西安市降尘中粉煤灰的岩石地球化学特征

利用X荧光光谱、化学分析、XRD、激光粒度分析和扫描电镜等方法,对西安不同城市功能区降尘样品中粉煤灰进行分析.结果表明,西安市降尘中粉煤灰颗粒主要为玻璃质物质,具有包裹结构和多孔性特征,降尘中粉煤灰平均含量24.99%,空间分布受电厂排灰控制.降尘中粉煤灰粒度小于10μm,平均粒径仅4.13μm,均属于可吸入颗粒,含有大量亚微米粒子,对人的呼吸系统危害极大.粉煤灰本身重金属含量较降尘低,说明城区的汽车和其它工业污染是更为重要的大气重金属污染源,粉煤灰本身带来的重金属元素在大气粉尘中不占主导地位.     

植物叶片仿生伪装结构模型设计

通过对绿色植物的光谱反射特征及其影响因素的分析和实验验证，首次提出了植物叶片仿生伪装结构的概念和设计模型，并初步验证了其可行性和有效性。实验结果表明，这种全新的伪装结构在紫外、可见光和近红外波段具有与绿色植被非常相似的光谱反射特征，其“同色同谱”效果可望有效对抗高光谱侦察。     

In vitro degradation of willow salicylates

Salicylates are defensive compounds against a great variety of generalist herbivores. Salicortin and its derivatives are labile compounds that degrade immediately when cell compartmentalization is ruptured, producing a 6-hydroxy-2-cyclohexenone (6-HCH) moiety that is a strong antifeeding cue. We studied the In Vitro degradation of willow salicylates in the presence and absence of foliar enzymes at acidic, neutral, and alkaline pHs. Higher substituted salicylates were degraded in the absence of foliar enzymes at alkaline pH and in the presence of foliar enzymes at all three pHs. Salicin and its diglucoside, on the other hand, were degraded only in the presence of foliar enzymes at acidic pH, probably by -glucosidase activity. The main degradation products of higher substituted salicylates were salicin, 6-HCH, and catechol in both the absence and presence of enzymes, suggesting that the production of 6-HCH and catechol do not necessarily demand enzymatic activity. We propose that the degradation of salicylates begins with the cleavage of a 1-hydroxy-6-oxo-2-cyclohexen-1-carbonyl moiety by foliar esterases and/or alkaline condition. This moiety is decarboxylated in nonenzymatic reaction to an anion of 2-hydroxy-3-cyclohexenone, which is tautomerized to the enol form and further to the keto form, 6-HCH. Hydroxyketone can be also oxidized to catechol, a substrate of polyphenol oxidases.     

叶面尘土量对大叶黄杨叶片图像的影响

采用典型的城市绿化树种大叶黄杨叶片图像为研究对象,用1种将均值偏移与边缘置信度相结合的聚类算法对大叶黄杨叶片图像进行分割,建立线性模型和对数模型对图像信息与叶面尘土量进行拟合,分析叶面尘土量对叶片图像RGB（红、绿、蓝）三分量和HSI（色调、饱和度、亮度）等参量的影响。结果表明：采用均值偏移与边缘置信度相结合的聚类算法能够有效分割出大叶黄杨叶片图像;以色调H为自变量的对数模型可较好地拟合叶面尘土量与叶片图像参数间的关系,在一定范围内,随着叶面尘土量的增加,叶片图像H参数值减小。研究结果可为树木图像校正及叶面尘土对叶片反射光谱的影响等研究提供参考。     

Strategies to reduce gaseous emissions of nitrogen from irrigated agriculture

Fertilizer nitrogen (N) is not used efficiently in irrigation agriculture because much of the N applied is lost from the plant-soil system by emission of gaseous compounds to the atmosphere. Nitrogen may be emitted by ammonia volatilization, and as nitrous oxide, nitric oxide and dinitrogen during nitrification, biological denitrification and chemodenitrification. Nitrogen emitted to the atmosphere as ammonia may be returned to the biosphere and recycled thus adding to the nitrous oxide and nitric oxide burden in the atmosphere. Thus ammonia volatilization needs to be controlled as well as nitrification-denitrification to limit emission of nitrogen oxides. Many approaches have been suggested for controlling losses of fertilizer N including optimal use of fertilizer form, rate and method of application, matching N supply with demand, supplying fertilizer in the irrigation water, applying fertilizer to the plant rather than the soil, and use of slow-release fertilizers. While these techniques have the potential to increase the effectiveness of the applied N none of them have a large impact on gaseous loss of N. However, the results of recent experiments in tropical and temperate regions with flooded rice, and irrigated cotton, wheat and maize show that use of newly developed urease and nitrification inhibitors has the capacity to prevent loss of N and increase the yield of crops.     

Post-establishment phosphatic fertilizer treatments in a New South WalesPinus radiata plantation

A five-year-oldPinus radiata plantation treated with a spot application of phosphatic fertilizer (13.5 g P per tree)(23 kg P ha^–1) at planting was given various additional booster treatments: two levels of superphosphate (48 and 72 kg P ha^–1) and one level each of basic superphosphate (61 kg P ha^–1) and monoammonium phosphate (70 kg P ha^–1, 35 kg P ha^–1) all broadcast applied. All fertilizer treatments resulted in significant increases in timber volume production which were not significantly different from each other. The stands which had received no additional treatment produced 108 m³ ha^–1 merchantable timber at age 17 years while the treated plots produced between 188 and 201 m³ ha^–1. The best financial gains were from the higher rate of superphosphate. The experiment is discussed in relation to foliar analysis and routine management practice.     

Soil and crop management technologies for enhancing rice production under micronutrient constraints

Micronutrient deficiency is considered as one of the major causes of the declining productivity trends observed in ricegrowing countries. The submergence created for rice cultivation influences electrochemical and biochemical reactions, and alters pH, pCO2 and the concentration of certain ions. This environment increases the availability of Fe and Mn with concomitant decrease in Zn and Cu. It is well known that Zn deficiency is predominant in lowland ecosystems. Sodic and upland soils and calcareous coarse-textured soils with low organic matter content suffer from Fe deficiency, besides Zn and Cu deficiencies. Rice cultivars do not experience deficiency of B and Mo. The acid soils and the lowlying, poorly drained alluvial and colluvial soils are prone to Fe toxicity. Experiments in different agroecological zones all over India showed that Zn doses to correct Zn deficiency varied from 2.5 to 22 kg ha-1; 5.3 kg Zn ha-1 proved optimum and economical, with a maximum rice yield increase of 4.8 t ha-1. In the lowland ecosystem, amending the soil with the required amount of Zn before transplanting was effective and easy to adopt, compared with repeated foliar sprays of 0.5% ZnSO4 or use of Zn-enriched seedlings through seed soaking in 2–4% ZnSO4 solution, fertilizing the nursery with Zn, or seedling root dipping in 2% ZnO slurry. Hepta as well as monohydrated ZnSO4 were better than other sources of Zn (ZnO, ZnCl2 and Zn frits). The Zn-blended diammonium phosphate (Zn-DAP), superphosphate, and nitrophosphates also proved effective. The Zn-enriched organic manures (farmyard manure, green leaf manure, and coir pith compost) were found advantageous for the direct and residual crops. Zinc fertilization with an optimal dose of 25 kg ZnSO4 ha-1 once a year yielded high economic return. A differential response of rice up to a maximum increase in yield of 4.8 t ha-1 was observed with the foliar spray (1–2% FeSO4 solution) or soil incorporation of Fe (50 kg FeSO4 ha-1) with bulky organic manure (12.5 t ha-1). The application of 12.5 kg CuSO4 ha-1 ameliorated Cu deficiency and significantly enhanced rice production. Management strategies such as liming and additional multinutrient supply (P. K, Mg, Zn, Cu, and B), besides improving drainage, enhanced the rice productivity of soils prone to Fe toxicity by correcting the multinutrient deficiency syndrome.     

Comparative foliar anatomical and pollen morphological studies of Acanthaceae using light microscope and scanning electron microscope for effective microteaching in community

In this study, foliar anatomy and pollen morphology of 10 species of Acanthaceae has been investigated using light and scanning electron microscopy. The study was aimed to highlight the role of microscopy in microteaching at community for proper characterization of plants using palyno‐anatomical characters including pollen type, exine sculpturing, shape of epidermal cells, pattern of anticlinal wall, type and size of stomata, and trichome. Most of the species have polygonal cell shapes but some species have irregular, tetragonal, and pentagonal shape of epidermal cells. The largest epidermal cell length on adaxial and abaxial surface were observed in Asystasia gangetica 66.95 and 87.40 μm whereas least was observed on adaxial surface in Justicia adhatoda 36.9 μm and on abaxial surface in Barleria cristata 35.65 μm. In anatomy, species have diacytic type of stomata, whereas stomata of paracytic type observed in two species, while in A. gangetica cyclocytic type of stomata are present. Quantitively on abaxial surface, largest stomata length 29.9 μm and width 24.30 μm was noted in B. cristata. While shortest stomata length was observed in Ruellia prostrata 25.95 μm whereas minimum width of stomata was examined in Barleria acanthoides 2.05 μm. The diversity of trichomes are present in all species except in Ruellia brittoniana. Acanthaceae can be characterized by exhibiting different pollen morphology having five types of pollen shapes, prolate, spheroidal, perprolate, subprolate, and oblate spheroidal. Exine peculiarities showing variations such as reticulate, granulate, coarsely reticulate, lophoreticulate, perforate tectate, and granulate surface were examined.     

降低爆破烟尘的降尘剂配方的实验研究

针对爆破烟尘的成分,采用了多种基料和表面活性剂来降低烟尘中的粉尘成分,同时还采用了相应的添加剂来降低爆破时所产生的有毒有害气体的含量。以润湿高度和表面张力为实验指标,运用对比实验的方法确定最佳基料和表面活性剂,并且研究添加剂对其性能的影响。实验结果表明：氯化钠为最佳基料,十二烷基苯磺酸钠为最佳表面活性剂,作为添加剂的硫酸铜和氯化铵对表面活性剂和基料的性能几乎没有影响。因此,爆破时在水袋中添加此降尘剂会有效地降低烟尘浓度。     

RNAi as a Foliar Spray: Efficiency and Challenges to Field Applications

RNA interference (RNAi) is a powerful tool that is being increasingly utilized for crop protection against viruses, fungal pathogens, and insect pests. The non-transgenic approach of spray-induced gene silencing (SIGS), which relies on spray application of double-stranded RNA (dsRNA) to induce RNAi, has come to prominence due to its safety and environmental benefits in addition to its wide host range and high target specificity. However, along with promising results in recent studies, several factors limiting SIGS RNAi efficiency have been recognized in insects and plants. While sprayed dsRNA on the plant surface can produce a robust RNAi response in some chewing insects, plant uptake and systemic movement of dsRNA is required for delivery to many other target organisms. For example, pests such as sucking insects require the presence of dsRNA in vascular tissues, while many fungal pathogens are predominately located in internal plant tissues. Investigating the mechanisms by which sprayed dsRNA enters and moves through plant tissues and understanding the barriers that may hinder this process are essential for developing efficient ways to deliver dsRNA into plant systems. In this review, we assess current knowledge of the plant foliar and cellular uptake of dsRNA molecules. We will also identify major barriers to uptake, including leaf morphological features as well as environmental factors, and address methods to overcome these barriers.