The Gravitational Responses of Young Apple Trees

A distinctive seasonal pattern in the outgrowth of shoots was observed in upright maiden apple trees. Until midsummer, extension shoot growth was confined to the apical region of the trunk. After midsummer, vigorous shoots grew from the basal region of the trunk, and the production of these shoots coincided with a decline in growth rates of shoots in the apical region. A similar pattern of shoot growth was evident in trees grown in horizontal and inverted positions but was modified by the effects of gravity, viz. growth curvatures, effects on the symmetry of shoot production about the axis, and changes in the vigour of shoots in the apical and basal regions of the trunk. Growing trees in horizontal and inverted positions caused a reduction in terminal extension growth, but did not reduce the total amount of shoot growth compared with vertically-grown trees. Changing the orientation of the trunk caused differences in the pattern of axillary flower bud formation, but had no detectable effect on the total numbers of flower buds initiated.     

桃、杏枝条萌芽前对~(15)N—尿素的吸收和萌芽后的运转与分布

在田间条件下研究了‘肥城桃’、‘红玉杏’萌芽前枝条对~(18)N—尿素的吸收及萌芽后的运转分布规律。结果表明:1.萌芽前‘肥城桃’和‘红玉杏’枝条对~(18)N—尿素具有一定的吸收能力,随着时间推移,吸收利用率有所上升,至6月2日二者分别可达27%～32%和29%.2.无论是桃或杏,对未着果的果枝来说,其新植叶片为萌芽前枝条所吸收~(18)N 最重要的“库”.3.对着果的果枝来说,果实为最重要的~(18)N“库”.4.果实能加强新生器官对于萌芽前枝条所吸收~(18)N 的“库”的作用.     

Controlling the growth and development of rose plants after planting

The effects of pinching and lateral bud removal (deshooting) on the development of structural shoots, the number of flowers, and the average flower stem length in young rose plants were examined, using the cultivars ‘Baccara’, ‘Sonia’ and ‘Belinda’. The effect of deshooting on flower yield varied with each cultivar. It did not affect the number of ‘Baccara’ flowers, but increased ‘Sonia’ and ‘Belinda’ flower production by 50% and 75%, respectively. Leaving flowers to bloom out on plants before the start of commercial harvest resulted in a decrease in the length of the flower stems and also reduced the beneficial effect of deshooting on flower yield. Deshooting enhanced structural shoot formation (“bottom breaks”). Pinching flower buds of structural shoots increased the number of ‘Baccara’ flowers in comparison with pruning these shoots to 40–60 cm, as in common practice. Deshooting of the structural shoots of ‘Sonia’ and ‘Belinda’ increased the number of flowers in both cultivars.     

Chilling response of ‘Granny Smith’ apple lateral buds inhibited by distal shoot tissues

Apple (Malus×domestica Borkh.) shoots were decapitated before or after chilling and then forced to budburst to determine the influence of distal inhibition (paradormancy) on the chilling response of lateral buds. Shoots were chilled and forced with the presence or absence of an inhibitory distal disbudded shoot piece. Endogenous cytokinins were determined from distal and proximal segments of shoots segmented before and after chilling and/or forcing. The isolation of lateral buds from distal inhibition by decapitation before chilling resulted in a dramatic increase in growth rate. This increase is greater than that observed in terminal buds during the normal development of acrotony on intact shoots. Distal shoot tissues appear to inhibit the chilling response of lateral buds. On intact shoots cytokinin increased more in the distal shoot tissues, but in decapitated shoots cytokinin increased more in the proximal shoot tissues. Increased cytokinin in the proximal stem segment following decapitation is possibly associated with an increased lateral bud growth rate.     

不同时期涂抹KT-30乳液对苹果幼树发枝的影响

以2 a生矮化中间砧"红富士"苹果幼树为试材,从萌芽前到7月份,对中心干延长枝剪口以下30～60 cm缺枝部位涂抹100 mg/kg KT-30乳液,研究不同时期涂抹KT-30乳液对促进苹果幼树芽体萌发及定位发枝的影响。结果表明:4月上旬、4月下旬、5、6与7月中心干延长枝剪口以下30～60 cm部位对照萌芽率分别平均为43.7%、6.07%、0%、0%与10.75%。涂抹KT-30乳液后,第7～10天芽体萌发,从萌芽前4月5日到生长季7月5日,各处理芽的平均萌芽率均大于80%,其中5月25日处理后萌芽率最高,为100%,与其它处理时期的差异极显著。4与7月处理的芽体成枝力低,多抽生为短枝,其中7月25日处理后成枝力最低,为0%,极显著小于其它处理时期的,并且抽生枝条成熟度较差。5月25日与6月10日处理的芽体成枝力高,分别为66.0%与57.6%,超长枝长度平均为66.7与91.1cm,枝条生长健壮,成熟度好。随处理时期的延后,枝干比呈现减小趋势,4、5、6与7月分别平均为0.43、0.40、0.38与0.28。     

Light quality regulates shoot cluster growth and development of MM106 apple genotype in in vitro culture

The interaction between shoot proliferation and regulative action of light quality was investigated in terms of cluster growth and development. In the commercial laboratory, the shoot multiplication procedure is normally conducted by growing clusters of shoots during several sub-cultures. Thus in this work the regulative action of light quality was evaluated by analysing the shoot cluster proliferation rate, the evolution of axillary bud differentiation, the axillary shoot development on both initial explant stem (order 1 axis) and three representative lateral branches (order 2 axes), growing from the lateral buds located at the bottom of the initial explant. Experiments showed that light qualities regulate bud differentiation and interact with apical dominance, leading to strong control of axillary bud outgrowth, and, finally, resulting in a differentiated architectural formation of clusters and type of branching.     

Stockplant factors affecting root initiation in cuttings of Triplochiton scleroxylon K. Schum., an indigenous hardwood of west africa

The ability of auxin-treated T. scleroxylon cuttings to root was affected by the prior management of potted stockplants. In undecapitated single-stem stockplants more cuttings from upper rather than lower mainstem nodes rooted; a difference paralleled by leaf water potential immediately after severance, although there was also a positive relationship with internode length. The rooting percentage of mainstem cuttings from unpruned stockplants ranged from 15% to 43% whereas that of cuttings from the lateral shoots of pruned stockplants ranged from 40% to 83%. Considerably more cuttings rooted from stockplants which were severely pruned than from those where decapitation removed only the top node; there seemed to be an inverse relationship with the number of shoots per plant and the carbohydrate: nitrogen ratio. However, in tall pruned stock- plants, more cuttings from lower lateral (basal) than from upper (apical) shoots rooted, although the differences between cuttings from basal and apical lateral shoots were less when the stockplants’ mainstems were orientated at 45° or kept horizontal, instead of vertically. Adding NPK 16 weeks before harvesting cuttings from 10-node vertical stockplants increased the rooting ability of cuttings from basal shoots without affecting the rooting of those from apical shoots. More lateral shoot cuttings rooted when two, instead of one or four lateral shoots were allowed to develop per stockplant, this being associated with less cutting mortality than occurred in pruned stockplants. In stock- plants with two shoots, cuttings from basal lateral shoots rooted better than those from apical shoots, although without competition from basal shoots. The rooting of apical shoots was enhanced by application of a complete fertilizer. The presence of basal shoots reduced the rooting ability of apical shoots even with the fertilizer application. Many of the effects of lateral branch position on rooting may be related to light intensity, for greater rooting percentages occurred among cuttings from lower, more shaded, than from upper less shaded branches. This positional effect was eliminated when branches were uniformly illuminated.     

The number of leaves required for floral induction and translocation of the florigenic promoter in mango (Mangifera indica L.) in a tropical climate

Mango flowering appears to be determined by a temperature-regulated florigenic promoter (FP) synthesized in leaves and translocated to buds in phloem. The number of leaves required for flowering was investigated in ‘Keitt’ and ‘Tommy Atkins’ mango trees exposed to tropical conditions in Colombia. Data were compared with a previous study conducted under cool, floral-inductive conditions in Florida (Davenport et al., 2006). Leaf-number treatments consisted of 0, 1/8, 1/4, 1/2, 1, 2, 3, or 4 leaves on each of 20–40 stems per branch. The long distance translocation experiment consisted of a terminal donor stem and five defoliated receiver stems on each treatment branch. Treatments were 0, 1, 3, or 5 leaves on the donor stem. Every treatment branch in both experiments was girdled to isolate it from the rest of the tree, and developing panicles were removed to stimulate lateral shoot initiation at a time when conditions were right for floral induction in those buds. Treatment stems bearing no leaves produced only vegetative shoots in both cultivars in both experiments. The minimum number of leaves per stem (1/8 of a leaf and 1/4 of a leaf) was sufficient to induce 6% and 1% reproductive shoots with 94% and 99% vegetative shoots in Tommy Atkins’ and ‘Keitt’ stems, respectively. Branches bearing 4 leaves per stem in ‘Tommy Atkins’ trees produced the maximum mean flowering response with 45% reproductive shoots and 55% vegetative shoots. The maximum ‘Keitt’ response was 22% reproductive and 78% vegetative shoots with 4 leaves per stem. The donor stem of the 1-leaf treatment and the donor and first receiver stem of the 3-leaf treatment in the translocation experiment were induced to flower in ‘Tommy Atkins’ trees. The more distal receiver stems from the donor were vegetative. The 5-leaf donor treatment-induced reproductive shoots as far as the third leafless receiver stem located 52 cm from the donor. Proportions of flowering shoots decreased with distance from the donor, and the level of the FP was apparently insufficient to reach the fourth and fifth receivers since their shoot responses were vegetative. Only vegetative shoot responses were obtained in the translocation experiment conducted in ‘Keitt’ trees. The leaf number and translocation experiment results support the hypothesis that far less FP is synthesized in both ‘Tommy Atkins’ and ‘Keitt’ leaves during warm, tropical conditions than is synthesized in ‘Keitt’ leaves exposed to cool, subtropical conditions.     

Manual and chemical induction of side-shoot formation in apple trees in the nursery

An experiment was set up to find a manual method for side-shoot formation as an alternative to the use of chemicals. On growing buds of 2 apple cultivars — budded August 1976 on M.9 rootstock — which often do not form laterals in the nursery (‘Red Boskoop’ and ‘Benoni’), the following treatments were carried out in the summer of 1977: decapitation (removal of the growing-point plus all young leaves); removal of the young leaves, leaving only the actual growing-point intact; spraying with 0.176% FR $\text{570}\text{3}$ (containing 0.15% May and Baker 25 105). All these treatments were applied at about 55 cm shoot length. In a separate series, the young-leaf removal was repeated at about 65–75 cm shoot length. Untreated trees served as controls.All treatments stimulated side-shoot formation; M&B 25 105 most of all. The manual treatments gave similar results with respect to total shoot number but not to height and orientation of the laterals or the vigour gradient along the stem. From the point of view of suitability of the side shoots (i.e. sufficient height above the soil and a large crotch angle), only the chemical treatment and the once-repeated removal of young leaves proved satisfactory. The latter method may offer an alternative to the use of chemical branching-agents.The results are discussed in relation to studies on apical dominance.     

Evidence for a translocatable florigenic promoter in mango

Movement of a putative florigenic promoter from leaves to buds was investigated in two cultivars of mango (Mangifera indica L.) over two flowering seasons through examination of the minimum number of leaves on each stem necessary for floral induction and movement of this component over various distances from stem to stem in isolated branches. The minimum number of leaves on individual stems necessary to induce flowering was less than 1/4 of a cross-cut leaf per stem. The putative florigenic promoter moved from donor stems bearing as few as one leaf to induce flowering in five receiver stems located as far down branches as 100 cm from the donor stem. Evidence suggests that movement of the putative florigenic promoter occurs in phloem and that far more of this component is available in trees than is necessary for floral induction of initiating shoots during cool, floral-inductive conditions of the subtropics.     

Differentiation of propagules and crop growth pattern in 20 pineapple cultivars

The growth pattern of 20 cultivars of pineapple (Ananas comosus (L.) Merr.), with particular reference to propagules differentiation, was studied under uniform, natural conditions over a period of 3 years. The propagules, depending on cultivar, were “suckers” (arising from below the soil, rooted), “shoots” (arising between the leaves), “hapas” (arising from the peduncle-base) and “slips” (arising at the base of the fruits). A few cultivars produced no slips or only a limited number of slips. In addition to the normal adaxial slips, abaxial slips were sometimes formed. “Crown slips” (arising at the top of the fruit) were occasionally encountered. Regular hapas production was confined to 2 cultivars. Marked variation existed in the pattern of shoot formation. Whereas in the majority of plants, shoots were found at regular intervals along the stem, in 2 cultivars the shoots grew as whorls at the base of the stem. Suckers were produced by all cultivars, with one prominent exception. The crown was most often single, but occasionally multiple and fasciated. Whereas bolting almost invariably preceded inflorescence emergence, in a few cases bolting was not followed by flower formation. The inflorescences of 2 cultivars constituted an exception in not having normal types of pigmentation. There were cultivar differences in the number of florets in an inflorescence. Many of the cultivars showed a distinct tendency for photoperiodic sensitivity.     

CaM在梨花芽分化过程中的含量变化

以梨为试材，对成花过程中的短枝芽和叶所含钙调素（ＣａＭ）的含量进行了测定。（１）短枝芽的ＣａＭ含量在整个成花前后都明显高于新梢芽的含量，特别是在成花的发端期突然成倍增加，形成高峰；（２）短果枝叶的ＣａＭ与新梢叶有着相近的变化趋势，但在成花前后，短果枝叶的ＣａＭ含量明显高于新梢叶；（３）ＣａＡｃ处理可以使短枝芽所含ＣａＭ的峰值提前出现，ＴＦＰ处理可明显降低ＣａＭ含量和延迟其峰值到来。还就ＣａＭ在成花过程中的作用及与Ｃａ２＋的关系等问题进行了讨论。     

Clonal propagation of Poncirus trifoliate through culture of shoot primordia

Summary

In Poncirus trifoliate, a highly efficient clonal propagation system for the culture of shoot primordia was devised. Shoot primordia were induced at the base of hypocotyl tissue cultured on MS medium supplemented with 44.4 µM BA, 3% sucrose and 0.8% agar. In MS liquid medium (44.4 µM BA, 3% sucrose) on a rotary shaker at two revolutions per minute, shoot primordia of Poncirus grew in size and number. Plant regeneration occurred on MS solid medium. Frequency of regeneration was highest on MS basal medium containing 3% sucrose and 0.8% agar. About 75 shoot buds regenerated from one shoot primordium. Histological observations showed that shoot buds arose from cells in the hypodermal layers of the shoot primordium. The shoot bud developed a vascular system, which became connected to the shoot primordium tissue. Regenerated shoots rooted on 1/2 MS basal medium or 1/2 MS medium supplemented with 0.5 or 5.0 µM IBA. These rooted shoots were acclimatized easily under intermittent mist.     

Rose flower production as related to plant architecture and carbohydrate content: Effect of harvesting method and plant type

Summary

The dependence between flowering cycles and woody stem parts of a rose crop was studied, with respect to plant architecture and carbohydrate content. Two harvesting methods (“control” versus “flush”) and two plant types (“control” versus “one stemmed”) were compared. Crop growth and partitioning of dry matter were studied as influenced by crop management during 18 months of culture. For a full-productive year, flush harvesting generally promoted bud break as compared with continuous harvesting but at the same time, also due to lower light interception, blind-shoot formation was enhanced and the individual flower weight reduced. Numbers of basal shoots were hardly related to flower production over a full cropping year. Flower production was much more sensitive to the number and diameter of branches at the height of cutting the flowers. The treatments did not affect carbohydrate allocation in the plant. Total carbohydrate storage was much too low to argue a clear role for the possible use of movement of carbohydrate reserves towards new growth. Maximum starch concentration was found at the beginning of summer and gradually dropped to a minimum in December and then increased again to a spring maximum. A cold treatment did increase the total non-structural carbohydrate (TNC) concentration but no positive influence on new basal-shoot formation was observed. No starch gradient was found in basal stem parts.     

The effect of rootstock shoot growth on the level of bud-grafting success in apple

Poor stands of ‘Queen Cox’ apple bud-grafted in summer onto M.9 rootstock were shown to be due to the scion bud not growing, or growing too late to produce a worthwhile ‘maiden’ tree, despite virtually all scion graft-chips forming unions with the rootstock. This problem was caused by raising the budding height to 30 cm above ground, as a method of increasing the height of lateral branches. The key element in higher budding which depressed subsequent scion bud growth was the complete removal of all rootstock shoots to a height of 35 cm to give a traditional ‘clean leg’ during the budding year. Removing rootstock shoots only at the budding position gave good stands of high quality trees. This appears to be a general effect, with the benefits of retaining rootstock shoots applying also to Malus tschonoskii when budded at 30 cm on M.9 rootstock. For both ‘Queen Cox’ and M. tschonoskii, failure of scion buds to grow vigorously often resulted in the development of ‘papery bark canker’ on the M.9 rootstock. The main benefit of root- stock shoots retained in the budding year was to ensure that scion buds grew early in the following ‘maiden’ year, whereas allowing these and new rootstock shoots to remain for the first two months of ‘maiden’ growth reduced the number of secondary scion buds which developed, and raised the height of laterals by delaying their emergence.     

Wood age and leaf area influence fruit size and mineral composition of apple fruit

Summary

The influence of wood age, fruiting position and leaf area within the tree canopy on fruit mineral content and quality for several apple (Malus domestica Borkh.) cultivars was investigated. Size and Ca, Mg and K content of individual fruit on one-year (lateral and terminal positions), two-year and older than three-year wood were compared for cvs Royal Gala, Braeburn, Granny Smith and Fuji. Fruit on two-year spurs and one-year terminals was generally larger at commercial harvest than that on one-year laterals and spurs older than three years. Flower receptacles at full bloom were larger and fruit growth rates were greater from 60 to 100 d after full bloom on two-year spurs than on one-year laterals. Fruit Ca and Mg concentrations and contents at commercial harvest were highest for terminal fruit, but there was no consistent difference between fruit from other positions. One-year terminals had the greatest primary and bourse leaf areas, two-year spurs were intermediate and one-year laterals had the lowest areas of both leaf types. Removal of 50% of primary leaves and/or removal of bourse shoots from clusters at bloom reduced fruit Ca content at commercial harvest for two-year spurs, one-year laterals and one-year terminals. Bourse shoot removal also reduced Mg content for all positions. However there was no effect of leaf removal on fruit size or K content. Ca content of individual fruit increased curvilinearly with increasing total spur leaf area for fruit on two-year spurs and one-year terminals but not for fruit on one-year lateral clusters. Terminal fruit with total spur leaf areas and fruit size similar to those on two-year spur fruit had higher Ca content.     

Flowering of tomato in vivo and in vitro in relation to the original position of the axillary bud on the main axis

In vitro cultured tomato seedlings were micropropagated using the single-node method. By periodically subculturing single nodes and shoot tips in vitro, tomato progeny were obtained that arose from axillary buds (nodes) 1 (base) to 9 (top). Rooted shoots were transferred periodically to soil and were grown further in a greenhouse to observe flowering. The number of leaves preceding the first inflorescence in the various groups of plants was not influenced by the original position of the axillary buds on the main stem. Similar results were obtained in decapitation experiments in vivo. These results indicate that axillary buds on the main stem of tomato plants do not differ in their flowering behaviour.     

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.     

Factors affecting the rooting of plum hardwood cuttings

Optimum conditions for rooting hardwood cuttings of several plum rootstocks have been determined with respect to season of cutting collection, the thickness of shoot and the part of the shoot used as the cutting, the concentration of rooting hormone applied to the base of the cutting and the basal temperature in the rooting medium.

Rooting occurred most readily during autumn and again in late winter and spring. Cuttings made from “thin” shoots generally rooted more readily than those from “thick” ones but the position along the shoot from which the cutting was made was usually unimportant.

Some clones, including Myrobalan B and St. Julien A, responded to increasing concentrations of 4(indolyl-3) butyric acid (IBA) to an optimum at 5,000 p.p.m. and to increasing bottom heat to about 20° C. Others, including Brompton and Pershore, were relatively unresponsive to both of these factors under the conditions of these experiments.     

垂枝桃枝条发育形态和内源激素的关系

以垂枝桃(Prunus persica var. pendula) 为试材, 分析了垂枝桃枝条发育过程中生物学形态和 内源激素含量的变化。直枝型枝条基角和延伸角极为接近, 平均值分别为52.5°和52.0°; 而垂枝型枝条基 角和延伸角则分别为51.7°和92.9°。说明这两种类型芽萌发后的生长方向一致, 直枝型枝条在生长过程中能维持原生长方向, 但垂枝型在生长过程中发生向下弯曲。根的基角与枝条的延伸角有相关性, 直枝类型和垂枝类型根的基角分别平均为78.3°和42.5°。倒置生长的垂枝桃枝条仍然表现为向重力生长, 说明枝条下垂是受重力诱导的。直枝桃枝条中木质素含量高于垂枝桃, 在枝条背上下两侧差异尤大。对内源植物激素含量的测定表明, 直枝型枝条中的赤霉素含量由基部至梢部递增, 在垂枝桃枝条背上侧赤霉素含量高于下侧, 与木质素分布状况一致, 赤霉素分布的不均衡是导致次生木质部发育不均衡的重要原因。垂枝桃梢端赤霉素含量较直枝桃更高, 导致枝条先端生长快于次生木质部发育, 使枝条无法支撑自身重量而下垂。外源GA₃处理的垂枝桃枝条中IAA /GA₃比例与CTK/GA₃比例均显著增高, 促进了垂枝桃枝条中部细胞分裂与木质部分化, 使其表现直立生长。