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1.
An aphid and virus survey was conducted from 1993 and 1999 on the eastern lowlands in Hungary. Aphid flight was monitored with two yellow pan traps placed on the edge and in the middle of seed potato fields. From 1993 and 1997, aphid flight was monitored with a Rothamsted type suction trap. The aphid and virus survey was continued in four different regions of Hungary in 2000. Aphid flight activity recorded by the suction trap and the yellow pan traps was different. Cumulative vector intensity based on yellow pan trap catches revealed a greater variation between years than among the different locations. In 4?years out of 8, aphid flight was less intensive and quality seed potato was harvested regardless of the production site. Cumulative vector intensity is a good means to forecast the time of haulm destruction in seed potatoes. 相似文献
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For the first time soil solarization was investigated in Croatia both in the field and in the greenhouse in 1991, 1992, 1993 and 1994. For two months (July and August), the soil was mulched with transparent polyethylene (PE) sheets of 0.015 or 0.050mm thickness. Soil temperatures at depths of 5, 10 and 20cm were recorded daily. In order to assess nematode population densities, soil samples were analysed before mulching and at the end of the mulching treatment. The results of these experiments showed that soil solarization drastically reduced the population of plant-parasitic nematodes (Meloidogyne, Pratylenchus, Paratylenchus, Tylenchus, Tylenchorhynchus spp.) by about 97–100% at a depth of 10cm and 92–97% at a depth of 20cm in the field, while in the greenhouse, the population of plant-parasitic nematodes was reduced by about 89–100% at a depth of 10cm and 98–100% at a depth of 20cm.In the same experiments, the population of saprophytic nematodes in the field was reduced by about 86–90% at a depth of 10cm and 72–89% at a depth of 20cm. In the greenhouse, the population of saprophytic nematodes was reduced by about 87–97% at a depth of 10cm and 87–93% at a depth of 20cm. This data shows that soil solarization was less effective in the control of saprophytic nematodes, which is considered to be an advantage. 相似文献
3.
Dinka Grubišić Ljerka Oštrec Tanja Gotlin Čuljak Sylvia Blümel 《Journal of pest science》2007,80(1):21-27
Potato cyst nematodes (PCN) Globodera rostochiensis (Wollenweber, 1923) Behrens, 1975 and Globodera pallida (Stone, 1973) Behrens, 1975 are the most troublesome pests of potatoes worldwide. Since 1968 there have been no investigations
of the presence of PCN in ware potato lands in Croatia although these pests were recognised as an A1 plant-health quarantine
species. After the first discovery of G. rostochiensis in the locality of Belica (Medjimurska County) in 2001, intensive monitoring of the distribution of PCN in Croatia started.
In 2001 G. rostochiensis was detected in 55% of soil samples taken in ware potato lands. In 2002 G. rostochiensis was detected in 4.1% of soil samples and in 0.08% of soil samples in mixed populations with G. pallida. The pathotype Ro1 was found in all tested populations and Ro1 and Pa 2/3 were detected in populations from localities Vidovec,
Ivanovec and Sivice. In 2003 G. rostochiensis was detected in 1.03% of soil samples, and also in 12.8% of soil samples collected in 2004. In 2003 cysts of G. rostochiensis were detected in several seed potato fields. These results indicate the urgent need for the application of further control
measures to determine the presence and distribution of PCN in ware and seed potato lands in Croatia, in order to prevent the
spread of PCN to non-infested areas. Integrated management strategies, neglected until 2001, have now been implemented and
will prevent the build-up of infestation and replace the previous practices of monoculture, the use of short rotations and
growing susceptible cultivars. 相似文献
4.
K. M. Shaifullah M. Mezbahuddin M. Sujauddin S. M. S. Haque 《林业研究》2008,19(1):32-36
Coastal zones comprising important intertidal tropical and subtropical ecosystems are characterized by high productivity, diversity and unique zonation of various plant and animal communities. The comparison of some selected physicochemical soil properties viz. texture, particle density, moisture content, pH, organic carbon and total nitrogen between planted site (Telir char) and barren site (Boyar char) has been investigated at surface (0-10 cm) and subsurface (10-45 cm) soil across three different land strips viz. inland, middle part and sea side in Lakshmipur coast of Bangladesh. Sand particles in the soil were lower in planted site than barren site. The reverse trend was found in case of both silt and clay percentage. Coastal afforestation had a significant effect on soil binding process since a common trend of increment in soil particle density was noticed. Maximum increment (20.43% to 23.30%) in soil moisture content was recorded in surface soil across the seaside while at subsurface soil both across the middle part (19.53% to 22.30%) and sea side (20.19% to 22.96%). Moreover, the highest reduction in soil pH was recorded at surface soil (7.27 to 6.60) across the sea side and subsurface soil (7.16 to 6.67) in inland due to the influence of coastal plantation. Across all the land strips and the soil depths studied, soil organic carbon was higher in planted site than in barren site with only exception at subsurface soil in the middle part (0.50% in both sites). Total soil nitrogen in the study area was increased at both depths due to forestation with the highest increment in the inland at both surface and subsurface soil. 相似文献
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We measured physiological parameters including water uptake, in-vitro embryo germination ratio, and seed coat structure observed by scanning electron microscopy (SEM) to explore the influence of seed coat on the germination of seeds of tallow tree (Sapium sebiferum (Linn) Roxb.). Tallow tree seeds had good water permeability. We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat. Seed coat structure at the side of the radicle appeared to be a barrier to seed germination. We tested methods to break tallow tree seed dormancy. Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L-1 or 1000 mg·L-1 GA3, followed by 100 days of cold stratification. 相似文献
7.
The research into the side effect of fungicides used in the control of the most serious disease in apples (Venturia inaequalis) i. e. the research into the influence of fungicides on the population of phytophagous mites, was carried out at Nedeli??e (North-West Croatia) during 1997 and 1998. The study is related to the population of the mites most present in apple orchards, such as red spider mite (Pananychus ulmi) and other mites (Aculus schlechtendali andTetranychus urticae). Fungicides which are known to be effective against scab, i. e.Venturia inaequalis, and used in fruit production in Croatia, were tested in order to investigate their secondary properties which have not yet been studied. The following fungicides were used: cyprodinil, dodine, dichlofluanid + bitertanol (as tank mix), and kresoxim-methyl. The tests were repeated three times; the application time was determined by monitoring the conditions for infection. The treatments were done curatively, i. e. up to 96 h after the onset of infection conditions. The mite population was estimated by the pressing method, which yielded the average number of mites per leaf. All the results were statistically processed by variance analysis and by Duncan’s Multiple Range Test, and are presented graphically and in tables. The paper also presents graphically the climatic conditions, scab infections and application time. The research over two years have shown a pronounced suppressive effect of dichlofluanid + bitertanol on populations of phytophagous mites, while the other fungicides used in the research had a neutral effect on the mite papulation. 相似文献
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Bamboos often negatively affect tree recruitment, survival, and growth, leading to arrested tree regeneration in forested habitats. Studies so far have focused on the effects of bamboos on the performance of seedlings and saplings, but the influence of bamboos on forest dynamics may start very early in the forest regeneration process by altering seed rain patterns. We tested the prediction that the density and composition of the seed rain are altered and seed limitation is higher in stands of Guadua tagoara (B or bamboo stands), a large-sized woody bamboo native from the Brazilian Atlantic Forest, compared to forest patches without bamboos (NB or non-bamboo stands). Forty 1 m2 seed traps were set in B and NB stands, and the seed rain was monitored monthly for 1 year. The seed rain was not greatly altered by the presence of bamboos: rarefied seed species richness was higher for B stands, patterns of dominance and density of seeds were similar between stands, and differences in overall composition were slight. Seed limitation, however, was greater at B stands, likely as a resulted of reduced tree density. Despite such reduced density, the presence of trees growing amidst and over the bamboos seems to play a key role in keeping the seeds falling in B stands because they serve as food sources for frugivores or simply as perches for them. The loss of such trees may lead to enhanced seed limitation, contributing ultimately to the self-perpetuating bamboo disturbance cycle. 相似文献
11.
Leaf-level physiological processes were studied in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to determine whether apparent increases in stand-level water use efficiency (WUE) observed in response to nitrogen (N) fertilization were attributable to foliar N effects on carbon fixation rates or on stomatal control of water loss. Photosynthesis and transpiration were measured at different light intensities and ambient CO(2) molar fractions and comparisons were made between current-year shoots with average foliar N concentrations of 1.58% (High-N) and 1.25% (Low-N). Photosynthetic rates and foliar N concentrations were positively correlated. In response to light, photosynthesis and stomatal conductance were closely coupled and a similar coupling was observed in response to different ambient CO(2) concentrations. Partitioning the photosynthetic responses into mesophyll and stomatal components indicated that foliar N altered mesophyll conductance but not stomatal control of water loss. High-N shoots had significantly greater rates of photosynthesis and transpiration than Low-N shoots and, as a result, instantaneous WUE did not differ significantly between High-N and Low-N shoots. 相似文献
12.
Armillaria root rot induces a reduction in the concentrations of N, P, K, Mg and Na; an increase in the levels of Ca, Mn, Fe and Zn; and a decrease in the annual height growth of the diseased trees of four coniferous species. The data indicates that these changes are caused by interferences in the metabolism of the infected host. 相似文献
13.
Potato tuberworm (PTW), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is one of the most important pests of potatoes in tropic and subtropic regions. Previous
studies suggested that tuber periderm may limit larval penetration and establishment of PTW. Short term influence of parental
host plant acclimatization, influence of tuber dormancy and influence of tuber periderm (the outer cork layer of tubers) on
aspects of PTW biology were investigated on tubers of a susceptible commercial potato cultivar, cv. Allegany (Solanum tuberosum L.), and a resistant hybrid potato clone, Q174-2 (S. tuberosum × S. berthaultii Hawkes). Short-term parental host plant acclimatization did not affect numbers of PTW larvae on resistant and susceptible
tubers. Numbers of larvae produced on tubers of Q174-2, and Allegany, were similar although larval weight was less on Q174-2
than on Allegany. Larval production increased with tuber age on both susceptible and resistant potato clones, suggesting that
bud sprouts may enhance fitness by providing food and shelter for first instars prior to tuber entry. Removal of tuber periderm
led to a significant increase in larval survival on Allegany and Q174-2, although proportional survival on Allegany and Q174-2
was similar to that on intact tubers, suggesting the involvement of internal rather than external periderm factors in tuber
resistance of Q174-2. Weights of larvae reared on Q174-2 were consistently less than those of larvae reared on susceptible
potato tubers in both intact and peeled tuber assays. Although the expression of periderm-mediated tuber resistance declines
with tuber age, such resistance could significantly reduce preharvest field infestations by PTW and constitute an important
component of sustainable PTW management, particularly for fresh market crops and for those potato crops stored for several
months or less in the absence of refrigeration. 相似文献
14.
利用ABT2号生根粉和NAA,研究不同叶面处理方式对长白落叶松移植苗生长量及质量的影响,结果表明:叶面处理方式不同,对长白落叶松移植苗生长的影响不同,其中,涂刷侧枝的处理方式对苗木生长量有促进作用,而喷洒处理方式则有抑制作用。涂刷侧枝时,ABT2号处理的苗高、地径平均为41.1 cm、0.46 cm,分别比对照提高了17%、5%;NAA处理的苗高、地径平均为37.4 cm、0.51 cm,分别比对照提高了7%、16%。喷洒时,ABT2号处理的苗高、地径平均为33.6 cm、0.41 cm,分别比对照降低了4%、7%;NAA处理的苗高、地径平均为31.4 cm、0.43 cm,分别比对照降低了11%、2%。 相似文献
15.
We investigated the effects of selective logging disturbances on tree diversity and soil characteristics in the Bia Conservation Area in southwest Ghana.The study was conducted in unlogged,29-35 years post-logged and swamp forests using ten 25 m×25 m plots.In total,we identified 310 individual trees belonging to 87 species.Mean ShannonWeiner index was highest in the post-logged forest but there were no significant differences in tree density,dominance,or DBH size class distributions between these forests.Soil physical properties such as pH and bulk density up to 30 cm depth were similar in the two of forests In terms of soil nutrient status,available P,exchangeable K and total N contents were all similar in the unlogged and post-logged forests.Our findings suggest that the effects of logging on tree diversity are comparatively long-term,in contrast to its short-term effects on some top soil physical and chemical characteristics. 相似文献
16.
凉风坳亚热带次生常绿阔叶林土壤种子库和种子雨的特征研究 总被引:1,自引:0,他引:1
选择四川省沐川县凉风坳亚热带次生常绿阔叶林为研究对象,在2004年5月、2004年12月和2005年5月对其林下土壤种子库、种子雨以及种子天然萌发状况等方面进行系统调查及分析研究。结果显示,种子下落前后土壤种子库储量,变动为643.2~889.2粒.m-2,物种和种子密度多年生草本物种均占优势。天然林土壤种子库Shannon-Wiener指数均在2004年5月最大,2004年12月次之,2005年5月最小;Simpson指数却和Shannon-Wiener指数H'的变化趋势相反;Pielou均匀度指数在2004年12月有所降低,此后又升高。种子均呈明显垂直分布,其中0~2 cm土层种子数量最多,其次是枯枝落叶层,其数量随着土层加深而降低。土壤种子库年输入活力种子142.3粒.m-2,年输出活力种子268.9粒.m-2,动物取食是造成种子损失的主要原因。对照人工林土壤种子库物种和密度均低于天然林地;种子库与地上植被物种相似性系数,人工林较高,而天然次生常绿阔叶林较低。 相似文献
17.
The major insects that destroy cones and seeds of eastern white pine, Pinus strobus L., were controlled with soil applications of the systematic insecticide carbofuran in orchards at Murphy and Morganton, NC, U.S.A. Carbofuran applied once a year at rates of 4.5, 9.0 or 13.5 g AI (active ingredient) per cm of diameter at breast height protected trees from the white pine cone beetle, Conophthorus coniperda (Schwarz), the leaffooted pine seed bug, Leptoglossus corculus (Say), the shieldbacked pine seed bug, Tetyra bipunctata (Herrich-Schäffer), and the white pine cone borer, Eucosma tocullionana Heinrich. Control was reflected by increased cone survival and increased yields of filled seeds per cone. Increasing the rate of application from 4.5 to 9.0 or 13.5 g generally improved control, but the improvement was not of statistical or practical significance. Carbofuran was ineffective against a seed chalcid, Megastigmus atedius (Walker). White pine clones varied in inherent susceptibility to insect attacks. 相似文献
18.
Overhead-cooling treatment used to delay flowering produced non-significant effects on germination capacity, germination rate, germination value, and abnormal germination of seeds from a 13-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedling seed orchard. The percentage of variation accounted for by cooling treatment ranged from 0.0 to 1.0%. In contrast, variation among trees within treatments ranged from 28 to 46%. These effects were significant, indicating that each tree has an individual germination pattern. The temporal delay of reproductive phenology caused by temperature manipulation as a result of the cooling treatment was judged to be within the species' biological limits. 相似文献
19.
Ramón Perea Alfonso San Miguel María Martínez-Jauregui María Valbuena-Carabaña Luis Gil 《European Journal of Forest Research》2012,131(3):623-631
We examine whether different guilds of foragers remove seeds differentially according to seed quality (seed size and insect
infestation) and seed location (habitat and microhabitat) in a mixed oak-beech forest. Video recordings indicated that the
wood mouse (Apodemus sylvaticus) was first to encounter seeds. Foragers preferred acorns to beechnuts, large to small size and sound to infested. Nevertheless,
infested seeds were removed by rodents even when sound seeds were present. Seeds that were not preferred by scatter-hoarding
rodents remained longer on the ground and were more vulnerable to predation and desiccation (4% moisture loss per day). However,
seeds that were removed by scatter-hoarders were moved away from their mother trees (96%) and cached individually (32%), increasing
their moisture content (3% per day). Buried seeds, simulating scatter-hoarding behavior, experienced only a 17% removal after
4 months. Seed removal differences among habitats were not due to habitat attributes but to the spatial distribution of rodent-preferred
microhabitats. Thus, a significant lower seed removal was observed under the tree canopy with no shrubs. However, seed removal
in forest gaps with deadwood cover was not significantly different from the preferred microhabitat (under shrub cover). In
pure beech forests, seed removal by rodents only occurred under Ilex aquifolium (the only perennial cover) and under woody debris. This study concludes that seed quality and seed location determine the
contribution of different removers (predators vs. dispersers), their seed selection and their removal speed, leading to different
seed fates which will eventually affect tree regeneration. 相似文献
20.
Height and diameter growth, biomass accumulation and leaf pigment concentrations were measured in loblolly pine (Pinus taeda L.) seedlings grown in soil containing 12 or 35 microg Mg g(-1) and exposed from May to October to subambient, ambient, or twice-ambient ozone (O(3)), and to simulated acidic rain with a pH of either 4.0 or 5.3. At the end of one growing season, height and diameter growth of seedlings exposed to twice-ambient O(3) were not statistically different from those of seedlings exposed to subambient O(3). Biomass of all plant parts was reduced by 7 to 16% in response to increasing O(3) concentration. No statistically significant growth responses to rain chemistry or soil magnesium status were observed, and there were no statistically significant interactive treatment effects. Needle pigment concentrations were not significantly affected by rain chemistry or soil Mg status and there were no visible signs of injury to needles that could be attributed to O(3) stress or Mg deficiency. Concentrations of chlorophyll a and b, and carotenes were 23, 30 and 21% higher (P = 0.05) respectively, in seedlings exposed to twice-ambient O(3) than in seedlings from the other ozone treatments. There were no interactive treatment effects on needle pigment concentrations. 相似文献