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排序方式: 共有313条查询结果,搜索用时 15 毫秒
41.
Economically Important Leatherjackets of Grassland and Cereals: Biology, Impact and Control 总被引:2,自引:0,他引:2
Despite the large number of cranefly species only two have been convincingly associated with crop damage. The larvae of Tipula paludosa are commonly found as pests in both grassland and spring cereals whereas those of T. oleracea are only established as pests of winter cereals following crops of oilseed rape in the rotation. The latter, however, is probably the species involved in opportunistic situations involving various minor crops. These epidemiological contrasts are attributable to differences in the morphology and behaviour of the adults of the two species in relation to crop rotations. Larvae are sufficiently similar as to cause confusion in identification and this has hampered development of a clear picture of the ecology of the two species. Little is known about the distribution of T. oleracea larvae but T. paludosa larvae are largely regulated by climatic factors, especially rainfall, although the operation of these varies across the distribution range. Many natural enemies have been identified but a commercially viable control method using them has not yet been developed for either species. Control of T. paludosa is relatively easy using broad-spectrum insecticides but inconsistent kills have been observed with winter pesticide applications against T. oleracea. Determination of those fields requiring applications in advance of the damage remains the major problem, especially in grassland and winter cereals, to be resolved for the management of leatherjacket pests. 相似文献
42.
M.C. Hare D.W. Parry M.D. Baker 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(9):859-866
The distribution of seeds by weight for three lots of winter wheat cv. Avalon infected by Fusarium culmorum and three lots of winter wheat cv. Riband infected by Microdochium nivale was determined. The distribution of infected seeds within each seed lot was then determined by isolating F. culmorum from seeds on moist filter paper and M. nivale from seeds on potato dextrose agar. The distribution of M. nivale infected seeds between seeds of different weight was similar to that of the seed lot as a whole, whereas the distribution of F. culmorum was greater in light seeds than heavy seeds. The percentage germination of infected seeds decreased with seed weight. A similar situation was found with respect to seedling emergence in compost for F. culmorum infected seeds. However, with M. nivale infection, similar numbers of seedlings emerged from both light and heavy infected seeds. Seed treatment with guazatine increased seedling emergence for both light and heavy seed infected by M. nivale. However, seedling emergence from F. culmorum infected seed was poor even following treatment with guazatine. Poor emergence was most evident from light seed. 相似文献
43.
几种益生菌发酵谷物饮料制作工艺研究 总被引:3,自引:0,他引:3
益生菌发酵谷物饮料既保存了谷物原有的营养价值,又具有益生茵发酵制品的有益作用,风味良好、口感独特,对人体有显著的营养保健作用.用1.5%的量接种从发酵谷物中筛选获得的酿酒酵母、嗜酸乳杆菌、保加利亚乳杆菌分别发酵糯米制作米酒、发酵玉米汁制作酸性饮料、多肽饮料,其发酵条件分别为:米酒发酵温度30℃,发酵时间72h,酸性饮料... 相似文献
44.
P. Ziegler 《Journal of Cereal Science》1999,29(3):195
Cerealbeta-amylases are perhaps best known in terms of the vital role they play in releasing easily fermentable sugars from cereal grain starch to fuel the production of alcohol by yeast in brewing. The extent to which they have been investigated is indeed largely due to their significance in this economically important industry. However, cerealbeta-amylases are also, or could be, employed in many other aspects of the food industry and the analysis of starch, and they constitute valuable markers in cereal assessment and breeding studies. Quite apart from their practical significance, they are rewarding objects of biochemical and physiological research. They are interesting models for the study of enzyme polymorphism, post-translational modification and the differential expression of isoenzymes. In spite of their often high activitiesin situand all that is known about their generation, they are an enigma in that their physiological function, or even necessity, remains unclear. It has been recently recognised that there are two different categories of cerealbeta-amylases which exhibit different tissue and taxonomic specificities and physiological developmental patterns. The «classical»beta-amylases present at high activities in cereal seeds appear to be limited to the endosperm of the species of the Triticeae tribe of the Festucoideae subfamily of the Gramineae (wheat, barley and rye), whereas all cereals exhibit a different, tissue-«ubiquitous» form of the enzyme which is present at much lower activity levels. The physiological phenomenology and the usage of cerealbeta-amylases are discussed in relation to these two categories of enzyme. 相似文献
45.
Patterns of biodiversity are influenced by habitat features at multiple spatial scales, yet few studies have used a multi-scale approach to examine ground-dwelling beetle diversity patterns. We trapped and quantified ground-dwelling beetle assemblages at two spatial scales: (1) microhabitat elements, represented by open ground, ground under trees and ground next to logs and (2) macrohabitat, represented by three vegetation types in a box-gum grassy woodland in south-eastern Australia. Species richness and evenness was highest at samples from under trees and lowest at samples in the open. At the macrohabitat scale, species richness and evenness did not differ among vegetation types. Assemblage composition was significantly different between trees, logs and open elements. Assemblage composition was different only between vegetation types with contrasting high and low shrub cover. Estimation of true species richness indicated assemblages at logs may have a higher number of species compared to trees and open elements, and implied greater spatial heterogeneity in assemblages at logs. Significant spatial autocorrelation in beetle assemblages was detected for logs at up to 400 m, but not for ground under trees or in the open. In agreement with previous studies, a mix of vegetation types at the macrohabitat scale is important for beetle conservation. Assemblage composition, however, appears to be more closely linked with habitat elements at the microhabitat scale, where logs support a high diversity of beetle species. This strongly supports the idea that restoring logs to box-gum grassy woodlands would be useful for increasing beetle species richness and assemblage heterogeneity. 相似文献
46.
We studied the leaf litter-dwelling fauna of managed deciduous forests and primeval reference sites in Western and Central Europe and addressed the questions if the higher overall species richness close to downed coarse woody debris (CWD) is related to intra-specific or inter-specific aggregation, if the aggregation pattern changes with the amount of CWD on the forest floor, and how much CWD is needed for different taxa. The analysis is based on shelled Gastropoda, Diplopoda/Isopoda, Chilopoda and Coleoptera. Among-sample heterogeneity was lower close to CWD than distant from CWD. This was most pronounced in Diplopoda/Isopoda and Gastropoda. Diplopoda/Isopoda are comparatively mobile and assemblages were already quite homogenous close to CWD at levels above 5 m3 downed deadwood ha−1. Gastropoda have a low mobility, and more than 20 m3 downed deadwood ha−1 is needed for assemblage homogeneity. We further focused on the Gastropoda as sensitive indicators. Enhanced densities and species richness close to CWD were not a simple function of leaf litter weight, thus effects of densities on heterogeneity are not solely driven by leaf litter accumulation close to CWD. In contrast to euryecious litter-dwellers such as the Punctidae, stenecious slow active dispersers such as the Clausiliidae clearly require more than 20 m3 CWD ha−1 for an even distribution. Specialists depending on CWD even seem to have gone extinct in some managed forests. For conserving the litter-dwelling fauna, we propose a target of at least 20 m3 downed CWD ha−1 in already managed forests and rigorous restrictions for deadwood removal from still (almost) pristine systems. 相似文献
47.
In this study, the stand level root respiration was estimated for two monoculture plantations: Acacia crassicarpa and Eucalyptus urophylla, based on in situ measurement of specific root respiration using simplified root chamber method. The respiration rates of fine roots (<5 mm) were significantly higher than those of coarse roots (>5 mm) for both A. crassicarpa and E. urophylla species. The root respiration of A. crassicarpa showed a clear seasonal pattern with a higher value in the wet season. For E. urophylla, the seasonal pattern was observed for fine roots but not for coarse roots. After determining the biomass of fine roots and coarse roots and their specific rates of respiration at different time points, root respiration at the stand level (Ra) was estimated using a direct up-scaling model. We found that the Ra accounted for 14% and 19% of total soil respiration (Rs) for A. crassicarpa and E. urophylla, respectively. The fine (RTf) and coarse (RTc) root respiration at the stand level accounted for about 47% and 53% of the Ra for A. crassicarpa, and accounted for 58% and 42% for E. urophylla. This suggests that coarse root respiration cannot be ignored when estimating the root respiration at the stand level. Our results showed that the Q10 values were more accurate in representing the temperature dependence when the confounding effect of soil moisture was considered. This study introduces an alternative approach to estimate stand level root respiration, but its reliability is largely dependent on the accuracy of root biomass quantification. 相似文献
48.
实验室试验与实际生产应该紧密结合,经发酵蒸制而成的杂粮馒头,具备色多、光亮、皮软、光润、膨松喧软、筋力适度、淡香微甜等的感官性状,其有宜于配菜,久食不厌的特点。而且,杂粮馒头还有经济、实惠、物美、价廉、易消化等优点。 相似文献
49.
Larvae of the cereal leaf minerSyringopais temperatella Led. (Lep.: Scythridae) collected from wheat and barley fields in the southeast Anatolian region of Turkey during 2005–2006,
and their parasitization rates, were determined in the laboratory,Bracon (Habrobracon) stabilis Wesmael andApanteles sp. (Hymenoptera: Braconidae) were identified as its parasitoids for the first time. 相似文献
50.