Seasonal changes in bud dormancy in relation to bud morphology, water and starch content, and abscisic acid concentration in adult trees of Betula pubescens

Annual cycles of change in bud morphology, bud burst ability, abscisic acid (ABA) concentration, and starch and water content were studied in mid-crown terminal buds of short shoots and underground basal buds of Betula pubescens Ehrh. In particular, we investigated the roles of ABA and bud water content in the regulation of bud growth. Basal buds differed morphologically from terminal buds of short shoots in that their leaf initials did not develop into embryonic foliage leaves and their total size did not increase significantly during summer. Bud burst ability, measured by forcing detached short shoots and stumps under controlled conditions, was maintained in the basal buds throughout the year, whereas the terminal buds of short shoots remained dormant until October, thereafter their bud burst ability increased gradually and reached a maximum in March-April. The ABA concentration of the basal buds was relatively constant throughout the sampling period (1-3 micro g g(DW) (-1)), whereas that of the terminal buds of short shoots, which was much higher (5-10 micro g g(DW) (-1)), showed a distinct seasonal cycle with a maximum from August to November. Bud ABA concentration decreased during the first 10 days of forcing, especially in basal buds. In both bud types, the amount of starch increased toward the autumn, declined in November, and was negligible in the terminal buds of short shoots between January and March, but in April, the amount was high again in both bud types. Water content varied characteristically in both bud types, although more distinctly in the terminal buds of short shoots, with an increase in spring before bud burst and a decrease during the summer until September. The significant morphological and physiological differences between the mid-crown terminal buds of short shoots and the underground basal buds may partly explain the characteristic growth habit of the basal buds and their development into coppice shoots after cutting the tree. The results also indicate a role for ABA in maintaining dormancy of the terminal buds of short shoots and emphasize the relationship between tissue water status and ABA concentration.     

Primary metabolite mobilization and hormonal regulation during seed dormancy release in Cornus japonica var. chinensis

The combination of gibberellin acid (GA) soaking with moist chilling plays a pivotal role in seed dormancy breaking. However, knowledge involving physiological and biochemical mechanisms for such a response is limited. This work focused on the effects of GA₃ and moist chilling on overcoming seed dormancy as well as the response of endogenous hormones and nutrient reserves to dormancy release in Chinese dogwood (Cornus kousa var. chinensis). Seeds subjected to GA₃ soaking and moist chilling exhibited a high germination percentage (average 97%), and the combination of 500 mg·L^?1 GA₃ soaking for 3 days followed with moist chilling for 50 days was more effective than other treatments. For GA₃ treatments, lipids were initially hydrolyzed during the first stage of moist chilling (0–20 days), resulting in the increase of starch and soluble sugars, while proteins were kept relatively stable. During the second stage (20–50 days), contents of lipids, starch, soluble sugars, and proteins decreased by 46%, 82%, 61% and 59%, respectively. Abscisic acid (ABA) contents and ratios of ABA to GA₃ in GA₃ treatments decreased by nearly 70% and over 90%, respectively, when dormancy was terminated. However, endogenous GA₃ contents in all treatments significantly increased with prolonged moist chilling. The present results provide insight into the metabolic mechanism involving hormonal regulation and mobilization of reserves during the release of seed dormancy in Chinese dogwood.     

Inhibition of flower bud formation inBetula platyphylla andBetula pendula by gibberellin (GA3) application

Birch (Betula) trees produce a large amount of pollen, which is a cause of serious pollinosis. To control the pollen scattering, we examined the inhibitory effect of gibberellin (GA₃) on flower bud formation of birch. Field-grown trees ofBetula pendula, nine years of age, were treated with a foliar spray of GA₃ (1, 10, and 100 mg L⁻¹),Betula platyphylla trees, 17–23 years of age, were treated with a stem injection of GA₃ (5, 50, and 500 mg per plant) in June or July, 1998. Male flower buds were not observed at the top of new shoots in June, but were observed in July. The number of inflorescence that emerged from randomly sampled branches was counted the next spring. The foliar spray of GA₃ in June at the dose of 10 or 100 mg L⁻¹ decreased the number of inflorescence. Stem injection in June at a dose higher than 50 mg per plant completely inhibited flower bud formation, although it increased bud mortality in some trees. The most effective dose of GA₃ for stem injection to inhibit flower bud formation was between 0.04 and 0.44 mg per cm² of stem cross-section area at breast height. These results indicate that GA₃ applied during the period of floral differentiation markedly inhibits flower bud formation in birch.     

Promotion of cone production on white spruce grafts by Gibberellin A4/7 application

White spruce [Picea glauca (Moench) Voss] grafts growing in a seed orchard were sprayed with gibberellin A_4/7 (GA_4/7), either at different periods of time during the growing season or in different concentrations, for a 3-year period. Whole-tree spraying in May through July 1983 significantly increased cone production in 1984, while spraying in June through August of the same year was not effective. The best treatment in branch spraying was at the highest concentration (800 mg/L GA_4/7). The spray was effective in a good, but not a poor, crop year. Vegetative budburst occurred in the first half of May and shoot elongation ended in late June. Needle primordia in a newly formed bud were not discernible until the end of June. Application of GA_4/7 during the period of bud scale initiation and shoot elongation, and before needle primordial initiation, could have influenced the course of bud differentiation to increase the formation of reproductive buds.     

油松种子萌发初始阶段的呼吸代谢

呼吸代谢是一切生物所共有的生理功能,其重要作用是释放能量供各种代谢的需要。种子萌发过程中糖氧化降解是通过呼吸代谢途径进行的,胚乳中的糖需经氧化分解才能为胚的生长提供可利用的能量,并为新器官、新组织的形成提供重要原料(傅道昭,1980)。种子萌发过程不同的呼吸代谢途径为胚的生长提供不同的能荷和还原力,呼吸代谢途径及强度的转变影响种子萌发的正常进行,因此研     

长蕊杜鹃扦插内源激素变化及解剖结构观察

以野生长蕊杜鹃半木质化茎段为试材,采用植物生长激素KIBA,KNAA和Hormodin对插穗进行处理,测定不同生根期内源激素IAA、GA3、ZR、ABA含量,对扦插不同时期插穗茎段进行电镜扫描。结果表明:先快蘸液态KNAA(3 000mg·L-1),再迅速蘸取粉状Hormodin#1处理对插条生根具有显著影响,插穗生根率达到了81.25%;较高浓度的内源IAA含量有利于根原基分化形成,GA3含量上升与插穗愈伤组织的诱导、不定根的形成呈正相关性,低水平的ABA更有利于长蕊杜鹃扦插生根;插穗在根原基分化和愈伤组织形成时期消耗內源ZR,在不定根长出后自身合成ZR;通过对淀粉粒研究表明扦插期补充糖类物质是必要的,簇状晶体产生表明钙调控等生理机制形成。     

高浓度6-BA诱导酸樱桃苗的玻璃化苗内源激素含量变化

研究了培养基中不同浓度6-BA对酸樱桃组培苗玻璃化率及内源激素含量的影响,利用酶联免疫吸附分析法测定正常苗与玻璃化苗愈伤组织和芽中IAA、GA3和ZR含量.结果表明:高浓度6-BA导致组培苗玻璃化,当培养基中6-BA浓度为0.5 mg·L-1时,组培苗未出现玻璃化苗;当培养基中6-BA浓度为3.0 mg·L-1时,组培苗玻璃化率高达95%.通过玻璃化苗和正常苗内源激素比较发现,玻璃化苗愈伤组织IAA和GA3含量明显高于正常苗愈伤组织中IAA和GA3含量,ZR含量基本相等;玻璃化苗芽中ZR含量远远低于正常苗中ZR含量,而IAA和GA3含量基本不变,高浓度6-BA导致组培苗内源激素比例失调发生玻璃化.     

Effects of fruit thinning on ascorbate–glutathione cycle metabolism in black currants (<Emphasis Type="Italic">Ribes nigrum</Emphasis> L.)

To elucidate mechanisms regulating ascorbic acid (AsA) biosynthesis and accumulation in the fruit and leaves of black currants, AsA and the activities of key enzymes in the ascorbate–glutathione (AsA–GSH) cycle were measured from fruit set to fruit ripening during fruit thinning treatments of three common commercial black currant cultivars that differed in their AsA levels: ‘Risager’ (low), ‘Brodtrop’ (medium) and ‘Adelinia’ (high). Treatments were 50% fruit reduction (50% of total fruit set) by hand, control was no thinning. Fruit thinning treatment significantly increased AsA content in fruit of all three cultivars from weeks 2 to 8, significantly decreased AsA content in leaves from weeks 3 to 8. Dehydroascorbate reductase and monodehydroascorbate reductase activities in fruit and leaves had a similar pattern, increasing during week 2, rose until they peaked in week 4. Ascorbate peroxidase activity in fruit in the thinning treatment was slightly lower than in the control. Fruit thinning was shown to be a good model to test AsA biosynthesis regulation and accumulation in black currants. The results from our study provided strong evidence that AsA–GSH cycle involved in AsA synthesis and accumulation in fruit.     

Chemical pre-treatments improve seed germination and seedling growth in <Emphasis Type="Italic">Semecarpus kurzii</Emphasis>: an ethnomedicinally important plant

Semecarpus kurzii Engl. is an important ethnomedicinal plant used for curing tumours, inflammation, fever and pain, and is also a source of iso ricinoleic acid. During the present investigation, effect of chemical pre-treatments on germination and seedling growth revealed significant differences. Different pre-treatments could improve germination and treatment with KNO₃ (9.9 mM) was significantly superior (94%) to the untreated control (76%). Mean daily germination varied among the treatments (0.90–4.14 seeds per day), when compared with 2.27 seeds per day in control. Mean germination time was significantly reduced from 22.14 days (control) to 16.40 days (19.8 mM KNO₃) and 17.16 days (1.45 mM GA₃). Treatment with KNO₃ (19.8 mM) and GA₃ (1.45 and 2.90 mM) significantly reduced the time for 50% germination. Treatment with higher concentrations of GA₃ and KNO₃ exhibited significantly faster germination initiation (11.0 and 12.0 days, respectively) over the control (17.0 days). Seedling vigour index was not improved by pre-treatments. Chemical treatments did not improve shoot growth, collar thickness, or number of seedling leaves; however, root growth was significantly improved over control. Treatment with GA₃ (2.90 mM) promoted leaf elongation but reduced leaf width significantly. Treatment with KNO₃ and GA₃ could be recommended to obtain healthy seedlings for establishing new plantations of this important medicinal plant species.     

不同生长调节剂处理对卡特兰开花的影响

通过花鞘注射生长调节剂的方法,研究不同浓度的生长调节剂对卡特兰开花和开花性状的影响,结果表明:注射GA₃浓度为60、120 mg·kg^-1,卡特兰盛花期显著提前13.34、22.34 d,萼片、花瓣、花柄和花葶的长度显著增加;注射10 mg·kg^-1的NAA能够使花期提前,花朵显著增大;注射ABA对卡特兰的花期没有影响,注射ABA浓度为40 mg·kg^-1时,开花率下降,花朵缩小。注射60 mg·kg^{-1相似文献}   

The effect of cold stress on endogenous hormones and CBF 1 homolog in four contrasting bamboo species

An unusually severe snow disaster in southern China in 2008 exposed variation among different species of bamboo: some species were highly tolerant to low-temperature damage, but some suffered extensive damage or death. Therefore, this study was conducted to determine the effects of cold stress on endogenous hormones and the expression of homologs of CBF ₁ in four bamboo species differing in their tolerance to cold. All four bamboo species were subjected to cold stress with a temperature gradient (10, 5, 0, −5, and −10°C), and each low temperature treatment was maintained for 48 h. Results showed that ABA, GA₁, and GA₄ were significantly affected by cold stress: ABA increased with cold stress in all species, while GA₁ and GA₄ reduced with cold stress. ABA levels and the ratio of ABA/(GA₁ + GA₄) in leaves of Neosinocalamus affinis and Bambusa rigida were both higher than those of hybrid bamboo (Bambusa pervariabilis × Dendrocalamopsis grandis) and Dendrocalamus latiflorus for all treatments, while GA₁ and GA₄ were conversely lower as compared to the hybrid variety and D. latiflorus. Moreover, CBF ₁ homolog was up-regulated during cold stress, with higher expression levels in the leaves of cold-tolerant species than cold-sensitive ones. Results revealed that high levels of ABA and CBF ₁ , as well as the ABA/GA_s balance, are important in increased plant resistance to cold stress.     

核桃子苗砧嫁接及相关生理指标的研究

2004年在北京门头沟区科技开发实验基地研究了核桃子苗嫁接技术和核桃子苗砧嫁接过程中相关生理指标的变化.结果表明:2 000 mg·L-1GA3浸泡种子、摘心处理能显著提高砧木茎粗度;愈合环境温度控制在26 ℃,锯末含水量控制在410 g·kg-1,箱上打孔,嫁接成活率可达80%以上;子苗展真叶1 ～10片时,IAA、GA3、ZR含量与IAA/ABA值相对较高;砧穗愈合过程中,砧木的可溶性糖、蛋白质含量与IAA/ABA值先降后升再降,PPO活性呈相反趋势,IAA、GA3、ZR含量先降后升,ABA含量一直呈缓慢上升的趋势.     

Effect of nitrogen in combination with elevated temperatures on insects,microbes and organoleptic characteristics of stored currants

In the present study, the effect of nitrogen, applied as a controlled atmosphere treatment on the microbial and entomological loads, as well as on the organoleptic characteristics of stored dried currants (Corinthian raisins, Vitis vinifera L. var. Apyrena), was investigated. Trials were conducted under “real world” conditions, in the nitrogen chambers of a commercial facility, in which nitrogen was introduced by using an incorporated nitrogen generator. Prior to the initiation of the trial, chambers were filled with pallets carrying dried black currants. Subsequently, currants were artificially infected with all life stages of Tribolium confusum, eggs and larvae of Ephestia elutella and adults of Oryzaephilus surinamensis. Currants were exposed for 3 days in nitrogen (O₂ concentration <1 %) at two temperature levels, 25 and 38–43 °C. After treatment, insect mortality was recorded and currant samples were collected and forwarded for microbial analysis and determination of their organoleptic characteristics. When nitrogen was applied at 25 °C, high insect mortality levels were noted; however, in most cases there were a number of insects that survived the nitrogen treatment. In contrast, complete control was achieved at 38–43 °C for all insect species and life stages tested, with the exception of T. confusum larvae. Nitrogen application at 25 °C had no effect on total microbial and yeast and mould counts, while both were reduced at 38–43 °C. Sensory attributes of Corinthian currants remained acceptable after nitrogen fumigation, although taste, odour, aroma and overall acceptance were affected by the treatments. Total phenolic as well as 5-hydroxymethylfurfural content increased after nitrogen application at 38–43 °C, while the lower temperature applied had no effect. The results of the present study suggest that nitrogen-based controlled atmosphere at elevated temperature could be a valuable tool for ensuring clean, pest-free, hygienic standards in dried Corinthian currants.     

Morphological and biochemical changes of Aesculus chinensis seeds in the process of maturation

Morphological and biochemical changes of Chinese horse chestnut (Aesculus chinensis Bge.) seeds were studied during the process of maturation. Fruit and seed diameter increased linearly from DPA (Days Post Anthesis) 60 to DPA 150 and were stable thereafter. The weight of fruit and seed increased sigmoidally between DPA 100 and DPA 160. The water contents of whole seeds, axes and cotyledons had a sharp reduction from DPA 110 to DPA 130 but changed little after DPA 130. The water contents of whole seeds, axes and cotyledons were 1.42, 1.93 and 1.30?g?g^?1DW, respectively at the end of maturation. The starch content of cotyledons from mature seeds was high on a dry weight basis (31.4%) while the total soluble sugar content varied between 12 and 20%. In both axes and cotyledons, the total soluble sugar content decreased during the process of maturation, as did all five soluble sugar components measured (glucose, sucrose, trehalose, raffinose and stachyose). Sucrose and stachyose contents remained relatively high at the time of seed maturation, followed by glucose and a trace level of trehalose. The oligosaccharide/disaccharide (O/D) ratio in the axes was 3.1 at DPA 140. The high level of sucrose and stachyose might contribute to the greater desiccation tolerance of Aesculus chinensis seeds relative to typical recalcitrant tropical seeds. High levels of ABA content in seed coats and a low GA₃/ABA ratio in both seed coats and axes might also influence the desiccation tolerance and shallow dormancy of mature Aesculus chinensis seeds.     

Quantitation of gibberellins A9, A1 and A3 in relation to flower bud differentiation in Picea abies

Endogenous gibberellin A₁ (GA₁), GA₃, GA₄ and GA₉ were quantitated in elongating shoots of Norway spruce [Picea abies (L.) Karst.] grafts with a good or a poor flowering history. The grafts were grown either in a natural environment outdoors, cool and wet (CW) treatment, or in a greenhouse with elevated temperatures and controlled drought stress, hot and dry (HD) treatment. The GAs were quantitated by gas chromatography‐mass spectrometry selected ion monitoring (GC‐MS SIM) using deuterated GA₁, GA₃, GA₄ and GA₉ as internal standards. Terminal shoots from the second whorl of branches were harvested at 76%, 86% and 96% shoot elongation for the CW treated grafts and at 90% and 99% shoot elongation for the HD treated grafts. The content of GAs in the CW grafts was highest during most rapid shoot elongation, GA₉ being the dominant GA. The levels decreased as shoot elongation ceased. This was also noted for GA‐content in shoots of the HD treated grafts. A comparison of the GA‐amounts at ca. 96% of total shoot elongation for the CW treated grafts and ca. 99% of total shoot elongation for the HD treated grafts revealed that shoots of the good flowering clone had a higher content of GA₉ and a lower content of GA, and GA₃. When comparing the HD treated and CW treated grafts, the shoots of HD treated grafts contained higher concentrations of GA₉ but lower concentrations of GA, and GA₃. Calculating the ratios between [GA₉] and [GA₁] resulted in a ratio of 12.5 and 36.6 for the good flowering clone grown outdoors and in greenhouse, respectively. The same ratios were for the poor flowering clone 1.45 and 3.8 when grown outdoors and in greenhouse, respectively. A higher ratio may indicate a higher capacity of synthezise the importance of flowering GA₄ from GA₉ and a lower conversion of GA₄ to GA₁, thereby favouring the diffentiation to reproductive buds.     

Effects of winter buds on winter nitrogen uptake and allocation in Pinus densiflora saplings

Studies of nitrogen (N) use by plants have confirmed some winter N uptake; however, the mode of regulation of plant N use in winter is unknown. The regulation of N use by plants during winter may differ from that in the growing season, as plant growth strongly affects N use. We investigated the effects of winter buds on winter N use by Japanese red pine (Pinus densiflora), as a previous study demonstrated that N absorbed during winter contributes significantly to leaf growth in the following spring. We conducted a bud pruning experiment during winter to examine the effects of winter buds on winter N uptake and allocation among plant organs using ¹⁵N labeling. Over a three-week labeling period, the ¹⁵N content in roots increased to 0.20 ± 0.12 mg N g DW^?1, which is equivalent to 1.8 ± 1.1 % of the total N content in the roots. However, this absorbed ¹⁵N rarely appeared in needles and buds. Bud pruning did not affect ¹⁵N uptake and allocation. On the other hand, significant total N retranslocation was found within the crowns of saplings without bud pruning, but N was not retranslocated in bud-pruned plants. The bud pruning experiment indicated that N was retranslocated from needles into winter buds. Since soil N availability changes dramatically and is unstable in many forest ecosystems, N contained in needles would be a more stable source of N than newly absorbed N.     

Atmospheric carbon dioxide enrichment reduces carbohydrate and nitrogen reserves in overwintering Picea mariana

Abstract

Elevated levels of atmospheric carbon dioxide (CO₂) can directly affect the cold hardening process in evergreens through their effect on the accumulation of carbon and nitrogen reserves. This study investigated the biochemical responses of black spruce [Picea mariana (Mill.) B.S.P.] seedlings to CO₂ enrichment during growth, cold hardening and dehardening. Seedlings were grown under 350 (ambient) or 710 (elevated) ppm of CO₂ for 12 months in eight mini-greenhouses. Photoperiod and temperature were gradually lowered in autumn to induce cold hardening, and the conditions were reversed in spring to promote dehardening. At regular intervals, cold tolerance was assessed and sugars, starch and amino acid concentrations were measured. The freezing tolerance differed between the two treatments only in early autumn, with seedlings growing under high CO₂ being more tolerant. The northern ecotype was more cold tolerant with concomitant higher concentrations of sucrose, fructose, pinitol, glucose and total soluble sugars. The concentration of soluble sugars increased in needles and roots of black spruce along with cold hardening, and the concentrations of the cryoprotective sugars sucrose and raffinose were lower under elevated CO₂. Amino acid concentrations were also lower under elevated than under ambient CO_2. The lower level of reserve did not translate into a lower level of freezing tolerance.     

Physiological Characteristics and Carbohydrate Contents of Spring-lifted Picea glauca Bareroot Seedlings Following Low-temperature Storage

This study examined the effects of low-temperature storage of white spruce [ Picea glauca (Moench) Voss] bareroot seedlings to determine whether the time between lifting and planting of spring-lifted seedlings could be extended. Seedlings were lifted from the nursery beds on May 4, 1994, and stored at- 2C (frozen storage) and 4C (cold storage) for 3, 5 and 7 weeks. Frozen storage of spring-lifted seedlings resulted in an increase in sugar levels in roots and needles that progressed with storage duration. Seedlings stored in cold storage maintained a relatively constant sugar content. Needle starch content decreased with storage duration in both frozen and cold storage. In the roots of cold-stored seedlings, starch content remained relatively constant during storage; however, in the frozen-stored seedlings, root starch levels sharply declined during the initial 3 weeks of storage. The levels of total non-structural carbohydrates (starch and sugars) decreased in both types of storage in needles, but not in roots. However, the decrease was more pronounced in the cold-stored than in the frozen-stored seedlings. Gas exchange, root growth potential and number of days to bud break were similar in frozen- and cold-stored seedlings planted in the greenhouse. However, following planting in the forest, cold-stored seedlings flushed buds earlier than did frozen-stored seedlings. The results indicate that tree nurseries could consider frozen storage of spring-lifted white spruce seedlings to facilitate lifting and planting schedules.     

氮磷钾配比施肥对油茶花芽生长及分化的影响

为给油茶高效栽培提供参考,选择8年生‘长林53号’油茶作为研究对象,按照3因素3水平L9(34)正交试验设计进行施肥试验,筛选最适油茶花芽分化及生长的施肥配比。施加的氮磷钾肥分别为尿素、钙镁磷肥、硫酸钾肥,其有效成分分别为有效氮(质量分数≥46.4%)、P2O5(质量分数≥12%)、K2O(质量分数≥51%)。结果表明:施加氮肥能显著促进花芽伸长,提高花芽分化率的最佳氮磷钾施肥量为N218.23g/株、P71.00g/株、K242.48g/株;在花芽生理分化期(前分化期),施肥处理显著提高了花芽中ABA和ZR含量,ABA和ZR含量与花芽分化率显著正相关;在花芽形态分化期,施肥处理下ABA含量呈现下降趋势,ZR、IAA和GA3含量呈现增加趋势,氮、磷、钾与多数形态分化期内源激素含量呈显著相关。施肥能促进花芽生长,并且通过影响花芽中内源激素含量来影响花芽分化。     

1年生泡桐不同部位顶芽内源激素的动态变化

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。