Absence of residual effects of a defeated resistance gene in poplar     

K.‐S. Woo  G. Newcombe 《Forest Pathology》2003,33(2):81-89

In a few plant pathosystems, defeated major genes have been shown to contribute to partial resistance to disease. This hypothesis has never been tested before in a forest tree, but pathogenic variation associated with recent hybridization in poplar rust in the Pacific northwest provided an opportunity. An F₂ progeny of 256 poplar clones in the field near Corvallis, Oregon, USA, has been monitored for rust severity and infection type since the advent of the new hybrid rust, Melampsora × columbiana, in the mid‐1990s. All 256 clones displayed a susceptible infection type in 1997 and again in 2000, and yet variation in uredinial density (i.e. partial resistance) was still observed. To determine which clones possessed a defeated resistance gene, a greenhouse inoculation was performed with an isolate of M. medusae, one of the parents of M. × columbiana. Clones that would have been resistant to M. medusae, prior to the advent of M. × columbiana, were thus identified. The inoculation resulted in a 1 : 1 segregation (χ²=0.772; p=0.38) for resistance, indicating the presence of a major gene. However, the F₂ clones possessing the defeated resistance gene displayed the same level of partial resistance in the field in both 1997 and 2000 as their full siblings lacking the gene.  相似文献   

Bursaphelenchus fungivorus (Nematoda: Aphelenchida) associated with Orthotomicus erosus (Coleoptera: Scolitydae) in Spain     

M. Arias  L. Robertson  A. Garcia‐Alvarez  S. C. Arcos  M. Escuer  R. Sanz  J. P. Mansilla 《Forest Pathology》2005,35(5):375-383

A survey of the xylophagous insects in the conifer forests, mainly Pinus pinaster woodlands, in Spain was carried out in order to study the phoretic vectors of nematodes of the genus Bursaphelenchus. Fifteen environmental sites were characterized on the bases of altitude, rainfall, temperature and conifer species. Specimens of Orthotomicus erosus (n = 3476) were captured of which 59% carried nematodes under their elytrous, most of them were aphelenchid fungal‐feeding nematodes, but B. fungivorus was found on the beetles from Las Cumbres, Villa Blanca, (Huelva), southern Spain, which represent the first record of O. erosus as vector of a Bursaphelenchus sp. The nematode is characterized by morphometric and biomolecular techniques and distribution and ecology of the insect is discussed.  相似文献   

广州市公益林生态效益价值分析及管理对策   总被引：11，自引：2，他引：11  

张小红  杨志峰  毛显强  何孟常  鱼京善 《林业科学》2004,40(4):22-26

在对广州市公益林分布和现状特点分析的基础上 ,从林种的生态功能角度对效益进行了分析。结果表明 :广州市水源涵养林生态效益比较高 ,生态效益从大到小排序为 :水源涵养林 >水土保持林 >风景林、自然保护区和小片林 >护岸林 ,从单个效益分析 ,维持大气平衡效益最大。最后提出了公益林管理对策  相似文献   

浅析"无标底"招标的建立     

汤燕群  何惊宇  刘华 《森林工程》2004,20(5):39-40

在“量价分离”改革原则的指导下 ,本文在查阅了中外有关资料的基础上 ,对“无标底”招标的建立谈了几点看法  相似文献   

立地管理措施对2代4年生杉木林生长的影响   总被引：14，自引：1，他引：14  

何宗明  范少辉  陈清山  杨旭  应金花 《林业科学》2003,39(4):54-58

在福建省南平峡阳国有林场开展5种不同立地管理措施对1片29a生第1代杉木人工林采伐后营造的4a生第2代杉木人工林生产力影响的研究。研究结果表明,5种处理的第2代杉木林地位指数与第1代相比均略有下降。BL3BM0(收获树干和树皮、加倍采伐剩余物)处理的4a生2代杉木林生长最好,地位指数仅比1代下降0．67;其次为BL0BM0(收获地上所有有机质)处理,地位指数比1代下降0．85;BL1BM0(清走树木的所有部分)处理杉木生长最差,地位指数下降1．67。炼山处理(BL2BM1)与保留相同数量采伐剩余物而不炼山的处理(BL2BM0)相比,杉木生长没有显著差异。  相似文献   

杉木种子园球果病虫害监测研究   总被引：1，自引：0，他引：1  

徐清乾  何建华  许忠坤 《湖北林业科技》2007,(4):35-38

经调查统计,杉木种子园健康果、发育不良果、病害果、虫害果、病虫兼有果比例分别为55.1%、3.4%、8.4%、9.0%、24.1%,各无性系之间球果产量、不健康果比例,百果重、千粒重、出粒率、发芽率都达到极显著差异水平。球果病虫危害率与球果产量、球果出籽率、种子发芽率之间存在极显著负相关,病虫危害是种子园种子产量下降的主要原因之一。用1%波尔多液或500倍敌克松溶液喷洒种子园接株,效果十分理想,病虫危害可以控制在10.0%以内。  相似文献   

湿地松子代测定中合适家系大小及小区大小的探讨          下载免费PDF全文

赵奋成  李宪政  何礼华  陈孝英 《林业科学研究》1993,6(5):573-578

  相似文献   

传真通信实现方式及其基本组成     

何平  唐百英 《林业科技情报》2005,37(1):48-49

本文以INTERNET网络传真机系统为对象，论述了系统的实现方法，并介绍了实现系统时所用到的一些关键技术。  相似文献   

推广种植乡土树种,发展社区经济     

杨云 《林业调查规划》2003,28(4):104-107

西双版纳有着丰富的乡土植物资源，当地居民有着采集野生林产品及种植四旁树的悠久历史，没有大面积种植乡土树种的习惯。中德技术合作西双版纳热带林保护与恢复项目通过示范和资助开展了乡土树种的育苗和种植活动，取得了一定的成果，并对今后工作提出了建议。  相似文献   

金沙江干热河谷台湾珍珠番石榴引种试种初报     

罗敬萍  段曰汤  何璐  沙毓沧  朱宏业  瞿文林  谭红 《热带农业科技》2005,28(2):16-17,44

台湾珍珠番石榴经在元谋金沙江干热河谷引种试验,表现速生、早结、丰产、抗逆性强,果大质优,供果期长,适应性强。  相似文献