共查询到20条相似文献,搜索用时 15 毫秒
1.
H. R. Irving G. Dyson R. McConchie R. W. Parish C. A. Gehring 《Journal of Plant Growth Regulation》1999,18(2):93-100
The effects of jasmonic acid (JA) on elongation growth of coleoptile segments from etiolated maize (Zea mays L.) were investigated in the presence and absence of auxin. When supplied alone, at physiological concentrations (10−9, 10−8, and 10−5
m), JA (or methyl-JA) inhibited growth. JA at a similar range of concentrations also inhibited auxin-induced elongation growth.
To determine whether this effect on growth depended on endogenous abscisic acid (ABA), we grew maize coleoptiles in the presence
of norflurazon (an inhibitor of carotenoid biosynthesis) that results in reduced endogenous ABA levels. Growth of etiolated
coleoptile segments from these plants was inhibited by JA (or methyl-JA) in both the absence and presence of auxin. Previously,
we have observed a correlation between elongation growth and cytosolic pH (pHi), in which auxin lowers pHi, and growth inhibitors such as ABA raise pHi. We examined the effect of low concentrations of methyl-JA on pHi with dual emission dye, carboxy seminaphthorhodafluor-1, and confocal microscopy. To confirm these studies, we also used
in vivo 31P NMR spectrometry to ascertain the changes in pHi after addition of jasmonate to maize coleoptiles. Coleoptiles grown in either the absence or presence of norflurazon responded
to methyl-JA or JA by increases in pHi of approximately 0.2 pH unit. This response occurs over a period of 15–20 min and appears to be independent of endogenous
ABA. This alkalization induced by JA is likely to form a permissive environment for JA signal transduction pathway(s).
Received February 5, 1999; accepted August 25, 1999 相似文献
2.
A Possible Role for Jasmonic Acid in Adaptation of Barley Seedlings to Salinity Stress 总被引:6,自引:0,他引:6
T. D. Tsonev G. N. Lazova Z. G. Stoinova L. P. Popova 《Journal of Plant Growth Regulation》1998,17(3):153-159
The changes caused by NaCl salinity and jasmonic acid (JA) treatment (8 days) on growth and photosynthesis of barley plants
(Hordeum vulgare L., var. Alfa) have been studied. Gas exchange measurements and analysis of enzyme activities were used to study the reactions
of photosynthesis to salinity and JA. Both 100 mm NaCl and 25 μm JA treatment led to a noticeable decrease in both the initial slope of the curves representing net photosynthetic rate vs
intercellular CO2 concentration and the maximal rate of photosynthesis. The calculated values of the intercellular CO2 concentration, CO2 compensation point, and maximal carboxylating efficiency of ribulose-1,5-bisphosphate carboxylase support the suggestion
that biochemical factors are involved in the response of photosynthesis to JA and salinity stress. The activities of phosphoenolpyruvate
carboxylase and carbonic anhydrase increased more than twofold. Pretreatment with JA for 4 days before salinization diminished
the inhibitory effect of high salt concentration on the growth and photosynthesis. The results are discussed in terms of a
possible role of JA in increasing salinity tolerance of the barley plants.
Received September 8, 1997; accepted May 19, 1998 相似文献
3.
J. A. Wilmer S. R. Abrams J. P. F. G. Helsper L. H. W. van der Plas 《Journal of Plant Growth Regulation》1998,17(1):19-23
Modification of the structure of abscisic acid (ABA) has been reported to result in modification of its physiologic activity.
In this study we tested the effect of removing methyl groups from the ring and of chirality of ABA on activity in microspore-derived
embryos of oilseed rape (Brassica napus L.). The natural (+)-ABA molecule induced growth inhibition and an increase in the amount of erucic acid accumulated in the
oil at medium concentrations less than 1 μm. (−)-ABA showed similar effects. Removing the 7′-methyl group resulted in a dramatic decrease in activity: (+)-7′-demethyl-ABA
retained some activity as a growth inhibitor; a 10–100 μm concentration of this compound was needed for a response, and (−)-7′-demethyl-ABA was almost completely inactive. Similar
effects were observed with regard to elongase activity, which catalyzes erucic acid biosynthesis from oleic acid. Removal
of the 8′- and 9′-methyl groups resulted in a more complex response. These compounds all showed intermediate activity; for
growth inhibition, the presence of the 9′-methyl was the more important determinant, whereas chirality dominated the response
on erucic acid accumulation, with the (+)-enantiomers being more active.
Received July 25, 1997; accepted October 31, 1997 相似文献
4.
L. Wijayanti S. Fujioka M. Kobayashi A. Sakurai 《Journal of Plant Growth Regulation》1997,16(2):115-119
The involvement of abscisic acid (ABA) and indole-3-acetic acid (IAA) in the regulation of flowering of Pharbitis nil was investigated through exogenous applications and analyses of endogenous levels. Both hormones inhibited the flowering
of P. nil when they were applied before or after a single 15-h dark treatment. The inhibitory effect of ABA and IAA was significant
when they were applied before the dark treatment, and the application to plumules was more effective than that to cotyledons.
In all applications, the inhibitory effect of IAA was stronger than that of ABA. Endogenous levels of ABA and IAA in the plumules
were compared between flower-inductive (15-h dark treatment) and noninductive (continuous light) light conditions. There was
no significant difference in the ABA level between light and dark conditions, whereas the level of IAA was decreased by the
dark treatment. These results suggest that biosynthesis and/or catabolism of IAA is affected by the light treatment and therefore
may be involved in the regulation of early flowering processes in the apex. The inhibitory effects of ABA and IAA were reversed
by an application of gibberellin A3, indicating that gibberellin A3 counteracts the flowering processes affected by ABA and IAA. Application of aminoethoxyvinylglycine restored the flowering
response inhibited by IAA, which suggests the possibility that the inhibitory effect of IAA is the result of enhanced ethylene
biosynthesis.
Received November 22, 1996; accepted February 17, 1997 相似文献
5.
Involvement of Abscisic Acid in Mesocotyl Growth in Etiolated Seedlings of a Foxtail Millet Dwarf Mutant 总被引:1,自引:0,他引:1
Etiolated seedlings of foxtail millet (Setaria italica Beauv.) dwarf mutant CH84113 were treated with various concentrations of abscisic acid (ABA), mefluidide, mannitol, or polyethylene
glycol (PEG) 6000. It was found that these chemicals, at suitable concentrations, could increase mesocotyl length significantly,
whereas these chemicals at higher concentrations had an inhibitory effect. Endogenous levels of ABA in mesocotyl were measured
by enzyme-linked immunosorbent assay. It was found that endogenous ABA increased progressively in a chemical (ABA, mefluidide,
mannitol, or PEG 6000) concentration-dependent manner, indicating that the effects of these chemicals on mesocotyl growth
may be mediated by increased endogenous ABA levels. On the other hand, S-3307, an inhibitor of the oxidative reactions in
gibberellin (GA) biosynthesis, inhibited the elongation of mesocotyl significantly. When ABA and GA3 were applied simultaneously, the effect on mesocotyl growth was additive. These results imply that ABA and GA may control
different processes in the regulation of mesocotyl growth.
Received October 27, 1997; accepted May 11, 1998 相似文献
6.
Potential Role of Abscisic Acid in Cotton Fiber and Ovule Development 总被引:11,自引:0,他引:11
Fibers and ovules of a cotton cultivar (Gossypium hirsutum L. Trambak-108) were analyzed for growth and free abscisic acid (ABA) content by indirect enzyme immunoassay. An inverse
correlation between fiber elongation and ABA content was observed. In the seed, accumulation of ABA was observed during secondary
thickening and the maturation phase. The potential role of ABA in fiber and seed development is discussed.
Received June 25, 1997; accepted October 15, 1997 相似文献
7.
Indole-3-Acetic Acid Control on Acidic Oat Cell Wall Peroxidases 总被引:2,自引:0,他引:2
Incubation of oat coleoptile segments with 40 μm indoleacetic acid (IAA) induced a decrease of 35–60% in peroxidase activity at the cell wall compartment. Treatment with
IAA also produced a similar decrease in the oxidation of NADH and IAA at the cell wall. Isoelectric focusing of ionic, covalent,
and intercellular wall peroxidase fractions showed that acidic isoforms (pI 4.0–5.5) were reduced preferentially by IAA treatment.
Marked differences were found between acidic and basic wall isoperoxidases in relation to their efficacy in the oxidation
of IAA. A peroxidase fraction containing acidic isoforms oxidized IAA with a V
max/s0.5 value of 2.4 × 10−2 min−1· g fw−1, 4.0 times higher than that obtained for basic peroxidase isoforms (0.6 × 10−2 min−1· g fw−1). In contrast, basic isoforms were more efficient than acidic isoperoxidases in the oxidation of coniferyl alcohol or ferulic
acid with H2O2 (5.6 and 2.1 times, respectively). The levels of diferulate and lignin in the walls of oat coleoptile segments were not altered
by treatment with IAA. The decrease in cell wall peroxidase activity by IAA was related more to reduced oxidative degradation
of the hormone than to covalent cell wall cross-linking.
Received November 1, 1998; accepted December 14, 1998 相似文献
8.
Simultaneous measurements of respiration, ethylene production, and abscisic acid (ABA) concentrations, as well as the growth
parameters length, fresh weight (FW), and dry weight (DW) of olive (Olea europaea L. cv. Konservolia) inflorescence were carried out at short intervals (3–7 days) during the period from bud burst until the
3rd week after full bloom (AFB), when young fruit reached 8 mm in length. The axis of inflorescence elongated remarkably during
the 3rd week after bud burst (ABB), massive bract shedding occurred during the 4th week ABB, full bloom (FB) was observed
7 weeks ABB, and massive floral organ abscission 1 week AFB. The results showed a continuous increase in inflorescence FW
and DW from bud burst until 4 days before FB. Respiration rate, ethylene production, and levels of ABA were relatively high
during the first 3 weeks ABB. After this period, respiration and ethylene followed a similar pattern of changes, inversely
to that of ABA concentration. An accumulation of inflorescence ABA 6 and 4 days before FB was associated with the minimum
values of respiration and ethylene production on the same dates. The sharp decrease in the ABA concentration during FB and
3 days later was followed by a high rise in ethylene and an increase in respiration rate, which both rose further 1 week AFB.
The results suggest a possible correlation of ABA with the early stage of floral abscission, whereas ethylene production seems
to be correlated with the terminal separatory activity in olive inflorescence abscission processes.
Received May 28, 1998; accepted November 17, 1998 相似文献
9.
The promotive effect of methyl jasmonate (JA-Me) on the induction of gum in tulip shoots (Tulipa gesneriana L. cvs. Gudoshnik and Apeldoorn) was studied in the presence of ethylene. Gum formation in the stem and the basal part of
the leaves was induced by JA-Me (1% w/w in lanolin) and stimulated strongly by the simultaneous application of 1 or 5 mm 1-aminocyclopropane-1-carboxylic acid (ACC). JA-Me at a concentration of 0.1% did not induce gum, but that together with
ACC at a concentration of 1 or 5 mm induced it substantially. Although JA-Me stimulated ethylene production substantially in the stem of intact tulips, ethephon
(1% w/w) or ACC (1 or 5 mm) did not induce gum formation in tulip shoots. JA-Me induced gum formation in tulip shoots even in the presence of aminooxyacetic
acid or cobalt ions. Moreover, gum formation was also observed in the cut shoot applied with JA-Me as a solution at concentrations
of 0.23 mm or more. These results strongly suggest that JA-Me is required for gum formation in tulip shoots, and ethylene probably makes
the tissues of shoots sensitive to JA-Me.
Received March 23, 1998; accepted June 10, 1998 相似文献
10.
Marian Saniewski Kensuke Miyamoto Junichi Ueda 《Journal of Plant Growth Regulation》1998,17(3):121-124
The effect of methyl jasmonate (JA-Me) on the induction of gum was studied in relation to the action of ethylene in peach
(Prunus persica Batsch cv. Benishimizu) shoots. JA-Me applied at concentrations of 0.1–2.5% (w/w) in lanolin paste to current growing or
older shoots substantially induced gums 3 days after treatment. The amount of gums exuded increased depending on the dose
of JA-Me. Ethephon (2-chloroethyl- phosphonic acid) at 1 or 2% (w/w) in lanolin induced gum and strongly enhanced the promoting
effect of JA-Me on gum formation. JA-Me also induced anthocyanin accumulation in current growing shoots, but ethephon did
not. Anthocyanin accumulation in response to JA-Me at a concentration of 10 mg/liter or higher was observed also in the cut
shoots of peach. Ethephon (100 mg/liter) substantially inhibited anthocyanin accumulation induced by JA-Me. These facts suggest
that JA-Me plays an important role in gum formation as well as ethylene and in anthocyanin accumulation and that these processes
are not necessarily accompanied by each other in peach shoots.
Received January 26, 1998; accepted March 4, 1998 相似文献
11.
M. L. Centeno B. Fernández I. Feito A. Rodríguez 《Journal of Plant Growth Regulation》1999,18(2):81-88
1-Naphthaleneacetic acid (NAA) and 6-benzyladenine (BA) were required for in vitro callus formation at the basal edge of
kiwifruit (Actinidia deliciosa [A. Chev] Liang and Ferguson, cv. Hayward) petioles. The uptake, metabolism, and concentration of NAA and indole-3-acetic
acid (IAA) content were examined in the explants during the callus initiation period. After 1, 6, 12, 24, 48, and 96 h of
culture in the presence of [H3]NAA, petioles were divided into apical, middle, and basal portions and analyzed. Except for a high IAA level measured at
12 h, IAA content decreased in tissues during a culture period of 96 h. NAA uptake was higher in petiolar edges than in the
middle portion, and NAA was rapidly conjugated with sugars and aspartic acid inside the tissues. The amide conjugation was
triggered in apical and basal portions from 12 h and in the middle part from 48 h, with α-naphthylacetylaspartic acid being
the major metabolite. Free-NAA concentration in cultured petioles achieved an equilibrium with the exogenously applied NAA
(0.27 μm) from 12 h, and it remained constant thereafter. The relationships between the role attributed to NAA and BA in the initiation
and the maintenance of disorganized growth of callus in kiwifruit cultures are discussed.
Received December 21, 1998; accepted July 20, 1999 相似文献
12.
M. A. Atta-Aly 《Journal of Plant Growth Regulation》1998,17(1):25-32
Soaking summer squash (Cucurbita pepo cv. Eskandarany) seeds in continuously aerated solutions of 0.25, 0.50, and 1.00 ppm Co2+ for 48 h before sowing strongly increased plant growth, femaleness, and fruit yield compared with those of water- (control)
or 0.5 mm AOA (aminooxyacetic acid)-soaked seeds. Following the same pattern, plants of Co2+-soaked seeds produced significantly higher ethylene levels as early as the seedling stage (14 days after seed sowing) up
to the onset of flower initiation (OFI) stage (30 days after seed sowing), with more pronounced levels of all measured parameters
for plants of 1.00 ppm Co2+-soaked seeds. Plants of AOA-soaked seeds, however, behaved in a pattern similar to those of control in all measured parameters.
The only exception was the significant ethylene inhibition noticed only at the plant seedling stage with AOA-seed soaking,
which indicated the short term of AOA inhibition to ethylene when applied as early as the seed germination stage. When AOA
was applied foliarly before and at the OFI stage, the increased plant femaleness obtained with Co2+ seed soaking was arrested. It is indicated, therefore, that summer squash plant femaleness is more responsive to plant ethylene-modulated
levels before or at the OFI stage than earlier stages. Furthermore, all seed soaking treatments had no effect on plant leaf
number or plant and fruit Co2+ content, which strongly indicated that the positive impact of Co2+ on summer squash plant growth and femaleness was mainly the result of the so-called ``low Co2+ level-induced ethylene.' The percentage of fruit yield increase reached about 26, 40, and 56% over the control by 0.25,
0.50, and 1.00 ppm Co2+ seed soaking, respectively, whereas AOA seed soaking resulted in only a 4.5% yield reduction. To ensure the permanent positive
impact of Co2+ on ethylene production as well as the short period of AOA inhibition, seeds were resoaked in water or AOA for 8 h after being
soaked in 1.00 ppm Co2+ solution for 40 h. The results obtained emphasized the previous findings because AOA inhibition was restricted on ethylene
production only at the seedling stage. Meanwhile, all Co2+ positive effects were obtained 2 weeks later, even with AOA seed resoaking. These data strongly suggested that the positive
impact of Co2+ on ethylene production is more permanent than the negative impact of AOA. Hence its application, in low concentrations, as
early as the seed germination stage, strongly increased summer squash plant growth, femaleness, and fruit yield by increasing
the plant ethylene level.
Received July 21, 1997; accepted November 10, 1997 相似文献
13.
K. R. Foster I.-j. Lee R. P. Pharis P. W. Morgan 《Journal of Plant Growth Regulation》1997,16(2):79-87
Plants of early flowering mutant and wild type genotypes of Sorghum bicolor were treated with ring D-modified gibberellins (GAs), and the effects on endogenous GA levels were determined. The growth
and timing of floral initiation in 58M plants grown under 18-h days (which significantly delays floral initiation in this
short day plant) following treatment with these compounds, relative to GA3 and GA5 treatments, were also investigated. Application of the endo-isomer of C16,17-dihydro-GA5 (endo-DiHGA5), the exo-isomer of C16,17-dihydro-GA5 (exo-DiHGA5), and C16α,17-dichloromethanodihydro-GA5 (DMDGA5) altered GA levels in both genotypes. Each ring D-modified GA significantly inhibited shoot growth while significantly decreasing
levels of GA1 and increasing levels of its immediate precursor, GA20. Gibberellin A8 levels also decreased. Tillering was not affected by any treatment. For the early flowering genotype 58M, grown under noninductive
long days, both dihydro-GA5 isomers promoted floral initiation while shoot growth was strongly inhibited, and floral development was strongly advanced
beyond floral stage 4. Gibberellin A3 and GA5, applied under the same conditions, promoted shoot growth slightly and gave ``floral-like' apical meristems that did not
develop past floral stage 1. These results suggest that the reduced shoot growth of sorghum, which follows application of
those ring D-modified GAs, is due to their inhibiting the 3β hydroxylation of GA20 to GA1, thereby reducing the GA1 content. That floral initiation was hastened and floral development promoted in genotype 58M by application of both isomers
of DiHGA5 are in contrast to the effects of other GA biosynthesis inhibitors, which act earlier in the GA biosynthesis pathway, but
are consistent with results seen for long day grasses. This suggests that endo-DiHGA5 and exo-DiHGA5 may be acting directly in promoting floral initiation and subsequent floral apex development of this short day plant under
long day conditions.
Received October 3, 1996; accepted January 22, 1997 相似文献
14.
At harvest, embryos of Fagus sylvatica are dormant. A cold pretreatment without medium at 30% moisture content allowed them to germinate. A comparison of the abscisic
acid (ABA) content before and after the pretreatment has no significant relevance since dormancy is expressed during the culture
at 23°C. During this culture, both de novo biosynthesis and conjugate hydrolysis contributed to maintain a high level of ABA
in the dormant axis. The level of conjugates and the rate of hydrolysis were not modified substantially by the cold pretreatment.
In contrast, the dormancy release was associated with a strong decrease in the capacity for ABA synthesis. Moreover, feeding
(+)-[3H]ABA to untreated and pretreated embryos proved that the cold treatment also induced a hastening of ABA catabolism.
Received August 15, 1996; accepted December 6, 1996 相似文献
15.
Guerrero JR Garrido G Acosta M Sánchez-Bravo J 《Journal of Plant Growth Regulation》1999,18(4):183-190
3H-IAA transport in excised sections of carnation cuttings was studied by using two receiver systems for recovery of transported
radioactivity: agar blocks (A) and wells containing a buffer solution (B). When receivers were periodically renewed, transport
continued for up to 8 h and ceased before 24 h. If receivers were not renewed, IAA transport decreased drastically due to
immobilization in the base of the sections. TIBA was as effective as NPA in inhibiting the basipetal transport irrespective
of the application site (the basal or the apical side of sections). The polarity of IAA transport was determined by measuring
the polar ratio (basipetal/acropetal) and the inhibition caused by TIBA or NPA. The polar ratio varied with receiver, whereas
the inhibition by TIBA or NPA was similar. Distribution of immobilized radioactivity along the sections after a transport
period of 24 h showed that the application of TIBA to the apical side or NPA to the basal side of sections, increased the
radioactivity in zones further from the application site, which agrees with a basipetal and acropetal movement of TIBA and
NPA, respectively. The existence of a slow acropetal movement of the inhibitor was confirmed by using 3H-NPA. From the results obtained, a methodological approach is proposed to measure the variations in polar auxin transport.
This method was used to investigate whether the variations in rooting observed during the cold storage of cuttings might be
related to changes in polar auxin transport. As the storage period increased, a decrease in intensity and polarity of auxin
transport occurred, which was accompanied by a delay in the formation and growth of adventitious roots, confirming the involvement
of polar auxin transport in supplying the auxin for rooting.
Received April 19, 1999; accepted December 2, 1999 相似文献
16.
The effects of pot size, timing of the application of paclobutrazol (PTZ) and gibberellic acid (GA3), and the counteractive effect of these two compounds on growth and tuber yield of greenhouse-grown Norland and Russet Burbank
potatoes were investigated. Plants were grown either in 1.5-liter pots (15 cm deep) or 3.0-liter pots (18 cm deep) and received
a foliar application of either 1.5 mm PTZ or 9 × 10−3 mm GA3 at early or late stolon initiation. Some plants that had been foliar treated with 1.5 mm PTZ at early stolon initiation were foliar treated with 9 × 10−3 mm GA3 at late stolon initiation. PTZ reduced haulm length in both cultivars significantly, particularly when the treatment was
applied at early stolon initiation, but the late treatment reduced haulm length only when growing in 3.0-liter pots. Irrespective
of the timing of treatment, GA3 increased haulm length in Norland growing in both pot sizes, but the treatment increased haulm length in Russet Burbank only
when applied at late stolon initiation. GA3 applied after PTZ did not overcome the growth-inhibiting effect of the PTZ treatment. The PTZ treatment effectively increased
usable tuber number/plant (UTN) in Norland, but PTZ had no effect on UTN in Russet Burbank. PTZ reduced usable tuber weight/plant
(UTW) only in Norland growing in 1.5-liter pots. By contrast, GA3 increased UTN only when treated at late stolon initiation of 1.5-liter pot-grown Norland, whereas the same treatment was
effective when applied only at early stolon initiation for Russet Burbank. For Norland, the increase in UTN by early applied
PTZ was reduced by the subsequent application of GA3. The use of 3.0-liter pots for minituber production in both Norland and Russet Burbank appears to have no advantage over
growing in 1.5-liter pots, particularly when PTZ or GA3 is used to enhance tuberization.
Received May 30, 1997; accepted February 3, 1998 相似文献
17.
F. Antognoni S. Agostani C. Spinelli M. Koskinen H. Elo N. Bagni 《Journal of Plant Growth Regulation》1999,18(1):39-44
In the present work the effect of several bis(guanylhydrazones) on the growth of Helianthus tuberosus tuber explants was studied. Different aliphatic congeners of glyoxal bis(guanylhydrazone) were tested. Most of the compounds
displayed an inhibitory effect on growth, and a correlation between the structure of the molecule and the inhibitory activity
was observed. Experiments carried out with glyoxal bis(guanylhydrazone) and its congeners methyl-, ethylmethyl-, and methylpropylglyoxal
bis(guanylhydrazones) show that as the total number of side chain carbon atoms in the molecule increases, the inhibitory potency
also increases. A depletion of spermidine levels was also found in the explants treated with ethylmethylglyoxal bis(guanylhydrazone),
which turned out to be one of the most potent growth inhibitors. The addition of spermidine caused a significant reversion
of the antiproliferative action of glyoxal bis(guanylhydrazone). The effect of these compounds on spermidine uptake in protoplasts
isolated from carrot phloem parenchyma was also investigated. Only a slight competition was found when antagonists were present
at concentrations 20 times higher than the polyamine, thus suggesting that bis(guanylhydrazones) do not share, at least at
low concentrations, the polyamine transport system in plant cells.
Received January 10, 1997; accepted January 22, 1999 相似文献
18.
Controlled environmental experiments were carried out to determine the phytotoxicity of several graminicides on wild oat
(Avena futua L.) as influenced by combination of drought and temperature stress or drought and low relative humidity. Compared with unstressed
conditions (20/15°C plus adequate soil moisture), imazamethabenz phytotoxicity to wild oat was reduced significantly when
plants were exposed to a combination of drought and high temperature (30/20°C) stress. Imazamethabenz phytotoxicity was reduced
almost as much by high temperature stress alone as by a combined temperature and drought stress. When herbicides were applied
to wild oat plants subjected to drought alone or to drought plus high temperature, the observed reduction in phytotoxicity
from greatest to least was: fenoxaprop = diclofop > flamprop > imazamethabenz. Fenoxaprop performance was most inhibited by
the combination of drought plus high temperature, although drought alone and to a lesser degree, high temperature alone, inhibited
fenoxaprop action. High temperature had an adverse effect on the efficacy of fenoxaprop at lower application rates. Raising
fenoxaprop application rates to 400 g ha−1 overcame the inhibition caused by high temperature alone but only partially alleviated the effect of drought combined with
high temperature. When plants were grown under a low temperature regimen the imposition of drought stress had little effect
on imazamethabenz phytotoxicity but did reduce fenoxaprop phytotoxicity. At 25/15°C drought reduced the phytotoxicity of fenoxaprop
and diclofop greatly but had no significant impact on the performance of any of the herbicides examined, regardless of soil
moisture regimen.
Received April 14, 1997; accepted September 22, 1997 相似文献
19.
Endogenous Levels of Cytokinins, Indoleacetic Acid, Abscisic Acid, and Pigments in Variegated Somaclones of Micropropagated Banana Leaves 总被引:4,自引:0,他引:4
The banana (Musa spp. AAA) micropropagation shows a high incidence of off-types, among whose variegated plants are very common. Endogenous
levels of growth regulators and pigment content were measured in normal and variegated leaves of the micropropagated banana
plants growing in a greenhouse. Growth regulators were separated by high pressure liquid chromatography and submitted to enzyme-linked
immunosorbent assay for quantification. Pigment content was measured using the colorimetric method. Green leaves contained
1.9 and 10 times more cytokinins compared with green and yellow sectors of variegated leaves, respectively. The levels of
indoleacetic acid in normal leaves were significantly higher than those found in green and yellow sectors of variegated leaves;
however, the levels of abscisic acid were lower in normal leaves. The lower content of chlorophylls in variegated leaves coincided
with decreased endogenous levels of cytokinins, which indicated that variegation in banana leaves may be associated with alterations
in the metabolism of this growth regulator.
Received December 3, 1997; accepted February 2, 1998 相似文献
20.
B. Hossain N. Hirata Y. Nagatomo R. Akashi H. Takaki 《Journal of Plant Growth Regulation》1997,16(4):239-243
A high zinc concentration of 520 μm, approximately 100 times that used most often in standard plant tissue culture media, was found to be superior in liquid
callus cultures of japonica rice, increasing growth to 146% compared with standard N6 medium. At the same time, the internal
zinc concentration increased 40 times in fast growing cells; soluble protein doubled, and free amino acids decreased. Under
zinc-free conditions the cultures slowed in growth, and several free amino acids such as aspartic acid, glutamic acid, asparagine,
and glutamine accumulated. We suggest that zinc acts as a direct regulatory factor in inducing auxin activity, but not auxin
levels, making high internal zinc accumulation mandatory if high auxin concentrations are required as in rice callus cultures.
Received July 16, 1997; accepted September 22, 1997 相似文献