黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的...黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的方法在同一田块模拟无紧实胁迫(NC:no compaction stress,容重1.0~1.3 g cm^(-3))、中度紧实胁迫(MC:moderate compaction stress,容重1.4~1.5 g cm^(-3))和重度紧实胁迫(HC:heavy compaction stress,容重>1.6 g cm^(-3))3个紧实程度处理,定量解析不同程度土壤紧实胁迫下不同品种玉米根冠生长各指标及产量的变化规律。结果表明,与NC相比,MC和HC处理导致玉米减产3.8%~10.3%和12.5%~33.3%。玉米根冠生长及产量形成对土壤紧实胁迫的响应存在基因型差异。MC处理下,DK517的根长、根干重及根冠比较ZD958和DH605分别提高6.0%和14.0%、15.7%和29.6%、18.8%和24.8%,但最大叶面积指数、植株总干物重和产量无显著差异;HC处理下,DK517的根长和根干重较ZD958和DH605分别提高8.4%和22.5%、29.6%和57.8%,且最大叶面积指数、植株总干物重和根冠比分别提高4.6%和15.5%、3.7%和20.9%、28.0%和32.1%,因此产量分别增加7.5%和27.2%。相关分析表明,土壤容重和贯穿阻力与玉米根冠生长各指标和产量呈显著负相关关系(P<0.01)。综上所述,土壤紧实胁迫会显著抑制玉米根系和地上部生长而造成减产,但不同品种玉米根冠生长对不同程度土壤紧实胁迫的响应存在着差异,重度土壤紧实胁迫下根冠生长均具有优势的品种能够维持较高的产量,研究结果可为玉米品种改良和土壤紧实下耕作措施优化提供理论依据。展开更多
Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective stra...Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective strategy for promoting sustainable agriculture in this region.Using twenty maize cultivars,plant dry matter production,N absorption and accumulation,yield formation,and NUE in summer maize were investigated under three N levels in two growing seasons.Based on their yield and yield components,these maize cultivars were categorized into four groups including efficient-efficient(EE)cultivars,high-nitrogen efficient(HNE)cultivars,low-nitrogen efficient(LNE)cultivars and nonefficient-nonefficient(NN)cultivars.In both two seasons,the EE cultivars improved grain yield together with increased plant biomass,and enhanced accumulative amounts as well as higher average grain yields than the other cultivar groups under deficient-N conditions.Significant correlations were observed between yield and kernel numbers(KN),dry matter(DM)amount and N accumulation at both post-silking and maturity stages.DM and N accumulation at late growth stage(i.e.,from silking to maturity)contributed largely to the enhanced yield capacity and improved NUE under N-deficient conditions.Compared with the NN cultivars,the EE cultivars also showed increased N assimilation amount(NAA)and N remobilization content(NRC),and elevated N remobilization efficiency(NRE),NUE and nitrogen partial factor productivity(PFPN).Our investigation has revealed N-associated physiological processes and may provide guidance for cultivation and breeding of high yield and NUE summer maize under limited N conditions in the NCP.展开更多
Double-maize cropping system is an effective option for coping with climate change in the North China Plain. However, the effects of changes in climate on the growth and yield of maize in the two seasons are poorly un...Double-maize cropping system is an effective option for coping with climate change in the North China Plain. However, the effects of changes in climate on the growth and yield of maize in the two seasons are poorly understood. Forty-six cultivars of maize with different requirements for growing degree days (GDD), categorized as high (H), medium (M) or low (L), and three cultivar combinations for two seasons as LH (using JD27 and DMY1 from category L in the first season;and YD629 and XD22 from category H in the second season), MM (using JX1 and LC3 from category M in the first season;and ZD958 and JX1 from category M in the second season) and HL (using CD30 and QY9 from category H in the first season;and XK10 and DMY3 from category L in the second season) were tested to examine the eco-physiological determinants of maize yield from 2015 to 2017. The correlations between the combinations of cultivars and grain yield were examined. The combination LH produced the highest annual grain yield and total biomass, regardless of the year. It was followed, in decreasing order, by MM and HL. Higher grain yield and biomass in LH were mainly due to the greater grain yield and biomass in the second season, which were influenced mainly by the lengths of the pre- and post-silking periods and the rate of plant growth (PGR). Temperature was the primary factor that influenced dry matter accumulation. In the first season, low temperatures during pre-silking decreased both the duration and PGR in LH, whereas high temperatures during post-silking decreased the PGR in MM and HL, resulting in no significant differences in biomass being observed among the three combinations. In the second season, high temperatures decreased both the PGR and pre- and post-silking duration in MM and HL, and consequently, the biomass of those two combinations were lower than that in LH. Moreover, because of lower GDD and radiation in the first season and higher grain yield in the second season, production efficiency of temperature and radiation (Ra) was the highest in LH. More importantly, differences in temperature and radiation in the two seasons significantly affected the rate and duration of growth in maize, and thereby affecting both dry matter and grain yield. Our study indicated that the combination of LH is the best for optimizing the double-maize system under changing climatic conditions in the North China Plain.展开更多
Inappropriate tillage practices and nitrogen(N) management have become seriously limitations for maize(Zea mays L.) yield and N use efficiency(NUE) in the North China Plain(NCP). In the current study, we examined the ...Inappropriate tillage practices and nitrogen(N) management have become seriously limitations for maize(Zea mays L.) yield and N use efficiency(NUE) in the North China Plain(NCP). In the current study, we examined the effects of strip deep rotary tillage(ST) combined with controlled-release(CR) urea on maize yield and NUE, and determined the physiological factors involved in yield formation and N accumulation during a 2-year field experiment. Compared with conventional rotary tillage(RT) and no-tillage(NT), ST increased the soil water content and soil mineral N content(Nmin) in the 20–40 cm soil layer due to reduction by 10.5 and 13.7% in the soil bulk density in the 0–40 cm soil layer, respectively. Compared with the values obtained by common urea(CU) fertilization, CR increased the Nmin in the 0–40 cm soil layers by 12.4 and 10.3% at the silking and maturity stages, respectively. As a result, root length and total N accumulation were enhanced under ST and CR urea, which promoted greater leaf area and dry matter(particularly at post-silking), eventually increasing the1 000-kernel weight of maize. Thus, ST increased the maize yield by 8.3 and 11.0% compared with RT and NT, respectively, whereas CR urea increased maize yield by 8.9% above the values obtained under CU. Because of greater grain yield and N accumulation, ST combined with CR urea improved the NUE substantially. These results show that ST coupled with CR urea is an effective practice to further increase maize yield and NUE by improving soil properties and N supply, so it should be considered for sustainable maize production in the NCP(and other similar areas worldwide).展开更多
文摘黄淮海地区农业集约化和机械化发展导致土壤紧实问题日益加重,限制玉米产量的进一步提升。明确不同品种玉米根系和地上部生长对土壤紧实胁迫的差异性响应特征,可为该区玉米高产栽培提供理论依据。本研究选用3个玉米品种,采用机械碾压的方法在同一田块模拟无紧实胁迫(NC:no compaction stress,容重1.0~1.3 g cm^(-3))、中度紧实胁迫(MC:moderate compaction stress,容重1.4~1.5 g cm^(-3))和重度紧实胁迫(HC:heavy compaction stress,容重>1.6 g cm^(-3))3个紧实程度处理,定量解析不同程度土壤紧实胁迫下不同品种玉米根冠生长各指标及产量的变化规律。结果表明,与NC相比,MC和HC处理导致玉米减产3.8%~10.3%和12.5%~33.3%。玉米根冠生长及产量形成对土壤紧实胁迫的响应存在基因型差异。MC处理下,DK517的根长、根干重及根冠比较ZD958和DH605分别提高6.0%和14.0%、15.7%和29.6%、18.8%和24.8%,但最大叶面积指数、植株总干物重和产量无显著差异;HC处理下,DK517的根长和根干重较ZD958和DH605分别提高8.4%和22.5%、29.6%和57.8%,且最大叶面积指数、植株总干物重和根冠比分别提高4.6%和15.5%、3.7%和20.9%、28.0%和32.1%,因此产量分别增加7.5%和27.2%。相关分析表明,土壤容重和贯穿阻力与玉米根冠生长各指标和产量呈显著负相关关系(P<0.01)。综上所述,土壤紧实胁迫会显著抑制玉米根系和地上部生长而造成减产,但不同品种玉米根冠生长对不同程度土壤紧实胁迫的响应存在着差异,重度土壤紧实胁迫下根冠生长均具有优势的品种能够维持较高的产量,研究结果可为玉米品种改良和土壤紧实下耕作措施优化提供理论依据。
文摘目的探讨总结新型冠状病毒(coronavirus disease-19,COVID-19)肺炎疫情时期急性缺血性卒中(acute ischemic stroke,AIS)的急诊取栓治疗经验。方法回顾性分析2020年1月20日-3月20日疫情期间,首都医科大学附属北京天坛医院神经介入中心进行急诊取栓治疗的AIS病例资料,包括患者的一般资料、NIHSS评分、ASPECTS评分(DWI)、病变部位、手术策略、恢复情况,以及COVID-19筛查、预防标准与流程。并与2019年1月20日-3月20日同期取栓病例进行对照分析。结果共纳入33例颅内大血管闭塞致AIS进行急诊取栓的患者,其中2020年18例,2019年15例。2020年疫情期间与2019年同期相比,入院到手术开始时间稍长[4.0(2.9~4.1)h vs 3.0(2.0~4.0)h,P=0.103],更少采用全身麻醉(55.6%vs 100.0%,P=0.003),更倾向采取直接导管抽吸取栓(27.8%vs 13.3%,P=0.32)。出院时死亡率低于2019年同期取栓患者(0 vs 20.0%,P=0.050)。2020年疫情期间纳入的患者及参与救治的医护人员无COVID-19可疑病例,无COVID-19疑似或确诊病例。结论COVID-19疫情期间,入院到手术开始时间受到疫情筛查的影响而有所延长,取栓策略倾向于采取局部麻醉、抽吸取栓策略,作为疫情期间的特殊考虑是合理的。
基金supported by the National Key Research and Development Program of China (2018YFD0300503)
文摘Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective strategy for promoting sustainable agriculture in this region.Using twenty maize cultivars,plant dry matter production,N absorption and accumulation,yield formation,and NUE in summer maize were investigated under three N levels in two growing seasons.Based on their yield and yield components,these maize cultivars were categorized into four groups including efficient-efficient(EE)cultivars,high-nitrogen efficient(HNE)cultivars,low-nitrogen efficient(LNE)cultivars and nonefficient-nonefficient(NN)cultivars.In both two seasons,the EE cultivars improved grain yield together with increased plant biomass,and enhanced accumulative amounts as well as higher average grain yields than the other cultivar groups under deficient-N conditions.Significant correlations were observed between yield and kernel numbers(KN),dry matter(DM)amount and N accumulation at both post-silking and maturity stages.DM and N accumulation at late growth stage(i.e.,from silking to maturity)contributed largely to the enhanced yield capacity and improved NUE under N-deficient conditions.Compared with the NN cultivars,the EE cultivars also showed increased N assimilation amount(NAA)and N remobilization content(NRC),and elevated N remobilization efficiency(NRE),NUE and nitrogen partial factor productivity(PFPN).Our investigation has revealed N-associated physiological processes and may provide guidance for cultivation and breeding of high yield and NUE summer maize under limited N conditions in the NCP.
基金This study was supported by the National Key Research and Development Program of China(2016YFD0300207 and 2017YFD0300305).
文摘Double-maize cropping system is an effective option for coping with climate change in the North China Plain. However, the effects of changes in climate on the growth and yield of maize in the two seasons are poorly understood. Forty-six cultivars of maize with different requirements for growing degree days (GDD), categorized as high (H), medium (M) or low (L), and three cultivar combinations for two seasons as LH (using JD27 and DMY1 from category L in the first season;and YD629 and XD22 from category H in the second season), MM (using JX1 and LC3 from category M in the first season;and ZD958 and JX1 from category M in the second season) and HL (using CD30 and QY9 from category H in the first season;and XK10 and DMY3 from category L in the second season) were tested to examine the eco-physiological determinants of maize yield from 2015 to 2017. The correlations between the combinations of cultivars and grain yield were examined. The combination LH produced the highest annual grain yield and total biomass, regardless of the year. It was followed, in decreasing order, by MM and HL. Higher grain yield and biomass in LH were mainly due to the greater grain yield and biomass in the second season, which were influenced mainly by the lengths of the pre- and post-silking periods and the rate of plant growth (PGR). Temperature was the primary factor that influenced dry matter accumulation. In the first season, low temperatures during pre-silking decreased both the duration and PGR in LH, whereas high temperatures during post-silking decreased the PGR in MM and HL, resulting in no significant differences in biomass being observed among the three combinations. In the second season, high temperatures decreased both the PGR and pre- and post-silking duration in MM and HL, and consequently, the biomass of those two combinations were lower than that in LH. Moreover, because of lower GDD and radiation in the first season and higher grain yield in the second season, production efficiency of temperature and radiation (Ra) was the highest in LH. More importantly, differences in temperature and radiation in the two seasons significantly affected the rate and duration of growth in maize, and thereby affecting both dry matter and grain yield. Our study indicated that the combination of LH is the best for optimizing the double-maize system under changing climatic conditions in the North China Plain.
基金funded by the National Natural Science Foundation of China(32071957)the Key National Research and Development Program of China(2018YFD0300504)+1 种基金the Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(2060302-2)the China Agriculture Research System of MOF and MARA(CARS-02)。
文摘Inappropriate tillage practices and nitrogen(N) management have become seriously limitations for maize(Zea mays L.) yield and N use efficiency(NUE) in the North China Plain(NCP). In the current study, we examined the effects of strip deep rotary tillage(ST) combined with controlled-release(CR) urea on maize yield and NUE, and determined the physiological factors involved in yield formation and N accumulation during a 2-year field experiment. Compared with conventional rotary tillage(RT) and no-tillage(NT), ST increased the soil water content and soil mineral N content(Nmin) in the 20–40 cm soil layer due to reduction by 10.5 and 13.7% in the soil bulk density in the 0–40 cm soil layer, respectively. Compared with the values obtained by common urea(CU) fertilization, CR increased the Nmin in the 0–40 cm soil layers by 12.4 and 10.3% at the silking and maturity stages, respectively. As a result, root length and total N accumulation were enhanced under ST and CR urea, which promoted greater leaf area and dry matter(particularly at post-silking), eventually increasing the1 000-kernel weight of maize. Thus, ST increased the maize yield by 8.3 and 11.0% compared with RT and NT, respectively, whereas CR urea increased maize yield by 8.9% above the values obtained under CU. Because of greater grain yield and N accumulation, ST combined with CR urea improved the NUE substantially. These results show that ST coupled with CR urea is an effective practice to further increase maize yield and NUE by improving soil properties and N supply, so it should be considered for sustainable maize production in the NCP(and other similar areas worldwide).
