桂西北高海拔地区光皮桦造林技术

广西隆林县地处高海拔地区,光皮桦(Betula luminifera)的次生林面积最大.高海拔山地营建光皮桦人工林,宜采集当地海拔1 200～1 400 m的优良林分种子育苗,使用容器苗造林,杉木采伐迹地,更适合光皮桦生长,造林密度2 500株/hm2.     

初烤烟叶中烟碱和新植二烯的提取工艺研究

为探究云南烟油的成分以及烟碱和新植二烯的提取工艺,本试验以云南典型初烤烟叶为原料,通过超临界CO2萃取、超声辅助萃取、索式回流萃取和溶剂萃取4种方法提取初烤烟叶中烟碱和新植二烯,采用气相色谱-质谱(GC-MS)分析萃取物组成,比较不同萃取方法和萃取溶剂下,烟叶萃取物得率及所得萃取物中烟碱和新植二烯的相对含量.结果 表明...     

植物生长调节剂配施对大菊观赏性状的影响

以对光周期敏感的14个观赏大菊[Dendranthema morifolium(Ramat.)Tzvelev]为试材,研究了不同浓度丁酰肼和不同喷施时间对大菊观赏性状的影响.结果表明,不同浓度的丁酰肼对同一品种株高影响较大,同一浓度丁酰肼对生根快、中、慢三类型的大菊品种株高影响较小.每7d处理的2个浓度丁酰肼,处理浓度...     

药剂防治香菇绿色木霉对比试验

绿色木霉（Ｔｒｉｃｈｏｄｅｒｍａ ｖｉｒｉｄｅ）是代料香菇栽培中危害最大的竞争杂菌。为了探寻高效、经济、安全的防治药物,笔者进行了不同药物防治绿色木霉对比试验。现将试验方法与结果介绍如下：１材料与方法１．１供认材料　①香菇２４１－４（庆元县食用菌所）;②药剂：４５％扑霉灵乳油（以色列Ｍ．Ａ农化公司）,５０％多菌灵可湿性粉（江阴农药厂）,硫酸铜（市售）。１．２试验方法　出菇间隙喷施①扑霉灵２０００倍液２次（间隔７天）;②扑霉灵１５００倍液１次;③扑霉灵２０００倍液１次;④多菌灵８００倍液１次;⑤硫…     

果大质优的白沙枇把新品种—冠玉

随着人民生活水平的提高,枇杷的选育工作趋向于果大质优的方向发展。生产上栽培的白沙枇杷品种品质虽佳,但果形偏小,仅２５～３５ｇ左右,难与果形大的红沙枇杷品种相匹敌。自１９８３年开始,本中心章鹤寿高级农艺师在白沙枇杷自然实生变异中选育出了果形大、品质优、可食率高的白沙枇杷新品种──冠玉。１选育经过 冠王枇杷是在１９８３年冬进行枇杷资源调查时发现,为白沙枇把自然实生变异的大果型优良单株,树龄约 １５～ ２０年,株行距 ３．５ｍ × ４ｍ不等,不规则种植。经多年高接观察,在太湖洞庭东山、西山及武进等地试验结果…     

果园生草兔耕栽培的关键技术

四川省特别是川南地区的冬干春旱严重,夏季多大雨和暴雨,对果树萌芽抽梢、开花结果、果实生长发育和品质产生较大的影响;大雨和暴雨对土壤冲刷严重而引起大量的水土流失,降低土壤肥力,严重时引发土台垮塌。生产上为防止果园土壤干旱和大雨、暴雨对土壤的冲刷,多采用农作物稿秆、塑料薄膜等材料对树盘、定植带或全园土壤进行覆盖,不仅增加大量的投入,而且薄膜覆盖还会造成“白色污染”。利用果树根系与某些草种根系在土层中分布深度不同而不易造成肥水争夺,以及草根死亡腐烂后形成的小孔道可增加土壤孔穴的特性,在果园林间十壤上蓄…     

梨干枯病的发生及防治技术

梨干枯病又名胴枯病,主要为害中国梨和日本梨,是梨树枝干的重要病害之一,在我国大部分梨区均有发生。经我们调查,近2年在我县的儒侣村、西武山、百江等梨园新发现的梨干枯病,有加重之趋势,梨树被害率达5％～10％,重者达20％左右,病树轻则造成树势衰弱,重则造成死枝或整株死亡,给我县的梨树生产造成了极大的损失。 1 为害症状 据1997～1998年观察,该病在我县梨园主要发生在3～4年生的幼树上,黄花梨比新世纪梨受害重。发病初期,枝干上并不表现出明显症状,只是抽梢较迟、无力,叶片明显比正常叶小,且有萎     

鱼类诺达病毒及其所导致的疾病

In recent years, piscine nodaviruses have emerged as major pathogens of a wide range of larval and juvenile marine finfish resulting in high mortality in aquaculture worldwide. Affected fish exhibit a range of neurological signs, such as erratic swimming behaviour with the associated microscopic lesions of necrosis and vacuolation of the central nervous tissues and retina. Numerous roundshaped, unenveloped and 25-30 nm in diameter virus particles were found in the cytoplasm of affected retinal and nerve cells. Nodaviruses have a bipartite genome of positivesense RNA,with RNA1 encoding the RNAdependent RNA polymerase and RNA2 encoding the capsid protein. Both RNA are capped, but not polyadenylated. The family Nodaviridae comprises two genera: Alphanodavirus and Betanodavirus, members of which primarily infect insects and fish, respectively. Therefore, betanodavirus is also named piscine nodavirus. At present, piscine nodaviruses are divided into four genotypes based on partial sequences of the coat protein gene. ELISA and RT-PCR amplification have been developed as specific diagnostic methods for the d etection of the virus. Antibodies to striped jack (Pseudocaranx dentex) nervous necrosis (SJNNV) were found in 65% of plasma samples collected from wild and domestic brood stocks of striped jack, suggesting that the virus is very prevalent. Viral antigens were detected in eggs, larvae, and ovaries of hatcheryreared and wild spawner fish, suggesting both horizontal and vertical modes of transmission of the virus. Selection of nodavirusfree spawners using ELISA for detection of antigens and RT-PCR techniques have successfully reduced incidences of the virus infections in juvenile sea bass (Dicentrarchus labrax),striped jack and barfin flounder (Verasper moseri). The SSN1 and GF cell lines have been successfully used in isolating piscinenodaviruses.Although there are many papers describing the molecular characteristics of betanodavirus, our knowledge of the genomic attributes of these viruses is still limited. Vaccination studies are being undertaken by a number of researchers and need to be fostered. In particular, the use of passive immunization of broodfish with homologous and heterologous, high titre antisera are worthy of investigation.     

浏河水芹浅水栽培技术

水芹采用浅水栽培技术,每667 m²产量可达4 200 kg,每667 m²产值达14 000元,且该技术操作简单、实用性强。为促进水芹浅水栽培技术的进一步推广应用,现从品种选择、整田、育苗排种、水肥管理、病虫害综合防治、采收等环节,对水芹浅水栽培技术要点进行总结介绍,以供种植户参考借鉴。