大豆连作对土壤纤维素酶活性的影响

试验结果表明,大豆连作土壤中纤维素酶活性的变化是：播期,成熟期的变化趋势基本一致,以连作２年酶活性最低。而结荚期酶活性则以连作二年酶活性最高,出现了与播期,成熟期截然不同的变化趋势,结荚期酶活性几乎都高于播期,成熟期。经相关分析表明,播期,成熟期纤维素酶活性变化与土壤有机碳和ｐＨ呈显著正相关。     

Effects of nitrogen and water stress on the rehydration,endogenous hormonal regulation and yield of maize

Water scarcity is known to be a strong limiting factor affecting maize grown and yield in cold semi-arid regions. Numerous studies have shown that rehydration improves maize growth. Our study aimed to explore the effects of rehydration treatments on maize growth and yield under water and nitrogen stress during different growth stages. We selected the drought-tolerant maize variety Nendan 19 (ND19) and subjected it to water stress during the V6 (sixth-leaf), R2 (filling) and R6 (maturity) growth stages and a rehydration treatment after each stress stage. Our results indicated that N1 (N100 kg N ha⁻¹) and N3 (N300 kg N ha⁻¹) treatments significantly increased the leaf moisture status relative to water content (RWC), bound water content (BWC), free water content (FWC) and water potential (WP)) at different growth stages. Similar trends were observed in the accumulation of plant leaf and root hormones (zeatin+zeatin riboside, indole-3-acetic acid, abscisic acid and gibberellic acid), photosynthetic pigments and chlorophyll fluorescence. However, under the same water stress conditions, they decreased as the N rate increased and reached a minimum value in the S3 (water stress for N3) treatments. In addition, with growth stage advancement and extension of the rehydration time, both showed a gradual upward trend. The results showed that to save water resources in the cold semi-arid region, rehydration treatments (R2S1 and R2S3) significantly increased the photosynthetic pigments and chlorophyll fluorescence parameters, leaf moisture status, biomass, 100-grain weight, hormone content, ear characteristics and grain yield of maize.     

花椒病虫害影响因素的初步研究

花椒Zanthoxylum bungeanum Maxim属芸香科花椒属植物,四川省北川县青片乡花椒种植面积较大,由于当地花椒风味独特,市场供不应求.但是,当地花椒树一直受根腐病、花椒虎天牛和花椒瘿蚊的危害,致使约80%的椒树未达到盛果期就死亡.     

The origin,evolution, cultivation,dissemination, and diversification of Asian and African rices

Summary Available evidences drawn from biosystematics, evolutionary biology, biogeography, archaeology, history, anthropology, paleo-geology and paleo-meteorology are pooled to reconstruct the series of events that led to the cosmopolitan cultivation of the Asian cultivated rice (O. sativa) and the regionalized planting of the African cultigen (O. glaberrima) in West Africa. The genus Oryza originated in the Gondwanaland continents and, following the fracture of the supercontinent, became widely distributed in the humid tropics of Africa, South America, South and Southeast Asia, and Oceania. The two cultivated species have had a common progenitor in the distant past. Parallel and independent evolutionary processes occurred in Africa and in Asia, following the sequence of: wild perennialwild annualcultivated annual. The weed races also contributed to the differentiation of the cultivated annuals. The corresponding members of the above series are O. longistaminata Chev. et Roehr., O. barthii A. Chev., O. glaberrima Steud., and the stapfii forms of O. glaberrima in Africa; O. rufipogon Griff., O. nivara Sharma et Shastry, O. sativa L., and the spontanea forms of O. sativa in Asia.The differentiation and diversification of the annuals in South Asia were accelerated by marked climatic changes following the last glacial age, dispersal of plants over latitude or altitude, human selection, and manipulation of the cultural environment.Cultivation of rice began in many parts of South and Southeast Asia, probably first in Ancient India. Cultural techniques such as puddling and transplanting were first developed in north and central China and later transmitted to Southeast Asia. Wetland culture preceded dryland culture in China, but in hilly areas of Southeast Asia, dryland cultivation is older than lowland culture. The planting method progressed from shifting cultivation to direct sowing in permanent fields, then to transplanting in bunded fields.Widespread dispersal of the Asian cultigen led to the formation of three eco-geographic races (Indica. Sinica or Japonica, and Javanica) and distinct cultural types in monsoon Asia (upland, lowland, and deep water). Varietal types changed readily within the span of a millenium, largely due to cultivators' preferences, socio-religious traditions, and population pressure. Genetic differentiation developed parallel to the ecologic diversification process.The African cultigen developed later than the Asian cultigen and has undergone less diversification. The wild races in South America and Oceania retain their primitive features mainly due to lack of cultivation pressure or dispersal.Both the African and Asian rices are still undergoing evolutionary changes at habitats where the wild, weed, and cultivated races co-exist.     

秋水仙素诱导美洲商陆四倍体的研究

利用改良L.D.Cua法对美洲商陆进行多倍体诱变,在秋水仙碱浓度为0.2%条件下,设置24h、48h和72h三个诱变时间,并对所得到的变异株和对照株进行形态学、细胞学等方面的比较研究,结果表明：诱变48h效果最好;与对照相比,变异株的叶片厚度增加43.75%;叶形指数减少37.95%;气孔纵横径分别增加52.94%和73.01%;保卫细胞内叶绿体数目增加20.91%;花直径增加22.96%;花粉粒直径增加22.47%;果实直径增加23.66%。对变异株进行花粉母细胞减数分裂染色体鉴定,小孢子细胞的染色体数为n=2x=36,而对照小孢子细胞的染色体数为n=x=18,证明变异株为四倍体。     

金属洗桶企业场地污染调查与分析实例

以某金属洗桶企业搬离时,对场地开展的污染调查与分析为实例,探讨了污染场地健康风险评估的方法和进行风险管控的手段,以期提供参考。     

AutoCAD制图软件在汕头林业调查规划中的应用

从已有图纸资料的扫描输入,设置绘图环境,矢量化地形图,创建图层,用GPS数据绘制小班图,面积或路程求算,绘制图签、图例,文件保存格式,打印出图等方面阐述了AutoCAD在汕头市林业调查规划设计制图中的应用方法.认为用AutoCAD制图较Photoshop精度、效率高,并能较精确地进行面积及距离的求算.     

The Effects of Climate Change on the Planting Boundary and Potential Yield for Different Rice Cropping Systems in Southern China

Based on climate data from 254 meteorological stations, this study estimated the effects of climate change on rice planting boundaries and potential yields in the southern China during 1951-2010. The results indicated a signiifcant northward shift and westward expansion of northern boundaries for rice planting in the southern China. Compared with the period of 1951-1980, the average temperature during rice growing season in the period of 1981-2010 increased by 0.4＆#176;C, and the northern planting boundaries for single rice cropping system （SRCS）, early triple cropping rice system （ETCRS）, medium triple cropping rice system （MTCRS）, and late triple cropping rice system （LTCRS） moved northward by 10, 30, 52 and 66 km, respectively. In addition, compared with the period of 1951-1980, the suitable planting area for SRCS was reduced by 11%during the period of 1981-2010. However, the suitable planting areas for other rice cropping systems increased, with the increasing amplitude of 3, 8, and 10%for ETCRS, MTCRS and LTCRS, respectively. In general, the light and temperature potential productivity of rice decreased by 2.5%. Without considering the change of rice cultivars, the northern planting boundaries for different rice cropping systems showed a northward shift tendency. Climate change resulted in decrease of per unit area yield for SRCS and the annual average yields of ETCRS and LTCRS. Nevertheless, the overall rice production in the entire research area showed a decreasing trend even with the increasing trend of annual average yield for MTCRS.     

金属网与木单板的复合

本研究着重考察不同胶粘剂种类、不同金属材料和不同规格金属网，在不同组坯条件下压制复合板的电磁屏蔽性能。确定木单板与金属网的复合工艺，结果表明，板材的电磁屏蔽效能在1-1000MHz范围内可达到40dB以上；采用处理剂A处理金属网，可改善金属网与木材的胶合；复合板的胶合强度符合国家标准GB9846.12-88的要求。     

福建省侵蚀坡地利用中存在的问题与对策

福建省开垦为果园的侵蚀坡地在利用中还存在工程措施不规范、地面覆盖度低、光能利用率不高和土壤肥力低等问题。这些问题目前都可以用成熟的技术措施加以解决。然而,由于农民科技水平不高,缺乏水土保持和果园生态栽培意识,先进的坡地果园管理措施屡推不开。因此,加大科普宣传力度,提高民众的水土保持意识,推行生草覆盖等果园生态栽培模式,是确保侵蚀坡地果园可持续利用的重要措施。