Stoffbildung, CO2-Gaswechsel, Kohlenhydrat- und Stickstoffgehalt von Winterweizen bei erhöhter CO2-Konzentration und Trocken-streß

Dry Matter Production, CO₂ Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO₂ Concentration and Drought Stress
Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO₂ concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO₂ concentration and of drought stress on dry matter production, CO₂ exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO₂ concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO₂ concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO₂ treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO₂ concentration showed a reduced response of net photosynthesis rate to increasing CO₂ concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.     

The nature,causes and consequences of desertification in the drylands of Africa

The dryland environment of Africa poses formidable problems for sustainable development. Among these are unpredictable and severe drought, desiccation or aridification due to persistent drought and dryland degradation or desertification. Because these problems overlap in their effects on the ground, often those who seek sustainable development for these drylands tend to view the problems as one and the same. Yet to facilitate the development of appropriate and effective mitigating measures it is important that the differences and interrelationships be clearly understood. This article starts by outlining the differences and interlinkages between desertification, drought, desiccation and climate change and their causal factors. The central theme is the human causes and consequences of desertification in the drylands of Africa. An attempt has been made to unravel the changing views on the human causes, this is followed by a brief outline of the intervening plans and actions to stem the problem. A significant drawback in combating desertification and drought is the failure of African governments to devolve power to the people who are affected, and to link environmental degradation to economic policy. Consequently, many programmes lack local support or are undermined by conflicting trade and agricultural policies pursued by governments. It is contended that, for sustainable development strategies to work, policies should put the welfare of the people in these drylands at the centre of the development agenda and give them the rights and the power to determine their future. They should empower the people to sustain adaptive strategies towards sustainable livelihoods. Also the threats posed to environment and sustainable development by protectionism and overconsumption in the north and structural adjustment programmes (SAPs), call for the removal of distortions created by the import barriers of developed country, the curbing of overconsumption and a fundamental revision in the structure of SAPs to help alleviate poverty and protect the environment in these African countries. It is in the interest of the global community that the environment in Africa is protected. © 1998 John Wiley & Sons, Ltd.     

转基因玉米试管苗移栽影响因素及移栽技术要点

在海南省三亚地区,通过转基因技术获得规模化的转基因玉米试管苗的移栽成活率往往不高,这主要由其自身条件和外界环境引起的。该研究探讨了影响三亚地区转基因玉米试管苗移栽成活率的因素及移栽技术要点,为提高试管苗在三亚地区的移栽成活率提供参考依据。     

基于Logistic模型的新疆农村劳动力转移就业影响因素分析

为促进新疆农村经济发展,以新疆实际调查数据为依据,采用Logistic回归模型,对新疆农村劳动力转移就业的影响因素进行实证分析。结果表明：年龄、文化程度、双语教育、家庭年收入、养老保险、培训以及工作得到的途径对转移就业都有显著的影响。基于分析结果提出应大力发展农村教育事业,特别是双语教育的普及,加强对农村劳动力的培训力度,完善农村社会保障体系,加快小城镇建设步伐,发展劳动密集型产业,培育农村劳动力就业新的经济增长点等对策。     

人才甄选面试中应聘者印象管理策略的采用及其影响因素

论述了人才甄选面试中应聘者采用管理策略的作用及其影响因素对面试官甄选人才的影响。     

浅谈影响混凝土施工的质量因素和控制措施

结合施工实践,从原材料、配合比、生产搅拌、运输、施工浇筑、养护等诸多方面分析了各种因素对混凝土质量的影响,并提出了相应防治措施;同时强调了需要加强和提高综合控制理念。