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1.
The hormonal control of stem unit (foliar appendage and axillary structure, if present, plus subtending internode) number and length was investigated in shoots of Scots pine (Pinus sylvestris L.) and white spruce (Picea glauca (Moench) Voss). Seedlings were treated with six gibberellins (GA1, GA3, GA4, GA5, GA9 and GA20) and two auxins (indole-3-acetic acid (IAA) and naphthaleneacetic acid (NAA)) when either neoformed growth was occurring or the terminal vegetative bud was developing. Hormones were applied by drenching the shoot tip, injecting the stem or spraying the foliage. Combined results for all three application methods indicated that shoot elongation in first-year seedlings (i.e., neoformed growth) was promoted in both species by GA1, GA3, GA4 and, less obviously, by GA9. This promotion was attributable to an increase in length, rather than number, of stem units. However, the number of stem units formed during terminal bud development, as reflected in the number of needles (white spruce) or cataphylls (Scots pine) present on the shoot resulting from the terminal bud, was stimulated by GA1, GA3 and GA4 in both species and by GA9 in Scots pine. The GA-induced increase in the number of preformed stem units was associated with increased bud width in white spruce and increased bud length and resulting shoot length in Scots pine. In contrast, application of IAA or NAA either did not affect or inhibited both neoformed growth and terminal bud stem unit number, depending on the application method and concentration. We conclude that, in the Pinaceae, (1) GA stimulates the activity of both the subapical meristem during neoformed growth and the apical meristem during vegetative bud development, and (2) the early non-hydroxylation pathway, via GA9, is the major route of GA biosynthesis. The role of auxin in the control of stem unit number and length remains to be resolved. 相似文献
2.
Buds of ponderosa pine (Pinus ponderosa var. scopulorum Engelm.) from which the shoot apical meristems had been surgically removed elongated normally but did not form new terminal buds. Shoot, stem unit and needle growth were similar to those of controls. Removal of needle fascicles from buds starting to elongate inhibited growth, whether or not the shoot apical meristem had been removed. The length of completely defoliated shoots increased by 8.3%, the length of shoots defoliated on the upper half increased by 29.6%, and the length of those defoliated on the lower half increased by 44.9%. The length of controls increased by 137.4% during the same period. On partially defoliated shoots, defoliated stem units elongated less than undefoliated ones. Shoots developing from buds enclosed in light-proof, aluminum-foil bags elongated normally but apparently lacked chlorophyll. Increases in dry weight were significantly correlated with number of stem units (r(2) = 0.53). Results suggest that shoot elongation is controlled endogenously. This control may be mediated by IAA outputs from axillary meristems proportional to meristem number, and the importation of carbohydrates, proportional to the output of IAA. 相似文献
3.
Eucalyptus nitens (Deane & Maiden) Maiden takes at least five years to initiate flower buds from seed and is an infrequent and light flowerer. Because this behavior constitutes a major impediment to breeding programs, we examined the mechanisms controlling floral induction in E. nitens, with the long-term aim of reducing generation time and increasing seed yield. Application of paclobutrazol reduced the concentration of endogenous gibberellic acid (GA) in apical tissue and enhanced the reproductive activity of grafted trees maintained outside over winter in Canberra, Australia. Grafts maintained in a warm greenhouse over winter did not produce flower buds, despite the paclobutrazol-induced reduction in GA concentration of the apical tissue. Exposing untreated grafts, which had been maintained over winter in a warm greenhouse, to low temperature the following spring reduced growth but did not induce flower bud production. Addition of GA(3) to paclobutrazol-treated grafts reduced the effect of paclobutrazol on reproductive activity. 相似文献
4.
Maarit Kytö 《New Forests》1993,7(3):275-286
The effect of Lygus rugulipennis Popp. feeding and artificial damage on the apical bud of Scots pine (Pinus sylvestris L.) late in the growing season was studied on two-year-old seedlings. Lygus feeding in late July and August caused inhibition of bud formation in the subsequent year's shoots, which led to loss of apical dominance and formation of interfascicular buds. Mechanical damage caused by piercing the apical bud with a needle in July, August and October produced scars and malformations on subsequent year's shoots and buds, but did not inhibit bud formation. Damage to the apical meristem could not be detected visually on the dormant bud before shoot elongation. 相似文献
5.
《Scandinavian Journal of Forest Research》2012,27(1-4):343-349
The tarnished plant bug (Lygus rugulipennis) and occasionally L. punctatus were found to feed on pine seedlings in central Finland. Both the nymphs and adults of Lygus bugs injured the apical meristem of the seedlings. This led to the death of the apex, and the opening of the lateral buds, resulting in a seedling with multiple leaders. L. rugulipennis may also oviposit on pine seedlings and the development from egg to adult on pine alone is possible. In laboratory experiments it was shown that the main factor in the apical meristem injury is the mechanical damage caused by the bug's stylet. The feeding damage and artificial mechanical damage caused by needles to the apical meristem of pine seedlings resulted in increased numbers of multiple‐leader seedlings and reduced shoot length and dry weight of the shoot and root. 相似文献
6.
Reiteration is the process whereby architectural units are replicated within a tree. Both immediate (from apical buds) and delayed (from suppressed or adventitious buds) reiteration can be seen in many tree species where architectural units ranging from clusters of shoots to entire branches and stems are replicated. In large old trees and suppressed trees, delayed reiteration occurs without an obvious external stimulus such as defoliation or traumatic loss of the branch apex. This suggests that, in trees that are growth-limited, reiteration is an adaptive mechanism for crown maintenance. We discuss theories about the aging process and how delayed adaptive reiteration may help maintain crown productivity and increase longevity. These include: (1) reducing the respiration/photosynthesis ratio; (2) increasing hydraulic conductance to newly developing foliage; (3) reducing nutrient loss from the tree; and (4) rejuvenating the apical meristem. The ability to reiterate various architectural units may contribute to increasing lifetime reproductive output by prolonging tree longevity. Further studies on the physiological and ecological implications of reiteration are needed to understand its adaptive significance in the life history of trees. 相似文献
7.
对5年生和7年生青海云杉苗进行了不同方式的修剪,同时用不同的生长调节剂对其主干和侧枝上的芽进行了处理,发现除去青海云杉顶芽,能够促进苗木侧芽和隐芽的生长发育,提高侧芽的抽枝率,增加新枝的生长量.不同种类的生长调节剂和修剪方式对青海云杉芽的生长发育影响效果显著不同,去顶芽修剪的效果优于纺锤形修剪和篱式修剪,对于7年生苗,主干上仅留3个饱满芽的强度修剪能明显地减少主干上的芽数,使抽枝数也随之减少,处理效果最差.去顶芽能够明显的增加当年新梢数量和长于6 cm的新梢总长度,同时还能增加当年新梢上冬芽数.6BA对青海云杉芽和枝条的生长发育有较好的促进作用,抽枝宝在各个修剪处理中表现均最差,甚至在一定程度上抑制了青海云杉芽的萌发和延长生长.修剪和生长调节剂处理对5年生苗侧枝芽抽枝数影响均极显著,而对7年生苗的影响却不显著;修剪和生长调节剂的交互作用明显地影响了对7年生苗的处理效果,而对5年生苗的影响不显著.去顶芽后再用6BA涂抹青海云杉苗上的保留芽,能有效地促进青海云杉保留芽的生长发育,有利于形成更多枝条,对青海云杉采穗圃苗的处理效果最佳,强度修剪和用抽枝宝抹芽不适于青海云杉采穗圃苗的培育. 相似文献
8.
Bud dormancy of root wrenched and unwrenched slash pine (Pinus elliottii Engelm.) seedlings growing in a forest nursery was measured on five lifting dates. Determination of bud dormancy was based on days to budbreak (DBB) under optimal growing conditions, mitotic activity in the apical meristem, chilling hours accumulated, and bud morphology. Based on DBB, seedlings were most dormant at Lift 2 on November 24 after exposure to 189 hours below 10 degrees C and 93 hours below 6.7 degrees C. Mitotic activity in the apical meristem was at its lowest 23 days later at Lift 3, possibly indicating the period when seedlings are most resistant to transplanting stresses. Multiple wrenching resulted in a slight shift in the dormancy cycle as wrenched seedlings set bud sooner in the nursery and broke bud sooner at the planting site in the spring than control seedlings. This implies that wrenched seedlings can be successfully lifted from the nursery earlier and will initiate spring shoot growth earlier than control seedlings. 相似文献
9.
In rhythmically growing woody species such as common oak (Quercus robur L.), stem growth is discontinuous and a bud forms at regular intervals at the shoot apex. These buds are composed of different types of leaves: laminate, aborted lamina and scale. The change in heteroblastic leaf shape from laminate to aborted lamina leaves is regarded as one of the events marking shoot growth arrest. To better understand the determinism of heteroblastic leaf shape change and thus, of rhythmicity, we studied morphogenetic events during the early days of the second flush of growth in oak, as well as changes in sucrose metabolism and abscisic acid (ABA) concentrations in control plants expressing the heteroblastic leaf shape change and in defoliated plants showing no heteroblastic leaf shape change and producing only laminate leaves. In control plants, the leaf shape change was underway on Day 5 of the second flush with the differentiation of the first two aborted lamina leaves. Sucrose concentration in the apices of control plants decreased between Days 3 and 5 during differentiation of the aborted lamina leaves. An inverse pattern was observed in defoliated plants, suggesting that sucrose acts as a signal triggering heteroblastic leaf shape changes. During the same period, acid cell wall invertase activity was high in young stem and laminate leaves of control plants, whereas the activity remained constant and low in the apices. If the laminate leaves were removed, the increase in apical sucrose concentration was proportionally higher than the decrease in apical acid vacuolar invertase activity, suggesting that, in the absence of young leaves, sucrose is imported to the apex. The sucrose concentration in the apex is therefore likely to be affected by trophic competition with the expanding laminate leaves. The decrease in apex sucrose concentration may be one of the mechanisms driving heteroblastic leaf shape change. Differentiation of aborted lamina leaves was followed by a decrease in the organogenic activity of the shoot apical meristem (SAM) between Days 7 and 9. High concentrations of ABA are associated with differentiation of aborted lamina and scale leaves and with low SAM organogenic activity. Shoot apical meristem organogenic activity remained high and ABA concentration in the apex remained low in defoliated plants producing only photosynthetic leaves. These results suggest that (1) ABA is involved in the gradual conversion of embryonic leaves to abnormal leaves, thereby regulating heteroblastic leaf shape changes and (2) changes in ABA concentration influence the intensity of SAM organogenic activity. Heteroblastic development and therefore rhythmic growth could be the result of competition between apices and laminate leaves, with competition first involving sucrose and thereafter ABA. 相似文献
10.
本文对三台核桃进行动态和定态观测，结果表明：牙于3月下旬开始分化，先后顺序是叶芽、雄花芽、混合芽；品种不同，顶（侧牙的抽生情况不同，其中结果母枝粗是影响顶（侧）芽抽生数的主要性状；雄花芽的抽生数大于混合芽的抽生数，雄花序开放至脱落历时16d左右。 相似文献
11.
银杏雄花芽分化期间内源激素、碳水化合物和矿质营养含量的变化 总被引：14，自引：1，他引：14
银杏雄花芽生理分化期间花芽中赤霉素 (GA1 3)、脱落酸 (ABA)含量下降 ,玉米素 (ZRs)、异戊烯基腺嘌呤类 (iPAs)的含量以及ZRs GA1 3、iPAs GA1 3、ZRs ABA、iPAs ABA上升且高于叶芽 ;形态分化开始后 ,花芽内ZRs、iPAs的含量以及ZRs GA1 3、iPAs GA1 3、ZRs ABA、iPAs ABA下降且维持低水平 ,花芽内ABA含量和ABA GA1 3在高于叶芽的水平上波动。在银杏雄花芽分化过程中 ,雄花芽叶中钾和总糖含量均高于同期雄叶芽叶 ,而全氮的含量基本低于同期雄叶芽叶 ;生理分化期雄花芽叶内磷含量高于同期雄叶芽叶。 相似文献
12.
Spring-flushing, over-wintered buds of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) produce new buds that may follow various developmental pathways. These include second flushing in early summer or dormancy before flushing during the following spring. Second flushing usually entails an initial release of apical dominance as some of the current-season upper lateral buds grow out. Four hypotheses concerning control of current bud outgrowth in spring-flushing shoots were tested: (1) apically derived auxin in the terminal spring-flushing shoot suppresses lateral bud outgrowth (second flushing); (2) cytokinin (0.5 mM benzyladenine) spray treatments given midway through the spring flush period induce bud formation; (3) similar cytokinin spray treatments induce the outgrowth of existing current lateral buds; and (4) defoliation of the terminal spring-flushing shoot promotes second flushing. Hypothesis 1 was supported by data demonstrating that decapitation-released apical dominance was completely restored by treatment with exogenous auxin (22.5 or 45 mM naphthalene acetic acid) (Thimann-Skoog test). Hypothesis 2 was marginally supported by a small, but significant increase in bud number; and Hypothesis 3 was strongly supported by a large increase in the number of outgrowing buds following cytokinin applications. Defoliation produced similar results to cytokinin application. We conclude that auxin and cytokinin play important repressive and promotive roles, respectively, in the control of second flushing in the terminal spring-flushing Douglas-fir shoot. 相似文献
13.
拟南芥 AtFBDL1 基因是FBD-like基因家族的一员,其编码蛋白含有类似于F-box的结构域。表达模式网络预测结果显示该基因在茎顶端分生组织中高丰度表达,但对于FBD-like基因家族的研究还很少,其功能目前尚不明确。为此,本研究通过组织半定量表达分析和GUS染色显示 AtFBDL1 基因在拟南芥中具有时空表达特异性。结果表明:在真叶形成前和形成初期,该基因主要在茎顶端分生组织和下胚轴区域表达;真叶形成后,该基因在下胚轴的表达明显减少,而主要集中在茎顶端分生组织表达。遗传转化显示:与野生型植株相比,过表达 AtFBDL1 基因的植株生长发育缓慢,抽薹时间推迟3 4 d,莲座叶叶片面积减小,叶片数目平均增多10片,并且伴随有变态叶出现;过表达植株株高比野生型矮,株高最大差值达到12 cm。共表达网络预测 AtFBDL1 与多个与生长素和花发育相关的基因具有共表达关系。以上研究结果表明: AtFBDL1 基因在拟南芥的生长发育过程中,特别是在顶端分生组织分化过程中起重要作用。 相似文献
14.
Large numbers of cones (strobili) were induced in a 10-year-old plot of mature grafts of Picea sitchensis (Bong.) Carr. All trees injected with 20 mg GA(4 + 7) in June initiated female and male cones in the same year. This treatment increased the number of female cones per plant 12-fold above the controls, more than doubling the percentage of cones that were female. Complete bark-ringing (done in May of the previous year) showed an additive effect with GA on the number of female cones formed, but a negative interaction on the number of male cones induced. Ringing promoted male cone production most when used alone. Treatments, singly or combined, also increased the proportion of cones that were lateral, compared with the preponderance of terminal male cones in the controls. The effects were apparently not directly associated with alterations in vegetative vigor, although these occurred causing a reduction in the proportion of buds containing vegetative shoots the following year. The clones differed in most characteristics, but both sparse and prolific clones were induced to reproductive activity. Viable seed yields per tree, and notional production from seed-orchards were enhanced almost 10-fold by GA injection, and about 4-fold by bark-ringing and GA + bark-ringing. 相似文献
15.
在河南省郑州市以1年生毛白33泡桐为试验材料,利用间接酶联免疫吸附测定法(ELISA)测定梢枝顶芽、上部侧枝、中部侧枝和下部侧枝的顶芽内源激素含量动态变化。结果表明:1)梢枝顶芽、上部侧枝顶芽、中部侧枝顶芽及下部侧枝顶芽IAA的变化趋势一致,变化趋势为"降低-升高-降低",只是上部侧枝顶芽IAA升高后降低的趋势可能会推迟;2)梢枝顶芽、上部侧枝顶芽和下部侧枝顶芽GA3含量变化趋势基本相同,均呈现出"上升-下降-上升-下降"的"双峰"形;而中部侧枝顶芽GA3含量呈现出"下降-上升-下降"的趋势;3)不同部位顶芽ABA含量均是先升高,之后下降,最后在较低水平上趋于稳定状态;4)泡桐不同部位顶芽ZR含量随时间的变化呈现出不同趋势,但总体呈下降趋势,且不同部位顶芽间存在着竞争关系及抑制作用;5)8月15日—9月15日,IAA,GA3,ZR,ABA及(IAA+GA3+ZR)/ABA比值均呈下降趋势,表明促进生长类激素与导入休眠类激素均较低,泡桐顶芽和其他邻近组织相比其竞争优势在逐渐丧失,内源激素的动态平衡被打破。本研究结果初步探明顶芽死亡与内源激素的关联性,为进一步探讨泡桐死亡机理奠定基础。 相似文献
16.
17.
Bodson M 《Tree physiology》1986,1(1):95-99
Apical buds of evergreen azalea (Rhododendron sp.) were treated with GA(4 + 7) at different stages of development. Treatment of vegetative buds stimulated shoot growth, slightly delayed both flower initiation and development, but increased the number of flower primordia. Treatment at the time of floral transition induced bud abortion at an early stage of the reproductive development. Treatment of inflorescence buds which contained at least one complete flower substituted for chilling in overcoming dormancy and prevented inflorescence bud abortion. 相似文献
18.
以长白落叶松成熟合子胚诱导出的不定芽为外植体,通过筛选不定芽增殖的最适培养基及激素配比、探讨不同浓度赤霉素(GA_3)及活性炭(AC)对不定芽伸长的作用以及比较不同处理对试管内及试管外生根的影响,最终建立离体再生体系。结果表明:BM+1.0 mg/L TDZ时,不定芽增殖最快,增殖系数为5.0;GA_3对不定芽的伸长有毒害,2.0 g/L活性炭(AC)对不定芽伸长促进作用明显,伸长比率达262%;1/2BM+0.5 mg/L IBA+1.0 mg/L NAA为试管内生根的最佳组合,生根率达26%,不定芽在750 mg/L NAA中浸泡25 s,试管外生根率(37%)最高。 相似文献
19.
Patterns of lateral shoot growth following decapitation in 1-meter tall, rooted Triplochiton scleroxylon K. Schum. cuttings varied with clone and in response to a range of environmental conditions and growth regulator treatments. Two phases of bud activity were identified, the Sprouting Phase, in which many buds were released from correlative inhibition, and the Dominance Phase (starting 3-4 weeks after decapitation) in which uppermost laterals began to dominate and suppress growth, and sometimes cause apical abscission of lower lateral shoots. Except in non-erect plants, the most distal lateral to elongate became the new leading shoot. During the Sprouting Phase, the proportion of active buds was increased by removing leaves from the upper part of the stem, and by reducing the photoperiod from 13-15 h to 11 h, particularly at 20 degrees C rather than 25 degrees C. Conversely, the proportion of sprouting buds was decreased by injecting plant stems with NAA (250 microg/plant). During the Dominance Phase, suppression of lateral shoot growth was hastened by stem injection with GA(3) (200 microg/plant), especially when applied to the uppermost shoot at the end of the Sprouting Phase. Reimposition of dominance was delayed, however, by (1) high rates of N:P:K fertilization, (2) low temperature (20 versus 25 degrees C) under relatively long days (13 and 15 h), (3) low photon flux density (160 micromol m(-2) s(-1)) and (4) severe defoliation. Plant orientation had no effect on bud activity of decapitated plants, but affected the relative vigor and orientation of new lateral shoots. High temperature (25 versus 20 degrees C) and injection with GA(3) increased the erectness of newly developing lateral shoots. 相似文献