Rapid, Micro-Methods to Estimate Plant Silicon Content by Dilute Hydrofluoric Acid Extraction and Spectrometric Molybdenum Method

By treating 0.5 g DW of a plant sample directly with 10 ml of a dilute hydrofluoric acid solution (HF solution, 1.5 M HF—0.6 M HCl), all the silica in plant (as much as 150 mg SiO₂) was dissolved within 1 h. After dilution of the extract with 40 mL of distilled water, the silica in the extract was measured by the spectrometric molybdenum yellow method. The molybdenum yellow method, in which silica in 0.1 mL of the diluted extract can be determined in 8 min, is well suited to rapid, micro-estimations of the silica content in plants. In the micro-modification, the size of the plant sample was reduced to 100 mg DW. The analytical procedure was simple, and the analytical time was less than 2 h. The method can save much labor and time, compared with the gravimetric analysis. The dissolution with HF solution and the molybdenum yellow method were also applied to the measurement of the content of silica separated by acid digestion of rice plants. Excellent agreement in the silica measurement of rice plants was confirmed among the direct extraction method, the gravimetric method and the digestion-separation-dissolution method. In the molybdenum yellow method, the addition of boric acid enabled to mask the interference of hydrofluoric acid, and the least amount of citric acid required for the elimination of phosphorus interference was proposed. In conclusion in this report, recommended methods for the rapid estimation of the silica content in rice plants were presented.     

离子束生物技术在小麦育种上的应用

阐述了离子束生物技术在小麦育种领域应用情况 ,概括介绍了离子束诱变育种和离子束介导转基因技术的原理及方法 ,对离子束小麦育种过程中涉及的主要技术参数作了详细描述。还介绍了最近发现的离子束诱变小麦遗传新规律和离子束辅助外源裸露大分子DNA转移在小麦育种中的新进展 ,提出了离子束生物技术在育种领域急待解决的问题和应用前景     

浅谈温室油菜蚜虫危害

油菜蚜虫是油菜上一种常发性的害虫,常年发生较重,油菜蚜虫对油菜的危害一是直接取食为害,二是传播病毒病,世代重叠危害,严重影响产量。本文论述了油菜蚜虫的生活习性、危害发生情况、控制虫害发生的原则、防治方法等。并提出了防止油菜蚜虫危害工作的建议。     

Influence of land use in small karst watersheds on the chemical status of peloid sediments on the eastern Adriatic coast

Background, Aim and Scope  

Most of the cathment areas supplying water and mineral matter to the Adriatic bays with healing mud/peloids are affected by various degrees of human impact, i.e. activity that is introducing various types of contaminants to environment. The bays represent shallow marine depositional environments where organic-rich sediments accumulate. Investigations for balneological characterization of several localities along the Croatian coast have shown that these organic-rich sediments may be classified as healing mud, i.e. peloids. Healing mud due to its balneologic features is in treatment of various diseases and in improvement of the overall health conditions and general well-being. Various components of mud, particularly trace elements, could be absorbed through dermal contact. Therefore, the study of the abundance of such potentially toxic elements as As, Pb, Hg, Cd, Se, Sb, Cu, Zn in marine sediments used as healing mud is necessary in order to know their mobility and to avoid possible intoxications.     

The effects of organic amendments on the interactions between a nematophagous fungus Arthrobotrys oligospora and the root-knot nematode Meloidogyne mayaguensis parasitizing tomato plants

The aim of this study was to examine the effects of amendments with leaf biomass on the development of tomato plants in a soil where root-knot nematodes (Meloidogyne mayaguensis) and/or a nematophagous fungus (Arthrobotrys oligospora, strain ORS 18697) had been inoculated. Six origins of leaf biomass were chosen: Acacia mangium, Acacia holosericea, Eucalyptus camaldulensis, Casuarina equisetifolia, Azadirachta indica and Sorghum vulgare. These leaf biomass types inhibited the development of the aerial parts of the tomato plants. This negative effect was not observed when the fungus was inoculated. On the contrary, plant growth was stimulated. Moreover, the antagonistic activity of Arthrobotrys oligospora was strengthened in the presence of ground leaf powder, especially that from Acacia holosericea. The effects of phenolic compounds on fungal growth and predatory activity and on plant growth are discussed.     

Influence of various phosphopeptides of caseins on iron absorption

The influence of the origin and kind of caseinophosphopeptide (CPP) on iron absorption was assessed by comparing a commercially available CPP mixture (CPPs) and derived chromatographic fractions with the purified, chemically phosphopeptide of beta-casein [beta-CN(1-25)] using a perfused rat duodenal loop system; gluconate iron was used as control. Only iron complexed to beta-CN(1-25) displayed a better bioavailability than gluconate iron. The results obtained with various chromatographic fractions indicated that phosphopeptides of different origins (alpha(s)- versus beta-caseins) display specific effects. These findings contribute to the explanation of the discrepancy about the role of caseinophosphopeptides on mineral bioavailability in vivo.     

赤水河上游次生林林窗特征及森林更新

为研究林窗大小对幼苗更新的影响,以赤水河上游次生林中23个林窗为研究对象,分析林窗大小结构、光照强度和土壤化学性质等空间特征及其对森林更新的影响。结果表明：林分内形成的林窗以中小型为主,光照强度为林窗＞林缘＞林内;林窗内光照强度与林窗面积、边缘木平均胸径的相关性不显著,而与边缘木平均高之间具有极显著的指数函数关系,边缘木平均高度越低则林窗内光度值越高;土壤养分上,80－160 m2林窗较高,＜80 m2林窗较低;环境综合指数上,80－160 m2林窗和＞240 m2林窗较高,161－240 m2林窗和＜80 m2林窗较低;植物群落优势种的幼苗在林窗内出现的频度最高。综合来看,80－160 m2的林窗较有利于森林更新,＜80 m2的林窗最不利于森林更新。在森林经营时,根据需要形成合适的林窗能够保持森林的自然更新。     

黄花苜蓿野生种群遗传多样性的初步研究

对来自我国不同地区的黄花苜蓿野生种群的种子千粒重、发芽率及贮藏蛋白进行了初步研究。结果表明，黄花苜蓿野生种群内和种群间均存在着较大的变异，种子千粒重在1.098～2.012g之间，其中二倍体黄花苜蓿种子千粒重最低，仅为1.098g，是四倍体黄花苜蓿种子平均千粒重的62.01%；种子发芽率也十分不整齐，种皮不经磨擦的自然发芽率十分低，从0～40%不等，平均发芽率仅为16.9%，二倍体种子的自然发芽率为0；种子贮藏蛋白SDS凝胶电泳亦显示出其具有多态性，平均多态位点百分比为37.9%，基因多样性为0.3066，种群分化系数为0.2257。     

Microscopic studies of the skin of the Turkish Angora goat. I. Skin layers

The study describes basic structural aspects of the integumental layers (epidermis, dermis, hypodermis) of the Turkish Angora goat. The results have been obtained by light- and electronmicroscopical methods. Central topics are measurements of layer thickness as related to annual season and life period, as well as typical criteria of integumental layer construction as connected with the hair cycle. Remarkable is a trimerous organization of the dermis and cyclic changes in the thickness of the stratum adiposum of the hypodermis. The findings are discussed with regard to comparable observations from other domestic mammals.