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1.
The efficacy of two commercial products of Bactospeine and Bio-fly onPrays citri of lime trees was studied under laboratory and field conditions throughout the two seasons of 1996 and 1997. Laboratory results indicated that the pathogenic effect of Bactospeine,Bacillus thuringiensis (Berliner) was higher than that of Bio-fly,Beauveria bassiana in spite of the latter was applied with higher doses. Bactospeine at the rate (2 cc/1 l.w.) effected on the larvae more than on the adults, that treatment reduced no. of eggs/female by 81.70% and decreased the larval infestation by 90.08%. Bio-fly at the highest concentration (4 cc/1 l.w.) reduced the infestation with the eggs, the larvae and the pupae by 65.83%, 68.45% and 72.55%, respectively. Advanced effects of bacterial and fungal treatments on the final reduction rates ofP. citri infestation were recorded. Field applications revealed that two sprays with Bactospeine or Bio-fly gave good control ofP. citri more than one spray. Bactospeine at the rate (2 cc/1 l.w.) and Biofly at the rate (4 cc/1 l.w.) reduced the infestation by (89.82–93.43%) and (76.32–78.83%), respectively. In all cases, higher doses of bioinsecticides produced potentiation effects of infestation reduction. It is recommended that two sprays of Bactospeine at a rate (2cc/1 l.w.) are adequate effective to reduce the population of P. citri in lime orchards during the main flowering period of trees without need of chemical insecticides. An erratum to this article is available at .  相似文献   

2.
Abies nordmanniana and Abies lasiocarpa, established for Christmas tree production in southwestern Norway (58°44′N, 5°38′E), were treated with different weed control methods, including chemicals, use of black plastic mulch, grass or clover as ground cover, living mulch and mechanical hoeing. Ground cover with black plastic mulching resulted in the best growth and quality in A. lasiocarpa; the least favourable treatment was when grasses were allowed to grow close to the trees. Unless measures were taken to remove this competing vegetation, the ground cover grew over the trees, smothering 94% of them. A. nordmanniana plants grew to the same height on plots with no weed control as on plots with thorough weed eradication. Stem diameter decreased on plots with ground vegetation compared to seedlings grown in the weed-free environment. The use of Trifolium repens as ground cover decreased height growth by 30% compared to thorough weed control. Both grasses and clover sown as living mulch, damaged the trees more than did natural weed vegetation.  相似文献   

3.
If some suitable treatments are used plantations can be grown and established on thesoil of soda-saline-alkali with the soil condition of PH 8.5—9.6,salinity 0.1—0.3％ and normalityratio of saline base Na~+/(Ca~(++)+Mg~(++))≥4.From the results of plot Inventery and tree stem ana-lysis,the increment of Poplus simonigra is highest. For 9 years,the volume can reach 100 m~3/ha,the biomass(above ground)can reach 28.7 ton/ha.Poplus simonigra grows very well on the allkinds of soda-saline-alkali soils except for the alkali spot with the worst Soil condition.So Poplussimonigra is a good tree species for planting on the Soil of soda-saline-alkali.  相似文献   

4.
This study estimates the efficacy of an attract-and-kill (A&K) technique to control the horse chestnut leaf miner, Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae), an invasive insect pest of the horse chestnut, Aesculus hippocastanum L. (Hippocastanaceae). The A&K formulation was dispensed as 50 μl droplets of paste-like matrix, containing C. ohridella sex pheromone, (8E,10Z)-tetradeca-8,10-dienal (85% + pure; 0.16% w/w) and a fast acting contact toxicant, pyrocides (94% pure; 6% w/w), applied directly to the bark of the trees. It was tested in 2003 at rates of 30 and 45 droplets/tree at the Ostrobramska site and at rates of 30, 60 and 90 droplets/tree at the Woloska site in Warsaw, Poland, for the first insect generation. A set of untreated plots (0 droplets/tree) was established at each site as well. The treatment efficacy was estimated using two indices: (1) moth catches in pheromone traps and (2) the number of mines per leaf. Trap catches were significantly higher in the untreated plots than in the treated plots regardless of the application rate in all sites. However, there were no significant differences in leaf damage amongst all plots on each site. At the “Lazienki Krolewskie” park the attractiveness of two types of pheromone sources were compared: traps were baited with rubber septum lures or with A&K droplets. The catches of C. ohridella in traps baited with lures were lower than captures in A&K droplet-baited traps, but the difference was not significant. Possible reasons for the low efficacy of the A&K method in management of C. ohridella and reducing leaf damage are discussed.  相似文献   

5.
Restoring longleaf pine (Pinus palustris Mill.) over much of its original range requires artificial regeneration. In central Louisiana, USA, two fertilization levels—No (NF) or Yes (F-36 kg/ha N and 40 kg/ha P) in combination with three vegetation treatments—Check, four prescribed fires (PF), or multi-year vegetation control by herbicidal and mechanical means (IVM) were applied to container-grown longleaf pine plantings in a grass savanna. After 10 years, P concentration in longleaf pine foliage was less on NF plots than F plots, but fertilization did not significantly affect tree stature. Survival was greater on NF plots than F plots, and so, NF plots were more productive (NF—63 m3/ha and F—45 m3/ha). Pine trees on IVM plots (37 dm3/tree) were significantly larger than on Check and PF plots, which averaged 17 dm3/tree. Survival was better on IVM plots (88%) than PF plots (78%), which was better than Checks (58%). Consequently, IVM plots were most productive (99 m3/ha), followed by PF plots (44 m3/ha), and lastly Checks (28 m3/ha). PF plots had greater grass cover (38%) than Check and IVM plots, which averaged 5%, whereas PF and IVM plots had less understory arborescent cover (an average of 25%) than Checks (91%). A wildfire in March 2007 reduced pine survival by 22, 14, and 1 percentage points on IVM, Check, and PF plots, respectively. Seven months later, longleaf pine production had decreased to 92 m3/ha on IVM plots while increasing to 55 m3/ha on PF plots and 30 m3/ha on Checks. Overall, the wildfire rejuvenated the herbaceous plant community. Grass cover on Check and IVM plots averaged 20% while grass cover on PF plots was 36%. Forb cover increased on all treatments from 2% before the wildfire to 13% seven months after the wildfire. Understory arborescent cover decreased on Checks to 62% but increased slightly on PF and IVM plots and averaged 30%.  相似文献   

6.
The effects of fertilizer treatment on nutrient transfers to the forest floor were examined in regrowth Eucalyptus diversicolor F. Muell. forest. Dry weight and nutrient content of leaf litterfall and total litterfall were measured for 3 years in a stand to which two levels of N (0, 200 kg ha-1 year-1) were applied each year at each of three levels of a single initial application of P (0, 30, 200 kg ha-1). Annual accessions of litter to the forest floor were significantly increased by additions of both N (by 17%, 18% and 21% in the 3 years) and 200 kg P ha-1 (by 8%, 8% and 4% in the 3 years) but there was no interaction between effects of N and P treatments. Fertilizer application also had a significant effect on the nutrient content of leaf litterfall and total litterfall. Concentration of N in leaf litterfall was 9% to 23% greater on plots treated with N fertilizer compared to untreated plots. The amounts of N in litterfall were about 30% greater on N-treated compared to untreated plots. On plots treated with 200 kg P ha-1, P concentrations in leaf litter were 50% to 100% greater than in litter from plots receiving no P. Application of 200 kg P ha-1 increased the amounts of P in annual litterfall by 32% to 87%. The greatest increase in P accessions occurred soon after fertilizer treatment. The amounts of Ca, K, and Na in litterfall were also significantly increased by fertilizer application. For Ca and K this was due partly to increases in element concentrations in litterfall following application of treatments. The effect of fertilizers on internal recycling of plant nutrients and on litter accumulation and nutrient dynamics in forest floor litter is discussed.  相似文献   

7.
Layering, long-term development of foliation, beech nut fertility and plant species composition have never before been studied in Fagus sylvatica stands above the alpine timberline in Central Europe. F. sylvatica forms and is present above the timberline (1,260 m a. s. l.) on only one south-facing slope along a 1-km-long stretch of the Giant Mts., which represents the northernmost timberline featuring F. sylvatica worldwide. We investigated the long-term development of this unique stand in which layering of F. sylvatica was discovered (LP—1,310 m a. s. l.), comparing it with a control plot (CP—1,190 m a. s. l.). Research plots were established in 1980, with monitoring of foliation, masting, beech nut fertility and plant species composition performed over the following 30 years. In the LP plot, F. sylvatica was able to reproduce only clonally by layering. Development of adventitious roots on branches reaching the ground took many years. In the LP plot, F. sylvatica was able to survive heavy air pollution during the 1980s and since that time substantial improvement of its health status has been recorded. Generative reproduction of F. sylvatica in the LP plot was extremely rare, as production of fertile nuts was recorded only once in 2007 and seedlings have never been recorded at all. An improvement in F. sylvatica foliation in the LP plot was probably the reason for a decrease in species richness and cover of bryophytes. The herb layer, dominated by Calamagrostis villosa, was highly stable in the LP plot over the 30-year period, contrasting significantly with the marked changes in species composition observed in the understory of the CP plot where massive regeneration of F. sylvatica occurred. Layering, stability of herb layer and rare masting can be expected in F. sylvatica stands above the alpine timberline.  相似文献   

8.
G. Singh 《New Forests》2012,43(3):349-364
Natural resource conservation and rehabilitation are the best options to control land degradation and enhance biomass for fodder and fuelwood. Rainwater harvesting structures viz. Contour trench (CT), gradonie (G), box trench (BT) and V-ditch (VD) with a control were prepared in <10%, 10–20% and >20% slopes and Acacia catechu L. seedlings were planted in August 2005 to enhance soil water, nutrient and biomass and to rehabilitate degraded hill. Soil pH, SOC and NH4-N decreased while EC, NO3-N and PO4-P increased in June 2009. Soil water, nutrients, plant growth and biomass were highest (P < 0.05) in <10% and lowest in 10–20% slopes. Soil waters were 13 and 52% greater in >20 and <10% than in soil at 10–20% slope. The soil waters were 18, 16, 24 and 14% greater in CT, G, BT and VD treatments, respectively over control, which enhanced plant height and collar diameter in December 2009 over 2005. The highest growth and biomass were in CT and VD plots, respectively. Herbage biomass was highest (P < 0.05) in <10% slope in 2005, 10–20% slope in 2006/2008 and >20% slope in 2007/2009. Harvesting of rainwater increased herbage biomass by 24–71%, and was highest in VD plots. Conclusively, rainwater harvesting enhanced soil water, nutrients, vegetation covers and plant growth and biomass during restoration of degraded hills. Gradonie and CT/BT facilitated herbage and plant growth, respectively, whereas V-ditch was effective for both.  相似文献   

9.
Understanding the changes in soil properties in silvopastoral systems is important in regulating the interactions between tree and understorey pastures. In this study, the effects of understorey management on soil mineral N and moisture availability, soil temperature, soil C, and tree growth were investigated in a seven-year-old silvopastoral agroforestry experiment in Canterbury, New Zealand. The systems included understorey treatments of bare ground and ryegrass (Lolium perenne) pasture. Soil mineral N, moisture content, and temperature were monitored from July 1997 to July 1998 in two positions (0.9 and 3.5 m north of tree rows) and two soil depths (0–10 and 10–20 cm). Soil C and N in the 0–10 cm depth were higher in the ryegrass than in the bare ground plots, reflecting the organic C and N input in the ryegrass plots, as well as greater N loss from the bare ground plots in the form of nitrate leaching and/or denitrification. Soil C was higher in the position 0.9 m than 3.5 m away from the tree rows, possibly caused by the greater C input from decomposing fine tree roots and needle litterfall at the 0.9 m position. Soil moisture availability was greater in the bare ground than in the ryegrass plots in the summer. No effect of understorey management on soil temperature was found. Soil nitrate levels were lower in the ryegrass plots and may be limiting when soil moisture supply was adequate. Tree volume growth from winter 1997 to 1998 was significantly greater in the bare ground treatment, reflecting better soil moisture and N supply conditions. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

10.
Nutrient contribution and maize performance in alley cropping systems   总被引：3，自引：0，他引：3  
Dry matter yield and potential contribution of N, P and K of some woody perennials as well as performance of maize were assessed in an alley cropping system at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Dry matter yield was highest forCassia, followed byGliricidia and theFlemingia. Whereas dry matter yields ofCassia varied significantly at the various pruning times, those ofGliricidia andFlemingia were relatively uniform.Gliricidia contributed the highest amount of N from the cutback (first pruning) and three subsequent prunings. Dry wood yield at cutback was 14.5, 6.8 and 29.7 tonnes/ha forGliricidia, Flemingia andCassia respectively. Coppicing rate was faster inGliricidia thanFlemingia andCassia. Maize height, stover and cob weights were reduced though insignificantly, for the maize rows close to the shrub hedgerows compared to those in the middle of the alleys. For the plots without N application and prunings removed, the maize near the hedgerows showed better performance than those in the middle of the alleys. The results indicate that N supplementation is needed in the alley cropping systems to optimize yield. The amount of N required is higher inFlemingia alleys than forGliricidia andCassia. Root growth of maize was found to be restricted in control plots without hedges; uptake of the major nutrients (N, P and K) was also found to be similarly affected in those plots.  相似文献   

11.
Two experiments were conducted using dried leaves ofAlchornea cordifolia, Ficus capensis, Manniophytum fulvum andAlbizza niopoides. In Experiment 1, dry matter (DM) degradation characteristics were investigated using thein sacco nylon bag technique in West African Dwarf (WAD) sheep, WAD goats and Bunaji steers. In Experiment 2, voluntary intake of the browse forage when fed as supplements to sheep at 0, 10 and 30% levels was measured. In Experiment 1,A. cordifolia andM. fulvum had significantly higher rapidly degradable DM fraction thanA. niopoides andF. capensis. Averaged across browse species, the extent of DM degradation for sheep (58.3%) was significantly higher than for goat (47.7%) or cattle (44.1%). Ranking order of browse species for the extent of DM degradation was:F. capensis>A. cordifolia=M. fulvum=A. niopoides. In Experiment 2, as the level of supplementation increased from 10 to 30%, voluntary intake ofA. niopoides andM. fulvum increased while voluntary intake ofA. cordifolia andF. capensis declined. The results suggest that dried leaves ofA. niopoides andM. fulvum are more acceptable to WAD sheep than those ofA. cordifolia andF. capensis.  相似文献   

12.
不同栽培措施对尾巨桉生长的影响及经济效益分析   总被引：18，自引：2，他引：18       下载免费PDF全文
试验采用列区试验设计,设造林密度和追肥2个因素,每个因素6个水平,4次重复.密度因子作主区,追肥因子作副区,各个因素和各处理按随机区组排列.每个试验小区面积0.04 hm2(20 m×20 m),共计144个小区,连续5 a观测.经过方差分析得出,造林试密度对林分平均高、平均胸径和蓄积量都有极显著的影响.在6种参试密度中,造林密度越大,林分平均高、胸径越小,蓄积量越大;6种配方追肥对林分平均高影响不显著,对胸径和蓄积量生长影响显著;密度与追肥的交互作用不显著.在所有36个列区试验组合中,按经济效益排列前5名的密度和追肥最佳组合分别为:2 222株.hm-2和每公顷施N、P、K分别为200、150、100 kg,1 667株.hm-2和每公顷施N、P、K分别为300、200、200 kg;1 667株.hm-2和每公顷施N、P、K分别为200、150、100 kg;2 222株.hm-2和每公顷施N、P、K分别为100、50、50 kg;1 250株.hm-2和每公顷施N、P、K分别为200、150、100 kg.它们的蓄积量分别为183.94、188.43、169.95、164.33、163.03 m3.hm-2;利润值分别为14 977.44、14 965.09、13 832.83、13 785.80和13 345.18元.hm-2.  相似文献   

13.
The net photosythetical rate, respiration rate, light compensation point and light saturation point ofLarix olgensis andFraxinus manshurica were measured by Model-865 Co2 Infrared Analyzer under controlled conditions (in coviron phytotron). For net photosythetical rate ofLarix ogensis andFraxinus manshurica, the optimum air temperature was 25, 28 °C respectively, the optimum soil water potantial was −20, −10 kPa repectively, the optimum soil water content was 20.31 %, 23.42% respectively, and the optimum air humidity was 90%. The optimum soil water potantial of respiration rate was −30 kPa. The light compensation point for the two species was 3.36, 4.8 μ mol / m2s respectively and light saturation was 804, 880 μ mol / m2s. The project supported by National Natural Science Foundation of China  相似文献   

14.
The performance of the leaf mulches ofLeucaena leucocephala, Gliricidia sepium andFlemingia macrophylla in weed control has been tested in two trials. The length of the period during which a mulch layer yields significantly less weedbiomass compared to the control plots is called the ‘effective life-span’ of the mulch. Of the three mulch materials only that ofF. macrophylla shows promise in retarding weed development. In the second trialF. macrophylla leaf mulch was applied at rates of 3, 6 and 9 tons dry matter per ha. The effective lifespan of a mulch layer of 3 tons is between 12 and 13 weeks. The treatments 6 and 9 tons have effective life-spans of over 14 weeks. For moderate quantities (up to 5 tons of dry leaf mulch per ha) the effective life-span is estimated at about a 100 days. The value of mulching in weed control is limited to the control of weed species that multiply by seed. Regrowth originating from roots or stumps from former vegetation is unlikely to be checked by a mulch layer. The subject of this paper is part of a broader study, presently conducted in Southern Ivory Coast, on the production, agronomical value and use in alley-cropping systems of the species mentioned in the title of the paper. A final report is scheduled for publication in 1988.  相似文献   

15.
A study was established to evaluate several management practices for improving American sycamore (Platanus occidentalis L.) establishment on land subjected to daily paper-mill sludge spray irrigation, and where a dense herbaceous cover dominated by pokeweed (Phytolacca americana L.) was nearly 2 m tall. Treatments studied included: two sludge application treatments (spray vs no spray), five weed control treatments (control, hand-release, oxyfluorfen, glyphosate and atrazine, and sulfometuron methyl), and two tree shelter treatments (control vs tree shelter). Survival and growth of sycamore seedlings were evaluated after one growing season. Sludge application treatment had the greatest effect on tree survival; survival was greatest on plots that were not sprayed during the year of tree growth. Among the weed control treatments, the hand-release treatment resulted in best survival; survival was 100% when hand release was used on unsprayed plots. Tree shelters provided no benefit to tree establishment.  相似文献   

16.
Seedling growth response of two tropical tree species (Schima superba and Cryptocarya concinna) to simulated N deposition was studied during a period of 11 months. One-year-old seedlings were grown in forest soil treated with N as NH4NO3 at Control–no N addition, N5–5, N10–10, N15–15, and N30–30 g N m−2 year−1. The objective was to examine the effects of N addition on seedling growth and compare this effect between the two tropical tree species of different species-N-requirement. Results showed that both species responded significantly to N addition and exhibited positive effect to lower rate of N addition and negative effect to higher rate of N addition on growth parameters (height and stem base diameter, biomass production, and net photosynthetic rate). The highest values were observed in the N10 plots for S. superba and in the N15 plots for C. concinna, but the lowest values were observed in the N30 plots for both species. However, the reduction in the N30 plots was more pronounced for S. superba than for C. concinna relative to the control plots. Our findings suggest that response of seedling growth of tropical tree species to atmospheric N deposition may vary depending on rate of N deposition and species-N-requirement.  相似文献   

17.
To meet their wood, fodder and fruit needs, resource-poor farmers with only small land holdings are forced to mix trees in their food crop plots. An experiment was conducted to study the effect of nine tree species planted at 312.5 trees ha–1 (4×8 m) on the yield of bananas planted at 625 stools ha–1 (4×4 m) and beans (80000 plants ha–1) as well as the wood production of the trees when intercropped. In addition, an economic analysis was done to compare the different tree/banana/bean associations.After three and one-half years, wood volume (in m3 ha–1) ofGrevillea robusta (18.1), was highest and that ofErythrina poeppigiana (2.7),Cedrela odorata (2.4) orMarkhamia lutea (0.8) was the lowest. Volume ofCedrela serrata (13.7) was not significantly different from that ofAlbizia chinensis (12.8) but was significantly higher than that ofLeucaena diversifolia (6.8),Acrocarpus fraxinifolius (6.7) orCalliandra calothyrsus (6.0).None of the tree species had a significant influence on the yields of the bananas and none affected the yield of the bean crops until the seventh cropping season, three years after the trees were planted. In that year, Grevillea reduced bean yield by 29%, Albizia by 34% and Leucaena by 36%. From the economic analyses, all the treatments except Leucaena and Markhamia had positive net benefits relative to the control (banana/bean) but the results were highly variable.C. serrata was found to be the best tree to be intercropped in a banana/bean system.  相似文献   

18.
A species introduction experiment including several tropical pines and eucalypts was established in 1966/1967 in the Tchianga research station in Angolan Highlands. Despite 27 years of political conflict (1975-2002) and lack of management, the research experiment has remained relatively well conserved. We measured the best conserved plots that were 41 years old in 2007 to obtain information on the growth of different pine species. We calculated stand characteristics including basal area, dominant height, mean diameter, and stand volume for Pinus patula Schiede ex Schiltdl. Et Cham., Pinus pseudostrobus Lindl., Pinus kesiya Royle ex Gordon, Pinus devoniana Lindl., Pinus chiapensis (Martinez) Andresen, Pinus elliottii Engelm., Pinus greggii Engelm. Ex Parl., Pinus montezumae Lamb. and Pinus oocarpa Schiede ex Schltdl. The growing stock volume at 41 years was the highest in P. pseudostrobus, 1,325 m3·ha-1, followed by P. kesiya with 1,200 m3·ha-1. The widely planted P. patula had a growing stock volume of 892 m3·ha-1. P. oocarpa and P. pseudostrobus had the highest stand basal area, over 80 m2·ha-1. Using increment core analyses we studied the temporal development of stand characteristics. Analysis of the mean annual increment (MAI) showed that rotation lengths of 20-30 years would maximize wood production. With these rotation lengths, the MAI of P. pseudostrobus would be 35 m3·ha-1. Other productive species were P. kesiya, P. oocarpa and P. chiapensis. P. patula had a maximum MAI of 20 m3·ha-1. P. greggii had the lowest mean annual volume production, only about 13 m3·ha-1.  相似文献   

19.
In the Sahel zone, there is an increasing interest of farmers in conserving and enriching tree diversity on their farms as a source of food and income. Ziziphus mauritiana Lam. is one of the tree species farmers maintain on their farms. Even though the local variety of Ziziphus mauritiana Lam. was ranked as one of the most preferred species, it produces small fruit whereas farmers are interested in varieties producing bigger and tasty ones. A factorial experiment in a split split-plot design was carried out to assess the performance of three introduced cultivars of Indian jujube in Burkina Faso. Investigated factors were irrigation (irrigated with 30 l plant−1 week−1, non-irrigated), rock phosphate containing 25% P2O5 (0 and 150 g P plant−1) and cultivar (Gola, Seb, Umran, and local variety as control). Eighteen months after planting, Umran responded positively to irrigation and rock phosphate treatments by displaying the tallest height (313 cm) and the biggest collar diameter (6.4 cm). Gola gave the largest crown diameter (316 cm) at 18 months and the highest fruit production at the first (15.3 kg tree−1) and second (71.6 kg tree−1) fruiting seasons in the irrigated and fertilized treatment. The local variety was less productive compared to the introduced cultivars. In terms of income generation irrigated and fertilized Gola and irrigated Umran showed the highest potential after two fruiting seasons with net revenues of F CFA 2,526,915 and F CFA 1,930,546 per hectare respectively. Therefore, Umran and Gola may be recommended in intensive sub-Saharan peri-urban systems while Seb needs further investigation to improve its water and nutrient use efficiency through either better timing of water and fertilizer application or symbiotic association with arbuscular mycorrhizal fungi.  相似文献   

20.
A six-year soil conservation trial was conducted on a steep slope, 44%, with a subhumid climate, based on very closely spaced (90 cm) hedgerows, using three intraspecific hybrids ofLeucaena leucocephala. Soil loss averaged 2.0 t/ha per year on theLeucaena plots compared with an initial 80 t/ha per year on the unprotected control plot, falling to 27 t/ha per year after the top soil had been eroded. After 6 years, micro terraces of 35 cm high and 81 cm wide had developed on the intercropped plots, with substantially improved soil properties. Maize yield (unfertilized) were maintained at 1.5–2.0 t/ha on the protected plots, compared with a progressive fall from 0.8 to 0.5 t/ha on the sole maize control.  相似文献   

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