耕作方式与长期定位施肥对雨养农田冬小麦产量的调控效应

为了明确西北黄土高原半湿润偏旱区耕作方式与长期定位施肥对冬小麦产量的调控效应,以设在半湿润偏旱区连续12年的耕作与肥料长期定位试验为平台,采用裂区设计,以传统耕作和免耕耕作为主处理,不施肥(CK)、单施无机氮肥(N)、单施无机磷肥(P)、单施有机肥(M)、无机氮磷肥配施(NP)、有机无机肥配施(NMP)为副处理,栽培制度为1年春玉米-3年冬小麦轮作,研究耕作及施肥措施对冬小麦产量的影响及其在生产年型间的变化关系。结果表明,不同年型及耕作方式均以有机无机配施冬小麦产量最高,有机肥单施高于化肥单施,磷肥单施高于氮肥单施。耕作方式间表现为传统耕作高于免耕耕作,年型间表现为丰水年>平水年>干旱年,耕作和施肥方式的增产效果以干旱年最好,平水年和丰水年差异不显著。有机无机配施与传统耕作结合优化了冬小麦冠层温度、叶绿素相对含量等生理指标,提高了光合速率、气孔导度及蒸腾速率,因而改善了有效穗、穗粒数和千粒重等产量性状而使冬小麦增产。在550 mm左右降水量的陇东旱塬雨养农业区,无论何种耕作方式及生产年型,长期采用有机无机或无机氮磷肥配施均表现出持续提高冬小麦产量的良好作用。因此,有机无机配施结合传统耕作是提高陇东半湿润偏旱区冬小麦产量的最佳耕作栽培模式。     

基于食物安全视角的我国畜产食品进口依赖性风险评价

新时期下,保障我国畜产食品供给安全是保障我国食物安全的重要内容之一,而“适度进口”是保障我国畜产食品供给安全的重要途径之一。如何才算“适度进口”,需对畜产食品进口的相关风险进行分析方可评判。运用进口依赖性评价模型对我国猪肉、鸡肉、羊肉、牛肉、鲜牛奶的进口依赖性风险进行分析发现,上述5种畜产食品均存在进口依赖性风险。其中,猪肉的风险来自美国、德国、丹麦、西班牙和加拿大;鸡肉的风险来自美国、巴西、阿根廷和波兰;羊肉的风险来自澳大利亚、新西兰和乌拉圭;牛肉的风险来自乌拉圭、澳大利亚、新西兰、阿根廷和加拿大;鲜牛奶的风险来自德国、法国、新西兰和澳大利亚。为降低我国畜产食品进口依赖性风险,短期内应采取畜产食品进口市场多元化策略以及用进口饲草料替代进口畜产食品的进口方式;长期应在保障“口粮安全”的前提下,调整农业结构,大力发展草地农业,减少对国际市场的依赖性。     

基质对黑果腺肋花楸幼苗生长的影响

以黑果腺肋花楸(Aronia melanocarpa)为试验材料,选用田园土、泥炭土、珍珠岩和黄沙,采用正交试验设计,研究不同基质配比对黑果腺肋花楸成苗率以及幼苗形态指标和生理指标的影响。结果表明,不同育苗基质对黑果腺肋花楸出苗率、苗高、地径、主根长、侧根数和高径比等形态指标以及根系活力、可溶性糖、淀粉和蛋白质等生理指标的影响差异显著,综合分析各项指标,筛选出适合黑果腺肋花楸容器育苗的栽培基质为田园土(40%)+泥炭土(30%)+黄沙(30%)、田园土(40%)+珍珠岩(30%)+黄沙(30%)、田园土(40%)+泥炭土(30%)+珍珠岩(30%)和田园土(60%)+泥炭土(20%)+黄沙(20%)。     

The value of vegetation cover for ecosystem services in the suburban context

Latin-American cities can be characterized by dynamic processes of urbanization that encroach upon the natural and semi-natural surrounding landscapes. Our study presents the effects of landscape development, transformed from semi-natural conditions into a mostly disperse suburban settlement. We explore the impact that this transformation has had on this context by three ecosystem services that regulate rainwater runoff, enhance microclimate conditions and help to improve air quality by monitoring vegetation cover. We have designed a spatio-temporal hierarchical analysis which employs remote sensing techniques to capture the structural changes of this landscape over long, medium and short term scales on two spatial levels. This methodological approach was tested in the Metropolitan Area of Santiago (MAS) as case study area. Despite of the increase in impervious surfaces due to urban processes, there has also been an increase in vegetation cover, which has led to an improvement in the provision of the above-mentioned ecosystem services. Hence, if diverse urbanization processes continue and they are coupled with an increase in vegetation cover, the provision of ecosystem services could also expand. This phenomenon can be observed in some areas, where public and private green spaces are created and maintained. Our data analyses give evidence that certain types of suburban areas which increase the share of vegetation cover can provide daily ecological benefits for urban neighborhoods, and beyond, for adjacent areas. Moreover, suburban development can successfully provide ecological benefits to citizens. Such processes can only be ecologically sustainable if the composition of vegetation is well-adapted to the regional climatic conditions.     

Yield Performance of Wheat Isolines with Different Dosages of the Short Arm of Rye Chromosome 1

Translocations of the short arm of rye (Secale cereale L.) chromosome 1 (1RS) in wheat (Triticum aestivum L. cv. Pavon 76) are known to increase root biomass. Such an increase enhances water and nutrient uptake and may improve grain yield. Two greenhouse experiments and a field experiment were carried out at the University of California, Riverside, in 2012 and 2013 under well‐watered and terminal drought treatments to evaluate phenotypic characters associated with varying dosages of 1RS, including grain yield. The genotypes used were cultivar Pavon 76 (R₀), Pavon 76/Pavon1RS.1AL (F₁ hybrid) with a single dosage of 1RS (R₁A), Pavon 1RS.1AL with two dosages of 1RS (R₂A), Pavon 1RS.1DL (R₂D) also with two dosages of 1RS and Pavon 1RS.1AL‐1RS.1DL (R₄AD) with four dosages of 1RS. There was a significant positive correlation between number of dosages of 1RS and root biomass. However, no correlation was found between root biomass and grain yield per plant. Drought in the field experiment reduced grain yield significantly. Under well‐watered field conditions, grain yield of R₂A (215.9 g plant^?1) was significantly greater than those of R₂D (191.8 g plant^?1) and R₄AD (161.7 g plant^?1). Also, grain yield of R₄AD was significantly less than those of F₁, Pavon 76 and R₂D under well‐watered conditions. Under drought field conditions, no significant differences were found among the genotypes for grain yield was found between F₁ (14.7 g plant^?1) and R₄AD (12.4 g plant^?1). Harvest index was significantly greater in well‐watered (44.2 %) than in drought (34.6 %) field conditions. On average, genotypes F₁ (42.3 %) and R₂A (40.6 %) had higher harvest index than R₂D (38.3 %) and R₄AD (35.5 %) in the field. Also, Pavon 76 (40.2) and R₂D (38.3) had higher harvest index than R₄AD. Drought tolerance was lowest for R₄AD due to its relatively lower grain yield potential. In general, Pavon 1RS.1AL carrying two dosages of 1RS showed higher grain yield under wet treatments. Pavon 1RS.1AL‐1RS.1DL carrying four dosages of 1RS produced the largest shoot and root biomasses, but the least grain yield.     

Determination and Analysis of Heavy Metal Content in the Soil from Beef Cattle Farms in Three Regions of Xinjiang

In order to study and evaluate the feeding environment of the beef cattle farms in Xinjiang, the contents of heavy mentals in the soil from 8 beef cattle farms in Xinjiang Aksu, Yili and Tacheng regions were tested according to the Field of Livestock and Poultry Environment Quality Standard (NY/T 388—1999).The atomic absorption spectroscopic method was used to determine the contents of As, Hg, Pb, Cd, and Cr.The mean contents of As, Hg, Pb, Cd, and Cr in 8 beef cattle farms soil were 0.389, 0.568, 22.708, 0.573 and 149.449 mg/kg, respectively, and they were all below the upper limit of NY/T 388—1999.The comprehensive heavy metal pollution index of 8 beef cattle farms were 0.577 to 0.994, and the index were 0.7 to 1 of two observation points in Yili and one observation point in Tacheng.The soil environment quality of these 3 farms were at the level of slight cleaning.The comprehensive heavy metal pollution index of other five observation points were ≤0.7, the soil environment was in a clean level.The soil environment of beef cattle farms in these three regions conformed to the standards of livestock for environment quality and safe products.     

Response of labile organic C and N pools to plastic film removal from semiarid farmland soil

To examine the effects of plastic film removal on grain yield and soil organic matter (SOM), a spring maize (Zea may L.) field experiment was conducted for 5 yr at Changwu Agricultural and Ecological Experimental Station of Northwest China. Compared with traditional plastic film mulching during entire growing stages (FM), plastic film removal at the silking stage (RM) resulted in a 6.3% higher average maize yield. Under the RM treatment, soil organic carbon and total nitrogen significantly increased after the 5‐yr cultivation in the 0‐ to 20‐cm layer. Significant increases in extractable organic C (EOC), KMnO₄‐oxidizable C (KMnO₄‐C) and C management index (CMI) in the 0‐ to 20‐cm layer, and light fraction organic C and EOC in the 20‐ to 40‐cm layer were observed in response to plastic film removal after the 1‐yr treatment; the responses were more significant after 5 yr. Under the RM treatment, significant increases in microbial biomass C, light fraction organic N, extractable organic N, KMnO₄‐C and CMI were also observed after five years in the 20‐ to 40‐cm layer. Moreover, KMnO₄‐C and EOC were much more sensitive than other labile SOM fractions to the application of RM, even after only 1 yr of cultivation. Therefore, compared with mulching for the whole growing season, plastic film removal at the maize silking stage is an effective option for increasing yields and enhancing SOM concentration and soil sustainability in the regions with semiarid monsoon climates that have sufficient rainfall during maize reproductive stages.     

茶叶杜瓜高效立体栽培技术研究初报

茶树在进化过程中形成了喜阴喜湿和喜漫射光、怕强光直射的特性,适度遮阴的条件下,可改变茶园田间小气候,从而提高茶叶产量和品质。本研究茶叶和杜瓜立体栽培,充分利用了土地资源,提高复种指数,增加单位面积产出率。作者认为,一般茶树品种皆可套种,然白化类黄化类茶树品种尤为适应。杜瓜密度以每667m~220~30株为宜,杜瓜藤蔓在棚顶30%~40%左右的遮阴率为佳,将有利于茶树生长提高产量并改善茶叶品质。过密藤蔓造成茶园过度遮阴,茶树冠面阳光不足将影响茶树生长降低茶叶产质量。杜瓜套种使春茶开采期提早2~3天;每667 m~2茶园增收茶叶450元,杜瓜籽增收2700元,净产值增加2100元,比普通茶园增收20%~30%。     

枸骨的药用功效与保健作用

该文系统地综述了枸骨的化学成分和药用价值,并讨论了枸骨资源今后的开发与利用前景。     

线性红利界下带干扰风险模型的破产概率

考虑到保险公司在实际经营中收益所具有的不确定性和分红策略，建立一类具有线性红利界和带随机扰动的双复合Poisson风险模型，利用鞅方法给出模型关于破产概率的一个定理及上界．