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1.
Plant-based products, namely essential oils (EOs), are environmentally friendly alternatives for the control of disease vectors, hosts and/or parasites. Here, we studied the general toxicity and biopesticidal potential of EOs and phenylpropanoids from Foeniculum vulgare var. vulgare (bitter fennel), a perennial plant well adapted to temperate climates. EO/compound toxicity was tested against a freshwater snail and potential intermediate host of Fasciola hepatica (Radix peregra), a mosquito and former European malaria vector (Anopheles atroparvus) and one of the most damaging plant-parasitic nematodes, the root-knot nematode (Meloidogyne javanica). Lethal concentrations (LC50; LC90) of EOs (infrutescences/stems with leaves) and compounds were calculated by probit analysis. All displayed noteworthy activity against R. peregra adults (LC50 21–39 µg ml?1) and A. atroparvus larvae (LC50 16–56 µg ml?1). trans-Anethole revealed acute nematicidal activity after 24 and 48 h (LC50 310 and 249 µg ml?1, respectively), and estragole (1,000 µg ml?1) showed some effectiveness against M. javanica hatching and juveniles after 15 days. Plant and EO yields were determined to evaluate the bitter fennel productivity. The chemical composition of the EOs was analyzed by gas chromatography coupled to mass spectrometry. EOs extracted from whole plants, infrutescences and stems with leaves were characterized by estragole-dominant profiles (28–65 %), considerable amounts of phellandrene (10–34 %) and fenchone (6–16 %), and minor trans-anethole contents (1–4 %). Although additional toxicological studies against nontarget organisms are required, our study demonstrates that bitter fennel is a productive source of molluscicides and larvicides, and thus a potential sustainable biological agent to control particular host species, namely freshwater snails and mosquitoes.  相似文献   

2.
Bioassays and scanning electron microscopy of Conidiobolus obscurus for bamboo aphids as well as its effects on the fecundity of bamboo aphids were carried out to estimate bamboo aphid biocontrol potential. Multi-concentration bioassay and fecundity assessment were performed on aphid species of Takecallis taiwanus, Takecallis arundinariae, Melanaphis bambusae, and Metamacropodaphis bambusisucta. C. obscurus can effectively infect four species of bamboo aphids, and most cadavers appeared in the first 2 days after inoculation. The final mortalities reached 74–91 % at high concentrations of conidia among the tested species. Based on the fitted time–concentration–mortality models, the estimates of the median lethal concentration (LC50) of the fungal conidia differed significantly among different aphid species and decreased with observation days. The lowest LC50 was estimated to be 57 conidia mm?2 for T. taiwanus on day 5 after conidial shower. Moreover, the C. obscurus-infected aphids only produced 3.9–18.2 % progeny of the corresponding healthy aphids, which strongly presented fungal influence on host fecundity. In conclusion, C. obscurus has the ability of restraining the development of bamboo aphid populations, which is suitable for further application in aphid biocontrol in bamboo forests.  相似文献   

3.
Thiamethoxam (ACTARA® 25WG) was evaluated for its insecticidal activities against the bamboo powder post beetle Dinoderus minutus Fabricius (Coleoptera: Bostrichidae). The study showed that thiamethoxam had contact toxicity against D. minutus. Based on dose-mortality responses, LC50 values for thiamethoxam against D. minutus ranged from 1.74 to 7.94 μg ml?1. Laboratory and field exposure tests showed that thiamethoxam at concentration of atleast 10 μg ml?1 may have anti-oviposition or anti-feeding effects on D. minutus and can protect post harvest Bambusa vulgaris Schrad. culms against the infestation of this bamboo boring beetle.  相似文献   

4.
The present study describes an efficient method for in vitro plant regeneration in B. arundinacea through axillary shoot bud proliferation. Nodal explants were excised, cultured on MS medium containing different concentrations of 6-benzylaminopurine (BAP), kinetin (KIN) (0.5–5.0 mg l?1) alone and/or in combinations with KIN/BAP (0.5 mg l?1). The highest frequency (91.5 %) of multiple shoot bud induction with maximum number of shoots (85 shoots/explant) was noticed on MS medium + 3.0 mg l?1 BAP + 0.5 mg l?1 KIN. The regenerated multiple shoots were elongated on MS medium + 4.0 mg l?1 KIN + 2.0 mg l?1 gibberellic acid (GA3) with maximum shoot length (4.9 cm). The elongated shoots were transferred to MS medium containing indole-3 butyric acid (IBA; 0.5–5.0 mg l?1) alone and/or in combination with 0.5 mg l?1 KIN and BAP. Highest frequency of rooting (75 %) was obtained on half-strength MS medium + 2.0 mg l?1 IBA + 0.5 mg l?1 KIN. After hardening, the plantlets were shifted to the green house and subsequently established in the field conditions with 90 % survival rate. random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic stability of the regenerants. RAPD profiles generated from the regenerated plants were found to be monomorphic, similar to the control. Results confirmed that the regenerated plants were true-to-type in nature and the developed micropropagation protocol could be used for large scale plant production of B. arundinacea.  相似文献   

5.
This paper attempts to provide a new perception of the weed Chromolaena odorata (Asteraceae) which is considered as a plague in agriculture or as a soil fertility indicator. The study was conducted in the forest-savanna transition zone of C?te d??Ivoire and aimed to compare soil biological activity and plant nutrient availability under three well-represented vegetation features, including C. odorata lands (ChrO), shrub savannas (ShrS), and grass savannas (GraS). Each of these vegetation features included five plot replicates (50?m?×?50?m size) distributed in the landscape. Soil chemical parameters such as pH, organic matter, soluble phosphorus, exchangeable bases, and biological parameters such as abundance and diversity of earthworms, and soil enzymatic activities were investigated. Composite soil samples were collected and analyzed for chemical and microbial parameters while earthworms were sampled using the Tropical Soil Biology and Fertility 25?×?25?×?30?cm soil monolith method. A principal component analysis showed a clear demarcation between C. odorata plots and the savanna ones. Soluble P and exchangeable bases were significantly higher under ChrO than under both savannas. Earthworm density was twice higher under ChrO (433.3?±?90.8?ind?m?2) than under ShrS (173.9?±?61.5?ind?m?2) and GraS (176.0?±?40.6?ind?m?2) and this was accounted for by the abundance of detritivores and polyhumics. Acid and alkaline phosphatase activities under ChrO (2.9?±?0.2 and 2.5?±?0.3???mol pNP?g?1 soil?h?1, respectively) were twice higher than under both savannas. Based on the fact that ChrO and ShrS were located on similar soil types and had the same topographic position, we concluded that the establishment of C. odorata in a savanna land and its subsequent high biomass and quality-litter production were mostly the reasons of the improvement in soil biology and plant nutrient availability. Between-savanna comparison showed that ShrS, with higher CEC and exchangeable bases, was somewhat more fertile than GraS, probably because of a better soil physical status. In view of the agronomic potentials of the shrub C. odorata, it may be taken as a basis for improved fallow in Africa.  相似文献   

6.
The relationship between Xenorhabdus nematophilus and Photorhabdus luminescens, the bacterial symbionts of the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora, against the diamondback moth, P. xylostella (L.), pupae showed the pathogenic capability of P. luminescens to be over that of X. nematophilus. They gave 60 and 40?% mortality with LC50 values of 5?×?104 and 5.5?×?105 cells/ml, respectively.The number of bacterial cells influences the rate of killing the pupae of P. xylostella and a direct correlation between mortality of the pupae, percentage of deformed adults and the spraying dose with significant differences were observed. An inverse correlation found between the no. of eggs laid/female, percentage of hatching, adult survival and the spraying dose. These bacterial effects have been attributed to different toxic bacterial enzymes which damage the haemocytes and inhibit activation of the humoral immune system of the insect.  相似文献   

7.
Various plants are well known for their insecticidal activity and their use was maintained for millennia throughout all the agricultural regions of the world. In a current context, the use of Botanical insecticides represents one of the best alternatives to chemicals for the development of environmental-friendly strategies for stored grain pest control. Datura alba Nees is a plant found extensively in the warmer regions of the world and it is used as a medicinal plant. This study aims to assess the contact toxicity and the trans-generational effect of D.?alba leaf extract (DLE) against two important insect pests on stored rice, Trogoderma granarium and Sitophilus oryzae, under laboratory conditions. Filter papers were soaked in three DLE concentration solutions and in two control treatments: water and acetone. The survivor specimens (F0) were transferred to a new untreated feeding substrate and the population build up of the two following generations (F1 and F2) were counted after 30 and 60?days, respectively. The highest DLE concentration (2.5?%) induced the significantly highest mortality with 33.5 and 45?% mortality in T.?granarium and S.?oryzae after 7?days of exposure, respectively. The DLE long-term effect toward both tested species was also proved by the high demographic decrease in the F2 generations, when compared to control groups. This study is the first step toward establishing a scientific basis for the effective application of D.?alba plant materials as biorational tools to control stored grain pests.  相似文献   

8.
The insecticidal activity of an entomopathogenic fungus, Isaria farinosa on pine bark-weevil (Pissodes punctatus) at different life stages underwent laboratory testing. Larvae, pupae and adults of Pissodes punctatus were exposed to a range of concentrations of fungal conidia in suspension for 5 s; mean mortality and LC50 values were calculated. The results showed I. farinosa can effectively infect larvae, pupae and adult pine bark-weevils, and the highest mean mortalities at each life stage can exceed 88%. The mean mortalities increased with higher concentrations of I. farinosa. Larvae were most susceptible with LC50 1.2 × 106 conidia ml−1 (15 days), pupae (30 days) exhibited the second largest effects, and adults (15 days) with LC50 1.72 × 106 and 1.99 × 106 conidia ml−1, respectively, at end of the experiments. This suggests that I. farinosa could be a potential bio-control agent against the pine bark-weevil.  相似文献   

9.
Habrobracon hebetor Say (Hymenoptera: Braconidae) is an ectoparasitoid that is used for inundative biological control of various lepidopteran insect pests. Lethal and sublethal effects of two biorational insecticides, methoxyfenozide and pyridalyl, were evaluated on H. hebetor under laboratory conditions. The adults were exposed to dry insecticide residues that were applied on glass plates. Bioassays showed that the LC50 values of methoxyfenozide and pyridalyl were 155 and 1,226 μg a.i./ml, respectively. The LT50 values of methoxyfenozide and pyridalyl were 2.1 and 3.3 days, respectively. The effects of methoxyfenozide and pyridalyl on larvae were tested using a dip method with field-recommended concentrations of either insecticide. The emergence rates were reduced by 24.4 and 29.3 % for methoxyfenozide and pyridalyl treatments, respectively. In order to assess the sublethal effects of low-lethal concentrations of methoxyfenozide and pyridalyl, adult wasps were exposed to the LC30 concentration of each insecticide, and demographic parameters of live wasps were recorded. Exposure of adults to low-lethal concentrations (LC30) negatively affected the fecundity, fertility, and sex ratio, and also the intrinsic rate of increase (r m), finite rate of increase (λ), generation time (T), and doubling time (DT). The longevity and net reproductive rate (R 0) of H. hebetor were not affected by sublethal exposure to these insecticides. The results showed that despite low acute toxicities of both insecticides on larval and adult stages of H. hebetor, they may negatively affect the population of the parasitoid and interfere in IPM programs.  相似文献   

10.
The lethal and sublethal effects of chlorantraniliprole against Spodoptera exigua (Hübner) were evaluated under laboratory conditions by oral exposure of neonate larvae to the compound. The 72 h LC50 value of this insecticide to S. exigua was found to be 12.747 μg l−1. A progressive larval mortality of 24.32% for LC30 treatment and 42.61% for LC50 treatment was observed from 4th to 6th day after exposure, which resulted in the reduced pupation rates in exposure groups. The sublethal effects of this chemical were indicated by prolongation of larval period, the increase of pupal weight and decrease in hatch rate of egg. Chlorantraniliprole at LC30 and LC50 rate significantly delayed larval development; the developmental duration of surviving larvae was extended for 22.5 and 28.6%, respectively, compared with that of control group. LC30 treatment increased the mean weight of pupa and induced to the production of heavier pupa (>150 mg). In LC50 treatment, heavier pupa also showed up but the mean weight of pupa was not influenced. The egg hatch rate in LC50 group was significant lower than that in control and LC30 groups. No significant differences in pupal duration, emergence rate, sex ratio, egg number per female, and longevity of adults were observed among treatments. Chlorantraniliprole had exceptional activity against S. exigua according to concentration–response bioassay in laboratory, and the toxicities were primarily resulted from immediate lethality.  相似文献   

11.
An efficient, in vitro clonal propagation protocol has been established for Gardenia latifolia Ait. using mature nodal explants on Murashige and Skoog (MS) medium fortified with cytokinins (BA/Kn/2-iP) (1.0–5.0 mg l?1) in combination with auxin IAA (0.5 mg l?1). Maximum bud break (87 %) with shoot number (7.2 ± 0.26) observed on MS medium supplemented with BA (4.0 mg l?1) and IAA (0.5 mg l?1). Maximum number of shoots (30 ± 0.46) with shoot length of (0.9 ± 0.03 cm) observed on MS medium supplemented with BA (2.0 mg l?1), Kn (2.0 mg l?1) and IAA (0.5 mg l?1). Further elongation of shoots (3.5 ± 0.06 cm) was achieved on MS medium supplemented with BA (1.0 mg l?1) and IAA (0.1 mg l?1). About 70 % of root induction occurred in half-strength MS medium supplemented with IBA (4.0 mg l?1) in 4–6 weeks. Further elongation of roots with average length (9.0 cm) was achieved in culture bottles containing vermiculite and ¼ strength MS salts. After their partial hardening in these bottles for 30 days they were transferred to pots containing a mixture of soil and vermicompost (1:1) for acclimatization. The acclimatized plantlets were established in the field successfully with 85 % survival rate.  相似文献   

12.
Bactimos was incubated for 30 days under 7 constant temperatures (i. e. ?20, ?10, 5, 25, 35, 40 and 45°C). The insecticidal activity of the compound was evaluated against 2nd and 4th instar larvae ofCulex pipiens molestus after 1, 3, 7, 10, 15 and 30 days of storage. No loss in the insecticidal activity of the Bactimos was detected after 30 days at ?20, ?10 and 5°C. At temperatures above 25°C the insecticidal activity reduced as the storage period increased. The LT50 value of Bactimos for the 2nd and 4th instar larvae at 24 h and 48 h exposure was found to decrease as the temperature increased.  相似文献   

13.
  • ? We investigated the effects of flooding for three weeks on physiological responses and uptake of NH 4 + and NO 3 ? by black spruce (Picea mariana (Mill.) BSP.) and tamarack (Larix laricina (Du Roi) K. Koch) seedlings fertilized with labeled (15NH4)2SO4 or K15NO3 in a growth chamber experiment.
  • ? Flooding reduced photosynthesis (A), transpiration (E), water use efficiency (WUE), and current uptake of NH 4 + and NO 3 ? in both species.
  • ? Under flooding, there were no significant differences between the two species in uptake of either NH 4 + or NO 3 ? at the whole-plant level but black spruce had higher translocation of NH 4 + to the shoots than did tamarack.
  • ? Under non-flooded conditions, black spruce seedlings exhibited higher uptake of both NH 4 + and NO 3 ? than did tamarack and demonstrated preferential uptake of NH 4 + (19. 7 mg g?1dw) over NO 3 ? (12.3 mg g?1dw after three weeks). In contrast, non-flooded tamarack seedlings had equal uptake of NH 4 + (4.96 mg g?1dw) and NO 3 ? (4.97 mg g?1dw).
  • ? We hypothesize that the ability of tamarack to equally exploit both 15NH 4 + and 15NO 3 ? would confer an advantage over black spruce, when faced with limitations in the availability of different forms of soil nitrogen.
    •   相似文献   

    14.
    The antifungal activity of twenty-two common spices was evaluated against plant pathogens using direct-bioautography coupled Colletotrichum bioassays. Turmeric, nutmeg, ginger, clove, oregano, cinnamon, anise, fennel, basil, black cumin, and black pepper showed antifungal activity against the plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides. Among the active extracts, turmeric and nutmeg were the most active and were chosen for further investigation. The bioassay-guided fractionation led to the isolation of three compounds from turmeric (1–3) and three compounds from nutmeg (4–6). Their chemical structures were elucidated by spectroscopic analysis including HR-MS, 1D, and 2D NMR as curcumin (1), demethoxycurcumin (2) and bisdemethoxy-curcumin (3), erythro-(7R,8R)-Δ8′-4,7-dihydroxy-3,3′,5′-trimethoxy-8-O-4′-neolignan (4), erythro-(7R,8R)-Δ8′-7-acetoxy-3,4,3′,5′-tetra-methoxy-8-O-4′-neolignan (5), and 5-hydroxy-eugenol (6). The isolated compounds were subsequently evaluated using a 96-well microbioassay against plant pathogens. At 30 μM, compounds 2 and 3 possessed the most antifungal activity against Phomopsis obscurans and Phomopsis viticola, respectively.  相似文献   

    15.
    Wood density and pulp yield are key parameters in the evaluation of tree productivity and quality for pulping and their relationships are of high practical importance. The influence of wood density on pulp yield and other pulp quality parameters was investigated using Acacia melanoxylon and its natural variability as a case study. Twenty trees were harvested (five trees in each of four sites in Portugal), and wood discs taken at different height levels, from the base to the top of the tree, providing 100 wood samples, covering the natural variability of wood density ranging from 449?kg?m?3 to 649?kg?m?3. Under the same experimental conditions of kraft pulping, screened pulp yield ranged 47.0?C58.2?%, Kappa number 10.9?C18.4, ISO brightness 14.9?C45.6, fibre length 0.660?C0.940?mm and fibre width 16.2?C22.9???m. The pulp yield and Kappa number were not correlated with wood density. Higher pulp yields were associated with lower Kappa numbers and alkali consumption, suggesting the important role of chemical composition of wood on kraft cooking. The results confirm the high pulping potential of Acacia melanoxylon trees grown in Portugal and suggest the possibility of tree selection using both wood density and pulp yield.  相似文献   

    16.
    In the laboratory, a commercial neem-based insecticide—Nimbecidine®—was evaluated as a potential pest management tool for the terrestrial snail, Monacha obstructa (Pfeiffer, 1842) (Hygromiidae). Effects of different concentrations of the botanical insecticide on food consumption and egg hatchability of the terrestrial snail were studied. Generally, food consumption of immature and adult snails decreased as the concentrations of Nimbecidine® increased. At the highest concentration (10 ml/l), the snails avoided contacting with food completely. The food intake of immature individuals was significantly (p < 0.05) more affected by the Nimbecidine® treatment (at 1.25 ml/l) than that of adults. LC50 of Nimbecidine® for the treated eggs was 2.18 ml/l, and eggs failed to hatch at concentration of 10 ml/l. Nimbecidine® showed sufficient biological activity against the food consumption and eggs viability of M. obstructa, thus the preparation has a potential to protect field crops from this pest snails.  相似文献   

    17.
    The bioefficacies of essential oil and aromatized clay powder based on the mixture of clay and essential oil extracted from Clausena anisata were evaluated for their insecticidal activities and their effects on progeny production of Acanthoscelides obtectus. Contact toxicity assayed by coating on bean grains showed that these chemicals caused significant mortality of the test insect. Beetle mortality was dose dependant and after 2-day exposure the aromatized clay powder was more toxic (LD50 = 0.069 μl/g grain) than the pure essential oil (LD50 = 0.081 μl/g grain). There was, however, a highly significant loss of toxicity after 24 and 36 h following treatment with essential oil and aromatized powder, respectively. Both aromatized clay powder and pure essential oil considerably reduced the F1 progeny insect production. The essential oil evoked moderated repellent action and high fumigant toxicity (LC50 = 0.093 μl/cm3) against adults of A. obtectus. These results suggest that the clay powder could be used to stabilize the essential oil to increase its efficacy for use as an alternative to synthetic insecticides.  相似文献   

    18.
    We monitored variation in seasonal and annual net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration (R E) based on 7-year eddy covariance measurements above a cool?Ctemperate deciduous broad-leaved forest (Japanese beech forest). The 7-year means (±SD) of annual NEP, GPP, and R E were 312?±?64, 1250?±?62, and 938?±?36?g?C?m?2?year?1, respectively. Variation in NEP was much larger than variation in GPP and R E. During the growing season, the main factor controlling carbon balance was air temperature; variation in seasonal integrated NEP was regulated by accumulated air temperature (degree-day) with a significant negative correlation, whereas the seasonal ratio of R E to GPP was correlated positively with accumulated air temperature. Because the deviation of seasonal NEP was also significantly correlated with seasonal R E/GPP, NEP was controlled by R E/GPP, depending on air temperature during the growing season. Seasonal R E in the defoliation and snow seasons was also important for evaluating the annual carbon balance, because the total number of days in the two seasons was quite large owing to a long snowy winter. In the defoliation and snow seasons, we found defoliation season length was a major factor determining seasonal integrated R E, illustrating the positive correlation between R E and defoliation season length. The major factors controlling interannual variations in forest carbon balance are discussed.  相似文献   

    19.
    Carbon dioxide (CO2) flux was measured above the forest at the Fujiyoshida site on the northern slope of Mount Fuji in Japan in 2000?C2008 using an eddy covariance technique. The forest mainly consists of Japanese red pine (Pinus densiflora) and Japanese holly (Ilex pedunculosa). The 9-year average of monthly mean net ecosystem production (NEP) ranged from ?0.1?g?C?m?2?day?1 in January to 2.5?g?C?m?2?day?1 in May. The maximum net uptake was observed in May, although gross primary production (GPP) was highest in July. Variation in the leaf amount did not notably affect seasonal variation in GPP. This site was characterized by carbon uptake even in winter, if the meteorological conditions were conducive for photosynthesis and a resulting long period of carbon uptake. The 9-year averages of annual NEP, GPP, and ecosystem respiration (RE) were 388, 1,802, and 1,413?g?C?m?2?year?1, respectively. The annual NEP was lowest in 2003 and highest in 2004 over the 9?years. Year-to-year variability of NEP mainly depended on air temperature and photosynthetically active radiation in summer, and the dependence of the deviation of annual NEP on that of GPP was greater than that of RE. Long-term observational data indicated that the carbon uptake ability at the study site was at a moderate level in comparison with other temperate humid evergreen forests around the world. These data also indicated that the site had a high carbon uptake ability compared with other deciduous forests in Japan because of the duration of carbon uptake.  相似文献   

    20.
    Interactive effects of elevated atmospheric CO2 and soil N fertility on above- and below-ground growth, mycorrhizal colonization, and water relations of juvenile ponderosa pine (Pinus ponderosa Dougl. ex Laws.) were investigated. One-year-old seedlings were planted in undisturbed field soil within open-top chambers which permitted creation of atmospheres with 700 μl l−1, 525 μl l−1, or ambient CO2 concentrations. High and medium soil N treatments were imposed by incorporating sufficient (NH4)2SO4 to increase total N by 200 μg g−1 and 100 μg g−1, respectively, while unamended soil, which had a total N concentration of approximately 900 μg g−1, constituted the low N treatment. Following each of two consecutive field growing seasons, whole seedlings of every combination of CO2 and N treatment were harvested to permit assessment of shoot and root growth and quantification of ectomycorrhizal development. Late in the second growing season, a simulated drought episode was imposed by withholding irrigation during which predawn and midday xylem water potential and soil water potential were measured. The initial harvest revealed that coarse and fine root weights were increased by CO2 enrichment during the first growing season. This result was most apparent in the 525 μl l−1 CO2 treatment and high soil N, which produced the greatest root volume as well. Shoot/root ratio decreased with increasing CO2 at the first harvest. After two growing seasons, elevated CO2 increased seedling diameter, shoot and root volume, and shoot and coarse root weight, again most prominently in high N. Unlike the initial results, however, stimulation of seedling growth by the 700 μl l−1 CO2 atmosphere exceeded that in 525 μl l−1 CO2 after two growing seasons, and shoot/root ratio was unaffected by either CO2 or N. At both harvests, seedlings grown in the enriched atmospheres generally had higher mycorrhizal counts and greater percentages of colonized root length, but differences among treatments in ectomycorrhizal development were nonsignficant regardless of quantification method. During the imposed drought episode, xylem water potential of seedlings grown in elevated CO2 descended below that of seedlings grown in the ambient atmosphere as soil water potential decreased, most notably in the predawn measurements. These results suggest that CO2 enrichment stimulates shoot and root growth of juvenile ponderosa pine under field conditions, a response somewhat dependent on soil N availability. However, below-ground growth is not increased proportionally more than that above ground, which may predispose this species to greater stress when soil water is limited.  相似文献   

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