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1.
Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China. Nitrogen requirements for producing robust seedlings, growth and nutrient dynamics were investigated using exponential fertilization treatments. Root collar diameter, height, dry mass and nutrient contents of seedlings increased exponentially in all fertilization treatments as time progressed. Moreover, with water soluble fertilizer (Plant Products plus microelements N–P2O5–K2O: 20–20–20), 300 mg N seedling?1 was adequate. Vector analysis revealed that P was the most responsive nutrient element, followed by N and K. Dilutions of N and K were evident in the plants without N addition, which induced initial P sufficiency and then luxury consumption probably due to the antagonistic interaction between N and P. However, deficiencies of N, P and K were mostly observed in all exponential regimes during the experiment because seedling growth rate exceeded nutrient uptake rate, inferring that further study on improving the nutrient uptake efficiency is needed. Analysis of relationships among nutrient supply, dry mass, N content and N concentration demonstrated that 100–400 mg N seedling?1 induced sufficiency to luxury consumption of nitrogen without significant change in dry mass, and 400 mg N seedling?1 is recommended to apply for nutrient loading of seedlings before outplanting. The findings will help improve seedling quality and enhance the production of robust seedlings for plantation forestry of this species.  相似文献   

2.
Fall nutrient loading of deciduous forest nursery seedlings is of special interest because of foliage abscission and varied translocation patterns. For non-deciduous seedlings in the nursery, fall fertilization typically can reverse nutrient dilution and possibly increase nutrient reserves; however, this technique has received little attention with deciduous conifer trees that translocate nutrients before abscising foliage. We evaluated how fall nitrogen (N) fertilization affected N storage and translocation in the deciduous conifer Olga Bay larch (Larix olgensis Henry) seedlings during the hardening period. Seedlings were supplied with 25 mg N seedling?1 for 15 weeks before hardening and fall fertilization treatments began with a three week application period of K15NO3 at 0, 5, 10 and 15 mg N seedling?1. During the hardening period, fall N fertilization had little effect on seedling morphology. The N concentration and content of needles decreased dramatically as needles abscised, while that of stems and roots increased. Six weeks after fall N fertilization ceased, all seedlings translocated similar net N from their needles. For the control seedlings, this accounted for 84 % of the N stored in stems and roots. For fall fertilized seedlings, however, the proportion of N stored in stems and roots translocated from needles accounted for only 41–61 % of the total because of absorption of fall fertilizer that was translocated directly to stems and roots. Six weeks after fall fertilization, the distribution pattern of N concentration and content in seedlings was found in this order: stems > fine roots > coarse roots > needles. Our results suggest that providing deciduous conifer seedlings N during hardening, in this case Olga Bay larch, is a way to promote nutrient loading during nursery production.  相似文献   

3.
Maintaining proper seedling nitrogen status is important for outplanting success. Fall fertilization of evergreen conifer seedlings is a well-known technique for averting nitrogen (N) dilution caused by continued seedling growth during hardening. For deciduous seedlings, this technique is much less understood, and regardless of foliage type, the interaction of N status prior to fall fertilization and the rate of fall fertilization have yet to be fully explored. Therefore, we fertilized Quercus variabilis container seedlings with either 25, 100, or 150 mg total N seedling?1, applied exponentially, during a 23-week pre-hardening regime, followed by either 0, 12, or 24 mg total N seedling?1 applied during hardening (i.e., fall fertilization) in equal aliquots for 4 weeks. For seedlings without supplemental N during hardening, N concentration in stems and roots increased significantly despite substantial growth. The absence of N dilution was attributed to N translocation from foliage to these tissues, which was independent of pre-hardening N status. Overall, 32 % of foliar N was translocated and accounted for 75 % of the total N increase in stems and roots. Final stem N status was a function of pre-hardening fertilization, whereas root N concentration was affected by the interaction of pre-hardening and fall fertilization. Roots appear to be the main site of N storage, and root N content was significantly affected by pre-hardening and fall fertilization, but not their interaction. A combination of pre-hardening and fall fertilizer at a rate of 100 and 24 mg total N seedling?1, respectively, yielded seedlings with the largest root systems.  相似文献   

4.
The growth patterns of annually resolved tree rings are good indicators of local environmental changes, making dendrochronology a valuable tool in air pollution research. In the present study, tree-ring analysis was used to assess the effects of 16 years (1991–2007) of chronic nitrogen (N) deposition, and 10 years (1991–2001) of reduced nitrogen input, on the radial growth of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) growing in the experimental area of Lake Gårdsjön, southwest Sweden. In addition to the ambient input of c. 15 kg N ha?1 year?1, dissolved NH4NO3 was experimentally added to a 0.52-ha watershed at a rate of c. 40 kg ha?1 year?1. Atmospheric N depositions were reduced by means of a below-canopy plastic roof, which covered a 0.63-ha catchment adjacent to the fertilized site. The paired design of the experiment allowed tree growth in the N-treated sites to be compared with the growth at a reference plot receiving ambient N deposition. Nitrogen fertilization had a negative impact on pine growth, while no changes were observed in spruce. Similarly, the reduction in N and other acidifying compounds resulted in a tendency towards improved radial growth of pine, but it did not significantly affect the spruce growth. These results suggest that spruce is less susceptible to changes in the acidification and N status of the forest ecosystem than pine, at least in the Gårdsjön area.  相似文献   

5.
We tested the effects of exponential nutrient loading and springtime carbon loading during nursery culture on the field performance of black spruce (Picea mariana (Mill.) B.S.P.). Seedlings were grown from seed with a conventional, fixed dose fertilizer (10 mg N seedling−1) or an exponential nutrient loading regime (75 mg N seedling−1). The following spring, seedlings were exposed for two weeks to either ambient (370 ppm) or elevated levels of CO2 (800 ppm) and then planted in the field; seedling growth was followed for the next six years. Exponential nutrient loading increased seedling height, stem diameter and leader growth, with the largest increases in height and leader length occurring in the first three years after outplanting. Carbon loading increased seedling height and leader length, but only in seedlings that had been exponentially nutrient loaded. A combination of carbon and nutrient loading increased shoot height 26%, stem diameter 37% and leader length 40% over trees that received neither treatment. These results demonstrate that the growth enhancement seen under exponential nutrient loading is maintained under field conditions for at least six years. Carbon loading just before outplanting was a useful supplement to nutrient loading, but was ineffective in the absence of nutrient loading.  相似文献   

6.
Sesbania sesban (L.) Merr is a perennial N2-fixing tree with high potential for use in agricultural production systems as a green manure and livestock forage. We studied the interactive effects of soil type and water level on the growth, biomass allocation, nutrient and mineral content of S. sesban. Four-week old seedlings of S. sesban were grown for 49 days (n = 5) in a factorial mesocosm set-up with six soil types (sediment, sand, alluvial, acid-sulfate, saline and clay) and three water levels (drained, water-saturated and flooded). The soils tested represent the predominant alluvial soil types of the Mekong delta, Vietnam. Sesbania sesban grew well with relative growth rates (RGR) around 0.08 g g?1 d?1 in all studied soil types, except the saline soil where plants died. In the low-pH (3.9) acid sulfate soil, that constitute more than 40 % of the Mekong delta, the RGR of the plants was slightly lower (0.07 g g?1 d?1), foliar concentration of calcium was 3–6 times lower, and concentrations of iron and sodium up to five times higher, than in other soils. The nutrient and mineral contents of the plant tissues differed between the soils and were also affected by the flooding levels. Foliar concentrations of nitrogen (50–74 mg N g?1 dry mass) and phosphorus (5–9 mg P g?1 dry mass) were, however, generally high and only slightly affected by water level. The results show that S. sesban can grow well and with high growth rates on most wet soils in the Mekong delta, except saline soils where the high salt content prevents establishment and growth. The nutrient and mineral contents of the plants, and hence the nutritional value of the plants as e.g. fodder or compost crops, is high. However, soil type and water level interactively affect growth and tissue composition. Hence, optimal growth conditions for S. sesban differ in the different regions of the Mekong delta.  相似文献   

7.
Physiological mechanisms by which nitrogen (N) fertilization affects growth and development in temperate deciduous forest trees are not clearly understood, especially under intensive silvicultural systems. Grafted, Tippecanoe 1 cultivar black walnut (Juglans nigra L.) trees were grown in an intensively managed plantation in west-central Spain and subjected to six, fixed-nutrient-ratio complete fertilizer treatments (defined as 0, 25, 50, 75, 150, and 300 g N tree?1) delivered via daily fertigation. Leaf chemistry and morphology were evaluated from June to September, and gas exchange was measured in July. Specific leaf mass, leaflet nitrogen (N), and chlorophyll concentrations varied over the course of the growing season, yet consistently increased with increasing fertilization. Net photosynthesis at ambient (A net) and light-saturated (A max) conditions increased from the unfertilized control to lowest treatment (25 g N) but did not increase at higher fertilizer rates. Photosynthetic N and chlorophyll use efficiencies decreased with increasing fertilization, but photosynthetic phosphorus and water use efficiencies increased. Transpiration rates and dark respiration were not significantly affected by treatment. Overall, the lowest fertilizer treatment (25 g N) had the greatest photosynthetic efficiency. Interactions between N and other nutrients with increasing fertilizer application suggested potential for nutrient imbalances at high fertilization rates. Our results provide a physiological justification for the use of low-to-moderate fertilization as an efficient strategy to promote black walnut plantation establishment under intensive cultural systems.  相似文献   

8.
Some land-use systems in Saskatchewan, Canada include the nitrogen-fixing trees buffaloberry (Shepherdia argentea Nutt.), caragana (Caragana arborescens Lam.) and sea buckthorn (Hippophae rhamnoides L.). These species provide various ecological functions such as ameliorating soil moisture, light and temperature but little work has been done quantifying biological nitrogen fixation by these species. Greenhouse experiments were conducted to quantify N2-fixation using the 15N natural abundance and the 15N dilution methods. Buffaloberry failed to form nodules in all but one of the four replicates in the natural abundance experiment. Using the 15N dilution method, the percentage of N derived from atmosphere (%Ndfa) in the shoot of buffaloberry averaged 64 %. For caragana, the mean  %Ndfa was 59 and 65 % and seabuckthorn was 70 and 73 % measured using the natural abundance and dilution methods, respectively. Because of large variability in biomass production between plants grown in the natural abundance experiment and the dilution experiment, the amounts of N2 fixed also were very variable. Buffaloberry fixed an average of 0.89 g N m?2; the average for caragana ranged from 1.14 to 4.12 g N m?2 and seabuckthorn ranged from 0.85 to 3.77 g N m?2 in the natural abundance and dilution experiments, respectively. This corresponds to 16 kg N ha?1 year?1 for buffaloberry; an average of 15–73 kg N ha?1 year?1 in caragana and 11–67 kg N ha?1 year?1 in seabuckthorn. The substantial amounts of N2 fixed by these species indicate that they have the potential to contribute to the overall N balance in land-use systems in which they are included.  相似文献   

9.
Second-year Norway spruce seedlings [Picea abies (L.) Karst.] grown in containers were divided into three fertilization levels in August [5, 15 and 25 mg nitrogen (N) seedling?1]. The resulting foliar concentrations of N were 11.0, 13.1 and 15.8 g kg?1, respectively. Seedling height (mean 26.0 cm) did not differ among treatments. The next spring, the seedlings were tested in two experiments. (1) The seedlings were transplanted into pots containing sandy soil in the greenhouse, where they were fertilized with either pure water or nutrient solution (22 mg N l?1). (2) The outplanting performance of the autumn-fertilized seedlings was tested on a sandy field. In the greenhouse experiment, the autumn fertilization level affected height growth and root egress of the seedlings significantly, but less than fertilization with a nutrient solution after planting. In the field experiment, during the first season after transplanting shoot growth of the seedlings increased with the level of autumn fertilization. After the second and third seasons, the seedling stem volume was highest with the highest level of autumn fertilization. These results suggest that, by improving the preplanting nutrient status of seedlings, the growth of shoot, stem diameter and root biomass can be enhanced after planting, especially on nutrient-poor soils. However, heavier autumn fertilization than that used here may yield a greater and more persistent increment in growth.  相似文献   

10.
The hypothesis that soil chemistry is a main constraint for the vigour of Norway spruce trees on calcareous soils is scrutinised based on data from 60 existing and new intensive study sites in the Bavarian Alps, where comprehensive information on soils, climate, foliar nutrient concentration, ground vegetation, and tree growth is available. We characterised ecological gradients of the response variables site index (SI), foliar nutrient level and needle weight by constrained ordination, identified nutrient limitations based on regression trees and modelled SI based on vegetation-based mean Ellenberg indicator values. Our study confirms the assumption that soil development and concurrent acidification are key determinants for the vitality and growth of spruce in the Bavarian Alps, which surpass the importance of climate on nutrition and growth. Pools and availability of P and N are limiting nutrition and growth of spruce in this region. We hypothesize that N-limitation persists despite considerable deposition inputs because N tends to be locked up in organic horizons with low biological activity. K and trace elements, especially Fe, can also be deficient in some cases but do not appear as major limiting factors. High foliar Mn concentrations are a reliable indicator of mature soils and favourable site conditions in the Bavarian Alps, but Mn itself is usually not limiting. P must be regarded as the most critical macronutrient in the Bavarian Alps, particularly in the face of biomass harvesting. Consequently, at sites with shallow soils forest, management should focus on sustaining or restoring humus stocks. SI of spruce can be predicted from composition of ground vegetation and Ellenberg indicator values with remarkable precision (R 2 = 0.75).  相似文献   

11.
Twenty weeks forage re-growth from 20 multipurpose trees and shrubs (MPTS) species (Albizia ferruginea, Albizia gummifera, Albizia niopoides, Berlinia grandiflora, Bauhimia monandra, Dialium guineense, Dalbergia sissoo, Enterolobium cyclocarpum, Leucaena leucocephala, Lonchocarpus sericeus, Milletia griffoneanus, Milletia thoningii, Napoliana imperialis, Parkia bicolor, Pterocarpus santalinoides, Senna spectabilis, Treculia africana, Terminalia superba, Tetrapluera tetraptera and Xylia xylocarpa) were investigated for their feed value. The MPTS were grown on an ultisol in southeastern Nigeria and were subjected to proximate analyses, nylon bag degradability studies and cluster analysis. Among species, crude protein (CP) ranged from 104 g kg?1 DM in P. bicolor to 205 g kg?1 DM in A. gummifera, neutral detergent fibre (NDF) ranged from 498 g kg?1 DM in L. leucocephala to 771 g kg?1 DM in L. sericeus, acid detergent fibre (ADF) ranged from 303 g kg?1 DM in T. superba to 661 g kg?1 DM in L. sericeus, acid detergent lignin (ADL) ranged from 75 g kg?1 DM in T. superba to 305 g kg?1 DM in L. sericeus. Also, ADF-ash ranged from 0.78 g kg?1 DM in E. cyclocarpum to 15.58 g kg?1 DM in D. guineense. Except E. cyclocarpum and S. spectabilis, the remaining 18 MPTS studied had effective degradabilities (ED) less than 500 g kg?1 DM effective degradability. Eight MPTS (A. ferruginea, A. niopoides, B. monandra, D. sissoo, E. cyclocarpum, L. leucocephala, S. spectabilis, T. superba) were classified as high quality, another eight (A. gummifera, B. grandiflora, L. sericeus, N. imperialis, P. bicolor, P. santalinoides, T. tetraptera and X. xylocarpa) as medium quality while, the remaining four (D. guineensis, M. griffoneanus, M. thoningii, T. africana) fell into the low quality class based on their nutrient composition and ruminal DM degradability. The results indicate that most of the MPTS could be used as good quality feed for small ruminants in Nigeria.  相似文献   

12.
Many forest soils in Finland are poor in boron (B), especially otherwise fertile (nitrogen-rich) soils and peatlands. Boron deficiency causes growth disorders affecting young Norway spruce (Picea abies) stands. We studied the effects of B fertilization on the growth and morphology of Norway spruce seedlings. Boron was applied in a nursery and/or after planting in a nursery-field and on a reforestation site, both known to be low in B. The B applied in the nursery increased foliar B concentration in a linear relationship to the amount of B fertilizer but did not affect seedling growth and morphology. Even the highest foliar B concentration (approx. 400 mg kg?1) did not have harmful effects on the seedlings. Therefore, B fertilization in the nursery can be used for increasing B storage in needles. Boron fertilization at planting increased foliar B concentration in the first season. Afterward, the concentration decreased but remained above the deficiency limit for at least 4–5 years. In the B-poor nursery-field, nonfertilized seedlings began to produce multiple leaders in the second year. On the reforestation site, fewer multiple leaders were found. At the nursery-field site, height growth was stimulated by B fertilization at planting. In conclusion, 200–400 mg m?2 (2–4 kg ha?1) of B applied at planting has longer-lasting effects on seedling B status than does B fertilization applied in the nursery, and can improve seedling quality and growth in the first years after planting on B-poor sites.  相似文献   

13.
Where there is limited availability of conventional fertilizers, the use of organic materials is considered a viable alternative to increase the productive capacity of soils. Many potential plant residues remain underutilized due to limited research on their use as a nutrient source. In this study, the nitrogen supplying capabilities of ten rarely-used leaf biomass sources (Acacia auriculiformis, Baphia nitida, Albizia zygia, Azadirachta indica, Senna siamea, Senna spectabilis, Tithonia diversifolia, Gliricidia sepium, Leucaena leucocephala and Zea mays) were tested based on their nutrient content, N mineralization patterns and effect on maize yield (in comparison with inorganic fertilizer). N mineralization was studied in the laboratory using an incubation experiment. Field trials were also established using a randomized complete block design. Plant residues were applied at 5 t dry matter ha?1 a week before planting maize while fertilizer was split-applied at 90 kg N ha?1 on designated plots. From the results on plant residue chemistry, most of the plant residues recorded relatively high N concentration (≥24.9 g kg?1) and low C/N ratio (≤20.1) although neither N content nor C/N ratio significantly (p > 0.05) affected their N mineralization patterns. Leaf biomass application of B. nitida, A. auriculiformis, A. zygia and maize stover resulted in an initial net N immobilization that lasted for 14 days. Application of all plant materials significantly increased the biological yield and N uptake of maize with G. sepium and T. diversifolia producing the greatest impact especially in the major rainy season. Relative to the control, total grain yield after four cropping seasons was comparable between inorganic fertilizer (9.2 t ha?1), G. sepium (8.8 t ha?1) and T. diversifolia (9.4 t ha?1) treatments. The results on maize biological yield were significantly correlated with the effects of the treatments on N uptake. The findings suggest that in locations where inorganic fertilizers are limited, leaf biomass from G. sepium and T. diversifolia could offer the most suitable option in comparison with the other species used in this study.  相似文献   

14.
Macro- (C, N, P, K, Ca and Mg) and micronutrient (Fe, Mn, Cu and Zn) reservoirs were estimated in the O (Oi+Oe+Oa) and in the A (0–10 cm depth) soil horizons of four stands of Nothofagus pumilio (lenga) from Tierra del Fuego which differ in their forestry characteristics. The type of soil layer (O and A) and the forest structure, as related to above-ground biomass storage, were assessed as a factor of variation in the nutrient reservoirs of both soils layers. Nutrient reservoirs showed similar ranges in both soil layers for total organic C (34–65 Mg ha?1), total N (1.5–3.5 Mg ha?1), rapidly available Ca (1.3–2.7 Mg ha?1) and Mg (0.18–0.36 Mg ha?1). Rapidly available K, available P, and medium-term available Fe and Cu were accumulated preferentially in A the horizons, whereas medium-term available Mn and Zn were mainly stored in the O horizons. The forest structure was not a statistically significant factor of variation on the nutrient reservoirs in the O horizons, although a legacy effect of the accumulated above-ground biomass on nutrient reservoirs in this soil layer can not be discarded. On the contrary, the pools of total organic C, total N, rapidly available K and medium-term available Cu and Zn in the A horizons varied significantly with the different forest structure. In terms of lenga forests sustainability, uppermost soils layers should be preserved as they accumulate most of the soil fertility which is essential for lenga regeneration after logging. The inclusion of the assessment of soil fertility in the management plans of the lenga forests in the ecotone of the Argentinean Tierra del Fuego is strongly recommended, as it will contribute to ensure a successful regeneration of lenga in logged areas.  相似文献   

15.
We developed a shoot multiplication protocol for Syringa reticulata Blume var. mandshurica Hara from in vitro cultured seedlings that derived from in vitro germinated seeds. The shoots could be induced on Murashige and Skoog (MS) medium with proper plant growth regulator combinations of 6-benzylaminopurine (BA) and indole-3-butyric acid (IBA). The better medium for shoot multiplication and growth was MS + 5 mg L?1 BA + 0.5 mg L?1 IBA + 20 g L?1 sucrose + 7 g L?1 agar, and the corresponding shoot induction rate was 75 %. The plantlets grew well after rooting on 1/2MS medium (macro-elements of MS medium are at half-strength) supplemented with 1 mg L?1 IBA, and the survival percentage was >80 % at 16 weeks after transplanting.  相似文献   

16.
Narrowing the uncertainties in carbon (C) and nitrogen (N) dynamics during decomposition of coarse woody debris (CWD) can significantly improve our understanding of forest ecosystem functioning. We examined C, N and pH dynamics in the least studied CWD component—tree bark in a 66-year-long decomposition chronosequence. The relative C concentration decreased by ca. 32% in pine bark, increased by ca. 18% in birch bark and remained stable in spruce and aspen bark. Nitrogen increased in bark of all tree species. In conifer bark, it increased along with epixylic succession. Over 45 years, the relative C/N ratio in bark decreased by 63 and 45% for coniferous and deciduous species, respectively. Bark pH did not change. Due to bark fragmentation, the total C and N amounts in bark of individual logs of aspen, birch, pine and spruce decreased at average rates of 0.03, 0.02, 0.26 and 0.05 year?1, and 0.02, 0.02, 0.03 and 0.03 year?1, respectively. At the forest stand level, the total amounts of C and N in log bark were 853 and 21 kg ha?1 or 11.2 and 45.5% of the C and N amounts stored in downed logs and ca. 2.3–3.8 and 2.2–2.4%, respectively, of total C and N amounts stored in forest litter. In boreal forests, decomposing log bark may act as a long-term source of N for wood-inhabiting communities.  相似文献   

17.
Few studies have analyzed how tree species within a mixed natural forest affect the dynamics of soil chemical properties and soil biological activity. This study examines seasonal changes in earthworm populations and microbial respiration under several forest species (Carpinus betulus, Ulmus minor, Pterocarya fraxinifolia, Alnus glutinosa, Populus caspica and Quercus castaneifolia) in a temperate mixed forest situated in northern Iran. Soil samplings were taken under six individual tree species (n = 5) in April, June, August and October (a total of 30 trees each month) to examine seasonal variability in soil chemical properties and soil biological activity. Earthworm density/biomass varied seasonally but not significantly between tree species. Maximum values were found in spring (10.04 m?2/16.06 mg m?2) and autumn (9.7 m?2/16.98 mg m?2) and minimum in the summer (0.43 m?2/1.26 mg m?2). Soil microbial respiration did not differ between tree species and showed similar temporal trends in all soils under different tree species. In contrast to earthworm activity, maximum microbial activity was measured in summer (0.44 mg CO2–C g soil?1 day?1) and minimum in winter (0.24 mg CO2–C g soil?1 day?1). This study shows that although tree species affected soil chemical properties (pH, organic C, total N content of mineral soils), earthworm density/biomass and microbial respiration are not affected by tree species but are controlled by tree activity and climate with strong seasonal dynamics in this temperate forest.  相似文献   

18.
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   

19.
Intensification of coffee (Coffea arabica) production is associated with increases in inorganic fertilizer application and decreases in species diversity. Both the use of organic fertilizers and the incorporation of trees on farms can, in theory, reduce nutrient loss in comparison with intensified practices. To test this, we measured nutrient concentrations in leachate at 15 and 100 cm depths on working farms. We examined (1) organically managed coffee agroforests (38 kg N ha?1 year?1; n = 4), (2) conventionally managed coffee agroforests (96 kg N ha?1 year?1; n = 4), and (3) one conventionally managed monoculture coffee farm in Costa Rica (300 kg N ha?1 year?1). Concentrations of nitrate (NO3 ?-N) and phosphate (PO4 3?-P) were higher in the monoculture compared to agroforests at both depths. Nitrate concentrations were higher in conventional than organic agroforests at 15 cm only. Soil solutions collected under nitrogen (N)-fixing Erythrina poeppigiana had elevated NO3 ?-N concentrations at 15 cm compared to Musa acuminata (banana) or Coffea. Total soil N and carbon (C) were also higher under Erythrina. This research shows that both fertilizer type and species affect concentrations of N and P in leachate in coffee agroecosystems.  相似文献   

20.
A 5-year field trial was conducted on a laterite soil to evaluate the effects of organic and inorganic fertigations in arecanut sole and arecanut–cocoa land use systems at Vittal, India. Arecanut registered similar yield levels in sole and arecanut–cocoa cropping situations (3,022–3,117 kg ha?1). Fertigation of 75 % NPK, vermicompost extract (VCE) 20 % N and VCE (10 and 20 % N)+25 % NPK registered the same yield levels (3,029–3,375 kg ha?1). Dry bean yield of cocoa was at par with fertigation of 75 % NPK and 20 % N VCE + 25 % NPK (291–335 kg ha?1). Fertigation @ 75 % NPK increased the yield of cocoa by 52 % over VCE alone. The productivity per unit area (kg ha?1) was significant and higher by 12 % in arecanut–cocoa system (3,450) than arecanut sole (3,090). Productivity was similar to fertigation of 75 % NPK, 20 % N VCE and VCE (10 or 20 % N) + 25 % NPK (3,316–3,665 kg ha?1). Leaf nutrient status of arecanut and cocoa indicated lower levels of N and K and above normal levels of Ca, Mg and micronutrients. The results indicate that drip fertigation increases the productivity, but precision application of N and K is required for sustaining the yields.  相似文献   

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