Abstract: The reflectance spectra were measured of some featured crops and typical vegetation with the ASD Handheld FieldSpec spectrometer FR2500 in Gansu province． By the computer programming technology，the spectra database of typical ground objects in northwest China was set up． This paper mainly introduces spectrum data collection，the establishment course of database system，application and problems of database．
A series of recent researchs focuses on the impact of climate change on agricultural production, land use, pollution and biodiversity, which implies the potential impactof climate change on food security is awidely debated and investigated issue. Nonetheless, the specific safety influence of food and feed for consumers has remained a less studied topic. This review identifies the various food safety issues from some literatures about climate change impacts on crop cultivation and livestock systems. According to general consensus, crop cultivation is recognized as a relatively susceptible partof the food and feed production sector thatcould be affected by climate change, variations in climatic parameters such as temperature, drought, precipitation, wind, and CO2levels are projected to have notable consequences on crops in terms of changes in the demand for fertilizer and pesticides, deterioration of the quality of soils,and expanding ranges of crop pests and altered transmission dynamics of insects, pests and plant diseases. Livestock production also could be heavily influenced by climate change, and the presence ofpathogenic bacteria in foods followingmore frequentextremeweather conditions, such as flooding and heatwaves. Therefore the challenges facing food securitywill pose new risks to human under the background of the global climate change.
With the development of system and computer sciences, crop growth simulation modeling was developed faster, and it is commonly accep ted as a new research field in agricultural science at p resent. On the basis of summarizing the characteristics and classification of crop simulation technology, this paper discusses the studies on growth simulation models ofwheat crop s and app lication status in China, also it suggests the p roblems and future app roaches in simulation models development
With the globalwarming, climate in northwest China is experiencing the same change in recent years, especially in cotton planting region: Xinjiang and Gansu Hexi Corridor. More and more studies aimed on the impact of climate change on cotton growth and yields. However, it ismore important to reasonably assess the impact of climate change on crop. Furthermore, the selecting of assessment index ismost important in the p rocess of estimation. So we have selected some importantmeteorological indices for cotton growth and development, p lanting structure, geographical distribution, disaster of agriculturalmeteorology, diseases and pests of cotton, and all of these were the base of assessment for impact of climate change on cotton in northwest China.
Water or drought stress is one of the most important factors limiting crop growth world - wide. Some changes would be observed in p lant growth, physiologicalmechanisms and hormone level under soil drying stress. In arid or semi - arid region, water deficit in soil evidently inhibit the root and the shoot growth, and decrease biomass, yields and harvest index. Usually, water stress during the grain - filling period would decrease photosynthesis, shorten the grain - filling period, decline the grain - filling rate and induce early senescence, however, itwould increase the remetabolism of non - structural carbohydrate (NSC) from the vegetative tissues to the grain. Grain filling is an intensive transportation p rocess regulated by soil drying and p lant hormones. The concentration ofABA, which is generally regarded as an inhibitory growth hormone, would increase markedly in leaves, floral organs and develop ing grains in responses to soil drying. Some of the adap tive responses to drought are due to physiological and morphological changes, such as changes in p lant structure, dry matter accumulation, tissue osmotic potential and stomatal conductance. Soil drying is unfavorable to p lant growth butmay be favourable to the critical point of p roducing stress. So it is possible to take advantage of soil drying to induce whole - p lant senescence and better carbon remetabolism to imp rove grain yield during the slow grain filling period. If mild soil drying is p roperly controlled during the later grain - filling period in some crop s such as rice (Oryza sativa) and wheat ( Triticum aestivum) , it could enhance yield and harvest index, and might contribute to water saving, which is imminently needed to develop sustainable agriculture in many parts of the world.
issues about ecological water use are summarized from its concep t, background, estimation method and research ad2 vances. On the basis of the summary, some questions in research at p resent and the possible breakthrough in mechanism investigation of ecologicalwater use are put forward. At last, it is pointed out that under the background of climate warming and shortage ofwater re2 source, the spatial and temporal variation of ecologicalwater use corresponding to supp ly and demand balance ofwater resource will be2 come hot scientific issue.
The distribution of regional biological environment and climate resource were studied by statistical analysis of sunlight，heat and moisture distributions in Gannan plateau，meanwhile，the main ecological problems at present and their formation were analyzed．The ecological agriculture division with thine types and six sub—types ecological al~a8 were suggested，and the major ways for the de-velopment of ecological agriculture，stockbreeding and forestry were put forward．
The photo—·physiological characteristics of Achnatherum splendens both in the enclosure an d the grazing pasture were moni-toted in Anxi．Th e results showed that the diference was significant between them．Th e air temperature and leaf temperature were rela．tively lower and the relative humidity Was higher in the enclosure compared with those in the grazing grassland．These indicated that the environment of grass growth Was greatly improved by enclosure means．At the same time，there Was higher photosynthetic rate of Ach-hat．rum splendens in the enclosured grassland．This Was beneficial to growth of grass and accumulation of dry matter．
The mainly research development over Qilian Mountain region in recent ten years is reviewed in this paper. The most research work focused on climate change and water resource. There are a lot of results about the paleoclimate and the interannual variability of neoteric climate and water resource over the QilianMountain region. The exp loitation and utilization of airwater resource over QilianMountain has been focused in recent years, which should be a way to mitigate water shortage in arid and semi - arid region in northwest China.
An observation and analysis on microclimate in greenhouse were carried out in semi一arid region which lies in Loess Plateau. "hhc results show that the temperature and the relative humidity in different height in greenhouses were different, that is to say, the temperature at 1.5 m height was higher than that at() .> m，and the relative humidity at 1.5 m height was lower than that at() .> m，thus, there was a microcnvironment of the lower temperature and higher RH at() .5 m height compared with that at 1. 5 m. IW ring cucumbers growth period，the temperature in greenhouses maintained around 12一23. 5 C，R H ex- cccdcd 77. 3%in lower layer. Additionally, the survey shows that downy mildew occurred in every growth stage from seeding to bearing period，and the degree of disease in under part of the plant was more serious. So the conclusion on optimum climate condition of occurring and spreading of disease was the lower temperature and higher RH. At last, we brought forward the in- tegrated control measure.
Photosynthesis and transpiration of diseased wheat leaves in field were measured with CI- 301PS(CID, Inc,USA) Photosynthetic System in the semi - arid region. The results show that obvious changes were happened, that is to say the photosynthesis rate decreased, while intercellular CO2concentration, stomatal resistance and the transpiration rate increased in comparison with those of the healthy plants, also there are different diurnal changes in photosynthesis and transpiration of diseased wheat leaves with various severity of stripe rust infection in field in the semi-arid region.
Based on the mean monthly, maximum and minimum temperature series, the temperature changing characteristics in Urumqi airport in recent 50 years were analyzed in this paper. The results show that the mean annual temperature trends was 0.033 ℃/a, and there were obvious warming trends in spring, autumn and winter, the temperature tendency rate was 0.0949℃/a in winter, which was the largest. But the temperature in summer was dropping by the rate of 0.028℃/a. In recent 50 years, there were cold- warm- cold- warm evolution processes in Urumqi airport. A long cold period was in 1950s which was obvious in four seasons, a warm period was from 1961 to 1975, the second cold period was from 1976 to 1988, another warm period was from 1989 to 2000. 70% of anomalous cold years (seasons) were in 1950s and 41% anomalous warm years (seasons) were in 1990s. The mean annual maximum and minimum temperatures presented obviously increasing trend, and the latter was much steadier. From the results it is known that the minimum temperature would be more sensitive to monitor the intensity of greenhouse.From 1989 to 2000,abrupt warming occurred mainly in nighttime.These facts would contribute to study the temperature change in Urumqi airport.
Atmospheric chemistry is an booming discipline in atmospheric sciences. Its researches started one hundred years ago.but the observation of atmospheric owne and theoretical researches in owne actinic chemistry are milestone. Many facts and phenomena in atmospheric chemistry field are not understood at present .especially some problems on sinks.sources and spatial and temporal distribution of some atmospheric trace elements and their migration .transfer and global cycle is necessary to more deeply and widely observe and research.
