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1.
Two gibberellin(GA)-like compounds were found in both rootsand shoots of sugar beet plants using the barley endosperm bioassay.One had chromatographic properties similar to GA3 and GA1; theother was highly non-polar, relatively inactive in the endospermassay, and may be a new gibberellin. Presence of the GA3/1-likecompound was confirmed with the dwarf rice bio-assay. The quantityof this GA was relatively high in the root compared with theshoot at the 34 leaf stage when the first supernumerarycambia are being formed in the root. As plants developed throughthe 89 leaf stage and the 1516 leaf stage thequantity of GA per unit fresh weight of material decreased. Application of gibberellic acid (GA3) to the roots of youngsugar beet plants caused a significant increase in root dryweight shortly after treatment and the rate at which supernumerarycambia were produced was increased. Application of GA3 to asingle petiole caused a significant increase in both root andshoot dry weight. GA3 applied to either root or shoot causeda reduction in the rate of leaf formation although total leafarea per plant and shoot dry weight were unaffected. The probablerole of GA-like substances in controlling the growth and developmentof young sugar beet plants is discussed. 相似文献
2.
The effects of foliar sprays of gibberellic acid (GA) on thegrowth of tomato plants cv. Potentate were studied in growthrooms and a glasshouse. Four sprays of GA (5 ppm) increasedleaf area and whole plant weight relative to water controlsgrown at constant temperatures (7, 17, 22, and 27 °C) for12 days, the largest plants being obtained with 5 ppm. Experimentsmade at four photoperiods (5, 10, 15, and 20 h) and at two lightintensities (7000 and 10 750 lx) showed that GA increased leafand whole plant weight at 15 h, leaf area at 10 and 15 h andstem height at all photoperiods; area, height, and weight increaseswere obtained at both light intensities, leaf growth being increasedmore by GA at 7000 lx and stem growth more at 10 750 lx. Four foliar sprays of GA (5 ppm) were combined with N supplementsapplied via leaf and/or root to plants in sand culture. Withlow supply to the roots (20 ppm N) GA failed to increase growth,but increased it at higher levels. Total N in leaf and stemwas increased by GA or by NH4NO3 (10 sprays 280 ppm N) at alllevels of N supplied to roots, but when applied together theeffect on total leaf N was more than additive except at thehighest level (540 ppm) GA increased the concentration of N(as per cent dry matter) in leaf and stem at all levels of Nsupplied to roots. GA and NH4NO3 together resulted in a greateramount and a higher concentration of N in the shoots (and usuallyalso in roots) than did NH4NO3 alone. Leaf thickness (as freshweight/unit area) could only be increased appreciably by sprayingwith a complete nutrient solution which reduced leaf area butnot dry weight. Growth increases induced by GA were detectable 43 days afterthe first of four sprays in the glasshouse and after 30 daysin the growth room. The persistence of GA effects was comparedwith those induced by sprays of NH4NO3. 相似文献
3.
Aqueous foliar sprays of N-dimethylaminosuccinamic acid (daminozide)at 2000 p.p.m. and gibberellic acid (GA) at 100 p.p.m. wereapplied 45, 59, 82 and 100 days after sowing to Chantenay carrotswith population densities of 244, 495 and 883 plants m2.The plants were harvested on ten approximately weekly occasions;fresh weights were determined and d. wt estimates were obtainedfor the separated shoots (s) and roots (r). Allometric linearregressions of the logarithm of s on that of r at each harvestseparately, clearly showed that GA always increased shoot: rootratio and reduced root yield (by approximately 35 per cent)but could sometimes also increase whole-plant weight. Daminozideincreased root yield (by approximately 7 per cent from 80 tonnesha1) and tended to have effects opposite to those ofGA. Daucus carota L., carrot, root weight, shoot weight, N-dimethylaminosuccinamic acid (daminozide), gibberellic acid 相似文献
4.
Changes in growth parameters, carbon assimilation efficiency, and utilization of 14CO2 assimilate into alkaloids in plant parts were investigated at whole plant level by treatment of Catharanthus roseus with gibberellic acid (GA). Application of GA (1 000 g m−3) resulted in changes in leaf morphology, increase in stem elongation, leaf and internode length, plant height, and decrease
in biomass content. Phenotypic changes were accompanied by decrease in contents of chlorophylls and in photosynthetic capacity.
GA application resulted in higher % of total alkaloids accumulated in leaf, stem, and root. GA treatment produced negative
phenotypic response in total biomass production but positive response in content of total alkaloids in leaf, stem, and roots.
14C assimilate partitioning revealed that 14C distribution in leaf, stem, and root of treated plants was higher than in untreated and variations were observed in contents
of metabolites as sugars, amino acids, and organic acids. Capacity to utilize current fixed 14C derived assimilates for alkaloid production was high in leaves but low in roots of treated plants despite higher content
of 14C metabolites such as sugars, amino acids, and organic acids. In spite of higher availability of metabolites, their utilization
into alkaloid production is low in GA-treated roots. 相似文献
5.
A foliar application of gibberellic acid (GA) (100 mg/l) 5 weeks after emergence increased the shoot/storage root ratios, measured 4 weeks later, of 9 cultivars representing a range of types of carrot. Chlormequat chloride (CCC) (2000 mg/l) decreased the ratio for seven of the cultivars. Assessment 8 weeks after treatment showed fewer significant effects of both growth regulators.At the first harvest, GA decreased the phloem/xylem ratio and significantly reduced the amount of secondary phloem produced in the storage root of all cultivars. CCC had no comparable effect except for an increase in the phloem/xylem ratio for one cultivar at both harvests. The significance of these results is discussed in relation to secondary vascular tissue production in storage roots as affected by assimilate partitioning in the whole plant. 相似文献
6.
Hormone-directed Transport of Assimilates in Decapitated Internodes of Phaseolus vulgaris L. 总被引:1,自引:0,他引:1
Application of ethylene, indole-3yl-acetic acid (IAA), 6-(benzylamino)-9-(2tetrahydropyranyl)-9-Hpurine (SD8339), or mixtures of IAA, gibberellic acid (GA),and cytokinins, increased the accumulation of 14C-activity indecapitated internodes of Phaseolus vulgaris seedlings. Differencesbetween treated and untreated tissues with respect to importof labelled assimilate were detected 3 h after application ofa mixture of IAA, GA, and SD8339. In longer-term experimentseffects of the growth-regulator mixture on translocation oflabel were greater than those of IAA alone. Inhibitory effectsof abscisic acid on import of assimilate were counteracted bySD8339. The ability of internode tissues to import 14C-photosynthatedeclines with time from decapitation, and a decrease in incorporationof 14C-leucine into protein was detected after 24 h. There wasan increase in protein and RNA synthesis in internodal tissuesfollowing a 2.5-h pre-treatment of decapitated internodes withIAA, GA, and SD8339. Concentrations of 2, 3, 5-triiodobenzoicacid which inhibit 14C-IAA translocation stimulate protein synthesisin decapitated internodes, and augment the IAA-effect on importof 14C-photosynthate. Hormone-directed assimilatetransport is discussed in relation to confounding effects ofgrowth responses and differential senescence of treated anduntreated tissues. It is suggested that accumulation of labelledassimilate in treated tissues results from effects of growthregulators on synthetic activities at the point of application. 相似文献
7.
A quantitative scheme to describe the growth of plant partsduring the vegetative phase of development is extended to includethe concept of hormone directed transport. The expected effecton shoot/storage root d. wt relationships of a single àxternalapplication of a growth regulating chemical is investigatedusing this approach. The theory predicts that the resultingchange in the pattern of assimilate partitioning will modifythe underlying relationship between shoot and storage root weightsin a simple measurable fashion. The theory is inevitably oversimplifiedand speculative in parts but when a derived equation was fittedto data from an experiment in which gibberellic acid and daminozidewere applied to carrots, close agreement was found between thepredictions and experimental data. Daucus carota, carrot, shoot weight, root weight, gibberellic acid, N-dimethylamino-succinamic acid (daminozide), growth analysis 相似文献
8.
Effects of photon flux density on carbon partitioning and rhizosphere carbon flow of Lolium perenne 总被引:1,自引:0,他引:1
Hodge Angela; Paterson Eric; Thornton Barry; Millard Peter; Killham Ken 《Journal of experimental botany》1997,48(10):1797-1805
The distribution and partitioning of dry matter and photoassimilateof Lolium perenne was investigated under two light regimes providingphotosynthetically active radiation of 350 µmol m2s1 (low light treatment) or 1000 µmol m2s1 (high light treatment). Plants were grown at specificgrowth conditions in either soil or sand microcosm units tofollow the subsequent release of carbon into the rhizosphereand its consequent incorporation into the microbial biomass(soil system) or recovery as exudates (sand system). The distributionof recent assimilate between the plant and root released carbonpools was determined using 14CO2 pulse-chase methodology atboth light treatments and for both sand- and soil-grown seedlings.A significant (P 相似文献
9.
Physiological responses to root pruning were investigated bycomparing 14CO2 fixation rates, the partitioning of 14C-labelledassimilate, and soluble and insoluble carbohydrate levels inthe leaves of carrot plants following the removal of some ofthe fibrous roots, or fibrous roots and part of the tap root.Root pruning reduced 14CO2 fixation by 2845% but leafspecific activity (14C assimilation g-1 leaf fresh weight) wasunchanged. The proportion of total assimilate exported to theroot system increased following root pruning and this was atthe expense of the developing leaves. In younger plants (wherethe tap root received 10% of the assimilate) the supply of 14Cto the tap root was maintained in spite of root pruning. However,shortening the tap root to 3 cm in older plants (in which 30%of the fixed 14C was normally exported to the developing storageorgan), reduced its sink capacity and resulted in slightly greaterretention of 14C in the mature leaves. Greater concentrationsof insoluble carbohydrate were found in the mature leaves followingroot pruning but soluble sugar content was unaffected. Onlysmall differences were observed in the distribution of 14C betweensoluble and insoluble carbohydrate fractions when plants werefed 14CO2 several days after the root pruning operations. Thesephysiological responses were mainly associated with the removalof fibrous roots and support the view that the fibrous rootsystem is more important than the developing storage organ inregulating growth in young carrot plants. 相似文献
10.
The treatment of potato tubers with 150 µmol dm3gibberellic acid (GA3) stimulated starch breakdown and hexoseaccumulation in tuber tissues and the transfer of dry matterto stems. These effects could not be accounted for by enhancedactivities of starch phosphorylase, amylase and acid invertase.Indeed enzyme activities either declined or remained relativelyconstant as starch degradation and hexose accumulation proceeded.Changes in the rate of starch depletion were related to changesin sink strength and sink type, the onset of tuber initiationin controls causing the rate of starch degradation to exceedthat in GA3-treated tissues, in which tuberization was inhibited. Solanum tuberosum L., gibberellic acid, starch breakdown 相似文献
11.
Exposure of ryegrass (Lolium perenne L.) cv. S23 to 0, 50, and400 µg m3 SO2 for an initial 29 d (first harvest),and for an additional 22 d period of regrowth (second harvest),resulted in distinct alterations in carbohydrate metabolismat each harvest. At the first harvest, exposure to 50 µgm3 increased concentrations of free and total carbohydrates,whereas exposure to 400 µg m3 resulted in concentrationshardly different from those in control plants. At both SO2 concentrations,more assimilate was retained as free carbohydrate rather thanas storage carbohydrate. Comparison of assimilate distributionat the end of the light, and at the end of the dark period atthe first harvest led to the conclusion that light-mediatedmetabolism is more sensitive to SO2 exposure than dark metabolism,and that assimilate distribution might be controlled by at leasttwo processes exhibiting different SO2 sensitivities. 相似文献
12.
Single leaves on growing sunflower plants were allowed to assimilate14CO2. Gibberellic acid was applied to the same leaf or to theterminal bud or the roots, and the distribution of assimilated14C was determined at intervals of 196 h. Gibberellicacid had no significant effect on initial distribution of 14Cduring the period of rapid export from the leaf, but enhancedre-export from the roots after translocation from the leaf hadvirtually ceased. Most of the 14C exported from the roots accumulatedin the shoot tip. The site of application of the hormone wasof relatively minor importance. Wherever it was applied themajor effect was enhancement of movement from the roots to theshoot tip. Application to the terminal bud was most effectivein this respect. There was no evidence that gibberellic aciddirectly affected the transport system, but the data supportthe hypothesis that it increases the strength of the sink inthe shoot tip. Helianthus annuus L., sunflower, assimilate transport, gibberellic acid, phloem transport 相似文献
13.
Plants of the biennial Arctium tomentosum were grown from seedto seed-set in an open field under three different treatments:control plants receiving full light intensity, plants with aleaf area reduced by 45 per cent, and shaded plants receivingonly 20 per cent of natural illumination. At various stagesof development the youngest fully expanded leaf of one plantin each treatment was exposed to 14CO2 for half an hour. Subsequentdistribution of labelled assimilates in various plant partswas determined after eight hours. In the first year, the mostdominant sink was the tap root irrespective of variation inassimilate supply. During the production of new vegetative growthin the second season, a larger amount of radioactive photosynthatewas recovered from above ground parts, especially during formationof lateral branches. Seed filling consumed 8090 per centof labelled carbon exported from the exposed leaf. In the secondyear, the most pronounced difference between treatments wasin the degree of apical dominance, being highest in shaded plantsand lowest in the plants with cut leaves. Results from 14C experimentsagreed fairly well with a partitioning coefficientderived from a growth analysis of plants grown independentlyunder the same experimental conditions. Reasons for discrepanciesbetween the 14C results and the partitioning coefficient arediscussed. Arctium tomentosum, burdock, variation in assimilate supply, assimilate distribution, 14CO2, labelling, growth analysis 相似文献
14.
This work examines the differences in partition and activityof 14C in two varieties of carrot (Daucus carota L.) contrastingin shoot to storage root ratio at maturity. Plants were grownin a controlled environment of 20 ?C and 500 µmol m2s1. During initiation of the storage root (1025d from sowing) plants were exposed to 14CO2 for 1 h and theradioactivity in ethanol-soluble and -insoluble fractions ofshoots, storage and fibrous roots estimated at various timesup to 48 h after exposure. Between 35% and 40% of radioactivityinitially present in the plants was respired during the first24 h and 2535% of that remaining after 24 h was foundin the roots, depending on age. The proportion found in thestorage region remained fairly constant between 15 and 25 dand was smaller than at 10 d. In the variety with a larger proportionof storage root at maturity (cv. Super Sprite), there was agreater proportion of label in both ethanol-soluble and -insolublefractions of the storage region soon after storage root initiationhad begun than in the variety with a smaller proportion of storageroot at maturity (cv. Kingston). There was no varietal differencein specific activities of the storage roots, but fibrous rootsof cv. Super Sprite showed a greater specific activity thanin cv. Kingston. Differences in shoot to storage root ratiomay thus be associated with characteristics of the fibrous roots.Partition and specific activities are discussed in relationto the initiation and development of the storage organ. Key words: Daucus carota, carrot, assimilate, partition, 14C, storage root 相似文献
15.
Abscisic acid (ABA) applied to the decapitated second internodeof runner bean plants enhanced outgrowth of lateral buds onlywhen internode stumps were no longer elongating. Applied toelongating internodes of slightly younger plants, ABA causesinhibition of bud outgrowth. Together with 104 M indol-3-ylacetic acid (IAA), ABA stimulated internode elongation and interactedadditively in the inhibition of bud outgrowth. A mixture of105 M ABA and 106 M gibberellic acid (GA3 ) causedsimilar effects on internode growth as IAA + ABA, but was mutuallyantagonistic in effect on growth of the lateral buds. Abscisic acid, apical dominance, gibberellic acid, indol-3yl acetic acid, Phaseolus coccineus, bean 相似文献
16.
Rood, S. B. and Larsen, K. M. 1988. Gibberellins, amylase, andthe onset of heterosis in maize seedlings.J. exp. Bot.39: 223233. The possible involvement of gibberellins and amylase in heterosisof maize seedlings was investigated in two parental inbreds,CM7 and CM49, and their single cross F1 hybrid, CM7xCM49. Germinationof all three genotypes was complete within 36 h after the onsetof imbibition. By 48 h, heterosis (hybrid vigour) for increasedshoot and root length was consistently observed. The endogenousconcentration of gibberellin A1 (GA1) was measured in 48 h seedlingsby gas chromatography-mass spectrometry with selected ion monitoring(GC-SIM) using [2H2]-GA1 as an internal standard. The GA1 concentrationwas highest in the hybrid (59 ng g1 dry wt.), intermediatein CM49 (9.0 ng g1), and lowest in CM7 (<5.0 ng g1).Amylase activities in all three genotypes were very low at 24h, but increased during the next 24 h, after which time amylaseactivity in the hybrid was significantly higher than that ofeither parental inbred. Inhibitors of gibberellin (GA) biosynthesis,AMO-1618 or CCC, inhibited germination, shoot and root growth,and amylase activity in all three genotypes. Conversely, exogenousgibberellic acid (GA3) increased amylase activity, particularlyin the inbred CM7. Amylase isozymes were separated through polyacrylamidegel electrophoresis and generally similar profiles of starchdegrading enzymes were observed in the three genotypes. SinceGA is known to control a-amylase biosynthesis in some cereals,these results are consistent with the hypothesis that GAs areinvolved in the regulation of heterosis in maize. A higher endogenousGA1 concentration in the hybrid could result in increased amylaseactivity in the hybrid seedlings and consequently, more rapidstarch hydrolysis which fuels heterosis for early growth. Key words: Amylase, germination, gibberellic acid, Gibberellin A1, heterosis, hybrid vigour, Zea mays 相似文献
17.
Clones of excised roots of wild type tomato (Lycopersicon esculentum,Mill., cv. Moneymaker) and a near-isogenic GA-deficient mutant(gib-1/gib-1) were cultured in modified White's medium containing1.5% w/v sucrose. The linear elongation rate of the main axisof the gib-1 mutant was 40% less than that of the wild type.In addition, the main axis of the gib-1 mutant was thicker thanthat of the wild type but main axis volume growth was the samein both genotypes, indicating that the gib-1 allele was affectingthe orientation of root expansion. There was no evidence tosuggest that the gib-1 allele affected either the pattern ofemergence or the density of lateral roots. Elongation rate andthickness of gib-1 mutant roots were restored to those of thewild type by the addition of low concentrations (0.11.0µM) of gibberellic acid (GA3). These concentrations ofGA3 caused a slight reduction in extension growth of wild typeroots, indicating that endogenous GAs were not limiting elongationof normal roots in culture. The GA biosynthesis inhibitor, 2S,3S paclobutrazol, at 0.1 µM, significantly reduced elongationof wild type roots and this inhibition was counteracted by 0.1µM GA3. It is concluded that the difference in growthbetween the gib-1 mutant and the wild type represented GA-dependentgrowth. Low concentrations of 2S, 3S paclobutrazol caused onlya small (5%) reduction in growth of the gib-1 mutant and thisgrowth inhibition was not reversed by GA3. This observation,and the fact that gib-1 mutant roots grow in the absence ofadded GA3, suggested that part of root growth was GA-independent.However, the possibilities that the gib-1 mutant is leakyand that paclobutrazol does not inhibit GA biosynthesis completelycannot be excluded. Key words: gib-1 mutant, gibberellic acid, Lycopersicon esculentum, 2S, 3S paclobutrazol, root growth 相似文献
18.
We examined the effect of pretreatments (18 h at 5 µmoldm3) with abscisic acid, the ethylene-releasing substanceEthephon, gibberellic acid, indoleacetic acid,kinetin and zeatin on nitrate uptake and in vivo nitrate reductaseactivity (NRA) in roots of nitrogen-depleted Phaseolus vulgarisL. Nitrate uptake showed an apparent induction pattern witha steady state after about 6 h, in all treatments. The nitrateuptake rate after 6 h was unaffected or at most 30% lower aftertreatments with the plant growth regulators. Gibberellic acid, kinetin and zeatin induced substantial NRAin roots in the absence of nitrate, whereas Ethephon enhancedNRA only during nitrate nutrition. Kinetin-induced NRA (Ki-NRA)was maximal after a pretreatment at 1 µmol dm3,and showed a lag phase of 68 h. Ki-NRA was additive tonitrate-induced NRA (NO3-NRA) for at least 24 h, independentof the induction sequence. After full induction, Ki-NRA approximated20% of NO-3-NRA. Abscisic acid counteracted the developmentof Ki-NRA, but not of NO3-NRA. Cycloheximide and tungstatewere equally effective to suppress the development of nitratereductase activity after supply of kinetin or NO3. Our data are consistent with the operation of two independentenzyme fractions (Ki-NRA and NO3-NRA) with apparentlyidentical properties but with separate control mechanisms. Theabsence of major effects of plant growth regulators on the time-courseand rate of nitrate uptake suggests that exogenous regulators,and possibly endogenous phytohormones are of minor importancefor initial nitrate uptake. The differential effect of someregulators on nitrate uptake and root NRA furthermore indicatesthat the processes of uptake and reduction of NO3 arenot obligatory or exclusively coupled to each other. 相似文献
19.
Pan, W. L., Jackson, W. A. and Moll, R. H. 1985. Nitrate uptakeand partitioning by corn (Zea mays L.) root systems and associatedmorphological differences among genotypes and stages of rootdevelopment.J. exp. Bot, 36: 13411351 Nitrate uptake and partitioning by root systems of corn inbredlines were examined. Six-day-old root systems of decapitatedseedlings of seven corn inbred lines were shown to differ markedlyin their capacity for nitrate uptake and partitioning. The magnitudeof nitrate uptake ranged from 4486 µmol NO3g 1 fr. wt. during an 8 h period. Relative nitrate translocation(% of total uptake) also varied among the seven genotypes from425%, and differences in the proportions accumulated(2873%) and reduced (2258%) were observed. Threeof these genotypes were then examined at 5,6, and 8 d aftergermination to determine the effect of lateral root proliferationon the previously observed differences in nitrate uptake andpartitioning. Nitrate translocation per unit mass increasedwith root elongation and lateral root proliferation, and genotypicdifferences in this partitioning process were associated withdifferences in these morphological parameters. In contrast,differences among genotypes in their capability to accumulatenitrate were not correlated with these differences in morphology.Evaluations of genotypic differences in nitrate uptake and partitioningat the seedling stage should include the rate and characteristicsof morphological development Key words: Lateral root, root morphology, nitrate translocation 相似文献
20.
Growth and Graviresponsiveness of Primary Roots of Zea mays Seedlings Deficient in Abscisic Acid and Gibberellic Acid 总被引:1,自引:0,他引:1
Moore, R. and Dickey, K. 1985. Growth and graviresponsivenessof primary roots of Zea mays seedlings deficient in abscisicacid and gibberellic acid.J. exp. Bot. 36: 17931798. The objective of this research was to determine if gibberellicacid (GA) and/or abscisic acid (ABA) are necessary for graviresponsivenessby primary roots of Zea mays. To accomplish this objective wemeasured the growth and graviresponsiveness of primary rootsof seedlings in which the synthesis of ABA and GA was inhibitedcollectively and individually by genetic and chemical means.Roots of seedlings treated with Fluridone (an inhibitor of ABAbiosynthesis) and Ancymidol (an inhibitor of GA biosynthesis)were characterized by slower growth rates but not significantlydifferent gravicurvatures as compared to untreated controls.Gravicurvatures of primary roots of d-5 mutants (having undetectablelevels of GA) and vp-9 mutants (having undetectable levels ofABA) were not significantly different from those of wild-typeseedlings. Roots of seedlings in which the biosynthesis of ABAand GA was collectively inhibited were characterized by gravicurvaturesnot significantly different from those of controls. These results(1) indicate that drastic reductions in the amount of ABA andGA in Z. mays seedlings do not significantly alter root graviresponsiveness,(2) suggest that neither ABA nor GA is necessary for root gravicurvature,and (3) indicate that root gravicurvature is not necessarilyproportional to root elongation. Key words: Abscisic acid, Ancymidol, Fluridone, gibberellic acid, root gravitropism, Zea mays 相似文献