Influence of female cones on the vegetative growth of Pinus contorta trees

Branches of Pinus contorta Dougl. bearing two-year-old female cones initiated fewer lateral buds than vegetative branches. However, the number of lateral shoots that differentiated and grew was not reduced on female cone-bearing branches. Neither the number nor the weight of female cones influenced the length of the terminal shoot. The total length of all lateral shoots was positively associated with the weight of two-year-old female cones. Branch units with two-year-old female cones produced significantly more total dry weight in the current year than vegetative branch units. There was, however, no significant reduction in the dry weight of terminal and lateral shoots. Branches bearing female cones allocated between 17 and 45% of the current year's dry weight to two-year-old cones and between 1 and 5% was allocated to one-year-old female cones. Female cones therefore apparently do not reduce the photosynthetic potential of trees. The influence of female cones compared with male cones on the growth of trees is discussed.     

Effects of gibberellin A(4 + 7) and bark-ringing on cone initiation in mature Picea sitchensis grafts

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.     

Control of shoot elongation in ponderosa pine: relative roles of apical and axillary meristems

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.     

不同修剪强度对无患子生长和结果的影响

通过对无患子春梢进行不同强度的修剪处理,结果表明:轻度修剪最有利于新梢的萌发,进行轻剪处理的标准枝,平均新梢数为5.67条,极显著高于中剪和重剪处理的标准枝,是不修剪处理组的2.73倍。进行中度修剪的标准枝上萌发的新梢,其基径和梢长的生长情况均明显高出不修剪或经过轻剪和重剪处理的标准枝;经轻剪处理的标准枝,其平均开花枝数和平均坐果枝数分别为3.75条和2.58条,较未做修剪处理的标准枝1.33条的开花枝数和0.83条的坐果枝数,分别高出了181.95%和210.84%;较中剪处理组高出了80.29%和63.29%,较重剪处理组则高出了220.51%和180.43%;各处理组标准枝的新梢开花枝率和结果枝率则是随着修剪强度的增强而呈递增趋势;修剪强度对各指标的关联序为:新梢平均梢长新梢平均基径平均结果枝数结果枝平均坐果数平均新梢数平均开花枝数。     

Gravimorphism in current-year shoots of Abies balsamea: involvement of compensatory growth, indole-3-acetic acid transport and compression wood formation

We investigated the cause of gravimorphic growth inhibition in current-year shoots of balsam fir (Abies balsamea (L.) Mill.) seedlings displaced from their normal orientation in the gravitational field. Tilting the main stem of seedlings decreased shoot elongation, cambial growth as measured by tracheid production, and leaf dry weight of the terminal shoot and the lateral shoots on the lower side of the tilted stem. Removing either the terminal shoot or all lateral shoots induced compensatory growth in the remaining shoots, but did not reduce the inhibitory effect of tilting on shoot growth. Bending the apical part of a tilted main stem to restore it to the vertical did not fully reverse the inhibition of terminal shoot growth caused by stem tilting. Stem tilting inhibited cambial activity at the base of decapitated terminal shoots treated apically with indole-3-acetic acid (IAA) and decreased the basipetal transport of a [1-(14)C]-IAA pulse. Stem tilting also induced compression wood formation on the lower side of the tilted stem. Compression wood formation was associated with increases in cambial activity and stem respiration. Stem tilting did not affect either the net photosynthetic rate in 1-year-old leaves or the xylem water potential in current-year lateral shoots. These results support the hypothesis that gravimorphic growth inhibition in a current-year shoot on a tilted stem involves reductions in (1) the shoot's capacity to export IAA, and hence to mobilize photoassimilates, and (2) the supply of photoassimilates available for import by the shoot, as a result of increased cambial sink activity associated with compression wood formation outside that shoot.     

Seasonal shoot and needle growth of loblolly pine responds to thinning, fertilization, and crown position

The impacts of thinning, fertilization and crown position on seasonal growth of current-year shoots and foliage were studied in a 13-year-old loblolly pine (Pinus taeda L.) plantation in the sixth post-treatment year (1994). Length of new flushes, and their needle length, leaf area, and oven-dry weight were measured in the upper and lower crown from March through November. Total shoot length was the cumulative length of all flushes on a given shoot and total leaf area per shoot was the sum of leaf areas of the flushes.

By the end of June, first-flush foliage reached 70% of the November needle length (14.3 cm) and 65% of the final leaf area (15.0 cm²). Cumulative shoot length of first- and second-flush shoots achieved 95% of the annual length (30.3 cm), whereas total leaf area per shoot was 55% of the final value (75.3 dm²). Fertilization consistently stimulated fascicle needle length, dry weight, and leaf area in the upper crown. Mean leaf area of upper-crown shoots was increased by 64% six years after fertilization. A significant thinning effect was found to decrease mean leaf area per shoot in the crown. For most of the growing season, the thinned-fertilized trees produced substantially more leaf area per shoot throughout the crown than the thinned-nonfertilized trees. These thinned-fertilized trees also had greater needle length and dry weight, longer first flush shoots, and more leaf area per flush than trees in the thinned-nonfertilized plots. Needle length and leaf area of first flush shoots between April and July were linearly related to previous-month canopy air temperature (T_a). Total shoot length strongly depended on vertical light gradient (PPFD) within the canopy, whereas shoot leaf area was a function of both PPFD and T_a. Thus, trees produced larger and heavier fascicles, more and longer flush shoots, and more leaf area per shoot in the upper crown than the lower crown. We conclude that thinning, fertilization, and crown position regulate annual leaf area production of current-year shoots largely by affecting the expansion of first flush shoots and their foliage during the first half of the growing season.     

几种化学调节剂及其组合对板栗雌花数量及结实性能的影响

用 BR、GA3 、PP3 3 3 、KH2 PO4 、H3 BO3 共 5种化学调节物质进行了叶面喷布试验 ,观察它们在板栗开花结果上的效应。结果表明 ,不同药剂、浓度及药剂组合对板栗母枝平均结果枝数、长度、每结果枝雌花序数 ,母枝平均雄花枝数 ,单果质量 ,三果率和空苞率的影响有明显的差异。综合考虑化学调节物质在提高板栗雌花量和果实产量 ,以及降低空苞率上的试验效果 ,最佳的化学处理为 BR0 .0 1mg· L-1 PP3 3 3 1g· L-1 KH2 PO4 7.5g· L-1 H3 BO3 5.0 g· L-1,可使板栗结果枝数目平均由 1.2个增加至 2 .833个 ,结果枝平均雌花数由 1.56 7个增加到 1.8个 ,平均空苞率由 30 .70 %降至 9.0 3%     

Fertilization has little effect on light-interception efficiency of Picea abies shoots

We investigated effects of nutrient availability on shoot structure and light-interception efficiency based on data from control (C) and irrigated + fertilized (IL) trees of Norway spruce (Picea abies (L.) Karst.). The sampling of 1-year-old shoots was designed to cover the variation in canopy exposure within the live crown zone, where current-year shoots were still found. Canopy openness was used as a measure of light availability at the shoot's position. Openness values for the sample shoots ranged from 0.02 to 0.77 on the IL plot, and from 0.10 to 0.96 on the C plot. Among needle dimensions, needle width increased most with canopy openness. At fixed canopy openness, needle width was larger, and the ratio of needle thickness to width was smaller in IL trees than in C trees. Specific needle area (SNA) and the ratio of shoot silhouette area to total needle area (STAR) decreased with canopy openness, so that the combined effect was a threefold decrease in the ratio of shoot silhouette area to unit dry mass (SMR = STAR x SNA) along the studied range of openness values. This means that the light-interception efficiency of shoots per unit needle dry mass was three times higher for the most shaded shoots than for sun shoots. A test of the effect of fertilization on the relationships of SNA, STAR and SMR indicated statistically significant differences in both slope and intercept for SNA and STAR, and in the intercept for SMR. However, the differences partly cancelled each other so that, at medium values of canopy openness, differences between treatments in predicted SNA, STAR and SMR were small. At 0.5 canopy openness, predicted STAR of IL shoots was 6.1% larger than STAR of C shoots, but SMR of IL shoots was 10% smaller than that of C shoots. The results suggest that light-interception efficiency per unit needle area or mass of the shoots is not greatly affected by fertilization.     

软枣猕猴桃露地栽培新梢越冬性初探及应用

为初步探讨高寒地区软枣猕猴桃新梢的越冬性,以“魁绿”为试材,测定露地栽培条件下不同新梢、新梢不同部位的枝条干物质含量、相对电导率及萌芽率、成枝率。结果表明:春梢干物质含量最高,夏梢的干物质含量中等,秋梢干物质含量最低,同一枝梢基部的干物质含量最高,顶部的干物质含量最低。秋梢顶部的相对电导率最高,其次秋梢中部、夏梢中部、夏梢顶部和春梢顶部的电导率中等,春梢中下部、夏梢基部和秋梢基部的相对电导率最低,呈现显著性差异。春梢中部的萌芽率最高,18%,春梢基部和秋梢顶部萌芽率为0%,其余部位的萌芽率中等,成枝率与萌芽率变化基本一致。综合评价新梢越冬性由强到弱为:春梢基部>夏梢基部>春梢中部>秋梢基部>春梢顶部≈夏梢中部≈夏梢顶部>秋梢中部>秋梢顶部。     

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。     

Control of longitudinal and cambial growth by gibberellins and indole-3-acetic acid in current-year shoots of Pinus sylvestris

We investigated the involvement of gibberellins (GAs) and indole-3-acetic acid (IAA) in the control of longitudinal and cambial growth in current-year shoots of Pinus sylvestris L. Elongating terminal shoots, located at the apex of previous-year (1-year-old) branches in the uppermost whorl on the main stem, were variously decapitated (apical 5 to 10 mm removed), defoliated (all developing needle fascicles removed) and treated with endogenous GA(4/7) or IAA, or both. Shoot length and the radial widths of xylem and phloem were measured, and the concentrations of GA(1), GA(3), GA(4), GA(9) and IAA in the stem were determined by combined gas chromatography-mass spectrometry with deuterated GAs and [(13)C(6)]-IAA as internal standards. Decapitation decreased the production of xylem and phloem and the IAA concentration, but did not alter either longitudinal growth or the concentrations of GAs. Defoliation markedly inhibited shoot elongation, as well as cambial growth, and reduced the concentrations of GA(1), GA(3), GA(4), GA(9) and IAA. Application of GA(4/7) to defoliated shoots promoted longitudinal growth and phloem production, without affecting xylem production or IAA concentration. Application of GA(4/7) and IAA together to decapitated + defoliated shoots increased shoot elongation, xylem and phloem production and IAA concentration, whereas applying either substance alone had a smaller effect or none at all. We conclude that, for elongating current-year shoots of Pinus sylvestris, (1) both the shoot apex and the developing needle fascicles are major sources of the IAA present in the stem, whereas stem GAs originate primarily in the needle fascicles, (2) GAs and IAA are required for both shoot elongation and cambial growth, and (3) GAs act directly in the control of shoot growth, rather than indirectly through affecting the IAA concentration.     

Inhibitory effect of flowering and early fruit growth on leaf photosynthesis in mango

Carbohydrate and nitrogen contents, chlorophyll fluorescence and gas exchange were measured in leaves from both vegetative and reproductive terminal shoots of 12-year-old flowering mango trees. Reproductive shoot leaves were close to swelling floral buds, inflorescences or panicles bearing set fruits. Leaves close to inflorescences had lower rates of mitochondrial respiration (Rd) and net photosynthesis (Anet), and lower stomatal conductance (gs) and quantum efficiency of photosystem II under actinic light than vegetative shoot leaves. Leaf nitrogen concentration, which decreased from the beginning until the end of flowering, was lower in leaves close to inflorescences than in vegetative shoot leaves. However, these differences and changes were counterbalanced by an increase in leaf mass-to-area ratio so that leaf nitrogen per unit leaf area (Na) remained nearly constant during the whole flowering period, except in leaves close to panicles bearing set fruits. Net CO2 assimilation rate simulated by a biochemical model of leaf photosynthesis (Urban et al. 2003) was much higher than Anet measured at an ambient CO2 partial pressure (Ca) of either 36 or 70 Pa. The overestimation of Anet was more pronounced in leaves close to inflorescences, to panicles bearing set fruits and to reversing inflorescences (characterized by the appearance of leaves in terminal positions on inflorescences) than in vegetative shoot leaves. It is concluded that low Anet in leaves close to inflorescences was probably due neither to changes in Na nor to a decrease in Rubisco activity induced by low gs, but rather to a decrease in electron flow in photosystem II. This decrease was not directly associated with higher starch or soluble sugar contents.     

Structural characteristics of Abies mariesii saplings in a snowy subalpine parkland in central Japan

Structural characteristics of Abies mariesii M.T. Mast. saplings growing in sun and shade in a snowy subalpine parkland in central Japan were assessed to infer how saplings acclimate to suppression by larger individuals in a conifer clump and to extremely snowy conditions. Sun and shade saplings produced structurally different current-year shoots, and allocated biomass to needles and stem differently. Compared with sun saplings, shoots of shade saplings had lower needle mass per unit shoot size, which indicates less dense needle packing and more effective use of the limited available light by avoiding mutual shading among needles. Biomass allocation within lateral branches also differed between sun and shade saplings. Compared with sun saplings, needle mass was a smaller proportion of total branch mass in shade saplings although shade saplings retained needles for longer, thereby compensating, in part, for their lower annual production of needles. Thus shade saplings incur a high mechanical cost to support their low-light acclimated, conspicuously flattened crowns in this snowy habitat. Suppressed saplings are an important component of the persistent conifer clumps in snowy subalpine parklands. The observed structural characteristics of A. mariesii saplings, which ensure high shade- and snow-tolerance, contribute to the dominance of the species in snowy subalpine regions in Honshu, Japan.     

Variation in needle longevity is related to needle-fascicle production rate in Pinus sylvestris

Latitudinal variation in needle longevity of conifers in response to climatic variability is a well-known phenomenon, but its significance has only rarely been studied. Scots pine (Pinus sylvestris L.) stands were investigated in four locations in Lapland (northern Finland and northern Sweden, 67-68 degrees N) and in four locations in Estonia (59 degrees N) to test the hypothesis that plasticity in needle longevity results in similar needle biomass per foliated shoot length across latitudes. The needle-trace method (NTM) revealed the dynamics of needle fascicles attached to stem shoots. Long-term mean needle age was 2 years greater in Lapland than in Estonia. In both regions, mean needle age was strongly and negatively related to yearly needle-fascicle production rate relative to the number of needles on the same shoot axis. Although significantly fewer needle-fascicles were produced annually in trees in Lapland than in Estonia, the overall number of fascicles attached to the stem shoots, needle-fascicle density and individual needle dry mass did not differ between regions. Consequently, needle biomass per foliated shoot length was similar in trees in both regions. Thus, our results support the theory that plasticity in needle longevity helps Scots pine to compensate for reduced needle production so that the same foliar biomass per shoot is retained under a wide range of growth conditions.     

Effects of light availability and tree size on the architecture of assimilative surface in the canopy of Picea abies: variation in needle morphology

Needle dimensions, needle surface area, needle dry weight per area (LWA) and needle density (ND, needle weight per volume) were measured in terminal current-year shoots in a natural canopy of variably sized Picea abies (L.) Karst. trees growing along a light gradient. Needle shape was described as a rhomboid. Needle width (D(2)) increased with increasing diffuse site factor, a(d) (relative amount of penetrating diffuse solar radiation), whereas needle thickness (D(1)) remained nearly constant, resulting in an inverse relationship between D(1)/D(2) and a(d) and an increase in the ratio of total (TLA) to projected needle surface area (PLA) with increasing a(d). Because of the variations in needle morphology with respect to light availability, the shoot parameters used in present canopy models are also expected to be light-sensitive, and studies involving shoot morphology should also consider the variability in needle geometry. Needle dimensions and total tree height were not correlated. However, LWA increase with both increasing a(d) and total tree height. When LWA was expressed as the product of ND and needle height (NH, height of the rhomboidal transverse section of a needle), LWA appeared to increase with irradiance, because of changing NH, and with total tree height, because of changing needle density.     

The growth of shoots and lateral roots of Quercus robur L. seedlings following simulated undercutting

The effect of cutting the tap root on shoot growth and development of lateral roots was observed in seedling Quercus robur L. growing in PVC tubes containing peat and perlite. Cutting the tap root had little effect on shoot height and leaf number although some treatments caused a significant but slight reduction in shoot dry weight and number of branches. Total root dry weight was similar in control and treated plants but distributed differently between the types of root present. The tap root always formed the largest part of the total root dry weight. In control plants most lateral root dry weight was in roots < 1 mm diameter whereas in treated plants most dry weight was in roots > 1 mm diameter. Development of the root system following root cutting was similar for all treatments: new long laterals > 1 mm diameter with relatively few branches, that formed replacement tap roots, developed near the cut end of the original tap root. Fine laterals (< 1 mm diameter) near the root collar continued to grow forming highly branched systems.     

Morphological acclimation to understory environments in Abies amabilis, a shade- and snow-tolerant conifer species of the Cascade Mountains, Washington, USA

Light-related plasticity in a variety of crown morphology and within-tree characteristics was examined in sun and shade saplings of Abies amabilis Dougl. ex J. Forbes growing in two late-successional forests with different snow regimes in the Cascade Mountains of Washington, USA. Compared with sun saplings, shade saplings typically had broad flat crowns as a result of acclimation at several scales (needle, shoot, branch, crown and whole sapling). Shoots of shade saplings had a smaller needle mass per unit of stem length than shoots of sun saplings, a feature that enhances light-interception efficiency by reducing among-needle shading. The low annual rate of needle production by shade saplings was associated with a longer needle lifespan and slower needle turnover. Reduced needle production within a shoot was reflected at the branch level, with lateral branches of shade saplings having a smaller needle mass than branches of the same length of sun saplings. Reduced allocation to needles permits greater investment in branches and stems, which is necessary to support the horizontally expanding branch system characteristic of shade saplings. Mean branch age of shade saplings was significantly higher than that of sun saplings. Shade saplings had lower needle mass per unit of trunk biomass or total biomass, reflecting greater investment in the trunk as a support organ. Increased investment in support organs in shade was more evident in the snowier habitat. The observed morphological acclimation makes A. amabilis highly shade and snow-tolerant and thus able to dominate in many late-successional forests in snowy coastal mountain regions.     

立地因子对雷竹林笋产量的影响研究

采用正交试验设计法研究了海拔高度、坡向和坡位对雷竹林出笋数、鲜笋产量和平均单笋质量的影响。结果表明,海拔、坡向、坡位3个立地因子均极显著地影响雷竹林的出笋数、鲜笋产量和平均单笋质量,雷竹笋用林造林应选择低海拔、阳坡和下坡的立地,其出笋数比平均值增加27.3%,鲜笋产量比平均值增加88.4%,单笋质量比平均值增加51.8%。     

不同早实核桃品种结果母枝结实能力的研究

为了改进栽培措施、使早实核桃连年丰产稳产,研究了不同早实核桃品种的不同类型结果母枝的结实能力以及1 a生枝的拉枝效果,结果表明,在所研究的早实核桃品种中,辽宁1号结果母枝连续结实能力最强,其4 a生枝段上连续3 a结果母枝比例及混合花芽比例分别为51.67%和55.83%;然后依次是辽宁3号、中林1号、绿岭和鲁果1号,分别为60.94%和36.30%、52.78%和36.99%、20.12%和42.83%、15.43%和15.30%。1 a生枝拉枝后的萌芽率平均为56%,未拉枝的仅36%,拉枝后平均新梢结果数提高了10%。     

Relationships between Shoot Length, Bud Number and Branch Production in Quercus petraea (Matt.) Liebl.

Over a 3-year-period the relationships between shoot length,number of buds and branch production were investigated on theleading shoots and major crown branches on 10-year-old Quercuspetraea. The pattern of growth was similar in leading shootsand branches indicating that for some aspects of growth observationof branches can substitute for study of the leader. There weresignificant relationships between shoot length and either numberof buds or branches, and between number of buds and branches;some of the relationships differed between years. There weresignificant between tree differences in the proportion of budsforming branches. Failure of the terminal bud increased lateralbranch production. The overall shape of the crown was relatedto the average annual extension growth. Results are discussedin relation to prediction of crown development and the selectionof superior genotypes in a tree improvement programme.