淮北地区小麦主栽品种对低温胁迫的响应及抗寒性评价

为给安徽淮北地区小麦安全生产提供指导,以当地主栽品种为材料,研究不同播期条件下小麦植株对低温胁迫的响应,结合自然低温下田间冻害情况及产量表现等,对主栽品种的抗寒性进行初步评价。结果表明,返青期-12℃以下时品种的抗寒性急剧下降;播期间小麦植株的抗寒性表现为：晚播>适播>早播;电解质渗出率均随温度的降低逐渐增大;地域间抗寒性差异明显;不同区域育成品种抗寒性强弱表现为山东省＞河南省＞安徽省;筛选出一批抗寒高产品种,如‘良星66’、‘山农20’、‘济麦22’、‘烟农19’等,可作为安徽淮北地区早播条件下种植的理想品种。     

铁路沿线沙生植物种子风传扩散的数值风洞模拟

为了研究铁路沿线沙生植物种子风传扩散机制所体现出的生态适应策略,本文以辽西北铁路沿线沙区段5种蒿属植物为研究对象,借助流体动力学方程和计算机图形学技术,采用数值风洞方法,模拟预测了在不同风速及释放高度条件下各物种种子扩散时间和扩散距离的变化趋势。软件模拟结果表明,（1）在释放高度和风速条件相同的情况下,5种蒿属植物种子的飞行时间和飞行距离与种子重量表现出相反的趋势,即随着种子重量的增大,其水平飞行时间和飞行距离减短。（2）在释放高度相同风速条件不同的情况下,5种蒿属植物种子的飞行时间和飞行距离与风速表现出相同的趋势,即种子的飞行时间和飞行距离随着风速的增大而增加。（3）在风速条件相同释放高度不同的情况下,5种蒿属植物种子的飞行时间和飞行距离与释放高度表现出相同的趋势,即种子的飞行时间和飞行距离随着释放高度的增加而增加。种子重量、风速及释放高度是影响种子扩散时间和扩散距离的敏感因素,在铁路沿线沙化地区筛选适宜的植物防沙措施进行生态修复的同时应结合考虑这些影响因素。     

Evaluation of the Low-Temperature Tolerance of Cotton Varieties in the Huang-Huai Region during Seed Germination

[Objective] To provide a theoretical foundation and germplasm resources for low-temperature-germination cotton breeding, the germination characteristics of 38 cotton varieties novel to or formerly widely planted in the Huang-Huai Region were evaluated under different low temperature stress conditions. [Method] Analysis of variance, the fuzzy membership function method, and cluster analysis were used to comprehensively evaluate the tolerance of these varieties to low temperature stress. [Result] As the temperature was lowered, germination rate, germination index, and vigor index exhibited a decreasing trend in all cotton varieties, but resistance to low temperature was significantly different among varieties. Cluster analysis divided the 38 varieties into three categories: highly resistant, resistant, and non-resistant. [Conclusion] Early-introduced varieties and those bred from early-introduced germplasm resources had weaker resistance to low temperature stress, with Stoneville and Deltapine series showing the lowest tolerance. The new transgenic insect-resistant cotton varieties SCRC 37 and SCRC 36 had the strongest resistance to low temperature stress.     

Effects of Exogenous 24-epibrassinolide on Photosynthetic Physiology of CottonSeedlings under Low Temperature

[Objective] The objective of this study was to investigate the effects of exogenous 24-epibrassinolide (EBR) on the photosynthetic physiology of cotton seedlings under low temperature and to provide basis for improving the cold tolerance of cotton by using EBR as growth regulator. [Method] Taking CCRI 60, Lumianyan 28 and Simian 3 as materials, a field experiment was carried out in Institute of Cotton Research of CAAS(Anyang county, Henan province). Before the first low temperature treatment, the cotton seedlings were sprayed with distilled water (Control) and different concentrations of EBR (0.1 mg·L^－1 and 0.2 mg·L^－1), respectively. After 3 days, the relative electrical conductivity, chlorophyll content, rapid chlorophyll fluorescence induction kinetic curve (OJIP) and fluorescence parameters were measured. [Result] Under low temperature, the relative conductivity of CCRI 60, Lumianyan 28 and Simian 3 spraying with EBR decreased by 17.7%～32.8% compared with control, and there was no significant difference between CCRI 60 and Lumianyan 28 in different concentrations of EBR treatments, butthe relative conductivity of Simian 3 treating with 0.2 mg·L^－1 EBR was significantly lower than those treatments with 0.1 mg·L^－1 EBR . The chl a and chl b contents increased by 9.7%～32.6% and 15.0%～18.9%, respectively. The maximum photochemical efficiency of photosystemⅡ (F_v/F_M) and photosynthetic performance index on absorption basis(PI_ABS) increased significantly. PI_ABS of CCRI 60 increase the maximum by 75.6% using 0.1 mg·L^－1 EBR. Lumianyan 28 and Simian 3 increased the maximum by 101.1% and 265.6% using 0.2 mg·L^－1 EBR, respectively; Absorbed photon flux per cross section (ABS/CSm), electron transport flux (further than QA) per active reactive center (ETo/RC) and probability for electron transport (φEo) are significantly increased. [Conclusion] Exogenous EBR can enhance the ability of low temperature tolerance of cotton seedlings and alleviate the inhibition of photosynthesis in cotton at low temperature. The study showed that 0.1 mg·L^－1 EBR performs well in CCRI 60 and 0.2 mg·L^－1 in Lumianyan 28 and Simian 3.     

A highly sensitive,non‐invasive qPCR‐based strategy for direct quantification of Yersinia ruckeri in fish faeces

Finfish with asymptomatic Yersinia ruckeri infections pose a major risk as they can transmit the pathogen and cause clinical outbreaks in stock populations. Current tools have insufficient quantitative ability for accurately detecting the trace levels of Y. ruckeri typically associated with asymptomatic infection, necessitate invasive or lethal sampling, or require long processing times. This study presents a highly sensitive qPCR‐based method, targeting part of the Y. ruckeri 16S rRNA sequence, that is capable of detecting extremely low levels of Y. ruckeri in noninvasively collected faecal samples. Quantitative precision and accuracy of faecal sample analysis was consistent, despite the complexity of the faecal matrix. The assay demonstrated linearity over a six log‐wide dynamic range. Its limit of detection (LOD) and limit of quantification (LOQ) were 4 and 10 copies of the target sequence, respectively. Sensitivity of the assay was comparable to other qPCR‐based methods without requiring invasive or lethal sampling. Applicability as a screening strategy was tested using passively collected faecal samples. Asymptomatic Y. ruckeri infection was detected in all samples, although none of the fish exhibited overt infection. This method will be beneficial for finfish disease management if developed further as a noninvasive, screening tool against asymptomatic Y. ruckeri infection.     

基于酶技术生产低黏度及超低黏度褐藻胶的工艺

为解决当前低黏度及超低黏度褐藻胶生产工艺中存在的不足,本实验以海带为原料,利用褐藻胶裂解酶降解制备低黏度及超低黏度褐藻胶,研究了分子量、p H、温度对黏度的影响,确定了碱消化的最佳条件,探究了酶解工艺中加酶量、酶解时间及原料的初始黏度对褐藻胶产品的影响。结果显示,通过控制加酶量(100~500 U/g),酶解30 min即可得到低黏度及超低黏度褐藻胶,其中加酶量为100~330 U/g时可得到低黏度褐藻胶,加酶量增加至330~500 U/g时,可得到超低黏度褐藻胶,且酶解法得到的褐藻胶样品分子量均一度高,工艺节水率高达10%~50%;同时研究发现酶解样品黏度与原料初始黏度相关性不大,只在较短时间内表现出相关性,该工艺具有较高的原料适用性。     

燕麦幼苗对干旱-低温交叉适应的生理响应及其综合评价

为探讨干旱能否诱导燕麦对低温的交叉适应性,采用20%聚乙二醇6000(PEG)模拟干旱预处理定莜6号幼苗3 d,以未经PEG预处理的幼苗作对照,恢复2 d后进行低温(昼/夜温度8℃/5℃)处理,分别在低温处理的0、1、3、5、7天采取幼苗叶片,测定超氧阴离子(O_2~-)、过氧化氢(H_2O_2)、丙二醛(MDA)、抗坏血酸(ASA)、谷胱甘肽(GSH)、可溶性糖(SS)、可溶性蛋白质(SP)、游离氨基酸(AA)和脯氨酸(Pro)含量及相对含水量(RWC)和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性等14项生理指标及处理7d后植株株高增量和生物量增量,采用主成分分析和隶属函数综合评价燕麦幼苗对干旱-低温的交叉适应能力。结果表明,与对照相比,干旱预处理显著提高了低温胁迫下燕麦幼苗株高增量和生物量增量,O_2~-和H_2O_2等14项生理指标值也发生了不同程度改变。对14项生理指标值离差标准化后进行相关性分析表明,不同变量间存在显著相关性。进行主成分分析提取了5个主成分因子,其方差贡献率依次为38.881%、18.219%、11.238%、9.616%和8.809%,累积方差贡献率达86.763%。第1主成分因子对SS、AA、Pro、O_2~-、H_2O_2、RWC、SOD和APX有较大载荷;第2主成分因子对POD、MDA和GSH有较大载荷;第3主成分因子主要包括CAT和GSH;第4主成分因子主要包括SP和Pro;第5主成分因子主要包括APX和ASA。隶属函数分析5个主成分因子得分值显示,除第1天外,干旱预处理在整个低温处理期间的综合评价值显著高于对照。研究表明干旱能够诱导燕麦对低温的交叉适应性。     

伞裙追寄蝇滞育诱导的温光周期条件和低温贮藏

伞裙追寄蝇是草地螟的优势寄生天敌,是对草地螟进行防控的有效手段之一。为了提高天敌防控效果,本试验在室内条件下通过温度和光周期的设定,研究了伞裙追寄蝇的外源滞育诱导条件和低温储藏。结果表明,17℃下光照时间小于12 h,伞裙追寄蝇滞育率为100%,随着温度的升高,滞育率逐渐下降,29℃时,伞裙追寄蝇不发生滞育;不同温度（4～25℃）储藏后伞裙追寄蝇羽化性比为1.38～1.63（P>0.05）;16℃时伞裙追寄蝇滞育诱导临界光周期为12.53 h,18℃时临界光周期为11.12 h;越冬虫茧低温储藏后羽化率随着储藏时间的延长而下降。结果说明,温度对伞裙追寄蝇滞育起主导作用,在伞裙追寄蝇幼虫期施以低温处理,可以有效的诱导滞育,4℃低温贮藏最佳时间为50 d。     

Highly specific assays to detect isolates of Pseudomonas syringae pv. actinidiae biovar 3 and Pseudomonas syringae pv. actinidifoliorum directly from plant material

Pseudomonas syringae pv. actinidiae (Psa) is responsible for bacterial canker of kiwifruit. Biovar 3 of Psa (Psa3) has been causing widespread damage to yellow‐ and green‐fleshed kiwifruit (Actinidia spp.) cultivars in all the major kiwifruit‐producing countries in the world. In some areas, including New Zealand, P. syringae pv. actinidifoliorum (Pfm), another bacterial pathogen of kiwifruit, was initially classified as a low virulence biovar of Psa. Ability to rapidly distinguish between these pathovars is vital to the management of bacterial canker. Whole genome sequencing (WGS) data were used to develop PCR assays to specifically detect Psa3 and Pfm from field‐collected material without the need to culture bacteria. Genomic data from 36 strains of Psa, Pfm or related isolates enabled identification of areas of genomic variation suitable for primer design. The developed assays were tested on 147 non‐target bacterial species including strains likely to be found in kiwifruit orchards. A number of assays did not proceed because although they were able to discriminate between the different Psa biovars and Pfm, they also produced amplicons from other unrelated bacteria. This could have resulted in false positives from environmental samples, and demonstrates the care that is required when applying assays devised for pure cultures to field‐collected samples. The strategy described here for developing assays for distinguishing strains of closely related pathogens could be applied to other diseases with characteristics similar to Psa.