葡萄霜霉病对葡萄生产构成严重威胁,尽早防治是治理霜霉病的关键。为了对该病进行早期检测,以PCR检测获取的霜霉病相对生物量作为霜霉病侵染的依据,从暗适应—光适应—暗弛豫3个光合生理状态连续变化过程中,采集80个人工接种霜霉菌叶片...葡萄霜霉病对葡萄生产构成严重威胁,尽早防治是治理霜霉病的关键。为了对该病进行早期检测,以PCR检测获取的霜霉病相对生物量作为霜霉病侵染的依据,从暗适应—光适应—暗弛豫3个光合生理状态连续变化过程中,采集80个人工接种霜霉菌叶片和80个健康对照叶片连续6 d的叶绿素荧光图像。对比健康和接种叶片叶绿素荧光动力学曲线、参数图像和参数值的差异,使用单因素方差分析评估叶绿素荧光参数对霜霉病侵染的敏感性,筛选叶绿素荧光参数最优特征子集,使用机器学习分类器构建霜霉病早期检测模型。结果表明,随着接种后天数(day post inoculation,DPI)的增加,霜霉病侵染程度不断加深,健康和接种叶片叶绿素荧光动力学曲线、参数图像和参数值从2DPI开始有显著差异(p<0.05),霜霉病侵染导致叶片光化学猝灭速率减小(Rfd变小),光合效率降低(F_(v)/F_(m)变小),叶片活力和光保护能力衰退(NPQ和qN变小),叶片吸收的光能更多以荧光的形式释放出来(F_(t)和F_(m)变大)。基于序列前向浮动算法优选的叶绿素荧光参数特征子集(qN-L3,Rfd-L2,NPQ-L1和F_(v)/F_(m)-D1)和BP神经网络分类器的SFFS-BP模型对3DPI健康和接种叶片识别准确率为83.75%,全实验周期连续6 d平均准确率达到85.94%。可为葡萄霜霉病光合表型分析和早期检测提供一种快速、准确的手段。展开更多
To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.N...To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.Nanographite powder(NGP)has excellent properties,such as high adsorption,conductivity,and lubrication,since it has the characteristics of small size,large specific surface area,and high surface energy.However,previous studies on the improvement of expansive soil with NGP are not processed enough.To study the improvement effect of NGP on expansive soil,non-load swelling ratio tests,consolidation tests,unconfined compressive strength tests,mercury injection tests,and micro-CT tests on expansive soil mixed with different NGP contents were performed.The results show that the non-load swelling ratio,mechanical properties,and porosity of expansive soil show some increasement after adding NGP.The strength of expansive soil reaches the maximum when the NGP content is 1.450%.The cumulative mercury volume and compressive strain of expansive soil reach the maximum with the 2.0%NGP content.Finally,the modification mechanism of swelling,compressibility,microstructure,and compressive strength of expansive soil by NGP is revealed.展开更多
文摘葡萄霜霉病对葡萄生产构成严重威胁,尽早防治是治理霜霉病的关键。为了对该病进行早期检测,以PCR检测获取的霜霉病相对生物量作为霜霉病侵染的依据,从暗适应—光适应—暗弛豫3个光合生理状态连续变化过程中,采集80个人工接种霜霉菌叶片和80个健康对照叶片连续6 d的叶绿素荧光图像。对比健康和接种叶片叶绿素荧光动力学曲线、参数图像和参数值的差异,使用单因素方差分析评估叶绿素荧光参数对霜霉病侵染的敏感性,筛选叶绿素荧光参数最优特征子集,使用机器学习分类器构建霜霉病早期检测模型。结果表明,随着接种后天数(day post inoculation,DPI)的增加,霜霉病侵染程度不断加深,健康和接种叶片叶绿素荧光动力学曲线、参数图像和参数值从2DPI开始有显著差异(p<0.05),霜霉病侵染导致叶片光化学猝灭速率减小(Rfd变小),光合效率降低(F_(v)/F_(m)变小),叶片活力和光保护能力衰退(NPQ和qN变小),叶片吸收的光能更多以荧光的形式释放出来(F_(t)和F_(m)变大)。基于序列前向浮动算法优选的叶绿素荧光参数特征子集(qN-L3,Rfd-L2,NPQ-L1和F_(v)/F_(m)-D1)和BP神经网络分类器的SFFS-BP模型对3DPI健康和接种叶片识别准确率为83.75%,全实验周期连续6 d平均准确率达到85.94%。可为葡萄霜霉病光合表型分析和早期检测提供一种快速、准确的手段。
基金Project(2017TFC1503102)supported by the National Key Research and Development Project,ChinaProjects(51874065,U1903112)supported by the National Natural Science Foundation of China。
文摘To reduce geological disasters caused by expansive soil,it is crucial to use a new type of modified material to rapidly improve soil strength instead of traditional soil improvement materials such as lime and cement.Nanographite powder(NGP)has excellent properties,such as high adsorption,conductivity,and lubrication,since it has the characteristics of small size,large specific surface area,and high surface energy.However,previous studies on the improvement of expansive soil with NGP are not processed enough.To study the improvement effect of NGP on expansive soil,non-load swelling ratio tests,consolidation tests,unconfined compressive strength tests,mercury injection tests,and micro-CT tests on expansive soil mixed with different NGP contents were performed.The results show that the non-load swelling ratio,mechanical properties,and porosity of expansive soil show some increasement after adding NGP.The strength of expansive soil reaches the maximum when the NGP content is 1.450%.The cumulative mercury volume and compressive strain of expansive soil reach the maximum with the 2.0%NGP content.Finally,the modification mechanism of swelling,compressibility,microstructure,and compressive strength of expansive soil by NGP is revealed.
