Identification and distribution of fungal pathogens associated with seedling blight of rice in the southern United States

Surveys were conducted in the five southern rice-producing states of Arkansas, Louisiana, Mississippi, Missouri and Texas in the United States during the 2018 and 2019 cropping seasons to determine the distribution and pathogenicity of fungal pathogens associated with seedling blight in rice. A total of 349 pathogenic fungal isolates were collected and identified as belonging to four genera: Rhizoctonia solani, Fusarium spp., Sclerotium rolfsii and Marasmius graminum based on morphological characteristics, molecular analysis and Koch's postulates. R. solani (252 out of 349 pathogenic isolates) was the most prevalent fungus isolated from diseased samples. Of the 252 pathogenic R. solani isolates, 245 were further classified as anastomosis group 11 (AG-11) and 7 as AG-4. Isolates of R. solani AG-4 and M. graminum were the most aggressive, with the highest stand loss (63% to 100%) and median disease rating (DR; 5.0), followed by isolates of R. solani AG-11 (stand loss = 4% to 100% and DR = 0.6 to 5.0), Fusarium spp. (stand loss = 26% to 48% and DR = 2.0 to 5.0) and S. rolfsii (stand loss = 33% to 48% and DR = 2.0 to 3.0) in causing seedling blight in rice. R. solani (62% to 83% of total pathogenic isolates) and Fusarium spp. (10% to 24% of total pathogenic isolates) were predominant in all the five states surveyed. S. rolfsii and M. graminum were present only in Louisiana and Texas. The results of this first systematic survey of rice seedling diseases in the southern United States will help develop effective fungicide seed treatment strategies for control of stand loss caused by seedling blight, one of the major factors limiting rice production.     

不同基因型大麦苗期对干旱胁迫的响应及HvPIPs基因表达特征分析

为研究不同基因型大麦苗期对干旱胁迫的响应,挖掘优质抗旱的大麦种质资源,以4份不同基因型大麦(2个高抗品种ZDM5430和ZDM5458,2个干旱敏感型品种7DCADA和IL-12)为材料,利用聚乙二醇(PEG-6000)模拟干旱条件,综合分析不同品种大麦的苗期抗旱性差异;并通过对不同品种根系进行PIPs实时定量分析,研究水通道蛋白AQPs基因与干旱胁迫之间的应答关系。结果表明,持续干旱胁迫会使大麦生长变缓,各处理苗长、根长、叶含水量和根含水量都呈下降趋势,其中,4个品种的大麦叶含水量在干旱胁迫14 d时下降最为显著,与对照相比,其降幅分别为29.14%、52.64%、21.67%和72.15%。干旱胁迫对大麦苗期干物质积累量和根冠比的影响较小,各处理间差异不显著;但持续干旱后,抗旱品种ZDM5430的根冠比呈上升趋势,在胁迫7、14、21 d时较CK分别增加了4.92%、42.86%和21.05%。随着胁迫时间的延长,大麦旗叶叶绿素含量和根系活力也呈下降趋势,其中ZDM5430和ZDM5458较对照组降幅较小,说明抗旱品种的形态指标、叶绿素含量及根系活力受干旱胁迫的影响较小。通过PIP...     

Tissue Culture and Rapid Propagation of Actinidia chinensis

It has been briefly studied and reported that Actinidia chinensis , one of economic woody plants, has been bred with the method of plant tissue culture. Aim at the shortage of traditional plant tissue culture ways which ignored the refinement and transplant of test-tube seedling, it strengthen the study to breeding and management of Actinidia chinensis seedlings before they grow up and become mature seedlings. Through our explore, the transplant survive rate of tissue-culture seedlings attain to about 85%.This study is the improvement to traditional breeding seedling means and it is helpful to the rapid propagation of those economic woody plants.     

Tissue Culture and Rapid Propagation of Echinacea Purpurea

It is a burgeoning application field for the biotechnology that to apply the technique of plant tissue culture breed seedling. The authors study the responses of Echinacea purpurea to different proportion plant growth hormone or auxin through adopting the culture tissue technique on the MS. The integrated seedling of Echinacea purpurea can be cultivated by callus, subculture, differentiation and rhizogenesis. The surviving rate of Echinacea purpurea seedling transplant are improved by appropriate sound stimulation appropriate. Study harvest offers the gist for the large-scale breeding seedling and the officinal resource exploitation of Echinacea purpurea in our country, and avoid some traditional handicap in breeding seedling of Echinacea purpurea, such as the difficult of seed collection, low burgeoning rate, and the disadvantage for large-scale propagation.     

葡萄组培苗瓶外生根技术研究

采用不同种类和浓度的生长素诱导葡萄组培苗瓶外生根，并观察组培苗在不同处理基质、不同的温度、不同的生理年龄条件下生根的效果。通过优化技术参数，建立了葡萄组培苗瓶接生根的技术优化体系，结果表明，用浓度为0.3mg/L的IBA浸蘸处理的插条，在温度为27~29℃的环境条件下在基质珍珠岩上培养，瓶苗茎段的生根率可达85.5 %，移栽后苗木的成活率达98 %，相对于其他方法有了较大的提高。该技术的建立有助于实现葡萄工厂化育苗技术的商业化扩大。     

北方粳稻“植生带”育秧设备定向排种装置的研制

为满足超级稻每穴(2±1)粒种子精量播种的特殊农艺要求,在纸夹定位水稻精密育秧设备研究基础上,研发出一种新型超级稻定向排种装置。初步排种试验表明,该装置可将种箱中杂乱无章的稻种分离出来后,在组合滑道上逐渐沿其长轴方向排列成连续的种子流,为超级稻植生带育秧设备的研制提供理论与实践依据。     

水稻田间育秧精密播种机设计与试验

为提高田间育秧播种机的播种合格率和播种稳定均匀性,设计了一种适用于南方水稻田间育秧的精密播种机。在深入分析螺旋勺轮式播种器的播种原理,以及播种器行走控制系统的基础上,采用正交试验方法,研究了螺旋勺轮的凹槽深度、螺旋升角、播种器行走速度对播种合格率和空穴率的影响规律,得出杂交稻播种合格率和空穴率影响因素的最佳参数组合:凹槽深度h为3 mm、螺旋升角α为81.73°、播种器行走速度v为0.35 m/s。试验表明,采用闭环控制系统后的播种机播种杂交稻2~6粒/格合格率由87.14%提升到93.21%,常规稻3~8粒/格的播种合格率为92.14%,播种性能满足常规稻和杂交稻精密播种育秧的技术要求。     

中国水稻栽植机械的发展

我国水稻生产历史悠久，在世界粮食生产中扮演着非常重要的角色。因此，选择一种适合于我国水稻种植的机械已成为当前及今后水稻生产中的主要问题。为此，阐述了我国水稻栽植机械化所面临的问题；同时，分析了几种水稻栽植技术模式，以对我国水稻栽植机械的发展提供依据和参考。     

穴盘播种控制器中的多任务分析与实现

在穴盘播种控制器的软件系统开发时，通过对穴盘播种控制器中存在的任务进行分析，运用实时系统前后台编程方式，合理使用单片机的中断系统，进行了播种器的控制软件设计。最后对软件性能进行了分析。经实际运行结果表明，该软件系统可以很好地满足播种器的实际工作要求。     

叶用型沙棘育种研究--“蒙×中”沙棘F1代雄株变异特性与选优标准的研究

通过对蒙古沙棘亚种优良品种与中国沙棘亚种优良类型F1代雄株的变异特性分析,建立了选择优 良单株的标准,为叶用型沙棘选择育种提供了科学依据。