棉花冠层叶面积的动态模拟

根据试验资料,在系统分析棉花冠层叶面积时空分布规律的基础上,充分考虑叶面积空间垂直分布的异质性,以生育期内累积的每日相对热效应为预报因子,构建了棉花叶面积垂直分布和叶面积指数的动态模拟模型。利用不同年份不同播期的试验资料对模型进行了验证,累积叶面积指数L（z）的模拟结果与1∶1直线之间的R^2和均方根误差分别为0.969和0.257,叶面积指数LAI的模拟结果与1∶1直线之间的R^2和均方根误差分别为0.936和0.305。结果说明模型具有较好的预测性和实用性。模型的模拟结果可作为冠层结构参数,用于冠层辐射传输模型和光合作用模型。     

变截面板簧轧机电液伺服系统性能分析

设计了变截面板簧轧机电液伺服系统,该系统采用了工控机和PLC组成的两级计算机控制方式。建立了由电液伺服阀、伺服液压缸和轧辊组成的伺服控制系统数学模型。在分析系统的稳态性能和动态性能基础上,采用PID校正方式,进一步增大了系统的剪切频率,缩短了调节时间,降低了稳态误差。结果表明轧机电液伺服系统的稳定性好、控制精度高,达到了设计目的。     

基于MK—SVR模型的小麦叶面积指数遥感反演

提出了运用多核支持向量回归(MK-SVR)算法构建小麦叶面积指数(LAI)遥感监测模型。以2010—2013年试验样点小麦拔节、孕穗、开花3期的实测LAI数据为基础,同步获取我国自主研发的环境减灾卫星HJ-CCD对该研究区域的影像数据,分析了各生育期小麦LAI与8种植被指数间的相关性。以显著相关的植被指数作为输入参数,使用MK-SVR算法构建了每个生育期的小麦LAI反演模型,即MK-SVR-LAI模型。为了评价模型,每期使用单一核支持向量回归(SK-SVR)、偏最小二乘(PLS)回归算法构建了SK-SVR-LAI、PLS-LAI模型。将模型估算LAI值和田间观测LAI值进行比对,以决定系数(R2)和均方根误差(RMSE)为指标评价并比较了模型。结果表明:3个生育期MK-SVR-LAI模型的RMSE值均低于参比模型,拔节期为0.293 1,孕穗期为0.466 8,开花期为0.548 6,且该模型的R2也都最高,拔节期为0.762 4,孕穗期为0.801 8,开花期为0.668 9。     

基于方向一致性特征的小麦条锈病与白粉病识别方法

针对小麦条锈病、白粉病这2种病斑颜色特征相近、形状特征不明显,但在方向分布的一致性上却存在较大差别这一特点,提出了一种方向一致性描述方法。通过不同的方向核与图像卷积得到多个方向图和边缘,对每个方向图依据边缘图进行统计得到图像的方向分布直方图;并计算方向分布直方图的标准差,作为图像方向分布的一致性特征。该方法能够较好地抑制噪声影响,得到的结果符合图像的实际分布情况。利用该方法对小麦病斑进行特征提取,并应用于小麦条锈病与白粉病的病斑识别实验中。实验结果表明,所提出的方向一致性特征使条锈病与白粉病的区别度较大,准确识别率达到99%。     

‘福山包头’大白菜叶柄黑点病发生特点及抗性分析

以‘福山包头’大白菜为试材,利用田间调查、显微观察和叶片离体培养的方法,对‘福山包头’系列大白菜叶柄黑点病的发生特点及抗性进行了研究,以期为改善‘福山包头’大白菜抗病性及新品种选育提供参考依据。结果表明:(1)大白菜叶柄黑点病主要发生于叶柄表皮细胞且起始于细胞周质或细胞壁,该病可发生于大白菜的整个生育期,且进入包心期后发展较快;(2)氮素能诱导叶柄黑点病的发生,且铵态氮较硝态氮诱导效果更明显;(3)氮素浓度与叶柄黑点病的发病程度呈正相关,但氮素并不是影响叶柄黑点病发生的唯一因素;(4)‘福山包头’系列大白菜种质资源中,‘福东2号’‘福山82’对叶柄黑点病的抗性较强,‘福小87-13-13’‘皱福’的抗性较弱。     

卵泡刺激素受体基因作为产仔数候选基因的研究

分析了FSHR基因2个位点（FSHRA、FSHRB）的PCR－SSCP、PCR－RFLPs多态性，利用SAS软件分析了多态性与母猪产仔数间连锁关系。找到了1个影响产仔数的新的变异位点FSHRB，该位点多态性显著地影响猪产仔数性状，即基因型BB的产仔数显著地高于AB、AA基因型。结果显示出该位点具有作为常规选育的辅助选择的有效的分子标记潜力。     

Senescence of Top Three Leaves in Field‐Grown Rice Plants

Abstract

The top three leaves play important roles in biomass production and grain yield of rice (Oryza sativa L.) crop since the three leaves not only assimilate majority of carbon for grain filling during ripening phase, but also provide large proportion of remobilized‐nitrogen (N) for grain development during their senescence. The objectives of this study were to (a) compare senescence of the top three leaves and (b) compare the changes in N, chlorophyll, and ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) contents of the top three leaves after their full expansion in field‐grown rice plants. When the basis of comparison among the top three leaves was plant age in terms of days after transplanting (DAT), senescence generally started earliest in ?3rd leaf, intermediate in ?2nd leaf, and latest in flag leaf. If the basis of comparison among the top three leaves was leaf age in terms of days after full leaf expansion (DAFE), it was not clear which leaf senesced earlier. Senescence rate was generally greatest in flag leaf, intermediate in ?2nd leaf, and smallest in ?3rd leaf. Ribulose‐1,5‐bisphosphate carboxylase/oxygenase content declined earlier, and at a faster rate than N and chlorophyll contents during the senescence of all top three leaves. Correlation analysis indicated a close relationship between N and chlorophyll contents. Ribulose‐1,5‐bisphosphate carboxylase/oxygenase content correlated with N content better than with chlorophyll content. The suitability of N, chlorophyll, and Rubisco contents for quantifying the leaf senescence of field‐grown rice plants is discussed.     

双抗虫基因三倍体毛白杨对舞毒蛾幼虫的抗性研究

用室内群体饲养舞毒蛾幼虫的方法,对15个双抗基因三倍体毛白杨株系进行饲虫试验。结果表明:校正死亡率划分了高抗、中抗、低抗虫植株,舞毒蛾校正死亡率在95以上为高抗株系;40～75为中抗株系,30以下为低抗株系。舞毒蛾的发育历期、蜕皮指数和毒效反映的规律相一致。     

Reflectance-based assessment of spider mite “bio-response” to maize leaves and plant potassium content in different irrigation regimes

It is widely accepted that pest infestations elicit a change in plant physiology, which cause detectable changes in crop leaf reflectance. In this study, we test the hypothesis that crop leaf reflectance may also be used to forecast the risk of pest infestation before they actually occur. We collected reflectance data in 160 spectral bands from 405 to 907 nm from excised leaf pieces from field grown maize plants under 3 irrigation regimes. Leaf material was collected at weekly intervals in two growing seasons. The same leaf pieces were used in choice bioassays with carmine spider mites to assess attractiveness to mites (spider mite “bio-response”) across irrigation regimes. In one growing season, we also obtained nutritional element data (lipid, protein, soluble sugar, starch, lignin, Ca, P, Mg, K, S, and Cl) from whole maize plants. Principal component analysis showed that potassium content (K) was highly negatively correlated with spider mite bio-response. Relative reflectance at 740 nm showed a highly significant and positive trend across spider mite bio-response classes, and that potassium content showed a highly significant and negative trend across the same classes. Thus, we argue that relative reflectance at 740 nm may be used to predict both potassium content and risk of spider mite infestation. Based on extensive reviews, potassium leaf content is known to reduce susceptibility of crops to pests. The results presented provide encouraging support for remotely sensed risk assessment of pest infestations through reflectance-based monitoring of maize leaf attractiveness and highlight that reflectance based monitoring of crop susceptibility may be possible through careful management of macro element crop properties, such as potassium content.     

冬枣锈病发生与叶龄及其解剖结构关系的研究

为探讨冬枣叶龄、叶片解剖结构与锈病侵染和发病程度的关系，对冬枣3种不同叶龄的叶片进行锈病接种试验，并对叶片组织解剖结构进行了测定。结果表明：3种叶龄叶片感病程度由低到高依次为：成熟叶< 长成叶<嫩叶，由此可见，成熟叶对锈病的抵抗力最强；3种叶龄叶解剖性状在角质层厚度、上表皮厚度、下表皮厚度、叶片厚度、栅栏组织厚度、海绵组织厚度、栅海比、叶片结构紧密度、叶片结构疏松度、气孔密度和气孔大小等指标有显著差异，但气孔开张结构性状差异不显著。文章筛选出了与冬枣锈病发生有关的叶片形态结构指标，为合理的控制冬枣锈病和筛选抗锈病冬枣优良单株的提供了理论依据。