Current Shoots Research Articles

Bone

Ahab stands at the mast, ranting invective against the wind;his left-leg a whale-bone prosthesis pivoting in its notch on-deck.The creaking of bone on oak soothing and haunting the shiplike the sullen rattle of an unseen snake in overgrown grass.At his desk, Ahab daydreams, wriggles his left toes, scratches his left knee,but as he swats a mosquito from his left calf, he'sjolted from his dream as his hand strikes unfeeling bone. Ahab hobbles out onto the dark deck, alone with the sea.No breeze but the ship glides along,lured by the phantom whale.While leaning against the bulwarks,searching the surface, whale-bone between flesh and oak,Ahab's a bearded conduit for Tragicall Nature;shards of current shoot out from the gold doubloon on the mast.Omens, presentiments charge through human sinew,shoot through wood/world/oceanic membraneas the past flits up for an ungraspable secondilluminating invisible whiteness impervious to surface. Within the frame:painted copies of paper American flagsattached to a painting of a painted doorenhanced by trompe l'oeil technique: shadow on a white vase.A black and white painting in the painting.Representations of representationsriding the white whale.Foreboding jaw wide open: tungsten steel teeth.Massive might twisted, wound tight, ready to strike,speaking through mists of mind and epistemic murkthat can only hope to glimpse yet never contain the vertical whale. An image is unhinged by yet another image.Ungraspable terror at the heart of the paint.The whale, copied from Moser's woodcut,copied from lithographs, words, the book Moby-Dick;copied from Melville's life, whaling tales, encyclopedias, the Bible.Everything a copy of a copy. Voices thrown hither and thither by sources unknown.Unwilled speech of free will that cannot be found or MEAN.Till the whale comes towards us, open-mouthed,raising the waves on all sides andbeating the sea before him into a foam.

CO2 uptake patterns depend on water current velocity and shoot morphology in submerged stream macrophytes

Summary1. The influence of current velocity on the pattern of photosynthetic CO2 uptake in three species of submerged stream macrophytes was described by analysing the grain density in autoradiographs of leaves exposed to 14CO2.2. In Elodea canadensis, the CO2 uptake was approximately two‐fold higher near the leaf periphery compared with the midrib section at high current velocity, whereas at low current velocity the area of relatively high CO2 uptake expanded from the leaf periphery towards the midrib and basal sections of the leaves.3. In Potamogeton crispus and Callitriche stagnalis the CO2 uptake was uniform throughout the leaves at low current velocity, whereas at high current velocity the CO2 uptake appeared to increase randomly in some areas of the leaves.4. The relationship between the photosynthetic CO2 uptake pattern and the dynamics of flow surrounding submerged shoots at low and high current velocity is discussed in relation to shoot morphology. In E. canadensis, thick diffusive boundary layers may develop between leaves because of screening effects at high current velocity. Increased diffusion path for CO2 may contribute to inhibitory effects on photosynthesis in this species.

A STUDY ON VEGETATIVE COMPENSATORY GROWTH OF SHRUB, CARAGANA KORSHINSKII, UNDER DIFFERENT CLIPPING TREATMENTS IN DISTURBANCE ENVIRONMENT

Background and Aims After browsing or clipping,Caragana korshinskii can compensate for loss of biomass,which is the foundation for repeated use of resources of this species. However,the pattern of vegetative compensatory growth under different clipping treatments is still poorly understood. Methods In order to test the effects of removal of partial shoot length (RSL) and partial shoot number (RSN) on vegetative growth,we removed 30% (30%RSL),60% (60%RSL) of main shoot length,and 25% (25%RSN),50% (50%RSN),and 100% (100%RSN) of main shoot number. Key Results Clipped shrubs overcompensated for tissue loss,and current year shoot number per shoot,current year shoot length,current year shoot biomass per shoot and current year shoot biomass per shrub were higher than those of the control. The control,30%RSL and 60%RSL shrubs did not resprout after clipping,while 25%RSN,60%RSN and 100%RSN treatments did resprout and the biomass per shrub increased when more shoot biomass were removed. Differences in resprout number per removal shoot,resprout length,individual resprout biomass were not significant between 25%RSN and 50%RSN treatment,but resprout number per removal shoot,resprout length,individual resprout biomass of both were less than those of 100%RSN treatment. Fruit production in clipping treatments was higher or equal to that of the control with the exception of 100%RSN,which grew no fruit. There was a negative relationship between annual shoot biomass and fruit production with the exception of the control,which had less fruit production and the annual shoots almost did not grow. During growth season,biomass of current year vegetative growth increased quickly from current year's shoot growth to fruit ripeness. In the following three months,from fruit ripeness to leaf abscission,however,it increased slowly. Conclusions 100%RSN treatment may be a reasonable mode to prompt shrubs to recover quickly from damage. Plants' responses associated with compensation may include: increased branching or tillering after alteration of the apical dominance,increased availability of water and/or nutrients after the change in the ratio of shoot to root,and remobilization of resources reserved in roots to aboveground organs. Decreased allocation of resources to reproductive growth may be another important mechanism for 100%RSN shrubs to compensate for the loss of organs.

Wetting and Temperature Requirements for Blotch Infection on Apple Current Shoot Leaves with Conidiospores of Diplocarpon mali

Wetting and Temperature Requirements for Blotch Infection on Apple Current Shoot Leaves with Conidiospores of <I>Diplocarpon mali</I>

Monitoring the European pine sawfly with pheromone traps in maturing Scots pine stands

Abstract During 1989–93, field studies were conducted in Finland to develop a method based on pheromone traps to monitor and forecast population levels of the European pine sawfly (Neodiprion sertifer Geoffr.) and tree defoliation. Three traps per site were baited with 100 µg of the N. sertifer sex pheromone, the acetate ester of (2S,3S,7S)‐3,7‐dimethyl‐2‐pentadecanol (diprionol), in maturing pine stands in southern and central Finland. In addition, three different dosages (1, 10 and 100 µg) of the pheromone were tested in 1991–92. The highest number of males was observed in traps baited with the highest dose. On average, there was a 10‐fold increase in trap catch between lure doses. Density of overwintering eggs was used to evaluate the effectiveness of pheromone traps in predicting sawfly populations. The proportion of healthy overwintering eggs was determined each year. A model based on the number of current shoots on sample trees, diameter at breast height and tree height was formulated to estimate eggs per hectare. Linear regression analysis produced high coefficients of determination between number of males in traps and density of total eggs in the subsequent generation, when populations were at peak densities. The relationships were not significant for low population densities. The results indicate a risk of moderate defoliation when the seasonal trap catch is 800–1000 males per trap or higher.

Dryocosmus kuriphilus

<i>Dryocosmus kuriphilus</i>

RAPD typification: phenetic analysis of Vaccinium inflorescences

The inflorescence of Vaccinium hiepii is described for the first time, and as predicted, its floral features are similar to those of V. chunii. However, this floral axis has nothing in common with the type of its putative section, i.e. Vaccinium sect. Galeopetalum. Subsequent numerical analyses of inflorescence types in Vaccinium using 43 taxa and 11 floral features suggest three inflorescence types for the genus: (1) the ‘myrtillus’ type where a single flower emerges directly from the axil of some leaves or bracts of the current shoot; (2) the ‘dialypetalum’ type where just the floral primordia are laid down within the confines of the perennating bud; (3) the ‘hiepii’ type where the complete floral axis is laid down within the perennating bud. Based on this tripartite division, a new taxon, Vaccinium sect. Calcicolus Vander Kloet sect. nov. is described for these Himalayan blueberries. A diagnostic key and brief description is provided for the eight species included in this new section. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148, 445–457.

Insecticides sprayed on seedlings of Picea abies during active growth: Damage to plants and effect on pine weevils in bioassay

In Finland, the planting period for Norway spruce [Picea abies (L.) Karst.] has lengthened from spring to summer so that seedlings are also planted during the active growing stage, not only when dormant. On many regeneration sites, there is a high risk of damage by the large pine weevil, Hylobius abietis L., and insecticide treatments are needed to protect seedlings against these weevils. However, all currently available insecticides have been tested and accepted for use only on seedlings that are not growing actively. In this study, actively growing Norway spruce seedlings were treated with three insecticides in mid-June, when the current year's shoot was about 7 cm and unlignified. At this stage of growth, GORI 920® (permethrin) damaged needles and reduced the following year's height growth. Decis Tab® (deltamethrin) and Karate Zeon® (lambda-cyhalothrin) caused no side-effects. All three products were also more or less effective in preventing feeding of pine weevils 1 yr after the treatments. Further studies are needed to investigate the possible harmful effects of insecticides in different stages of growth during the growing season.

Changes in shoot properties in relation to vertical positions within the crown of mature canopy trees of Abies mariesii and Abies veitchii

We investigated current shoot properties in two contrasting vertical positions (leader crown; LC, and lower branch; LB) within the crowns of mature trees of two subalpine conifer species, Abies mariesii and A. veitchii. For both LCs and LBs, shoot length decreased with increasing branching order. However, shoot properties were different between LCs and LBs. Shoots in LCs had more needle biomass per unit of shoot length. Shoots in sunny conditions pack needles closer along the shoot and intercept incoming light more completely. This causes the shoots in the LCs to have more needles. In contrast, less needle packing per unit shoot length in LBs results in the avoidance of mutual shading among needles in order to intercept limited light more effectively. Because branch systems in lower layers tend to be more shaded, the quantity of irradiance received by the shoots in LBs is smaller. Thus, reduced needle amounts on the shoots in LBs reflect the needle arrangement acclimating to the lower light availability. This study suggests the importance of changes in the properties of individual shoot as a component of a branch system and accordingly a whole-crown system in mature canopy trees of A. mariesii and A. veitchii.

Effects of Light Intensity and Temperature on Growth, Flowering, and Single-leaf CO2 Assimilation in Odontioda Orchid

We investigated the effects of light intensity and temperature on growth, flowering, and single-leaf CO2 assimilation of Odontioda orchid. CO2 assimilation in final leaves of back and current shoots was depressed significantly at a leaf temperature of about 30°C, in association with decreased stomatal conductance, although the light saturation point differed somewhat between back shoots and current shoots. A photosynthetic photon flux density (PPFD) of about 400 μmol · m-2 · s-1 was optimum for CO2 assimilation. Large quantities of sugar and starch were reserved in pseudobulbs of back shoots under high light intensity, but they contents decreased while the current shoot was developing new leaves. When growth stopped, the amount of reserve assimilates increased again. Thus, there appears to be a dynamic translocation of assimilates between the pseudobulbs of back shoots and current shoots. All plants cultivated under a 28/18°C (day/night) died within 2 months after the beginning of the experiment confirmed that this species has low heat tolerance. Growth and flowering were stimulated at 23/13°C and a PPFD ranging between 300 and 500 μmol · m-2 · s-1. These conditions seem to approximate the optimum conditions for CO2 assimilation.

First Report of Twig Canker of Hazelnut Caused by Fusarium lateritium in Italy.

Cultivation of hazelnut (Corylus avellana L.) has considerable economic potential in Italy, in particular, in the northern Lazio Region. Since early summer of 2000, cankered twigs have been observed on hazelnut trees that were severely affected by gray necrosis, which is a disease complex causing fruit drop (1). In subsequent years, sunken areas were observed on 1-year-old shoots from late April through May. The resulting cankers had reddish brown margins and the death of the cambium in the infected area and produced an L-shaped malformation of twigs. Girdling of the twig by the canker resulted in death of the foliage. Yellow-to-orange sporodochia were evident on cankers by early June. Isolations were made from the margins of young cankers from 20 twigs collected from 10 trees. Tissue pieces were plated onto potato dextrose agar (PDA) after surface disinfection with 1% sodium hypochlorite. Slow-growing, cream-to-reddish brown colonies with sparse aerial mycelium emerged from 80% of diseased tissue pieces within 10 days of incubation at 20 to 22°C. Conidial production was induced by keeping pure cultures at 22 to 25°C under natural light but out of direct sunlight. Within 1 month, sporodochia bearing ellipsoidal, spindle-shaped, commonly 1 to 3 septate macroconidia developed. Intercalary chlamydospores were often present in chains. Single conidia were subcultured on carnation leaf agar (CLA). On the basis of morphological and cultural characteristics, the fungus was identified as Fusarium lateritium Nees. (2). Pathogenicity tests were conducted outdoors on the current year's shoots of hazelnut trees with four isolates derived from single conidia of F. lateritium. Inocula used were either mycelial plugs cut from the margin of actively growing cultures or small (10 × 10 mm) pieces of sterile cheesecloth soaked in 1 × 106 conidia per ml suspension. The mycelial plugs were placed under the bark, while the soaked cheesecloth pieces were wrapped around an area that had been wounded by gently scraping off a length of the bark (approximately 10 mm) with a sterile needle. All the inoculations were wrapped with Parafilm to prevent desiccation. Six inoculations per isolate were performed. In a similar manner, controls were inoculated with agar plugs or water only. After 3 months, the length and width of each canker were measured. For both inoculation methods, cankers were similar to those observed in nature and averaged 20.6 × 5 mm, while the controls did not show any symptoms. F. lateritium was consistently reisolated from the canker margins of the inoculated shoots. To our knowledge, this is the first report of F. lateritium causing twig cankers on hazelnut. The fungus has been reported to cause cankers on several tree species, including Malus domestica (apple), Morus spp. (mulberry), Sophora japonica (Japanese pagoda tree), Robinia pseudoacacia (black locust), Citrus spp., and Pyrus pyrifolia (Asian pear).

The criteria for biomass partitioning of the current shoot: water transport versus mechanical support

In this study, we determine the theoretical criteria for biomass partitioning into the leaf and stem of the current shoot, using two quantitative models. The water transport model, based on the biochemical model of CO(2) assimilation, predicts the relationship between the water transport capacity per biomass investment in the stem (stem mass specific conductivity) and the partitioning of biomass that maximizes shoot productivity. The mechanical support model, based on Euler's buckling formula, predicts the relationship between the mechanical strength per biomass investment in the stem (the inverse relationship of stem mass density) and the partitioning of biomass to avoid mechanical failures such as lodging. These models predict the stem properties of mass specific conductivity and stem mass density that result in optimum partitioning just sufficient to provide adequate water transport and static mechanical support. In reality, the stem properties of plants differ from those predicted for optimum partitioning: the partitioning of biomass in the current shoot of both angiosperms and gymnosperms is mainly governed by the mechanical support criterion, although gymnosperms are probably more affected by the water transport criterion. This tendency is supported by actual measurements of biomass partitioning in plants.

Fungi associated with shoots of silver birch (Betula pendula) in Scotland

The fungi associated with diseased and healthy shoots of young, planted Betula pendula were studied at five sites in Scotland where crown die-back of birch is occurring. At each site, 30 diseased and 30 healthy shoots were sampled twice, with 1 yr-old shoots collected in May 2002, and 4-5-month-old shoots collected in September/October 2002. Overall, 34 different fungal species were recorded, with 92 % and 60 % of all diseased and healthy shoot pieces, respectively, colonised by at least one fungal species. The main colonisers of both diseased and healthy shoots were Melanconium bicolor, Discula betulina and Godronia urceolus, and the fungi most frequently found on diseased shoots only included Marssonina betulae and Fusarium avenaceum. The pathogenicity of these fungi was tested on seedlings of B. pendula and B. pubescens. Melanconium bicolor required a wound for lesion development on both birch species and caused larger lesions on B. pubescens than on B. pendula. Discula betulina caused lesions on stems and shoots of both birch species, including non-wounded current shoots. Marssonina betulae caused lesions and die-back of wounded and non-wounded current shoots of B. pendula seedlings. This fungus was not pathogenic on B. pubescens. Fusarium avenaceum caused restricted lesions on the main stems of both birch species. Godronia urceolus was not pathogenic on either birch species. Further work needs to focus on the role of these fungi in causing crown die-back of young, planted B. pendula in Scotland.

Biomass and nutrient distribution in a highland bamboo forest in southwest Ethiopia: implications for management

The Masha natural bamboo forest was stocked with 8840 trees ha −1, uniformly distributed with a mean height of 16.8 m, diameter of 7.6 cm and leaf area index (LAI) of 9.7. Age-structure was 13% of <1 year, 24% of 1–3 years and 63% of >3 years. Culm contributed 82%, branch 13% and leaf 5% to the 110 t ha −1 total above ground biomass, while trees mature for harvest (>3 year) made up 73%. The culm component of the mature trees was 60% of the above ground biomass, whereas the biomass of current shoots (<1 year) constituted only 7%. Annual shoot production was 8 t ha −1 and contained 44 kg ha −1 of N, 6 kg ha −1 of P, 122 kg ha −1 of K and 1 kg ha −1 of Ca. Significant variations in nutrient concentration of plant tissues were found among age-classes and between seasons. More than 8 t ha −1 year −1 plant litter containing 115 kg N, 8 kg P, 56 kg K and 22 kg Ca returned to the soil surface mainly during the humid season. Resorption efficiency of the foliage was 43% for K, 37% for P and 19% for N. Soil nutrient concentrations declined sharply with soil depth and a large fraction of the total soil nutrient pool was located in the organic layer; the soil was poor in P and K. Management approaches to improve the production efficiency of the forest and the quality of the harvested biomass are discussed.

A Comparison Study of the Effects of M.9 and Seedling Rootstocks on Two Iranian Cultivars, Golab Kohanz and Shafiabadi

The main aim of this study was to investigate the effects of two apple rootstocks (M9 and Seedling) on the growth, total yield, fruit quality and mineral composition in leaves and fruits of two Iranian cultivars Golab Kohanz and Shafiabadi. The 10-year-old experimented trees were on stage of commercial cropping. The experiment was conducted in a randomized complete-block design in split plot tests with two factors and four replications.The effects of rootstocks on trunk diameter, current seasonal shoot length, primary fruit set percentage, total yield/ha and individual fruit weight were significant (P &lt; 0.01) in first year, but not significant on total yield and individual fruit weight in the second year. The effect of cultivar was only significant at current seasonal shoot length in the first year and total yield and individual fruit weight in both years. Fruit characters were also affected by rootstock, so fruit on M9 rootstock had more flesh firmness, most PH, TSS, and dry matter, but the effect of cultivars was not significant on fruit quality characters in both years. Cultivar Shafiabadi on M9 rootstock produced the highest yield/ha in all treatment combinations. The results of mineral analysis relieved the effects of rootstock on N and Zn concentration in leaves. Golab Kohanz/M9 rootstock showed the highest K content in leaves while the highest Zn amount was Golab Kohanz/Seedling rootstock. Other nutrient contents were affected neither by rootstocks nor cultivars. In fruit, rootstock effect on Mg and P concentration was significant; and the highest K content was found in fruit of Golab Kohanz/M9 and the highest Mg and Ca amount was also recorded in Golab Kohamz/Seedling rootstock.

Differential grazing of female and male plants of prostrate juniper (Juniperus communisL.)

Summary Females and males of dioecious species may not allocate the same proportions of assimilate to plant protection and so may be differentially grazed. The distribution range of the dioecious, coniferous shrub, juniper (Juniperus communis) is declining in the UK and populations are becoming fragmented. The main aims of this study were to (i) assess the sex structure of populations of prostrate juniper at four sites in northern Scotland and (ii) assess the extent of grazing on individual plants. A total of 518 prostrate juniper plants were inspected in the four populations. The sex of 30–85 % of them could not be determined. There were differences between the sites in grazing intensity, plant density, plant size, and the proportion of females. Between June and September, there was almost no grazing of current growth and no difference between males and females in the amount of grazing. Most grazing took place over winter. This was supported by the observation that dung counts over summer did not correlate with grazing of current or old shoots. Female, male and unsexable plants had similar size ranges. Female and unsexable plants had similar numbers and proportions of old shoots grazed but male plants had significantly less. This suggests that many of the unsexable plants were non-reproducing females and that the greater grazing on unsexable plants might be responsible for the cessation of reproduction. The impact of differential winter grazing of prostrate female and male juniper plants is discussed in relation to the conservation of this species in Scotland and the UK.

Infestation of Paradiplosis manii (Diptera: Cecidomyiidae) on Abies firma in Honshu and Kyushu, Japan, and redescription of its morphological features

Paradiplosis manii infesting Abies firma needles was found for the first time in Honshu and Kyushu, Japan. The mature larva of Paradiplosis manii is described for the first time and some adult features that were not precisely referred to in the original description are described, together with notes on its host plant range, gall, life history, and geographical distribution. The percentages of galled needles were significantly different among census trees, and galls were not formed on the trees on which all shoots were unopened in the midge emergence season. Relative abundance of galled to ungalled needles on current shoots was significantly reduced from June to December, 1999, indicating that galled needles fell to the ground earlier than ungalled needles.

Association of Sphaeropsis sapinea with insect‐damaged red pine shoots and cones

SummaryThe association of the shoot blight and canker pathogen Sphaeropsis sapinea with red pine (Pinus resinosa) shoots and cones damaged by insects (especially Dioryctria sp.) was investigated. Samples from a single plantation approximately 35 years old, in Sauk Co., Wisconsin and also from three plantations, between approximately 40 and 50 years old, located in an area of pine shoot moth activity in the preceding year in Adams Co., Wisconsin were visually examined. Samples were arbitrarily collected from trees felled in the first plantation in May. Pycnidia of S. sapinea and insect damage were observed on 56 of 91 (62%) of closed cones and 17 of 165 (7%) of previous year's shoots. In the absence of insect damage, pycnidia of the pathogen were identified only on eight of 91 (9%) closed cones and never on previous year's shoots. In each of the other three plantations, 10 trees were located at intervals along transects in mid‐June; one branch from the lower half of the crown per tree was pruned off, and both current and previous year's shoots were examined. Insect damage and S. sapinea pycnidia were too rare on current year's shoots to draw any conclusions. Insect damage occurred on 20–40% of over 2000 previous year's shoots that were examined, but pycnidia of the pathogen were identified on only about 5%. Although infrequent, S. sapinea was identified in association with insect‐damaged previous year's shoots from these three plantations three times more frequently than those without insect damage. Random amplified polymorphic DNA (RAPD) markers from eight randomly selected isolates were consistent with the A group of S. sapinea, which can be aggressive on red pine. This ability to exploit insect‐damaged shoots may facilitate long‐term persistence of S. sapinea at low disease incidence and severity. The potential role of insect wounds as infection courts and insects as vectors of this important pathogen of pines deserves further study.

Effect of GA 3 spraying on lignin and auxin contents and the correlated enzyme activities in bayberry ( Myrica rubra Bieb.) during flower-bud induction

The effect of gibberellic acid (GA 3) spraying on the contents of lignin and auxin, and the activities of correlated enzymes during flower-bud induction was determined in 13-year-old bayberry trees ( Myrica rubra Bieb.) in the year of low crop. The results show that the activity of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) in the leaves of the control trees reached the maximum in turns during the period of flower-bud induction, catalyzing the biosynthesis of lignin which was depleted during flower-bud initiation. GA 3 spraying during flower-bud induction significantly inhibited the activities of PAL, PPO, POD and IAA-oxidase (IAAo), and increased the level of indole-3-acetic acid (IAA), delaying the biosynthesis of lignin in leaves of the current shoots, as well as inducing the more vigorous growth and inhibiting flower-bud initiation and formation.

Effects of Juvenility on the Rooting of Trifoliate Orange (Poncirus trifoliata [L.] Raf.) Stem Cuttings.

The rooting ability of cuttings of current shoots from trifoliate orange (Poncirus trifollata [L.] Raf.) trees at various ages was determined. All cuttings were collected in early June 2001. Rooting abilities varied among various ages of trifoliate orange trees. Forty-five days after cutting, the current shoots from one- and two-year-old trees had 100% rooting; those from 15- and 25-year-old trees had 0%. From three-year-old to five-year-old trees, the rooting percentage decreased as the age increased. The number of roots produced correlated positively with the rooting percentage. In another experiment, scions from current shoots from mature 'Aoshima' satsuma mandarin (Citrus unshiu Marc.) were grafted onto two-year-old trifoliate orange seedlings. All trifoliate orange portions of cuttings grafted with 'Aoshima' satsuma mandarin scions rooted.