Micropropagation of Cryptanthus with leaf explants with attached intercalary meristems excised from greenhouse stock plants

By using the leaves with attached intercalary meristems from greenhouse grown stock plants, five cultivars of Cryptanthus were cultured on modified MS media with 4.5 μM NAA and IBA and 3 μM BA to induce adventitious shoot formation from callus tissue. Contamination was 17–21% for explants taken from stock plants which were sprayed weekly with Agribrom and 27–75% for those taken from stock plants which were not treated. More than 99% true to type plantlets were obtained from non-chimeric plants. Green and albino plantlets were obtained from chimeric plants. The chimeric C. ‘Coster's Favorite’ DeCoster also produced a few chimeric plantlets with intermarginal pink stripes in addition to the green and albino plantlets. Most of the non-chimeric plants took a shorter time to produce plantlets of transplantable size (8–12 mm) than the chimeric ones. Except for albino plantlets, survival rate of plantlets exceeded 95%. A minimum average of 500 rooted plantlets can be obtained in a year from a single well-callused leaf explant. The protocol in this report should speed up the mass production and introduction of desirable new cultivars and hybrids of non-chimeric Cryptanthus.     

家蚕微粒子病血清学检验技术的研究 Ⅲ—N.b碳素凝集反应用于原种母蛾检微

对700个母蛾用N.b碳素凝集反应法进行检微,碳检检出率为95.45%,对检的镜检检出率为22.72%.碳、镜检检出率的比值是4.2倍(即碳检有微数>镜检有微数);碳检发生的阳性反应样品,再用显微镜复检有微吻合率达100%,准确性大,误判率为零.检出微孢灵敏度高,最高N.b浓度是7.5×10~6个/ml,最低N.b浓度是2.5×10~3个/ml,可视为碳检700个母蛾批的检微浓度范围,以上数据证实用N.b致敏碳素检查母蛾微孢是可行的.     

草粮轮作与农田生态平衡——兼论 Ladino 白三叶的生态经济效益

利用无性繁殖法定植Ｌａｄｉｎｏ白三叶（Ｔｒｉｆｏｉｕｍｒｅｐｅｎｓ）和雅安逸生白三叶（Ｔ．ｒｅｐｅｎｓ），地上部生物量前者比后者表现出极显著差异；地下部生物量和贮氮量表现为显著差异。后作玉米产量，Ｌａｄｉｎｏ白三叶地为６．２９ｔ／ｈａ大于雅安逸生白三叶地（６．１５ｔ／ｈａ）；农田生态系统里前者表现为正氮平衡，后者表现为负氮平衡，前者土壤固相、液相和气相比为１∶０．５∶０．２５明显优于后者；前者Ｃ／Ｎ比适中，后者Ｃ／Ｎ过窄，其抗性雅安逸生白三叶低于Ｌａｄｉｎｏ白三叶。三种种子直播的豆科牧草的生态经济特性表现为南苜蓿（Ｍｅｄｉｃａｇｏｈｉｓｐｅｄａ）大于苕子（Ｖｉｃｉａｃｏｒａｃｃａ），紫云英（Ａｓｔｒａｇａｌｕｓｓｉｎｉｃｕｓ）则介于两者之间。草粮轮作周期证明，Ｌａｄｉｎｏ白三叶和南苜蓿以及苕子是无性繁殖和有性繁殖的最佳材料，值得广泛推广利用。     

桑树芽条枯萎病病原研究 I.病原分离及致病性测定

笔者对陕西省安康地区桑园春季发生的一种梢条和嫩芽枯萎病害的病原作了初步研究,从感病材料各典型病部分离得到桑Ⅰ号菌和桑Ⅱ号菌,经LOPAT部分项目测定及常规致病性测定,究明桑Ⅰ号菌(丁香假单胞杆菌)为该病害主要致病细菌,桑Ⅱ号菌(草生欧氏杆菌)可以引起感染,其症状不如Ⅰ号菌典型,但两菌混合接种有加重病情的现象,故与本病害有密切的关系.     

三种拂子茅种群圆锥花序小穗分布规律的比较

对拂子茅、假苇拂子茅、硬拂子茅３种拂子茅种群圆锥花序小穗的分布格局分析，结果表明，３种拂子茅种群在各节位上的小穗数均适合于Ｗｅｉｂｕｌｌ分布，随着节位序的增加均呈饱和型指数增长，通过赋予各统计参数生物生态学涵义，从宏观上分析与揭示了有关生命现象与发展规律及其生物生态学机理。     

寒区高速公路沥青上面层的空隙率

以长平高速公路试验数据为依据 ,提出了寒冷地区高速公路沥青表层容许空隙率的界限 .     

矮秆小偃麦异附加系31504的遗传分析：Ⅰ鉴定与细胞遗传

本研究利用细胞学和同工酶电泳等方法对小偃麦二体异附加系３１５０４进行了鉴定；并在不同遗传背景下．分析了异附加染色体的传递特点。结果表明，３１５０４为３Ｆ２／７Ｆ２易位的二体异附加系，其单体异染色体通过胚囊和花粉传递的频率平均分别为２８．９％和２０．２％，且与遗传背景无关。     

猪衣原体感染的血清学调查报告

通过对平顶山地区6个县(市)29个猪场的3000头种猪血清进行鹦鹉热衣原体的间接血凝(IHA)抗体的检测。结果显示,血清的阳性率为3.2%～8%,平均为4.8%,猪场的阳性率为65%,该病在本地区较为普遍。     

A seasonal survey of surface water habitats within the River Spey basin,Scotland: major nutrient properties

• 1. Current monitoring strategies of governmental organizations tend to be focused on relatively large flowing and standing waters, and until recently those polluted by point sources. Consequently areas of high conservation interest tend to be understudied, and defining reference conditions, as required by current legislation, is difficult to achieve.
• 2. In order to address this imbalance, water samples have been collected and analysed once in each of four seasons during 2003 from 72 locations within a 100 km² area of the oligotrophic River Spey catchment in NE Scotland. The sampling design included examples of running water (headwater streams and the main rivers) and standing water (lochs, lochans, pools, ditches, backwaters, bogs). Altitude ranged from 220 to 980 m and incorporated a climatic regime from cool temperate to sub‐alpine. Each sampling campaign targeted low‐flow conditions to evaluate steady‐state nutrient concentrations.
• 3. Concentrations of the major soluble nutrients nitrogen and phosphorus demonstrated high spatial and temporal variability, with soluble organic and molybdate unreactive forms generally being dominant. Concentrations of ammonium‐N, nitrate‐N and soluble reactive phosphorus were extremely small, with 50% of samples falling below 8, 5 and 1 µg L^?1, respectively, during spring and summer.
• 4. Sampling sites were grouped either by water‐body type or by the properties of their immediate biophysical zone. Together these two groupings explained 33–38% of the variance in water chemistry. Certain changes were detectable across most habitats and biophysical zones.
• 5. A decline in the concentration of nitrate that occurred in reaches downstream from certain headwater streams draining the mountain areas indicated the potential for its within‐stream utilization. Inorganic N dynamics differed between small streams and large rivers.
• 6. Landscape‐scale patterns were recorded in spring and summer nutrient availability with inorganic N and P thresholds (arbitrarily defined) of 10 and 1 µg L^?1, respectively.

Copyright © 2006 John Wiley & Sons, Ltd.     

"过密化"背景下华北小农的行动逻辑

“过密化”理论是黄宗智评价和分析中国小农经济的理论基点,用来解释中国特定历史时期内“没有发展的增长”的经济现象。“过密化”现象也同样影响着20世纪初华北小农的行动逻辑。从小农的生存境遇出发研究小农的行动逻辑,这也是对国外研究中国小农的三种传统的回应。