The effects of Arceuthobium sichuanense infection on needles and current‐year shoots of mature and young Qinghai spruce (Picea crassifolia) trees

Arceuthobium sichuanense is a hemiparasitic angiosperm that infects Qinghai spruce (Picea crassifolia Kom.) in Qinghai province, China, and causes severe damage to spruce forests in Qinghai‐Tibet Plateau. In this study, the impact of A. sichuanense infection on mature and young trees of Qinghai spruce was evaluated by examining needle and current‐year shoot morphology, needle water and nitrogen‐use efficiency (NUE) and needle nitrogen concentration. The most apparent effect of A. sichuanense infection was a significant reduction in both needle size distal to infection and current‐year shoot length in the infected branches (p < 0.001). Per cent reductions in needle and current‐year shoot length were similar between mature and young trees (58.9 vs. 56.3%; 59.7 vs. 62.9%). There was a high degree of correlation in foliar δ¹⁵N values between the dwarf mistletoe and its host trees (R² = 0.9017, p < 0.001), while the foliar δ¹³C values of A. sichuanense were similar to those of infected mature and young spruce trees. The dwarf mistletoe infection also resulted in a significant decrease in host needle N concentration and δ¹³C values (p < 0.001). The per cent reduction in needle N concentration in young trees was nearly twice as much as that in mature trees (20.49 vs. 11.54%), while the per cent reduction in needle δ¹³C values was similar between young and mature trees (?0.98 vs.?1.1‰). The NUE in mature trees was not affected by A. sichuanense infection, but the NUE in young trees was increased by the infection.     

屏边空竹四季出笋及幼竹生长发育规律研究

[目的]揭示屏边空竹的发笋、退笋和幼竹生长规律。[方法]定点观测了30丛屏边空竹周年的出笋、退笋、秆高及地径生长数据,运用SPSS软件分析评价了不同季节出笋及幼竹生长规律。[结果](1)屏边空竹笋期历时9个月左右(从9月至次年5月),根据出笋量的差异可分为初期、盛期和末期,春季最多而夏季最少;其中5丛(16. 67%)每季出笋,具有四季发笋的习性。(2)退笋率随着笋期逐渐增加,在出笋末期达到最高,为87. 76%。(3)笋-幼竹高生长约130 d完成,平均秆高达6. 36 m;呈现"慢-快-慢"的生长规律,生长曲线可用三次曲线方程描述:H=0. 806-0. 029t+0. 001t2-5. 894×10-6t3,R2=0. 980。(4)地径的生长历时16 d左右,平均地径为18. 50 mm,也呈现"慢-快-慢"的生长规律。[结论]屏边空竹发笋期长约9个月,具有四季发笋的习性,但各季节出笋量差异显著;秆高和地径呈现"慢-快-慢"的生长规律。     

Antibacterial activity of moso bamboo shoot skin (<Emphasis Type="Italic">Phyllostachys pubescens</Emphasis>) against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

This study examined the antibacterial activity of moso bamboo shoot skin (Phyllostachys pubescens). Bamboo shoot skin itself and its dichloromethane extract had antibacterial activity against Staphylococcus aureus. Results suggest the possibility of effective utilization of antibacterial materials from bamboo shoot skins that are mainly discarded at present.     

A comparison on DNA methylation levels in bamboo at five developmental stages

Bamboo shoots grow quickly through the rapid elongation of internodes. In order to verify whether DNA methylation affects bamboo shoot elongation, we compared DNA methylation levels at five developmental stages of bamboo (Phyllostachys praecox), including young bamboo shoot of 40-cm at length (S1), bamboo shoot of 2-cm at length (S2), young leaf (Y1), leaf (Y2), and aging leaf (M), by using amplified fragment length polymorphism (AFLP) based on KpnI/MseI and Acc65I/MseI platforms. The polymorphism ratio of methylated to unmethylated DNA sites in bamboo shoot (S1 and S2) was higher than that in leaf (Y1, Y2 and M). The polymorphism ratio of methylated to unmethylated DNA sites in S2 was highest (32%). Our results suggest that DNA methylation changed greatly at bamboo growing stages, especially in stage of rapid elongation of internodes.     

Intra-specific variation for response to salt and waterlogging in <Emphasis Type="Italic">Acacia ampliceps</Emphasis> Maslin seedlings

Salinity is a major form of land degradation worldwide, with seasonal or temporary waterlogging often being an associated issue. Acacia ampliceps is a highly salt-tolerant small tree, naturally-occurring in north-western Australia, which produces abundant biomass with potential for fuelwood and fodder. We investigated the extent of variation amongst provenances and families of A. ampliceps for seedling response to salt and waterlogging. Seven-week old seedlings from 27 families (seven provenances, grouped into two regions), were treated in sand-filled pots in a glasshouse with either mixed salt (S) solutions (150 mol m⁻³ for 14 days, 300 mol m⁻³ for 33 days), waterlogging (W) or combined salt (S) and waterlogging (SW). Only 3% of seedlings died, mostly from the combined salt × waterlogging treatment. Seedlings from the Kimberley region had significantly greater height and shoot biomass than those from the Pilbara. Within these regions, Wave Hill (seedlot 14631) and Halls Creek (15738) provenances had the best growth. Height growth was reduced similarly for S- and W-treated plants, whereas that of SW-treated plants was reduced much more. Salt and waterlogging caused shoot dry weight reduction at harvest of 41 and 46%, respectively, with a slight interaction between salt and waterlogging; SW treated plants were most affected. Generally there were relatively small differences in the growth response of provenances and families to salt, but larger (often highly significant) variation in response to waterlogging. Genotypic variation for shoot and phyllode water content and phyllode number in response to salt and waterlogging was generally small. The good agreement found at the provenance level between seedling growth in this experiment and growth of young trees on saline land in a trial in Pakistan suggests that glasshouse screening may be a useful means for selecting potential provenances for field evaluation.     

The impact of shade on morphology,growth and biomass allocation in <Emphasis Type="Italic">Picea sitchensis</Emphasis>, <Emphasis Type="Italic">Larix</Emphasis> × <Emphasis Type="Italic">eurolepis</Emphasis> and <Emphasis Type="Italic">Thuja plicata</Emphasis>

To determine the effect of shade on morphology, growth and biomass allocation in Picea sitchensis, Larix × eurolepis and Thuja plicata, seedlings were grown in the open or under shadehouses providing 25%, 50% and 75% reductions of full-light for two growing seasons. For most of the characteristics assessed there was no significant interaction between species and shade indicating that the morphological responses to changing shade treatments were not species-dependent. After two growing seasons the mean height increment for the three species was significantly greater in 25% (76.1 cm) and 50% shade (74.9 cm) than in the open (69.5 cm). Root collar diameter increment, shoot, root and total biomass declined significantly with increasing shade while the opposite was true for the height:diameter ratio. In both western red cedar and hybrid larch the shoot:root ratio was significantly greater in the shade while in Sitka spruce this characteristic was not influenced by shade. While all species had significantly greater specific shoot areas in 75% shade than in 0% shade, this trend was particularly pronounced in hybrid larch. In hybrid larch and western red cedar, the normalised specific projected shoot area increased significantly with increasing shade. The opposite trend was observed for Sitka spruce. We conclude that in the main the species studied demonstrated similar shade acclimation responses despite their reported differences in shade tolerance.     

Studies on leaf spot and shoot blight of Eucalyptus caused by Cylindrocladium quinqueseptatum

In glasshouse experiments, Cylindrocladium quinqueseptatum, which was associated with outbreaks of leaf spot and shoot blight in a young plantation of Eucalpytus microcorys in north Queensland during the 1982 and 1983 autumns, was pathogenic on seedlings of E. microcorys and caused varying degrees of leaf spot and shoot blight in ten species of Eucalyptus from major taxonomic groupings of the genus, When the outbreaks occurred, the weather was unusually showery with minimum temperatures above 16°C. In vitro studies showed that free water was essential for conidial germination, which occurred between 14–32°C. The optimum for mycelial growth was 28.5°C. In vivo studies showed that leaf penetration. by germinated conidia was via the stomata. Mancozeb was more effective at controlling the disease than benomyl, captan or copper oxychloride. The potential importance of C. quinqueseptatum and options for control in young Eucalyptus plantations are discussed.     

Shoot drying and its cause in Calamus simplicifolius at Nanmeiling, Hainan, China

Many stems are subject to shoot drying in the plantations of Calamus simplicifolius Wei at the Nanmeiling Base of the Forestry Bu- reau of Baisha County, Hainan Province. As a palm, stems of C. simpli- cifolius stop growing and later die if the shoots are dry. Generally, shoot drying means reduced cane production and reduced profit for a rattan plantation. We aimed to quantify the incidence of shoot drying and de- termine its reason. We sampled eight 20 m × 20 m plots in the C. simpli- cifolius plantations. In each plot, we counted stems and categorized them as drying shoot or normal shoot, and mother stem or sucker stem. We measured stem length and categorized them as drying shoot and normal shoot for mother stems. We cut open each shoot-drying stem to deter- mine the cause of drying from drying part to fresh part. The frequency of mother stems (259 stem·ha -1 ), was significantly lower than sucker stems (588 stem·ha -1 ). The percentage of shoot drying was 33.8% for mother stems, not significantly higher than that for sucker stems (18.9%). The mother shoot stems were significantly shorter if they were drying than if normal. 80% of stems with a drying shoot were hollow within the leaf sheath, whereas 10% hosted lively mature larvae (one larvae per shoot) and 10% hosted several lively young larvae. Mature larvae were identi- fied as the Red Palm Weevil, Rhynchophorus ferrugineus Oliver. To confirm the present of the weevil, three pheromone traps for the weevil were set up in the plantations and adult weevils were trapped on the nextday and identified as the Red Palm Weevil. We conclude that shoot dry- ing of C. simplicifolius is probably caused by the Red Palm Weevil.     

Shoot multiplication and plant regeneration in <Emphasis Type="Italic">Caragana fruticosa</Emphasis> (Pall.) Besser

Different nutrient media can affect in vitro culturing protocols, and experimentation under varied growth conditions is valuable in plants where in vitro methods are in preliminary stages. We carried out the first in vitro propagation studies for the endangered species Caragana fruticosa (Fabaceae). We evaluated various nutrient media for their impact on shoot elongation and axillary bud proliferation using different concentrations of 6-benzylaminopurine (BA) and α-naphthaleneacetic acid (NAA). Shoot elongation was evaluated based on adventitious shoot primary culture and subculture regeneration from Caragana seedlings. Our goal was to improve both micropropagation and regeneration in C. fruticosa. MS nutrient media was superior to 1/2MS macronutrients, DKW, QL, and WPM for shoot elongation and axillary shoot proliferation. Shoots grown on 1/2MS and WPM exhibited some chlorosis, and shoots on QL produced larger leavers than plants growing on normal medium. The shoot proliferation coefficient on MS media supplemented with 2.22 μM BA and 0.44 μM BA + 2.69 μM NAA was significantly higher than that with other treatments in the primary culture. Shoots on 2.22 μM BA showed a higher proliferation coefficient (3.17) than others in the subculture. Shoots were rooted on 1/2MS medium with the addition of different concentrations of NAA. The optimal concentration for rooting was 0.27 μM NAA (74%). Roots exhibited many stout and long root hairs. Survivl of established plantlets was 82% at 30 days after transfer to soil. Plants established in the green house showed normal growth and displayed no apparent morphological differences compared to stock plants.     

Plant regeneration in <Emphasis Type="Italic">Actinidia polygama</Emphasis> Miq. by leaf,stem, and petiole culture with zeatin,and from stem-derived calli on low-sucrose medium

We examined the effect of zeatin on the formation of shoot buds from explants and callus tissues derived from stem segments of Actinidia polygama Miq. (matatabi or silver vine). Stem and petiole segments cultured on combined broad-leaved tree medium and woody plant medium (BW medium) supplemented with zeatin for 40 days formed many shoot buds. Callus tissues derived from the stem segments and subcultured on BW medium supplemented with 6-benzyladenine and 1-naphthaleneacetic acid formed shoot buds when the medium contained 13.7µM zeatin. BW medium containing low concentrations of sucrose strongly induced the formation of shoot buds from the callus.     

Influence of cytokinins,basal media and pH on adventitious shoot regeneration from excised root cultures of <Emphasis Type="Italic">Albizia lebbeck</Emphasis>

A highly reproducible and efficient in vitro shoot regeneration system was developed in a potential medicinal plant, Albizia lebbeck using root explants. Root explants from 15 day-old-aseptic seedlings were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations (0.5, 2.5, 5.0, 7.5 and 10.0 μM) of 6-Benzyladenine (BA), Kinetin (Kn), 2-Isopentenyl adenine (2-iP) singly as well as in combination with α-Naphthalene acetic acid (NAA) (0.1, 0.5, 1.0, 1.5 and 2.0 μM). The highest rate of shoot multiplication (16.0 ± 1.87 for the average shoot number and 5.16 ± 0.38 cm for shoot length) was achieved on MS medium supplemented with 7.5 μM BA and 0.5 μM NAA. The effects of medium type, medium strength, pH and subculture on shoot induction and proliferation were also tested. An average of 21.6±2.87 shoots per explants could be obtained following this protocol. Rooting was achieved on microshoots using half strength MS medium with 2.0 μM Indole-3-butyric acid (IBA) after four weeks of culture. The in vitro raised healthy plantlets were successfully established in earthen pots containing garden soil and grown in greenhouse with >80% survival rate.     

Genetic evaluation of twenty seed sources of <Emphasis Type="Italic">Asparagus racemosus</Emphasis>

A field trial of 20 seed sources of Asparagus racemosus was conducted at the Forest Research Institute, Dehradun, Uttarakhand, India to evaluate their performance of different economic traits. Genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV) and phenotypic coefficient of variance (PCV) for number of shoots, shoot height, shoot weight, number of roots, root length, root diameter and root weight were calculated. Maximum genotypic and phenotypic variance was observed in shoot height among the shoot — related traits and root length among the root — related traits. For the shoot height, genotypic variance, phenotypic variance, genotypic coefficient of variance, phenotypic coefficient of variance were 231.80, 3924.80, 61.26 and 1037.32, respectively, where those of the root length were 9.55, 16.80, 23.46 and 41.27, respectively. The maximum genetic advance and genetic gain were obtained for shoot height among the shoot-related traits and root length among the root-related traits. Index values were developed for all the seed sources based on the four most important traits, and Panthnagar (Uttrakhand), Jodhpur (Rajasthan), Dehradun (Uttarakhand), Chandigarh (Punjab), Jammu (Jammu and Kashmir) and Solan (Himachal Pradesh), were promising seed sources for root production.     

Effect of Melampsora rust on the growth and development of Salix burjatica‘Korso’in Northern Ireland

The impact of Melampsora rust on the growth of Salix burjatica‘Korso’was assessed. Comparisons were made between untreated plants and those where the disease had been partially controlled using fungicides. Fungicides delayed the onset of the disease and its effects on growth. Leaf loss was reduced whilst shoot growth and dry matter yields increased. The effect of secondary organisms was also reduced resulting in lower levels of shoot death in the following season.     

Direct evidence of Hymenoscyphus fraxineus infection pathway through the petiole‐shoot junction

The symptoms of ash dieback caused by the fungus Hymenoscyphus fraxineus include wilting of the foliage followed by dieback of shoots, twigs and branches. Necroses in shoots are assumed to develop after infection through leaf petioles; however, clear evidence of this infection pathway has not yet been provided. Considering the multiple pathogen genotypes in dead ash petioles, we aimed to obtain a spatial overview of all H. fraxineus genotypes colonizing individual shoots and their corresponding petioles before leaf shedding to acquire precise information about the infection biology of H. fraxineus and its ability to cross the petiole‐shoot junction. Individual genotypes of H. fraxineus were characterized by the analysis of microsatellites using DNA extracted directly from petiole segments or cultures isolated from the segments. We detected 150 different multilocus genotypes in 10 analysed shoots and their respective petioles; the highest number of genotypes was eight for a single petiole and three for a single shoot. The genotypes of most shoot lesions were identical to particular genotypes from the proximal segments of petioles, implicating the main pathway of shoot infections. To test whether the amount of colonized substrate or intraspecific competition have an effect on successful infection, genotypes that reached the most proximal end of the petioles were scored for the number of invaded petiole segments and for the number of other H. fraxineus genotypes co‐occurring in the segments. However, the extent of colonization of the scored genotypes and intraspecific competition with other H. fraxineus strains did not influence pathogen success in entering the shoot. This study confirms that the majority of ash shoot infections are caused by genotypes of H. fraxineus originating from petioles. Compared to petioles, the frequency of shoot colonization as well as number of H. fraxineus genotypes in shoots was much lower.     

Ecophysiological and genetic variation in seedling traits and in first-year field performance of eight <Emphasis Type="Italic">Acacia senegal</Emphasis> provenances in the Blue Nile,Sudan

The genetic variation in seed weight, seed number per kg and seedling traits was compared among eight Acacia senegal provenances originating from the clay plain (east) and sand plains (west) of the gum belt in Sudan. The main objective of this study was to identify germplasm sources of A. senegal that have a good seed germination capacity and seedling traits suitable for reforestation in the clay-soil part of the dryland gum belt in the Blue Nile region in Sudan. A specific objective was to tentatively explore the adaptive strategy of A. senegal populations. Seventeen-week-old seedlings were planted in the field at spacing of 3 m × 3 m, giving 100 trees per plot and replication; within a randomized complete block design with four replications. The experimental site was in the clay plain region. Seed variables showed significant differences. Clay plain provenances showed considerable variation in seed weight and seed number. They had the smallest seed weight but the highest seed number, while the sand (western) provenances had the largest seed weight but lowest seed number. Seedling branch number, root length, root to shoot ratio and shoot dry weight differed significantly among the provenances 12 weeks after germination. Clay provenances had the highest branch number and shoot dry weight but the shortest roots and lowest root to shoot ratio. This was interpreted as showing better adaptation to the site in these local provenances in comparison to those originating from the western sandy soil regions. High positive correlations were observed between seedling variables, such as root nodule and branch numbers; this could be used for early selection. The variation was greater between provenance groups than within them, suggesting that especially selection among groups would yield genetic gain.     

Inoculation with the ectomycorrhizal fungi <Emphasis Type="Italic">Pisolithus arhizus</Emphasis> and <Emphasis Type="Italic">Scleroderma</Emphasis> sp. improves early growth of <Emphasis Type="Italic">Shorea pinanga</Emphasis> nursery seedlings

Trees of the family Dipterocarpaceae are the dominant trees in Southeast Asian tropical forests where they play an important ecological role and are also important commercially. An experiment was conducted to determine the effect of ectomycorrhizal fungi on the growth of dipterocarp species in peat soils. Seedlings of Shorea pinanga were inoculated with spores of two ectomycorrhizal fungi, Pisolithus arhizus and Scleroderma sp. were grown in pots containing sterilized peat soil for 7 months. The percentage of ectomycorrhizal colonization on S. pinanga exceeded 86%. Colonization of S. pinanga roots by ectomycorrhizal fungi resulted in increased shoot height, stem diameter, number of leaves, and shoot fresh and dry weight. Survival rates of S. pinanga were greater for inoculated seedlings than control seedlings. These results suggest that inoculation of ectomycorrhizal fungi can improve the early growth of S. pinanga grown in tropical forests and that this technique will accelerate the rehabilitation of degraded dipterocarp forests.     

Forest biomass and root–shoot allocation in northeast China

Temperate and boreal forests act as major sinks for atmospheric CO₂. To assess the magnitude and distribution of the sinks more precisely, an accurate estimation of forest biomass is required. However, the determinants of large-scale biomass pattern (especially root biomass) are still poorly understood for these forests in China. In this study, we used 515 field measurements of biomass across the northeast part of China, to examine factors affecting large-scale biomass pattern and root–shoot biomass allocation. Our results showed that, Picea & Abies forest and coniferous & broadleaf mixed forest had the highest mean biomass (178–202 Mg/ha), while Pinus sylvestris forest the lowest (78 Mg/ha). The root:shoot (R/S) biomass ratio ranged between 0.09 and 0.67 in northeast China, with an average of 0.27. Forest origin (primary/secondary/planted forest) explained 31–37% of variation in biomass (total, shoot and root), while climate explained only 8–15%, reflecting the strong effect of disturbance on forest biomass. Compared with shoot biomass, root biomass was less limited by precipitation as a result of biomass allocation change. R/S ratio was negatively related to water availability, shoot biomass, stand age, height and volume, suggesting significant effects of climate and ontogeny on biomass allocation. Root–shoot biomass relationships also differed significantly between natural and planted forests, and between broadleaf and coniferous forests. Shoot biomass, climate and forest origin were the most important predictors for root biomass, and together explained 83% of the variation. This model provided a better way for estimating root biomass than the R/S ratio method, which predicted root biomass with a R² of 0.71.     

Efficacy of nine insecticides against shoot and fruit borer, <Emphasis Type="Italic">Leucinodes orbonalis</Emphasis> Guenee (Lepidoptera: Pyralidae) in eggplant

Shoot and fruit borer, Leucinodes orbonalis Guenee, is a serious pest of eggplant (Solanum melongena L.). Management practices of this obnoxious pest are limited to frequent spray of chemical insecticides. Due to increasing levels of resistance of L. orbonalis to different insecticides there is an urgent need to test new chemicals. In this study, nine insecticides such as azadirachtin 0.03EC, abamectin 1.8EC, flubendiamide 24WG, chlorpyriphos 20EC, cartap 50SP, carbosulfan 20EC, thiodicarb 75WP, cypermethrin 10EC, and lambdacyhalothrin 2.5EC belonging to different chemical groups were tested against eggplant shoot and fruit borer in laboratory and field. In laboratory trial, carbosulfan and flubendiamide showed the highest toxicity against fourth instar larvae of L. orbonalis after 24 and 48 h of exposure, respectively. In field trials, they reduced more than 80% shoot and fruit infestation in winter, and 80% shoot and 70% fruit infestation in summer over control. Carbosulfan protected the highest amount of healthy fruit yield in both cropping seasons. Flubendiamide also showed the similar efficacy. Cartap and thiodicarb were moderately effective in both the seasons. Efficacy of cypermethrin and abamectin was moderate in winter but low in summer. Lambdacyhalothrin and chlorpyriphos although reduced shoot and fruit infestation of eggplant and protected higher yield as compared to control, their effectiveness was not satisfactory. The performance of azadirachtin against the pest both in the laboratory and field trials was the poorest while that of carbosulfan and flubendiamide was the best. Thus, it is suggested that carbosulfan and flubendiamide may be used for the control of L. orbonalis in eggplant.