylene production from ACC decreased during seed maturation, and non-dormant mature seeds were practically unable to synthesize ethylene until germination and growth occurred, indicating that ethylene forming enzyme (EFE) activity developed during tissue imbibition and growth. ACC conversion to ethylene was reduced by the presence of pericarp, and in young seedlings it was less in cotyledons than in growing axes.ACC conversion to ethylene by cotyledons from young seedlings was optimal at c. 30°C, and was strongly inhibited at 45°C. Pretreatment of imbibed seeds at high temperature (45°C) induced a thermodormancy and a progressive decrease in EFE activity.Abscisic acid and methyl-jasmonate, two growth regulators which inhibit seed germination and seedling growth, and cycloheximide were also shown to inhibit ACC conversion to ethylene by cotyledons of 3-day-old seedlings and by inbibed seeds.Abbreviations ABA
abscisic acid
- ACC
1-aminocyclopropane-1-carboxylic acid
- CH
cycloheximide
- EFE
ethylene forming enzyme
- IAA
indole-3-acetic acid
- Me-Ja
methyl-jasmonate 相似文献
9.
G. H. EGLEY 《Plant, cell & environment》1989,12(5):581-588
Abstract Fresh dormant redroot pigweed (Amaranthus retroflexus L.) seeds were buried 5 cm deep in the field at Stoneville, MS in November 1981. Potassium nitrate (200 kg ha 1) or nothing was applied to the soil in the fall of 1981 and the late winter of 1982. Seeds were recovered at intervals under darkness during the following 2 years and tested for responses to ethylene, temperature, light and carbon dioxide. During the first overwintering, nitrate enhanced loss of primary dormancy and increases seed sensitivity to temperature, light and ethylene. The loss of dormancy reached a maximum at 25 to 30 weeks (early summer) after burial. Examination of the recovered seeds indicated that about 80% of the non-treated seeds and 98% of the nitrate-treated seeds germinated in situ during the period of maximum loss of dormancy. Thus, after one overwintering period, about 20% of the original buried seed population remained dormant in nontreted soil and 2% remained dormant in the nitratetreated soil. After the second overwintering, the percentages of dormant seeds remaining in nontreated or treated soil were both only 1–2%. Nitrate reduced dormancy and enhanced germination in early summer following the first overwintering. Regardless of treatment, the remaining 1 2% of seeds in soil after the second year were of low sensitivity to the germination stimuli (ethylene, temperature, light) and constituted the long-lived portion of the original seed population. 相似文献
10.
The conversion of 1-aminocyclopropane 1-carboxylic acid (ACC) to ethylene by hypocotyl segments of sunflower (Helianthus annuus L.) seedlings was inhibited by abscisic acid (ABA) and methyl jasmonate (Me-Ja), and this inhibitory effect increased with increasing concentration of both growth regulators. On the contrary, CaCl, enhanced ACC conversion to ethylene at the concentrations of 10-4 M and 5 x 10-4 M, however lower and higher concentrations had no significant action. CaCl, (5 x 10-4M) seemed to magnify the inhibition of the reaction induced by ABA, whereas it reduced (5 x 10-4M) and even abolished (10-3M) the inhibitory action of Me-Ja. The results obtained with a Ca2+ chelator (EGTA), a Ca2+ channel blocker (nifedipine) and calmodulin antagonists (W7 and TFP), given in association with ABA or Me-Ja, suggested that calcium was involved in the inhibition of ACC conversion to ethylene by ABA and Me-Ja through an interaction with calmodulin. However, the mechanism of action of the two growth regulators seemed to be different, since all treatments which resulted in a decrease in cytosolic Ca2+ concentration or in calmodulin action induced a decrease in the effect of ABA and an increase in the effect of Me-Ja.Abbreviations ABA
abscisic acid
- ACC
1-aminocyclopropane 1-carboxylic acid
- EFE
ethylene for enzyme
- EGTA
ethylene glycol-bis-2-aminoethyl tetraacetic acid
- Me-Ja
methyl jasmonate
- NIF
nifedipine
- TFP
trifluoperazine dihydrochloride
- W7
N-(6-aminohexyl)5-chloro-l-naphthalenesulfonamide hydrochloride 相似文献
11.
Gibberellic acid (GA3) is a commercially important plant growth hormone, which is gaining much more attention all over the world due to its effective
use in agriculture and brewing industry. Industrially it is produced by submerged fermentation technique using Ascomycetous
fungusGibberella fujikuroi. Solid state and immobilized cell fermentation techniques had also been developed as an alternative to obtain higher yield
of GA3. This review summarizes the problems of GA3 fermentation such as production of co-secondary metabolites along with GA3, substrate inhibition and degradation of GA3 to biologically inert compound gibberellenic acid, which limits the yield of GA3 in the fermentation medium. These problems can be overcome by various bioprocessing strategiese.g. two-stage and fed batch cultivation processes. Further research on bioreactor operation strategies such as continuous and/or
extractive fermentation with or without cell recycle/retention system need to be investigated for improvement in yield and
productivity. Down stream processing for GA3 isolation is also a challenge and procedures available for the same have been critically evaluated. 相似文献
12.
A novel method for the quantitative determination of gibberellic acid in fermentation broths has been developed. It is based on the kinetic of the reaction of conversion of gibberellic acid to gibberellenic acid. The method is simple, reliable, faster than most of methods known, and free of the interferences which commonly affect spectrophotometric methods currently in use. Its threshold sensitivity is 0.1 g and its accuracy is greater than 97% for concentrations of gibberellic acid ranging from 0.1 to 1 g l(-1). 相似文献
13.
Embryos of Avena sativa L. (cv. Moyencourt) show no high temperature dormancy. The dormancy is induced by the presence of endosperm-aleurone part of the seed. Germination of isolated embryos at 30°C can be prevented by ABA and the inhibition is reversed by GA. Inhibitors of GA synthesis also inhibit embryo germination. The embryos of dormant and non-dormant seeds vary greatly in their sensitivity to exogenous ABA. High temperature dormancy of the entire seeds can be relieved by low concentrations of ethanol. On the basis of these facts a hypothetic model is proposed showing how interaction between endogenous GA and ABA-like inhibitory substance, may regulate the high temperature dormancy of the seeds. 相似文献
14.
Factors affecting the induction and release of secondary dormancy in Kalanchoë seeds 总被引:2,自引:2,他引:0
Abstract. Several short daily R irradiations are required from the first day of incubation on water to induce germination of Kalanchoë seeds. When the same light treatment is given after a prolonged dark incubation period at 20°C, secondary dormancy prevents germination. Factors controlling the induction and breaking of secondary dormancy have been investigated. The induction of secondary dormancy is very temperature dependent. Locally puncturing the seed coat strongly delays it. Secondary dormancy is not induced in the presence of GA3 during the first 10 d of dark incubation, although this growth substance cannot induce dark germination. Prolonged or cyclic daily R irradiations can relieve secondary dormancy of seeds kept on water, even after a dark period of 20 d. A 24 h treatment at 4°C restores responsiveness to short R exposures of slightly secondarily dormant seeds. The synergism between GA3 and Pfr in non-dormant Kalanchoë seeds, leading to high effectiveness of even one short FR irradiation, still occurs in seeds made secondarily dormant before transfer to GA3 , but more R or FR irradiations, in combination with GA3 , are required for the release of secondary dormancy. A combination of red light and 6-benzyl-aminopurine is ineffective in removing dormancy. 相似文献
15.
To assess the evolutionary significance of persistent seed banks, phenotypes of naturally germinating seeds must be compared with those that remain dormant under the same environmental conditions. Dormant seeds can often be induced to germinate by application of gibberellic acid (GA). However, this method is valid only if there are no phenotypic “side effects” of GA that could confound comparisons between dormant and naturally germinating seeds. We examined this assumption in Lesquerella fendleri, a short-lived perennial mustard of the desert Southwest. We exposed 3840 seeds from 16 maternal sibships to two different GA treatments (0 or 1 g/L GA) in two different germination environments (greenhouse and growth chamber), and measured germination and postgermination traits. As expected, application of GA increased germination. GA also had strong and long-lasting effects on seedling morphology. Seeds that received GA developed into seedlings that were taller, with fewer but longer leaves, than seeds that did not receive GA. Effects of GA on both dormancy and postgermination traits varied among maternal sibships. Our results indicate that for this species and this concentration of GA, morphological effects can be substantial. Further study is required to determine whether such side effects are found for lower concentrations of GA, or under conditions that encourage faster seedling growth. Nonetheless, the present results illustrate the importance of testing potential confounding effects of GA in studies of the evolution of seed dormancy and its influence on postgermination traits. 相似文献
16.
Abscisic acid (ABA) levels in seeds from three cultivars of apple (Malus domestica Borkh.) which have substantially different chilling requirements were investigated by gas chromatography mass-spectrometry selected ion monitoring (GCMS-SIM) during stratification. The ABA content of dormant unchilled seeds was similar in the three cultivars, suggesting no relationship between the chilling requirement of those seeds and their ABA status. That chilling is not related to ABA changes during stratification was confirmed by warm (20°C) and cold (5°C) stratification experiments. ABA content dropped rapidly and nearly identically under both temperature regimes, but only cold stratification promoted germination. The decline in ABA during stratification was due in large part to leaching from the seed coat and nucellar membrane; the ABA content of the embryo remained nearly constant. The radicle in intact seeds stratified at 5°C began growing 20–30 days after the ABA in the seed coat and nucellar membrane had nearly disappeared. Radicle growth did not occur in unchilled seeds, even though ABA had leached from them as well. It is possible that the leaching of ABA from the seed allows certain promotive forces to develop, but if so, these can develop only at chilling temperatures. Studies were also conducted on 2-trans ABA relationships to apple seed dormancy, but no association was evident.Report No. 12, Department of Fruit and Vegetable Science, Cornell University. 相似文献
17.
The specific inhibitor of gibberellin biosynthesis, (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol (paclobutrazol), inhibited germination ofAmaranthus caudatus L. seeds. Addition of gibberellic acid (GA3), 2-chloroethylphosphonic acid (ethephon), or 1-aminocyclopropane-1-carboxylic acid (ACC) effectively antagonized inhibition. Ethephon was found to be the most efficient antagonist. The transfer of seeds after 1 day's incubation in paclobutrazol to solutions of GA3 or ethephon reversed the inhibition, the effect increasing with increasing concentration of GA3 or ethephon. Seeds incubated in paclobutrazol for 5 days decreased sensitivity to GA3 and ethephon. 相似文献
18.
Summary Residual macronutrients, carbon source, and gibberellic acid (GA3) in the culture medium were measured throughout the whole culture period of kiwi (Actinidia deliciosa Chev. cv. Hayward) explants cultured in liquid medium using cellulose plugs as explant support. The objective of this study
was to adapt the composition of the culture medium to an automated culture system with the possibility of applying 6-benzyladenine
pulses so as to improve the efficiency of kiwifruit micropropagation. Ammonium and phosphate were the most consumed ions at
the end of the culture period (35 d). Murashige and Skoog medium might be too rich for the culture of kiwifruit in liquid
medium except with respect to phosphate which decreased significantly toward the end of the culture period. Sucrose, and the
glucose resulting from the hydrolysis of the former, were taken up by the kiwi explants throughout the whole culture period.
GA3 absorption by the kiwi explants occurred gradually throughout the subculture, although 67% of this initially added plant
growth regulator remained in the culture medium at the end of the 35-d culture period. 相似文献
19.
High temperature (45°C) inhibits seed germinition and seedling sunflower ( Helianthus annuus L. cv. Mirasol). Treatment of imbibed seeds at 45°C for more than 48 h induces a secondary dormancy, which is associated with progressive decrease of germination ability at optimal temperature (25°C) as well as with abnormal seedling growth. Ethylene (55μl l−1 ) and 2-chloroethylphosphonic acid (ethephon) (2.5 m M ) improve germination of thermodormant seeds at 25°C. but the abnormal growth of the seedlings remains. O2 -enriched atmosphere and dry storage improve germination and normal seedling growth. The induction of thermodormancy in sunflower seeds seems associated with loss of their ability to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene. Possible effects of high temperature on membranes and ethylene forming enzyme (EFE) are discussed. 相似文献
20.
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. 相似文献