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71.
野生朱红硫磺菌驯化栽培研究   总被引:2,自引:2,他引:2  
营养试验、菌丝体培养和出菇温度试验、培养基酸碱度试验、出菇条件试验结果表明:朱红硫磺菌菌丝体适宜生长的温度范围为15-32℃,最适温度范围为22~28℃;子实体发生的最适温度为16~25℃,气温低于16℃,子实体色泽为淡橙色,16℃以上,子实体呈鲜橙红色;培养料适宜营养C/N为20-26/1;朱红硫磺菌菌丝体适宜酸碱度范围为pH3.0~8.0,最适酸碱度为pH4.0—6.5;朱红硫磺菌的产量与光照条件无关,但光照强度影响子实体的发生时间和色泽;朱红硫磺菌栽培原料广泛,凡栽培木腐菌的培养料均可用于栽培朱红硫磺菌。  相似文献   
72.
水分管理方式对香根草生长发育的影响   总被引:6,自引:0,他引:6  
对四种不同的水分管理条件下香根草生长研究发现:香根草最适宜在土壤水分饱和的湿润环境中生长,这时它的成活率最高,分蘖速度最快,植株高度生长也最快,定植后3个月,其对应的根体积、根干生物量、茎叶干生物量和根茎比也最高。  相似文献   
73.
Increasing urbanization of rural landscapes has created new challenges for wildlife management. In addition to changes in the physical landscape, urbanization has also produced changes in the socio-cultural landscape. The greater distancing from direct interaction with wildlife in urbanized societies has led to the emergence of a culture whose meanings for wildlife are less grounded in the utilitarian/instrumental orientation of rural agrarian systems. Urban perspectives on wildlife are comprised of more highly individualized emotional/symbolic values. This shift creates two problems with respect to managing wildlife in an urbanizing landscape. First the increased diversity in values and meanings increases the likelihood for social conflicts regarding wildlife management while at the same time making socially acceptable resolutions more intractable. This in turn requires fundamental changes in decision-making paradigms and the research approaches used to inform decision making. Second, as remaining rural communities feel the pressures of urbanization, wildlife conflicts become conflicts not just over wildlife but conflict over larger socio-political concepts such as equity, tradition, private property rights, government control, power, and acceptable forms of knowledge. This paper examines the wildlife management implications of changes associated with increasing urbanization and employs two case studies to illustrate these issues. First a study of a controversy over urban deer management provides insights into how to map conflicting values and search for common ground in an urban culture with increasingly individualistic values for wildlife. Specifically, the analysis illustrates that common ground may, at times, be found even among people with conflicting value systems. The second case study examined a ranching community faced with predator reintroduction. This case study illustrates tensions that occur when the community of interest (i.e. a national public) is broader than the community of place in which the problem occurs. In this latter situation, the debate centers around more than just different views about the rights of animals. It also entailed the rights of individuals and communities to decide their future. The conclusion discusses the need for wildlife institutions to adapt their underlying decision making philosophy including the way science is integrated into decision making processes in light of the changes in social context caused by urbanization.  相似文献   
74.
The aim was to identify biological and physical factors responsible for reducing maize yield in Cameroon. Two surveys were conducted in 137 fields in two agroecological zones in 1995–1997. In the Humid Forest (HF), Bipolaris maydis, Stenocarpella macrospora, Puccinia polysora, Rhizoctonia solani and soil fertility were factors that reduced maize production in 1995 and 1996. In the Western Highlands (WHL), Cercospora zeae-maydis, and the interaction between soil fertility and maize variety were the most important constraints to maize production in 1996. In 1997, C. zeae-maydis, S. macrospora, physiological spot and stem borer damage (Busseola fusca) were negatively related to ear weight. The combination of these biological factors (diseases and insects), and the physical parameter of soil fertility were responsible for reducing maize yield in these selected benchmarks of Cameroon. Maximum potential yield reductions were estimated at 68% due to B. maydis and 46% due to S. macrospora, respectively, in the HF in 1995. In 1996, maximum potential yield reductions in the HF were estimated at 34%, 41% and 30% due to S. macrospora, P. polysora and R. solani, respectively. In the WHL, C. zeae-maydis had the potential to cause a yield reduction of 79% in 1996. In the WHL in 1997, the interaction between C. zeae-maydis and B. fusca, stem diseases and the physiological spot caused potential reductions of 52%, 34% and 39%, respectively.  相似文献   
75.
Summary Differential competitive ability of six winter wheat cultivars and traits that confer such attributes were investigated for a range of seed rates in the presence or absence of weeds for a naturally occurring weed flora in two successive years in split-plot field experiments. Crop height and tillering capacity were considered suitable attributes for weed suppression, although competitiveness is a relative rather than an absolute characteristic. Maris Huntsman and Maris Widgeon were the most competitive cultivars whereas Fresco was the least competitive. Manipulation of seed rate was a more reliable factor than cultivar selection for enhancement of weed suppression, although competitiveness of cultivars Buster, Riband and Maris Widgeon was not enhanced by increased seed rate. Crop densities ranging between 125 and 270 plants m−2 were found to offer adequate weed suppression. Linear relationships were observed between individual and total weed species dry weight and reproductive structures per unit area.  相似文献   
76.
对山西菜田捕食性食蚜蝇优势种及对菜蚜的控制效果进行了研究,菜田常见捕食性食蚜蝇有黑带食蚜蝇,大灰食蚜蝇,斜斑鼓额食蚜蝇,野食蚜蝇,四条小食蚜蝇,短翅细腹食蚜蝇6种,以黑带食蚜蝇种群数量最大,平均占全年发生总量的36.3%,通过对食蚜蝇产卵量,卵化率,幼虫期捕食量和羽化率测试,筛选出的黑带食蚜蝇,大灰食蚜蝇,斜斑鼓额食蚜蝇幼虫对菜蚜均有较强的捕食能力,其中黑带食蚜蝇为山西菜田菜蚜捕食性食蚜蝇优势种,用黑带食蚜蝇三龄幼虫对菜蚜进行防治试验,结果以1:180防效最佳,72h后控制效果达93.5%。  相似文献   
77.
Imports of pesticides have long been subsidised for use in the cocoa agroforests of the humid forest zone of southern Cameroon. With the liberalisation of the cocoa and pesticides sectors and the devaluation of the local currency (CFA franc), farmers are facing fluctuations in the price paid for cocoa and the high cost of farm inputs. Without the support of the extension services, they themselves have developed traditional integrated control methods based on the use of plant extracts mixed with conventional pesticides. From a survey of 300 cocoa farmers, the study assesses the farmers' command of these methods, the pests controlled, the problems encountered and the institutional constraints in the definition and dissemination of integrated control methods. The study concludes with recommendations for research and development towards the better definition and dissemination of integrated control methods. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
78.
Cocoa is a key or source of income and poverty reduction in the humid forest of Southern Cameroon. Cameroon like other African countries went through a major economic crisis in the early 1980s with a decline in international commodity prices and significant changes in macroeconomic policies. Structural adjustment reforms following the economic crisis led to removal of fertilizers and pesticides subsidies, cocoa price liberalization and the overall withdraw of Government interventions from the cocoa sub-sector. Cocoa input price increases have been compounded by the devaluation of the CFA Franc, which doubled the prices of the imported pesticides which were considered key to the control of cocoa pests. This overall economic shock led to changes in cocoa producer's production decisions as a response to minimize cost. Among the changes the use of alternatives to imported chemicals for cocoa pest control. Farmers responded to the high prices of pesticides by developing, from local botanical knowledge and pest management strategies, which include plant extracts and plant extracts mixed with pesticides at different proportions. This is a major decision given the importance of imported chemical in the cost of production of cocoa. Valuable indigenous knowledge from farmers could be used also as an effective support system for communicating and diffusing modern knowledge and technologies to farmers. The paper describes the farmer knowledge-based alternatives to chemical pesticides for pest control in cocoa fields as a response to high pest control costs. Pest management specialists are urged to take advantage of this shift in practice and assess their effectiveness for further use. Two sets of questions are posed: (1) were the conventional insecticides, with all their problems, really necessary? and (2) are the materials derived from locally grown plants effective pest management agents or are they, in some way, placebos?  相似文献   
79.
80.
Glyphosate is a key component of weed control strategies in Australia and worldwide. Despite widespread and frequent use, evolved resistance to glyphosate is rare. A herbicide resistance model, parameterized for Lolium rigidum has been used to perform a number of simulations to compare predicted rates of evolution of glyphosate resistance under past, present and projected future use strategies. In a 30‐year wheat, lupin, wheat, oilseed rape crop rotation with minimum tillage (100% shallow depth soil disturbance at sowing) and annual use of glyphosate pre‐sowing, L. rigidum control was sustainable with no predicted glyphosate resistance. When the crop establishment system was changed to annual no‐tillage (15% soil disturbance at sowing), glyphosate resistance was predicted in 90% of populations, with resistance becoming apparent after between 10 and 18 years when sowing was delayed. Resistance was predicted in 20% of populations after 25–30 years with early sowing. Risks of glyphosate resistance could be reduced by rotating between no‐tillage and minimum‐tillage establishment systems, or by rotating between glyphosate and paraquat for pre‐sowing weed control. The double knockdown strategy (sequential full rate applications of glyphosate and paraquat) reduced risks of glyphosate and paraquat resistance to <2%. Introduction of glyphosate‐resistant oilseed rape significantly increased predicted risks of glyphosate resistance in no‐tillage systems even when the double knockdown was practised. These increased risks could be offset by high crop sowing rates and weed seed collection at harvest. When no selective herbicides were available in wheat crops, the introduction of glyphosate‐resistant oilseed rape necessitated a return to a minimum‐tillage crop establishment system.  相似文献   
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