Effects of Latent Infection of Stock Plants and Abundance of Thrips on the Occurrence of <Emphasis Type="Italic">Tomato spotted wilt virus </Emphasis>in Chrysanthemum Fields

DAS-ELISA proved to be reliable enough to detect a latent infection by Tomato spotted wilt virus (TSWV) in asymptomatic stock plants of chrysanthemum. A high density of Frankliniella occidentalis, the predominant vector, in the presence of latently infected stock plants resulted in a high incidence of disease in the chrysanthemum production field. The incidence of disease was low when the vector thrips were not abundant in spite of the presence of latently infected stock plants. These results suggest that an infestation of the vector thrips causes severe secondary spread of TSWV originating from latently infected stock plants in chrysanthemum production fields. Received 27 July 2001/ Accepted in revised form 27 November 2001     

库布齐沙漠穿沙公路沙害综合防治技术

库布齐穿沙公路修建在库布齐沙漠高大的流动沙丘区 ,风沙流侵袭与沙丘整体前移埋压公路是主要沙害形式。现有防沙措施是沙障保护下的人工植被及天然植被相结合的综合防护体系 ,固沙及阻沙效益明显。目前要解决的是尽快形成公路两侧稳定的植被群落 ,以保证公路的长期畅通     

优质茄子新品种引茄1号的选育

引茄 1号为杂种一代 ,植株生长势旺盛 ,果实细长、紫红色 ,果面光滑 ,果肉细嫩 ,平均单果质量 6 0～70kg ,抗青枯病和绵疫病 ,产量 30 0 0～ 4 0 0 0kg·(6 6 7m2 ) -1,适于我国喜食长茄地区的保护地和露地栽培。     

Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

Study of Resistance to Orobanche ramosa in Host (Oilseed Rape and Carrot) and Non-host (Maize) Plants

Orobanche ramosa is a parasitic Angiosperm responsible for severe yield losses in several economical crops. It is a serious threat in oilseed rape in France and Morocco and is appearing in carrot crops in Morocco. In this study, several varieties of oilseed rape and carrot were screened in order to identify resistant cultivars and to characterize the resistance mechanisms involved. All the 15 oilseed rape varieties tested were susceptible. In carrot, the varieties 'Colmar à coeur rouge' and 'Nantaise demi-longue' were susceptible, whereas 'Palaiseau' and 'Buror' were resistant. In the susceptible 'Colmar à coeur rouge' carrot no defence reactions were found and the development of the parasite inhibited carrot tap root formation. In the resistant carrot varieties, the parasite germinated, became attached to the host root but became necrotic before emergence. In 'Buror' carrot, formation of a mechanical barrier was associated with the restriction to the cortex of the parasite. In maize cv. 'Vigni', a non-host of O. ramosa, thickening of xylem vessels, cell divisions in the central cylinder and formation of an encapsulation layer were observed in association with restricted development of Orobanche haustoria.     

蜗牛液对不同果蔬病原菌的抑制及其细胞的溶解

蜗牛(Bradybaena kiangsinensis Martens)是我国的特有种群,它的腺体中含有多种生物活性物质。由于蜗牛在农业生产中具有一定的危害性,而忽视了其在生防中的作用。为探索蜗牛用于生防的可能性,作者对蜗牛提取液的抑菌和溶菌效果进行了研究。 1 材料与方法蜗牛液采用活体提取法,以无菌水作提取介质,用量为蜗牛量的30％,常温下浸提1h,然后过滤备用,以无菌水作提取液对照。抑菌试验采用含毒介质法,即取9ml PDA培     

广东省丝绸行业竞争力研究成果宣讲贯彻工作会议纪要

由广东省经济贸易委员会主办，广东省丝绸集团公司和广东省蚕学会协办的广东省丝绸行业竞争力研究成果宣讲贯彻工作会议于2004年6月3日至4日在佛山市顺德区召开，广东省丝绸集团公司蔡高声董事长、柯惠琪总经理、广东省蚕学会姚宏中理事长等全省丝绸行业158位代表出席了会议。国家茧丝办王北鹰主任、中国丝绸协会弋辉会长，杨永元、樊迅副会长莅临大会并在会上分别作了相关报告。会议由广东省经济贸易委员会工业处陈茜薇副处长主持。现将有关领导同志的报告内容纪要如下：     

Functional heterogeneity in resources within landscapes and herbivore population dynamics

Large mammalian herbivores are notorious for their propensity towards population irruptions and crashes, yet many herbivore populations remain relatively stable. I explore how resource heterogeneity within landscapes dampens population instability, using a metaphysiological modelling approach considering patch state distributions. Resource heterogeneity is functionally stabilizing through spreading consumption away from preferred resources before these become critically depleted. Lower-quality resources act as a buffer against starvation during critical periods of the seasonal cycle. Enriching resource quality is destabilizing, even if patch diversity is maintained, because food quantity then becomes the limitation. The potential consequences of landscape fragmentation are explored using the Serengeti ecosystem, characterised by broadscale resource gradients, as a hypothetical example. Further insights provided by the model are illustrated with specific examples concerning the effects of patch scales and waterpoint distribution. A metaphysiological modelling approach enables the basic consequences of landscape heterogeneity to be distinguished from further effects that may arise from specific patch scales and configurations, without the distracting detail of spatially explicit models.