Temperature-dependent resistance to crown rust infection in perennial ryegrass, Lolium perenne

Differences were found in the expression of resistance of perennial ryegrass, Lolium perenne, cultivars to crown rust, Puccinia coronata Corda, when plants were incubated at either 10°C or 25°C. In an extreme example, all the genotypes of ‘Carrick’ were resistant at 10°C but susceptible at 25°C. The variation between cultivars was due both to a general increase in expression of susceptibility and the proportion of plants which became susceptible. A BC₁ line containing a stay‐green gene derived from Festuca pratensis was insensitive to temperature, while a sister line was sensitive.     

河南省小麦茎基腐病调查及优势病原分析

小麦茎基腐病(CR)是近年我国普遍发生的病害之一。为进一步明确河南省小麦CR的发生情况及优势病原种类,2019年对河南省11个小麦主产区的96个生产点进行了调查,并对采自田间典型症状植株上的病害开展了病原菌分离、形态鉴定、rDNA-ITS分子鉴定及致病力分析。结果表明,除驻马店地区轻微发病外,其他10个地区均发病较重,田块发病率平均达78.85%,病情指数、病株率和白穗率分别平均为17.87、48.35% 和3.44%;被调查的小麦品种均不同程度感病,发病较轻的品种占30%、发病较重的占20%、中度感病的占50%;不同地块之间发病程度存在较大差异,土壤肥沃、水分充足、管理精细的地块发病较轻,干旱、盐碱地、肥力不足及管理粗放的地块发病较重;目前,河南省小麦主产区CR主要病原菌为假禾谷镰刀菌(Fusarium pseudograminearum),根据其形态分为6种类型,其中第 Ⅰ 和 Ⅱ 类病原菌分离频率高且分别在8个和6个地区均有分布,致病力分别为42.22和77.78。根据调查结果,建议河南省重视小麦CR防治工作,并加快开展CR致病、小麦抗病机理研究及抗病新品种的选育。     

以现代林业理论指导林业跨越式发展

林业跨越式发展是我国建设现代林业的重要途径,现代林业是跨越式发展战略的目标。以现代林业理论指导我国林业跨越式发展是我国林业健康发展的根本要求。因此,我们要深刻领会现代林业理论的内涵,以可持续林业理论为指导,从林业的多目标经营入手,采取多种经营方式,依靠科学技术进步,动员全社会力量,实现林业的跨越式发展。     

三维扫描技术在获取杨树树冠结构特征参数上的应用

【目的】树冠结构影响光能截获能力从而直接影响生物量的积累。杨树冠形特征参数的研究能够为杨树优良品种的选育提供有力的选择依据，但是因为杨树的树型高达，树冠结构复杂，树冠结构特征参数难以直接观测。【方法】建立了利用三维扫描技术获取树冠结构特征参数的方法，并测量了高密度(2 m ×3 m)人工林中6年生杨树03-04-171的冠形特征参数，包括不同生长单元早发枝和同期枝一级枝的枝长、分枝角度、方位角、枝条曲率及弯曲度。对直接测量(砍伐)与三维扫描方法测量的胸径、树高进行回归分析，检测三维扫描测量的精度。【结果】回归分析结果表明：胸径的回归系数分别为 R2=0.96772，显著值为 P =8.26×10－13，树高回归系数为 R2=0.96527，显著值为 P=1.44029×10－12。结果说明三维扫描方法具有较高的测量精度，可以应用于树冠结构特征的测量。扫描参数结果显示，树冠上每一个生长单元的上部枝条长度较长，分枝角度较小，曲率较大，数量少，为早发枝；中下部枝条数量多，短而平直，为同期枝，这与已有的研究结果一致。【结论】三维扫描技术可以应用于树冠结构特征的研究。     

Mapping water,oxygen, and pH dynamics in the rhizosphere of young maize roots

Rhizosphere processes are highly dynamic in time and space and strongly depend on each other. Key factors influencing pH changes in the rhizosphere are root exudation, respiration, and nutrient supply, which are influenced by soil water content levels. In this study, we measured the real‐time distribution of soil water, pH changes, and oxygen distribution in the rhizosphere of young maize plants using a recently developed imaging approach. Neutron radiography was used to capture the root system and soil water distribution, while fluorescence imaging was employed to map soil pH and soil oxygen changes. Germinated seeds of maize (Zea mays L.) were planted in glass rhizotrons equipped with pH and oxygen‐sensitive sensor foils. After 20 d, the rhizotrons were wetted from the bottom and time‐lapsed images via fluorescence and neutron imaging were taken during the subsequent day and night cycles for 5 d. We found higher water content and stronger acidification in the first 0.5 mm from the root surface compared to the bulk soil, which could be a consequence of root exudation. While lateral roots only slightly acidified their rhizosphere, crown roots induced stronger acidification of up to 1 pH unit. We observed changing oxygen patterns at different soil moisture conditions and increasing towards lateral as well as crown roots while extending laterally with ongoing water logging. Our work indicates that plants alter the rhizosphere pH and oxygen also depending on root type, which may indirectly arise also from differences in age and water content changes. The results presented here were possible only by combining different imaging techniques to examine profiles at the root‐soil interface in a comprehensive way during wetting and drying.     

基于LiDAR点云能量信息的樟子松郁闭度反演方法

为提高小光斑激光雷达估测针叶林郁闭度的精度,采用回归分析法建立多变量回归模型,通过对小光斑激光 雷达点云数据进行处理,分别提取3 个数量比值变量、3 个能量比值变量,并建立郁闭度单变量反演模型,接着在单 变量的基础上进行多元线性回归分析,建立郁闭度多变量反演模型,最后用剩余数据对所建立的反演模型进行精 度评价。结果表明:在郁闭度单变量反演模型中I2反演模型最好, 拟合相关性为R2 =0.818, Adj R2 =0.810, RMSE = 0.016,模型精度为P =0.978;多变量反演模型中LPI' 和I'3 组合的模型最好, 拟合相关性为R2 = 0.898, AdjR2= 0.889, RMSE =0.012,模型精度为P =0.972。由最终所得模型可知,能量比值变量模型所得结果相对数量比值变 量模型结果要好且稳定,多变量反演模型的拟合相关性及精度都比单变量模型要高。本研究所提取的参数相对较 少,且能量比值变量的提取有一定的局限性,未来研究中应提取更多的高效参数且进一步加强能量比值变量的探究。      

东北山樱桃对根癌病的抗性评价

以两年生实生苗新梢为试材,采用人工接种根癌土壤杆菌与发根土壤杆菌(浓度比为1∶1)混合液的方法,研究了东北山樱桃对根癌病的抗性。结果表明:接种后70d,接种根癌菌的东北山樱桃根部最大病瘤直径为10.24mm,病情指数为29.0,根据抗性评价标准判定东北山樱桃群体对根癌病中度抗病;其实生群体内存在显著的株间分离现象,有免疫、高度抗病、中度抗病、低度抗病、感病和易感病6种类型,分别占群体总数的18.0%、40.0%、28.0%、8.0%、5.0%和1.0%。东北山樱桃是优异的抗根癌病种质资源。     

基于改进爬峰法高分辨率遥感影像分割的树冠提取

对现有爬峰法利用高分辨率遥感影像分割进行树冠提取时存在的问题进行直方图压缩和基于类的二次合并两方面的改进,并将改进后的爬峰法在Matlab平台上模拟实现。以Quick Bird影像为基础数据源提取单木树冠,分析树冠面积提取精度,验证改进爬峰法对高分遥感影像树冠分割的可靠性。研究结果表明:实验样本精度均达到85%以上,与传统目视解译精度比较相差较少,满足应用需求。     

山桃对根癌病的抗性评价

为探明山桃(Prunus davidiana(Carr.)Franch.)的抗根癌病种质资源价值,采用人工接种的方法评价了实生山桃苗对发根土壤杆菌(Agrobacterium rhizogenes Conn)和根癌土壤杆菌(A.tumefaciens Conn)的抗性。结果表明:接种后70d,接种发根土壤杆菌的山桃株最大瘤茎为0~20.3mm,病情指数为59,根据抗性评价标准判定为低度抗病类型;接种根癌土壤杆菌的山桃株最大瘤茎为0~5.3mm,病情指数为15,根据抗性评价标准判定为高度抗病类型;实生山桃群体对根癌菌的抗性存在广泛的株间分离现象,其对发根土壤杆菌的抗性分离为免疫、高度抗病、中度抗病、低度抗病、感病和易感病6种类型,分别占群体总数的20.8%、5.0%、12.5%、11.7%、20.0%和30.0%;对根癌土壤杆菌的抗性分离为免疫、高度抗病、中度抗病和低度抗病4种类型,分别占群体总数的35.0%、55.8%、8.4%和0.8%。山桃实生群体存在大量对发根土壤杆菌和根癌土壤杆菌免疫型单株,是优异的抗根癌病桃树砧木种质资源树种。     

冠醚化合物为载体的PVC膜新型铝离子选择电极研究

研究了基于氮杂冠醚为中性载体的阳离子选择性电极,该电极在pH为3．0的硝酸缓冲介质中对铝离子有近能斯特响应,其线性范围为8．0×10^-5～1．0×10^-1mol／L,检测限为4．0×10^-5mol／L,斜率为20．0mV／dec．响应时间为20．0S．该电极用于EDTA的电位滴定,结果令人满意．