American sloughgrass(Beckmannia syzigachne(Steud.) Fernald) is one of the most competitive and malignant weeds in rice-wheat rotation fields in China. American sloughgrass populations in the Jiangsu Province of China ...American sloughgrass(Beckmannia syzigachne(Steud.) Fernald) is one of the most competitive and malignant weeds in rice-wheat rotation fields in China. American sloughgrass populations in the Jiangsu Province of China became less sensitive to acetohydroxyacid synthase(AHAS) inhibitors after repeated application for many years in these areas. Two suspected resistant American sloughgrass populations(R1 and R2) collected in the field were detected the resistance to inhibitors of AHAS in whole-plant dose-response assays, compared to the susceptible(S) population. These assays indicated that R1 showed low resistance to mesosulfuron-methyl(3.32-fold), imazapic(2.84-fold) and pyroxsulam(1.55-fold), moderate resistance to flazasulfuron(4.67-fold) and pyribenzoxim(7.41-fold), and high resistance to flucarbazone(11.73-fold). However, using a combination of the cytochrome P450 inhibitor, malathion, with mesosulfuron-methyl resulted in a reduction in R1 resistance relative to mesosulfuron-methyl alone. Furthermore, R2 was highly resistant to flazasulfuron(34.90-fold), imazapic(11.30-fold), flucarbazone(49.20-fold), pyribenzoxim(12.94-fold), moderately resistant to mesosulfuron-methyl(9.77-fold) and pyroxsulam(6.26-fold), and malathion had no effect on R2 resistance to mesosulfuron-methyl. The fulllength of AHAS genes was sequenced and the AHAS enzymes were assayed in vitro in order to clarify the mechanism of resistance to AHAS inhibitors in R1 and R2 populations. The results demonstrated that R2 had a Pro-197-Ser mutation in the AHAS gene, and the sensitivity of R2 to the five AHAS inhibitors was decreased, which may result in R2 resistance to AHAS inhibitors. There was no mutation in the AHAS gene of R1, and there were no significant differences in enzyme sensitivity between susceptible(S) and resistant(R1) populations. An enhanced metabolism may be the main mechanism of R1 resistance to AHAS inhibitors.展开更多
为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指...为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。展开更多
基金financed by the National Natural Science Foundation of China(31371952)the Special Fund for Agro-scientific Research in the Public Interest of China(201303031)
文摘American sloughgrass(Beckmannia syzigachne(Steud.) Fernald) is one of the most competitive and malignant weeds in rice-wheat rotation fields in China. American sloughgrass populations in the Jiangsu Province of China became less sensitive to acetohydroxyacid synthase(AHAS) inhibitors after repeated application for many years in these areas. Two suspected resistant American sloughgrass populations(R1 and R2) collected in the field were detected the resistance to inhibitors of AHAS in whole-plant dose-response assays, compared to the susceptible(S) population. These assays indicated that R1 showed low resistance to mesosulfuron-methyl(3.32-fold), imazapic(2.84-fold) and pyroxsulam(1.55-fold), moderate resistance to flazasulfuron(4.67-fold) and pyribenzoxim(7.41-fold), and high resistance to flucarbazone(11.73-fold). However, using a combination of the cytochrome P450 inhibitor, malathion, with mesosulfuron-methyl resulted in a reduction in R1 resistance relative to mesosulfuron-methyl alone. Furthermore, R2 was highly resistant to flazasulfuron(34.90-fold), imazapic(11.30-fold), flucarbazone(49.20-fold), pyribenzoxim(12.94-fold), moderately resistant to mesosulfuron-methyl(9.77-fold) and pyroxsulam(6.26-fold), and malathion had no effect on R2 resistance to mesosulfuron-methyl. The fulllength of AHAS genes was sequenced and the AHAS enzymes were assayed in vitro in order to clarify the mechanism of resistance to AHAS inhibitors in R1 and R2 populations. The results demonstrated that R2 had a Pro-197-Ser mutation in the AHAS gene, and the sensitivity of R2 to the five AHAS inhibitors was decreased, which may result in R2 resistance to AHAS inhibitors. There was no mutation in the AHAS gene of R1, and there were no significant differences in enzyme sensitivity between susceptible(S) and resistant(R1) populations. An enhanced metabolism may be the main mechanism of R1 resistance to AHAS inhibitors.
文摘为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。
