Apical Dominance and Flower Initiation in the Rose

The initiation of leaves and flowers by selected axillary buds of the glasshouse rose cultivar Sonia (syn. Sweet Promise) has been studied both while their extension growth was inhibited by apical dominance and after the inhibition had been removed at one of two times (“early” or “late”). Leaf initiation occurred during growth inhibition so that leaf primordia accumulated in the axillary buds. Flower initiation began, with both treatment times, only after removing apical dominance. Although the total number of leaf primordia formed before the flower was greater in plants of the “late” treatment, the axillary shoots produced in both treatments had similar numbers of leaves with expanded leaflets. Thus many leaf primordia of the “late” treatment plants became scales. The evidence suggests that flower initiation cannot begin while an axillary bud is subject to apical dominance, and that after its removal another factor results in the production of shoots with a relatively constant number of leaves with expanded leaflets.     

Relations Between Growth of Leaves,Fruit and Shoot of Glasshouse Tomato Plants

The weekly rates of shoot extension and total growth in leaf length of the glasshouse tomato variety Potentate increased from germination until soon after the start of ovary swelling. It is postulated that when, or soon after, the first flower primordia were initiated, an internal reaction was stimulated that eventually resulted in the cessation of the progressive increase in the rates of shoot extension and growth in leaf length. Increase in the rate of vegetative growth ceased soon after the start of ovary swelling, but this occurred even when no ovaries were allowed to swell.

The diameter of the shoot was unaffected by removal of leaves but increased when no fruits were allowed to develop. Conversely, shoot extension growth was unaffected by removal of fruit but decreased when alternate immature leaves were removed, although the removal of mature leaves had no effect on shoot extension growth.

Removal of leaves was associated with a reduction in total fruit volume and an increase in total leaf length.

Removal of immature fruit was associated with an increase in total leaf length. Removal of alternate immature fruits had little effect on total fruit . volume ; the difference between normally fruiting plants and plants from which alternate fruits had been removed was less than 0?5%.     

菊花花芽分化期超微弱发光及生理代谢的变化

 研究了菊花花芽分化期超微弱发光（UWL）,呼吸速率和ATP、可溶性糖、可溶性蛋白含量的变化。结果表明,菊花花芽分化起动期（II）与未分化期（I）相比,UWL强度增加119.3%,呼吸速率提高102.4%,ATP含量增加148.6%,可溶性糖增加95.5%,可溶性蛋白增加18.3%;在总苞鳞片分化期（III）、小花原基分化期（IV）和花冠形成期（V）,UWL强度、呼吸速率和ATP含量逐渐下降,可溶性糖在IV和V期下降幅度很大并接近对照水平,可溶性蛋白在II、III和IV期保持较高水平,在V期下降幅度较大,但仍比对照增加14.0%;而长日照处理的对照菊花UWL强度、呼吸速率以及ATP、可溶性糖和可溶性蛋白含量基本保持较稳定水平。显示菊花花芽分化期叶片UWL水平与呼吸速率和能量代谢密切相关。     

荔枝环剥时期对新梢生长及碳素储备的影响

 枝梢环剥显著抑制了‘怀枝’荔枝新梢的生长，并导致射线细胞和髓部大量积累淀粉。梢芽萌发或伸长前环剥可完全抑制新梢生长，而新梢快速伸长期环剥对其抑制效应最弱。秋季环剥对新梢的抑制和对淀粉积累的促进效应明显高于春季环剥。环剥口以上的老叶面积和环剥位置并不影响环剥对新梢生长的抑制效应和促进淀粉的积累效应，但环剥口以上单位枝梢长度的叶面积与淀粉含量呈显著正相关。     

Characteristics of Dormancy of June-Bearing Strawberry(Fragaria Xananassa Duch. cv. Elsanta)

Abstract

The development of Fragaria xananassa Duch. cv. Elsanta was analyzed during summer and fall in order to define the sequence of growth alteration and dormancy with regard to inflorescence initiation. The leaf growth as well as the initiation of the inflorescence buds were followed in the fall by conditions imposed in a climate chamber, with plants then being transfered to conditions favorable for growth. Results pointed to clear changes in leaf growth characteristics over the late summer-early fall (September-October) period while the leaf emergence rate remained constant up to mid-October when it stopped. The first sign of inflorescence initiation started in early October, and the differentiation of the terminal flower reached the stamen initiation stage within 2 weeks. From early November, the terminal flower had initiated the carpel primordia and no further differentiation was detected later on. The plant growth potential, expressed by the size, at full growth, of the leaf or inflorescence axis emerging from the terminal bud, decreased progressively from early September and reached a minimum between October and November. By mid-December, the growth capacity of the plant was restored to a situation similar to that described for early September.     

The effect of sucrose on the expression of the VvTFL1 and VFL genes during flower development in the “Xiangfei” grapevine

VFL and VvTFL1 genes expression patterns and the effects of sucrose on the expression of VFL and VvTFL1 genes in different organs of the “Xiangfei” grapevine (Vitis vinifera L.) were investigated. VvTFL1 gene expression was detected in the meristem of the apical bud and lateral bud, but was not detected during inflorescence differentiation and flower organ development. After sucrose treatment, VvTFL1 gene expression increased in the apical bud, but decreased in the lateral bud. These results suggested that the VvTFL1 gene might be mainly involved in the apical growth process of shoots, and exogenous sucrose had an effect on the VvTFL1 gene by increasing shoot apical meristem initiation of apical buds. The VFL gene was expressed primarily during inflorescence differentiation and early flower organ development, but it gradually reduced in later flower development. After sucrose treatment, VFL gene expression increased in the inflorescence and small or middle flower, but a little change was seen in the large flower. These results suggested that the VFL gene plays important roles in the initiation of inflorescence meristems and the morphological formation of flower organs. Exogenous sucrose had an effect on VFL gene expression at the early stage of flower development.     

茶树新品种‘石阡苔茶’

‘石阡苔茶’是从贵州省石阡县收集的地方品种中选出的中生、优质、中产、抗逆性强的绿茶新品种。灌木,中叶类,树姿半开张,分枝密。春茶独芽产量750 kg · hm^-2,夏秋茶一芽二叶产量6 000 kg · hm^-2。芽叶黄绿,茸毛中等,持嫩性强。适制单芽或一芽一叶类名优绿茶,色泽绿润,栗香持久,滋味醇厚,汤色黄绿明亮。适合贵州和武陵茶区栽培。     

Observations on the Winter Dormancy of tea (Camellia Sinensis L.) in Malawi

In Malawi, over 80 % of the tea yield is harvested during the five months of the hot, wet, tropical summer. Characteristics of shoot growth were examined to define the nature of the fall in yield during the subsequent winter months of May to August. Slower shoot extension and more apical bud dormancy reduced the rate at which shoots reached harvestable size in winter. No changes were observed in other characteristics of shoot growth such as individual shoot weight, shoot death or dormancy of the axillary buds in their initial state. During the winter there was a stimulation of root growth and the low yield was possibly related in part to a redistribution of assimilate. Altering the photoperiod had little effect on yield but maintenance of warm night temperatures (20°C) during parts of the cold season accelerated the rate of shoot growth to a level as high as that of the hot, wet season.     

郁金香更新鳞茎发育的碳同化物积累与内源激素变化研究

 应用扫描电镜和¹⁴C同位素标记技术, 并结合内源激素测定, 考察郁金香更新鳞茎膨大发育与碳同化物积累、分配的关系。结果表明: 在鳞片细胞内观察到明显的淀粉颗粒, 并随鳞茎的发育进程充满整个细胞腔。在盛花期前, ¹⁴C同化物主要分配到地上部; 进入叶枯期后¹⁴ C同化物以向地下部运输为主,分配比例达66.01% , 其中更新鳞茎中¹⁴C同化物的分配占60.85% , 这时¹⁴C库活性表现为: 鳞茎>叶片>花茎>根系。在郁金香更新鳞茎发育进程中, 叶片中GA、IAA含量呈下降趋势, ABA含量则不断增高并在盛花期出现峰值, 达65.86 ng·g^{- 1} FM。比较不同生育期的GA₃ /ABA比值, 在发叶期的叶片和盛花期的更新鳞茎中均出现高比值, 表明内源激素的平衡可能是郁金香更新鳞茎发生和发育的调节因子。     

The effect of ethephon on the growth and development of Liatris spicata

Summary

The first experiment studied the effect of applying ethylene biosynthesis regulating compounds (ethephon 1000 ppm, silver thiosulphate 0.4 mM and cobalt chloride 5 mM) on the growth and development of Liatris spicata cv. Callilepis. The results pointed to the important growth retardant properties of ethephon and the increased number of flowering stems per corm which could be obtained by pre-planting application. A second experiment aimed to optimize ethephon treatment in Liatris by applying the growth retardant in different concentrations (100, 700, 1300, 1900 and 2500 ppm) at three stages of development: stage I (pre-planting), stage II (immediately after the formation of basal leaf rosette) and stage III (when the main shoot began its rapid longitudinal growth). Besides confirming the effects produced by ethephon in the first experiment, the results suggested that the application of high ethephon concentrations (1900 and 2500 ppm) during stage II of growth produced many miniature flowering stems coming from the principal or secondary shoot.     

Influence of shoot age on floral development and early fruit set in avocado (Persea americana Mill.) cv. Hass

Floral bud development, early fruit set, bud size, leaf nitrogen and shoot starch content were recorded in spring, summer and autumn shoots of ‘Hass’ avocado (Persea americana Mill.). Floral initiation occurred in late autumn, but only in buds on terminal shoots (the last-formed shoot module on a terminal or axillary growth axis). In branching systems with three growth flushes, more flowers were produced and more fruit set on autumn and summer, than on spring flush terminal shoots. Floral development and leaf nitrogen accumulation occurred later in autumn than in summer shoots, but leaf numbers, dry and fresh weights, starch content of wood, mean floral status at anthesis and anthesis date were similar. The results suggest that nitrogen and starch were present in excess during floral development, and that shoot age did not influence the ability of a shoot to flower and set fruit, provided the shoot had sufficient vigour to produce new shoot growth in spring.     

Patterns of 14C-sucrose translocation in egg plant (Solanum melongena L.)

Summary

Patterns of distribution of ¹⁴C-sucrose were determined in egg plant (Solanum melongena L.) cv. Arka Shirish at the vegetative, flowering and fruit development stages. 5 μCi of ¹⁴C-sucrose was fed to the fifth leaf from the top at each growth stage and the plants were harvested, 48 h after feeding or at later stages, and the distribution of ^l4C-sucrose determined. Results indicated bidirectional transport of assimilates to both apical and basal portions of the stem. Within 48 h ¹⁴C moved to all the plant parts; roots, stem and leaves appeared to be strong sinks until the fruit began to develop. In plants fed at the fruit development stage, the fruit below the fed leaf were a major sink, although considerable activity was traced in other plant parts also. Only at later stages of crop growth did the fruit become a strong sink. Even at the fruit development stage, about 5-8% of the activity was still found in the roots and no retranslocation to fruit was observed.     

Clonal propagation of Rosa clinophylla Thory. through axillary bud culture

A protocol for clonal propagation of Rosa clinophylla, a rare and endangered species but very important for breeding purposes had been standardized through in vitro axillary bud culture. Although cytokinins alone were able to induce shoot buds, but their proper growth and number could be increased only when they were used in combination with GA₃. However, there was shoot tip necrosis and leaf fall in the proliferated shoots. AgNO₃ at 58.85 μM proved effective to avoid shoot necrosis and yellowing of leaves. Activated charcoal (AC) at 250 mg l⁻¹ was found necessary at all the stages of shoot multiplication as well as rooting. Ninety percent rooting could be achieved in 1/2 MS medium supplemented with 4.92 μM IBA and 250 mg l⁻¹ AC. Rooted plantlets were hardened and transferred to the field successfully with 80% survival rate.     

Growth of Betula pendula Roth. the first season after transplanting at two phenological stages

The root extension rate of Betula pendula, transplanted at two phenological stages, was studied in a Nordic climate. Landscape-size trees were transplanted from the field into root-study boxes (rhizotron) in early and late spring of 1999 and 2000. In early spring, 6 trees were transplanted when the leaves had just started to unfold; likewise, in late spring, six trees were transplanted when the leaves were fully unfolded and the shoot extension was in progress. Root growth was recorded during the first post-transplant season and the tree roots were finally excavated. Results indicate that the root extension rate of B. pendula follows seasonal soil temperature. The mean root extension rates at ten days intervals varied from 4 to 11 mm/day with a total average for the growing season of 7 mm/day in 1999 and varied from 4 to 9 mm/day with a total average for the growing season of 4 mm/day for 2000. The average length of new roots was 89 cm and there was no significant difference in length, dry weight or number of new roots between the two transplant times. It appears, therefore, that the phenological stage at transplanting during the period from bud break to fully developed leaves has minor effect on landscape establishment of B. pendula, when an adequate amount of water is provided.     

Direct somatic embryogenesis and adventitious shoot formation from immature axillary buds of Melastoma affine

Summary

Direct somatic embryogenesis and adventitious shoot formation were induced from immature axillary bud explants of Melastoma affine cultured on induction medium containing both naphthaleneacetic acid (NAA) and cytokinins. Among the cytokinins tested, thidiazuron (TDZ) played a greater role in the induction of somatic embryogenesis than 6-benzylaminopurine (BA) and kinetin (KT). Histological studies of paraffin sections showed that the same tissue from immature axillary buds produced different types of explants that developed floral primordia and vegetative bud primordia during the earlier and later flowering stages, respectively. These could result in different developmental pathways. Efficient mass propagation and plant regeneration systems were established for Melastoma affine.     

Flower initiation and development in the glasshouse rose

The initiation and development of a rose flower has been divided into a sequence of ten developmental stages. These numbered stages were used as a standard scale to follow flower development in various treatments for a number of cultivars. Flower initiation took place soon after stem extension occurred in a previously inactive bud, usually about two weeks after removal of the marketable flowering shoot above the bud. All actively growing buds appeared to initiate flowers, indicating that the abnormality known as ‘blind-wood’ is caused by the subsequent abortion of developing flower buds. There were seasonal differences in the rates of development which varied considerably between cultivars. The scale of development outlined here may provide a useful criterion for the selection of cultivars for year-round production programmes.The importance of light level as a factor determining development and productivity is discussed and some comparisons are made between rates of development with continuous production and with a period of inactivity. It is concluded that the latter technique does not enhance development and if growth is resumed too slowly, development may be delayed by the lower temperatures and abnormalities may occur.A correlation between apical development and apical size is demonstrated.     

Reproductive and vegetative bud differentiation in Olea europaea L.

Summary

The apical meristem of cv. Nocellara Etnea buds is described in the course of its anatomical progression, from July until bud break, the following spring. Differences in the apex of potentially vegetative and flower buds are already visible in the summer. In leaf buds the apex is a round dome, with two buttresses determined by leaf primordia. The cells of the outer layers are arranged in concentric rings, distinguished by different conditions of the nucleic acids. In flower buds the apical dome is less prominent, and the outer cell layers are histologically quite uniform. These characteristics remain unchanged in flower buds, and are little modified in leaf buds, until December; in January flower bud differentiation becomes more active, and both bud types start developing with increasing intensity. Our observations postulate a very early anatomical separation of the two bud types, on which further environmental factors might determine the final differentiation process.     

Changes in apical morphology during floral initiation and development in pyrethrum (Tanacetum cinerariaefolium L.)

Summary

Changes in apical morphology during floral initiation and development in pyrethrum (Tanacetum cinerariaefolium L.) were investigated by scanning electron microscopy. The sequence of events may be divided into eleven stages of apical development which are distinctive in both morphology and size. The environmental stimulus promoting rapid flower initiation was demonstrated to be vernalization. Flower initiation occurred after four months under non-vernalizing conditions through an autonomous flower induction process. Devernalization was observed under short day (10 h daylength), low photon flux density (200 µmol m² s^?1) conditions. Apices were never observed to revert to vegetative growth after the initiation of the first involucral bract and therefore this was considered to be the developmental stage at which the apex was committed to generative development.     

苹果叶片营养分析适宜采样时期研究

在渭北高原以盛果期“红富士”苹果树为采样对象,在幼果速长期、春梢停长期、花芽分化期、果实采前膨大期、果实采收期定位采集叶片,分析叶片中的氮、磷、钾、钙含量,以确定合理的叶分析采样时期.结果表明:从幼果速长期到果实采收期,叶片中氮、磷含量持续降低,钾为“反抛物线”,钙为持续升高.通过对不同生长期叶片营养元素含量分析,认为花芽分化期为测定叶片氮、磷、钙的适宜采样时期,钾应在果实采收期或春梢停长期采样分析较为合理.