Exploring Chenopodium album adaptive traits in response to light and temperature stresses

Weeds within canopies are depleted in photosynthetic photon flux density (PPFD) and red to far‐red light ratio (R/FR) throughout their lifespan. Growth cabinet studies isolated PPFD and R/FR effects and explored the adaptive traits of a model invasive weed, Chenopodium album, to light and temperature. Reproductive development progressed rapidly at high temperature, yet the rate of leaf appearance was insensitive to temperatures of 25:15 and 10:5°C (day:night). Low R/FR effects were detected early in the life cycle, but by seed set, growth was influenced by low PPFD. C. album adapted to the simulated canopy environments by delaying seed set, growing taller and producing more leaf area per mol of accumulated incident PPFD. Low PPFD reduced seed number per plant and the carbon/nitrogen ratio of those seeds, but not seed weight. PPFD was a primary cue for many shade avoidance traits and only under low PPFD did R/FR modify the expression of these traits. This study elucidates the adaptive strategies that make C. album a persistent weed.     

基于AnnAGNPS模型的三峡水库生态屏障区径流与土壤侵蚀的变化

利用调查统计和生态产业化工程建设数据,基于GIS技术和AnnAGNPS模型预测三峡水库生态屏障区7条典型农林小流域4种情景模式下径流和土壤侵蚀的变化。结果表明,与2000年相比,2020年7条流域地表径流量将平均减少40.7 mm,土壤侵蚀量将减少5.41 t·hm^-2;流域径流量与坡度呈显著正相关性(p<0.05),与林地面积比率呈显著负相关性(p<0.05),与农地比率相关性不显著; 土壤侵蚀量与林地面积呈显著负相关性(p<0.05),与农地面积呈显著正相关性(p<0.05),土壤侵蚀量空间变异系数均值为160%,为径流量的4.35倍,土壤侵蚀影响因素的不确定性远多于径流量;三峡水库屏障区实施退耕还林和生态产业化工程建设后,水土保持功能持续增强。利用AnnAGNPS模型输出的方法能较为客观地计量流域尺度径流量和土壤侵蚀量,但该方法所需数据量庞大,可能会限定其他地区的推广。     

烟草黑胫病菌的寄主范围

【目的】探究烟草黑胫病菌（Phytophthora parasitica var. nicotianae）的寄主范围,为烟草黑胫病菌的相关研究提供理论依据,为烟草黑胫病菌所致病害的综合防治提供决策依据。【方法】人工模拟烟草黑胫病菌在田间的侵染途径,采用菌丝块创伤和不创伤接种61种农作物及杂草的活体或离体组织,结合柯赫氏法则鉴定,对烟草黑胫病菌的寄主范围进行较为系统的大样本研究。【结果】烟草黑胫病菌在人工创伤条件下可侵染21科41属51种植物,在不创伤条件下可侵染10科15属16种植物,首次发现烟草黑胫病菌在人工创伤接种条件下可以侵染21科40属47种植物,在人工不创伤接种条件下可以侵染10科12属12种植物。【结论】烟草黑胫病菌在人工模拟条件下的寄主范围较为广泛,其中包括一些常见农作物和烟田常见杂草,当这些植物在有利于病害发生的高温阴雨潮湿气候条件下,在田间农事活动中受到机械创伤或遭受虫伤甚至没有损伤时,烟草黑胫病菌可能会对这些植物造成侵染,生产中应注意避免烟草同潜在寄主作物间作或连作。及时防除烟田杂草对烟草黑胫病菌所致病害的有效治理具有积极意义。     

White spot syndrome virus: an overview on an emergent concern

Viruses are ubiquitous and extremely abundant in the marine environment. One of such marine viruses, the white spot syndrome virus (WSSV), has emerged globally as one of the most prevalent, widespread and lethal for shrimp populations. However, at present there is no treatment available to interfere with the unrestrained occurrence and spread of the disease. The recent progress in molecular biology techniques has made it possible to obtain information on the factors, mechanisms and strategies used by this virus to infect and replicate in susceptible host cells. Yet, further research is still required to fully understand the basic nature of WSSV, its exact life cycle and mode of infection. This information will expand our knowledge and may contribute to developing effective prophylactic or therapeutic measures. This review provides a state-of-the-art overview of the topic, and emphasizes the current progress and future direction for the development of WSSV control strategies.     

Characterization of Passionfruit severe leaf distortion virus,a novel begomovirus infecting passionfruit in Brazil,reveals a close relationship with tomato‐infecting begomoviruses

Molecular and biological characterization of the begomovirus isolate BR:LNS2:Pas:01, obtained from yellow passionfruit plants in Livramento de Nossa Senhora, Bahia state, Brazil, was carried out. Sequence analysis demonstrated that the BR:LNS2:Pas:01 DNA‐A had highest nucleotide sequence identity with Tomato chlorotic mottle virus (77%) and had five ORFs corresponding to the genes cp, rep, trap, ren and ac4. The DNA‐B had highest nucleotide sequence identity with Tomato yellow spot virus (74%) and two ORFs corresponding to the genes mp and nsp. These identity values indicate that this isolate represents a new begomovirus species, for which the name Passionfruit severe leaf distortion virus (PSLDV), is proposed. Phylogenetic analysis clustered the PSLDV DNA‐A and ‐B in a monophyletic branch with Brazilian tomato‐infecting begomoviruses. The isolate’s host range was restricted to species from the Passifloraceae and Solanaceae. PSLDV‐[BR:LNS2:Pas:01] was capable of forming pseudorecombinants with tomato‐infecting begomoviruses, reinforcing its close relationship with these viruses and suggesting a possible common origin. However, the virus was not capable of infecting tomato.     

裸仁美洲南瓜叶枯病病原菌鉴定及其寄主范围和侵染条件

近年来,在甘肃省武威地区裸仁美洲南瓜发生了一种叶枯病,采用常规组织分离法对罹病组织进行了病原菌分离培养,以及病原菌的形态、分离培养性状观察和致病性测定.结果表明,引起裸仁美洲南瓜叶枯病的致病菌为瓜链格孢Alternaria cucumerina(E11.et Ev.)E11iott.寄主范围测定表明,该病原菌可侵染所有供试葫芦科植物,其中南瓜、西葫芦和甜瓜发病最严重;丝瓜和苦瓜发病较轻;该病原菌还可引起白菜和菜豆发病.温度和保湿时间对病原菌的侵染影响较大,25～30℃温度范围内最易侵染,病害潜育期仅为2～3天;当保湿时间60h时,病叶率达到88%,而保湿时间为6h时,病叶率仅为8%.南瓜不同品种对叶枯病的抗性差异较大,其中二星、天然、光板1号、无壳(李建民)和金无壳为高抗品种;四星、粒赛金、金大地、郑峰光板、日本南瓜为高感品种.     

桉树枝瘿姬小蜂国外研究现状

桉树枝瘿姬小蜂Leptocybe invasa Fisher La Salle是近年来新发现的1种有害生物,在多种桉树的叶脉、叶柄及新生枝上形成典型的瘤状虫瘿。该蜂已在世界很多桉树种植区出现并造成危害。文章综述了桉树枝瘿姬小蜂在国外的研究现状,以便更清楚的了解该蜂,为国内的研究提供参考,期望找到合适的防治策略。     

金琥优质高效栽培技术研究初报

对金琥的生长特性进行观察,探讨不同遮荫条件和不同栽培基质对金琥生长的影响。结果表明:(1)随着金琥球龄的增长,其生长速度会逐渐放缓。(2)1 a苗龄的金琥以80%遮光率的全年遮荫球径周年平均生长量比对照提高1.2 cm(P0.01);2 a、3 a球龄夏秋季采取60%遮光率的遮荫球径周年平均生长量分别比对照提高1.2 cm(P0.01)和1.1 cm(P0.01),商品率分别比对照提高24.1个百分点(P0.01)和23.9个百分点(P0.01);4 a、5 a球龄夏秋季采取30%遮光率的遮荫球径周年平均生长量分别比对照降低0.8 cm(P0.01)和0.7 cm(P0.01),商品率比不遮荫的分别降低9.6个百分点(P0.01)和9.7个百分点(P0.01)。(3)种子播种采用煤渣、椰糠和河沙的混合基质(体积比为1∶1∶1)发芽率比对照提高30.4%,小球采用煤渣基质效果较好,烂球率比对照降低8.9个百分点(P0.01),中球煤渣和干猪粪的混合基质(体积比为2∶25)栽培的金琥中球较理想,株高平均月增量、球径平均月增量分别比对照增加0.3 cm(P0.01)、0.4cm(P0.01)。     

4种DGPS模块动态定位精度测试与分析

采用RTK-DGPS为参照,对GARMIN GPS15L、Ublox LEA-4S、Gstar GS-87和Gstar GS-89m-J共4种DGPS模块在单机模式、地面伪距差分模式和卫星差分模式下的动态定位精度进行了测试和分析.结果表明:(1)对于GARMIN GPS15L和Ublox LEA-4S,单机定位精度为米级,使用地面伪距差分定位可分别提高动态定位精度20%和87%;(2)总体上看,DGPS模块的地面伪距差分定位精度优于卫星差分定位,卫星差分定位精度优于单机定位;(3)在视野狭窄地段,无论单机定位、伪距差分定位还是卫星差分定位,动态定位精度都受到一定影响,和视野开阔地段相比,精度明显下降.     

大叶白蜡幼苗生长对不同光强遮荫处理的响应

在不同光照梯度(55.44%自然全光照(natural sunlight,NS)、21.12%NS、3.47%NS和0.86%NS)的人工遮荫条件下,研究了大叶白蜡(Fraxinus rhynchophylla)幼苗的生长特点。结果表明,幼苗株高、基径、主根长、单株叶面积、总干重、相对生长率和净同化率等生长参数均在55.44%NS最大,分别为70.0 cm、6.84 mm、31.95 cm、798.80 cm2、10.28 g、31.13×10-3g.d-1和3.25×10-5g.cm-2.d-1,而且随光照的减弱而减小。幼苗比叶面积随着光照强度的减弱先增大后减小,在3.47%NS处理最大(597.43 cm2.g-1)。