ABA and GA3 affect the growth and pigment composition in Andrographis paniculata Wall.ex Nees., an important folk herb

In this study, 5 μmol·L-1 abscisic acid (ABA) and gibberellic acid (GA3) were used to study the effect of both growth regulators on the morphological parameters and pigment composition of Andrographispaniculata. The growth regulators were applied by means of foliar spray during morning hours. ABA treatment inhibited the growth of the stem and internodal length when compared with control, whereas GA3 treatment increased the plant height and internodal length. The total number of leaves per plant decreased in the ABA-treated plants, but GA3 treatment increased the total number of leaves when compared with the control. Both growth regulators (ABA and GA3) showed increased leaf area. ABA and GA3 treatments slightly decreased the total root growth at all the stages of growth. The growth regulator treatments increased the whole plant fresh and dry weight at all stages of growth. ABA enhanced the fresh and dry weight to a larger extent when compared with GA3. An increase in the total chlorophyll content was recorded in ABA and GA3 treatments. The chlorophyll-a, chlorophyll-b, and carote-noids were increased by ABA and GA3 treatments when compared with the control plants. The xanthophylls and anthocyanin content were increased with ABA and GA3 treatments in A. Paniculata plants.     

Modification of growth habit of Majestic potato by growth regulators applied at different times

The effect of gibberellic acid, CCC (2-chloroethyltrimethylammonium chloride) and B 9 (N-dimethylaminosuccinamic acid) was studied on growth of potato plants in pots. Growth was analysed on four occasions and changes in habit defined in terms of internode lengths, leaf areas and growth of lateral branches. Soaking seed pieces for 1 hr. in GA solution caused six internodes to elongate greatly, an effect not prevented by CCC applied when the shoot emerged from the soil. The effects on internode extension were determined by the length of the interval between GA treatment and CCC treatment. Treatment at emergence with CCC shortened all internodes and more CCC applied 4 weeks later had no effect. Late application of CCC or B9 shortened the top two lateral branches, usually very long in untreated plants. The regulators affected leaf growth differently from internode growth: usually growth regulators had less effect on leaf growth. Effects on growth depended on when the regulators were applied. Treatment with GA alone inhibited bud development at higher nodes than in untreated plants; when followed by late treatment with CCC, lateral growth at higher nodes was also less. CCC retarded development of lateral branches especially when applied early. B9 had a similar effect to CCC applied late. When regulators retarded growth of lower laterals, upper laterals often grew more than in untreated plants. Treatments did not affect the number of leaves on the main stem at first but later GA hastened senescence. GA increased the number of leaves on lateral stems, and the effect was enhanced by CCC. CCC alone increased the number of first- and second-order lateral leaves. GA lengthened and CCC shortened stolons. The effect of CCC persisted throughout the life of the plant. CCC or B 9 shortened stolons whenever applied. CCC hastened tuber initiation but slowed tuber growth. CCC at first retarded formation of lateral tubers but had no effect on the ultimate numbers of lateral and terminal tubers. The value of E (net assimilation rate) did not alter with time. CCC applied at emergence increased E, probably because it hastened tuber initiation and temporarily increased sink capacity. Although tubers formed earlier with CCC, their growth was slower and their demand for carbohydrate was also less. The increase in second-order laterals in CCC-treated plants indicates that they utilize carbohydrate that would normally go to tubers. This experiment also demonstrates that crowding leaves by shortening stems did not diminish E, possibly because another over-riding process (bigger sinks) offsets the effect of shading.     

CONTROL OF THE INTERNODAL INTERCALARY MERISTEM OF CYPERUS ALTERNIFOLIUS

In the growing culm of C. alternifolius, surgical removal of parts indicated that the stimulus for the prolonged activity of the internodal intercalary meristem (IM) came from the matured leaves and upper internode and that buds were not involved in maintaining internodal growth. Decapitation of the culm resulted in cessation of internodal extension. Various growth regulators were applied to the decapitated internode, and both the total extension and growth rates were analyzed statistically. Gibberellin A₃ (GA) and benzyladenine (BA) substituted for the excised parts in their effect on internodal extension. Indoleacetic acid (IAA) had little effect. (2-chloroethyl) trimethylammonium chloride (CCC) inhibited internodal growth, and its effects were reversed by GA. IAA was antagonistic to BA but not to GA. BA and GA were somewhat antagonistic. The quantitative effects of growth regulators on epidermal and ground parenchyma cell length and number of interstomatal cells were examined. Extension induced by GA was due to both cell division and cell elongation in the IM. Cells were longer, and fewer stomates differentiated than in the control. In internodes induced to extend by GA + BA cell division, cell length, and stomate differentiation were similar to the control. The results indicate that prolonged internodal IM activity is maintained by cytokinins and gibberellins coming from the matured upper portions of the culm. Changes in the levels of these regulators during growth presumably result in the histological gradient in the internode.     

Mixed Compound of DCPTA and CCC Increases Maize Yield by Improving Plant Morphology and Up-Regulating Photosynthetic Capacity and Antioxidants

DCPTA (2-diethylaminoethyl-3, 4-dichlorophenylether) and CCC (2-chloroethyltrimethyl- ammonium chloride) have a great effect on maize growth, but applying DCPTA individually can promote the increase of plant height, resulting in the rise of lodging percent. Plant height and lodging percent decrease in CCC-treated plants, but the accumulation of biomass reduce, resulting in yield decrease. Based on the former experiments, the performance of a mixture which contained 40 mg DCPTA and 20 mg CCC as active ingredients per liter of solution, called PCH was tested with applying 40mg/L DCPTA and 20mg/L CCC individually. Grain yield, yield components, internode characters, leaf area per plant, plant height and lodging percent as well as chlorophyll content, chlorophyll fluorescence, enzymatic antioxidants, membranous peroxide and organic osmolyte were analyzed in two years (2011 and 2012), using maize hybrid, Zhengdan 958 (ZD 958) at density of 6.75 plants m^-2. CCC, DCPTA and PCH were sprayed on the whole plant leaves at 7 expanded leaves stage and water was used as control. Compared to control, PCH significantly increased grain yield (by 9.53% and 6.68%) from 2011 to 2012. CCC significantly decreased kernel number per ear (by 6.78% and 5.69%) and thousand kernel weight (TKW) (by 8.57% and 6.55%) from 2011 to 2012. Kernel number per ear and TKW increased in DCPTA-treated and PCH-treated plants, but showed no significant difference between them. In CCC-treated and PCH-treated plants, internode length and plant height decreased, internode diameter increased, resulting in the significant decline of lodging percent. With DCPTA application, internode diameter increased, but internode length and plant height increased at the same time, resulting in the augment of lodging percent. Bending strength and puncture strength were increased by applying different plant growth regulators (PGRs). In PCH-treated plants, bending strength and puncture strength were greater than other treatments. Compared to control, the bending strength of 3rd internode was increased by 14.47% in PCH-treated plants in 2011, increased by 18.40% in 2012, and the difference was significant. Puncture strength of 1st, 3rd and 5th internode was increased by 37.25%, 29.17% and 26.09% in 2011 and 34.04%, 25% and 23.68% in 2012, compared to control. Leaf area and dry weight per plant reduced significantly in CCC-treated plants, increased in DCPTA-treated and PCH-treated plants from 2011 to 2012. Chlorophyll content and chlorophyll fluorescence improved with CCC and DCPTA application. Due to the additive effect of DCPTA and CCC, PCH showed the significant effect on chlorophyll content and chlorophyll fluorescence. Compared to control, total enzyme activity (SOD, POD, CAT, APX and GR) and soluble protein content increased, malonaldehyde (MDA) and hydrogen peroxide (H₂O₂) content reduced in PCH-treated plants. The transportation of soluble sugar from leaf to kernel improved significantly at the late silking stage. The research provided the way for the further use of DCPTA and CCC into the production practice.     

Suppression of floral induction inBryophyllum daigremontianum by a growth retardant

Summary Flower formation in the long-short-day plantBryophyllum daigremontianum induced by the shift from long to short day is fully suppressed by applying the growth retardant CCC [(2-chloroethyl)-trimethylammonium chloride]via the roots during short day treatment at a level of at least 1 g per plant. At the same time CCC applications strongly reduce the internode length, but the rate of leaf formation does not seem to be affected. CCC also causes the production of more anthocyanin in the leaves.Gibberellin A₃ appliedvia the apices and youngest leaves at a dose of 1.5 g per plant, completely overcomes the inhibition of flower formation caused by CCC. Ten times higher quantities are needed for a complete reversal of the reduction in stem elongation.The growth retardant CCC seems to keep the level of physiologically active GA below that which is normally required for floral initiation and stem elongation. Thus, the results are in agreement with the hypothesis that a high GA level is necessary for the production of floral stimulus inBryophyllum daigremontianum.With 2 Figures in the TextThis work was supported by the National Science Foundation, grants G-16408 and G-17483.     

THE DEVELOPMENTAL MORPHOLOGY OF NICOTIANA TABACUM ‘WHITE BURLEY’ AS INFLUENCED BY VIRUS INFECTION AND GIBBERELLIC ACID

Stein , Diana B. (U. Montana, Missoula.) The developmental morphology of Nicotiana tabacum ‘White Burley’ as influenced by virus infection and gibberellic acid. Amer. Jour. Bot. 49(5): 437–443. Illus. 1962.—‘White Burley’ tobacco with Severe Etch Virus (SEV) displayed a reduction of plant height which was overcome to a limited degree by spraying with gibberellic acid (GA). Spraying with GA, while hastening maturity in terms of earlier elongation and flowering, also prolonged the life of treated plants. Infection with SEV caused an increased rate of leaf production, and since flowering was also delayed, the greater number of leaves is produced by infected plants. Spraying with GA also increased the rate of leaf production but did not increase the final number of leaves produced. All groups except the unsprayed virus-infected plants showed a spurt in leaf production just prior to flowering. The pattern of internode elongation was obtained by the periodic measurement of individual internodes. In general, this pattern reflected the stunting properties of the virus and the growth-promoting properties of the GA. Internodes which were mature at time of spraying with GA were not affected. Infection with virus generally delayed elongation and shifted the internode pattern. Infection with SEV tended to reduce the size of leaves already present prior to inoculation, but some leaves produced after infection were actually 1arger than the same leaves on the controls. Spraying a healthy plant with GA made older leaves longer and wider, while less mature leaves at time of treatment tended to be longer and narrower. Spraying with GA reversed the reduction in size caused by the virus only if the leaf was a very young primordium or was formed during the course of treatment with GA.     

THE INFLUENCE OF GROWTH STAGE ON THE RESPONSE OF RED CLOVER (TRIFOLIUM PRATENSE L.) TO GIBBERELLIC ACID

The response of seedling and first harvest year plants of red clover ( Trifolium pratense L.) to treatment with gibberellic acid (GA) at various growth stages is described.
Seedlings sprayed before the seventh leaf stage developed into single-stemmed plants; treatment with GA at the third- or fourth-tiller stage resulted in final stem numbers similar to those of controls. Emergence was earliest, and the number of heads per plant greatest where sprayings were delayed until the third- or fourth-tiller stage.
In first harvest year plants significant increases in the number of heads per stem were obtained with certain treatments, especially those which had two applications of 0.5 mg. GA per plant during the elongation of the first four internodes. This was related in all treatment groups to modifications of the branching pattern, and also to the increased incidence of multiple heading. Earlier emergence resulted from treatment at all growth stages, the effect being maximal where three well-spaced sprayings were applied during active stem extension.     

Modulation of leaf elongation, tiller appearance and tiller senescence in spring barley by far-red light

Supplemental far-red (FR) illumination of light-grown grass seedlings inhibits tiller production while enhancing leaf elongation. Although much is known about FR enhancement of internode elongation in dicots, relatively little research has been conducted to determine the effects of FR on monocot development. In growth chamber experiments, fibre optics were used to direct supplemental FR to elongating leaf blades, main stem bases and mature leaf blades of light-grown barley (Hordeum vulgare L.) seedlings. Our objective was to identify specific sites of perception for FR enhancement of leaf elongation and inhibition of tiller production, and to assess potential FR effects on tiller senescence. Far-red illumination of elongating leaves or of the main stem base reduced the total number of tillers per plant, primarily by reducing secondary and tertiary tiller production, and enhanced leaf elongation. However, leaf elongation was less sensitive to stem base treatments than to illumination of the elongating blade. Increased leaf length resulted from increased leaf elongation rate, while the duration of leaf elongation was unaffected. Exposure of mature leaf blades to FR had no effect on tillering or leaf elongation. None of the FR treatments led to tiller senescence. Localization of FR perception in vertically oriented tissues such as elongating blades and stem bases permits early detection of reflected light from neighbouring plants, allowing rapid response to impending competition.     

Internodal elongation and orientation of cellulose microfibrils and microtubules in deepwater rice

Excised stem sections of deepwater rice (Oryza sativa L.) containing the highest internode were used to study the induction of rapid internodal elongation by gibberellin (GA). It has been shown before that this growth response is based on enhanced cell division in the intercalary meristem and on increased cell elongation. In both GA-treated and control stem sections, the basal 5-mm region of the highest internode grows at the fastest rate. During 24 h of GA treatment, the internodal elongation zone expands from 15 to 35 mm. Gibberellin does not promote elongation of internodes from which the intercalary meristem has been excised. The orientation of cellulose microfibrils (CMFs) is a determining factor in cell growth. Elongation is favored when CMFs are oriented transversely to the direction of growth while elongation is limited when CMFs are oriented in the oblique or longitudinal direction. The orientation of CMFs in parenchymal cells of GA-treated and control internodes is transverse throughout the internode, indicating that CMFs do not restrict elongation of these cells. Changes in CMF orientation were observed in epidermal cells, however. In the basal 5-mm zone of the internode, which includes the intercalary meristem, CMFs of the epidermal cell walls are transversely oriented in both GA-treated and control stem sections. In slowly growing control internodes, CMF orientation changes to the oblique as cells are displaced from this basal 5-mm zone to the region above it. In GA-treated rapidly growing internodes, the reorientation of CMFs from the transverse to the oblique is more gradual and extends over the 35-mm length of the elongation zone. The CMFs of older epidermal cells are obliquely oriented in control and GA-treated internodes. The orientation of the CMFs parallels that of the cortical microtubules. This is consistent with the hypothesis that cortical microtubules determine the direction of CMF deposition. We conclude that GA acts on cells that have transversely oriented CMFs but does not promote growth of cells whose CMFs are already obliquely oriented at the start of GA treatment.     

赤霉素诱导甘蔗节间伸长的效应与相关酶活性的关系

以甘蔗品种'新台糖22号'为试验材料,在伸长初期以200 mg/L GA3进行叶面喷施处理,对照喷清水,研究GA3处理后甘蔗节间糖苷酶、过氧化物酶、过氧化氢酶的变化,以揭示赤霉素诱导甘蔗节间伸长与相关酶活性的关系.结果表明:(1)GA3处理的株高在各个时期显著高于对照,而且在处理后7、14和28 d分别比对照提高了17.32%、14.50%和8.35%,GA3处理引起甘蔗植株表现的高度优势一直保持到后期,节间伸长效果主要是在茎的中部(5～10节).(2)GA3处理后α-葡萄糖苷酶和α-甘露糖苷酶的活性较对照显著下降;POD和β-半乳糖苷酶的活性也略有下降;α-半乳糖苷酶、β-N-乙酰氨基已糖苷酶、过氧化氢酶的活性显著提高;β-葡萄糖苷酶的活性也有一定程度提高.由此推测,外源GA3主要通过调节α-葡萄糖苷酶活性、α-甘露糖苷酶、α-半乳糖苷酶、β-N-乙酰氨基已糖苷酶活性和过氧化氢酶,其次是POD、β-半乳糖苷酶和β-葡萄糖苷酶活性,最终达到节间伸长效果.     

Enhancement of transpiration by ethylene is responsible for absence of internodal elongation in floating rice at low humidity

Internodal elongation in floating rice (Oryza sativa) is known to be enhanced by treatment with ethylene or gibberellic acid (GA3) at high relative humidity (RH). However, ethylene-induced internodal elongation is inhibited at low RH, while GA3-induced internodal elongation is hardly affected by humidity. We examined the effects of ethylene and GA3 on the rate of transpiration in stem segments incubated at 30% or 100% RH. Ethylene promoted the transpiration of stem segments at 30% RH, but not at 100% RH, while GA3 had little effect on transpiration at either 30% or 100% RH. We propose that the absence of ethylene-induced internodal elongation at low RH is due, at least in part, to ethylene-induced transpiration.     

深水稻节间伸长生长的机制

淹水可促进深水稻节间快速伸长生长,其主要受内源赤霉素、乙烯、脱落酸等激素信号分子的调控。淹水能促进深水稻植物株体内乙烯、赤霉素的生物合成、抑制脱落酸的生物合成,外源乙烯、赤霉素会加速深水稻节间伸长,而外源脱落酸抑制淹水节间的伸长,其中赤霉素是直接作用因子,乙烯能降低内源脱落酸水平、增加节地赤霉素的敏感性;还与渗透调节、细胞壁组份如膨胀素等有关,淹水及赤霉素都大大增加了膨胀素基因的表达。并就深水稻的     

深水稻节间伸长生长的机制

淹水可促进深水稻节间快速伸长生长,其主要受内源赤霉素、乙烯、脱落酸等激素信号分子的调控。淹水能促进深水稻植株体内乙烯、赤霉素的生物合成、抑制脱落酸的生物合成,外源乙烯、赤霉素会加速深水稻节间伸长,而外源脱落酸抑制淹水节间的伸长,其中赤霉素是直接作用因子,乙烯能降低内源脱落酸水平、增加节间对赤霉素的敏感性;还与渗透调节、细胞壁组份如膨胀素等有关,淹水及赤霉素都大大增加了膨胀素基因的表达。并就深水稻的进一步研究进行了展望。     

植物生长调节剂对西南桦苗木生长的影响

用 ABT6 和 GA3对西南桦苗木进行叶面喷施试验。试验结果表明 ,GA3的 3种浓度即 2 0× 10 - 6 m g/L、50× 10 - 6 m g/L、80× 10 - 6 m g/L在苗木高生长、地径大小、苗木干鲜重及苗木根系生长发育方面都比清水对照( CK)有明显地提高。ABT6 各浓度特别是 50× 10 - 6 m g/L处理的在苗木分枝数、单株叶面积、苗木干鲜重及苗木根系生长发育方面也比对照有显著的提高。综合各指标 ,用 A BT6 生长调节剂的 50× 10 - 6 mg/L比 2 0× 10 - 6mg/L、80× 10 - 6 mg/L处理及 GA3生长调节剂各浓度处理在生产实践上更适宜用于培育西南桦苗木。     

Interactions of auxin and gibberellin in the control of basal growth of <Emphasis Type="Italic">Arabidopsis</Emphasis> rosette leaves

Arabidopsis is a species that naturally displays the rosette form. Therefore, elucidation of the factors, which control basal leaf development, is of particular interest. Most evidence points that auxins and gibberellins are important in the control of rosette leaf development. In this paper, we report on a regimen that disrupts the normal rosette growth in Arabidopsis and induces internodal growth, which we have termed unbasal. The growth conditions are: (1) seed germination in the presence of 2,3,5-triiodobenzoic acid (TIBA); (2) transfer of the seedlings to a medium containing exogenous auxin (NAA) and GA₃; (3) transfer of the seedlings to a GA₃-only medium for all subsequent growth. Under these conditions, auxin and GA interact to induce internode elongation. Polar auxin transport appears to have a temporal effect on this synergistic interaction. In this regimen, GA increases auxin activity in the basal portions of the stem. Cross sectional morphology of the elongated internodes between two rosette leaves in an un-basal plant was similar to that seen for the pin1 Arabidopsis mutation.     

The effects of gibberellic acid and nutrient sprays on growth and yield of brussels sprout

Young plants of brussels sprout, cv. Cambridge Special, growing in pots in a glasshouse, were sprayed on ten occasions with gibberellic acid (GA) at 0, 25, 100 and 400 p.p.m. and ammonium nitrate (NH₄NO₃) at 0, 0·0125, 0·025 and 0·05 M concentrations in all combinations. In 24 days both GA and NH₄NO₃ increased leaf area, leaf number, dry weights of leaf, stem and root, and fresh weights of leaf and stem. GA increased stem height and decreased fresh weight/unit leaf area (leaf thickness), whereas NH₄NO₃ did not affect stem height and increased leaf thickness. Of the GA treatments, 100 p.p.m. gave the largest plants as judged by fresh weight of the whole plant and leaf area, and of the N treatments 0·05 M NH₄NO₃ increased growth most. The best treatment combination was 0·05 M NH₄NO₃ with 100 p.p.m. GA, which gave the greatest fresh and dry weights of the whole plant, leaf area and leaf dry weight as well as increasing leaf thickness. Significant interactions were found between GA and N for dry weight of leaf, fresh and dry weight of root, and leaf thickness but not for leaf area or stem growth (fresh weight, dry weight, height). The combination of levels of GA and N that can be expected to increase leaf area, leaf dry weight and leaf thickness simultaneously, may lie within narrow limits for a particular crop. In a second experiment plants were sprayed with all combinations of GA (0 and 100 p.p.m.) seven times under glass in pots and ten times in the field, and three levels of KH₂PO₄ on twelve occasions in the field. Sprouts (axillary buds) were harvested in October and February. At the first harvest GA did not affect fresh weight or number, but increased both the total number of sprouts picked (with GA = 80·7; without GA = 69·8 per plant) and the total fresh weight of saleable sprouts (with GA = 2·59; without GA = 2·33 lb/plant). KH₂PO₄ also increased the weight and number of sprouts at the final harvest and the number of small sprouts at the first. There were interactions between GA and KH₂PO₄ (P= < 0·001) for both tota weight and number of saleable sprouts.     

Co-regulation Of ear growth and internode elongation in corn

Ear is the harvest part of corn (Zea mays L.) and we are interested in studying its growth and development in our effort in corn yield improvement. In our current study, we examined the relationship between ear growth and internode characteristics using different approaches. Correlations between stem growth rate and number of ears per plant (prolificacy) were assessed among several genotypes. Internode elongation of 2 genotypes was modified by plant hormones and by population density manipulations. Among the 7 genotypes examined that have different prolificacy levels, there was a general correlation of slower stem elongation at middle growth stages and larger ear number. When the internode elongation was enhanced by application of gibberellic acid (GA), ear growth was suppressed; and when a GA synthesis inhibitor uniconazole was applied at early stages, internode length was reduced and ear growth was promoted in terms of both ear size and visible ear number at silking stage. Higher population density caused longer internodes and fewer ears per plant and the effect of lower density was the opposite. Our results suggested that internode elongation in the middle section of corn plants was linked to suppression of ear development in corn.