Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population wa...Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population was evaluated for seven yield and five agronomic traits under four water and nitrogen conditions:water stress and low nitrogen,water stress and high nitrogen,well-watered and low nitrogen,and well-watered and high nitrogen.Respectively eight,six,and six traits varied in response to genotype–water interactions,genotype–nitrogen interactions,and genotype–water–nitrogen interactions.Using a linkage map consisting of 896 single-nucleotide polymorphism markers and multipleenvironmental quantitative-trait locus(QTL)mapping,we identified 31 QTL,including 12 for genotype–water–nitrogen interaction,across the four treatments.A set of 8060 genes were differentially expressed among treatments.Integrating genetic analysis,gene co-expression,and functional annotation revealed two candidate genes controlling genotype–water–nitrogen interactions,affecting both leaf width and grain yield.Genes involved in abscisic acid biosynthesis and bZIP,NAC,and WRKY transcription factors participated in maize response to water and nitrogen conditions.These results represent a step toward understanding the genetic regulatory network of maize that responds to water and nitrogen stress and provide a theoretical basis for the genetic improvement of both water-and nitrogen-use efficiency.展开更多
Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elast...Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elastic structures, aiming to gain insights into the characteristics of the problem. The results of the rigid cases showed the significance of air compressibility during the impact process, while the slamming phenomena became quite different without the effect. In the elastic cases, the trapped air made the structure vibrate at frequencies much smaller than its eigenfrequencies. Besides, the structural deformation made it easy for the trapped air to escape outwards, which weakened the air cushioning effect, especially at high impact velocities. The above analysis gives the results when the structural symmetry axis was vertical to the water(vertical impacts). In addition, the results were given when the axis was oblique to the water(oblique impacts). Compared with the vertical cases, the impact phenomena and structural response showed asymmetry. This work used the computational fluid dynamics(CFD) method to describe fluid motion and the finite element method(FEM) for the deformable structure. A two-way coupling approach was used to deal with the fluid-structure interaction in the elastic cases.展开更多
The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw...The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.展开更多
Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with ...Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with three soil water conditions(severe drought,moderate drought,and fully water supply referring to 45%-55%,65%-75%,and 85%-95%field capacity,respectively)and four N application rates(N0,N150,N240,and N330 referring to 0,150,240,330 kg N ha^(-1)respectively)under drip fertigation in 2014 and 2015 in the Huang-Huai-Hai Plain of China.The results indicated that drought stress inhibited physiological activity of plants(leaf relative water content,root bleeding sap,and net photosynthetic rate),resulting in low dry matter accumulation after silking,yield,and N uptake,whereas increased WUE and NUE.N application rates over than 150 kg ha^(-1)aggravated the inhibition of physiological activity under severe drought condition,while it was offset under moderate drought condition.High N application rates(N330)still revealed negative effects under moderate drought condition,as it did not consistently enhance plant physiological activity and significantly reduced N uptake as compared to the N240 treatment.With fully water supply,increasing N application rates synergistically enhanced physiological activity,promoted dry matter accumulation after silking,and increased yield,WUE,and N uptake.Although the N240 treatment reduced yield by 5.4%in average,it saved 27.3%N under full water supply condition as compared with N330 treatment.The results indicated that N regulated growth of maize in aspects of physiological traits,dry matter accumulation,and yield as well as water and N use was depended on soil water status.The appropriate N application rates for maize production was 150 kg ha^(-1)under moderate drought or 240 kg ha^(-1)under fully water supply under drip fertigation,and high N supply(>150 kg ha^(-1))should be avoided under severe drought condition.展开更多
叶绿素含量是植物生长状况的重要指标。传统的测量叶绿素的方法费时费力,会对植物造成损伤。近年来,数字图像处理技术在估测植物叶绿素含量方向上取得了较好的进展,但针对银杏等经济林木的研究依旧偏少。以不同水氮互作条件下的2年生银...叶绿素含量是植物生长状况的重要指标。传统的测量叶绿素的方法费时费力,会对植物造成损伤。近年来,数字图像处理技术在估测植物叶绿素含量方向上取得了较好的进展,但针对银杏等经济林木的研究依旧偏少。以不同水氮互作条件下的2年生银杏幼苗为研究对象,使用数字扫描仪采集银杏幼苗叶片图像,利用数字图像技术构建颜色特征参数,结合相关性分析初筛出对叶绿素显著相关的颜色特征参数,并进一步基于高斯过程回归(gaussian process regression, GPR)和偏最小二乘回归(partial least squares regression, PLSR)优选建模中最为重要的颜色特征参数,建立基于银杏叶片颜色特征参数的叶绿素含量估测模型。结果表明,叶绿素含量随着施氮水平和水分处理水平的上升总体上呈现逐渐提高而后缓慢下降的趋势。基于单一颜色参数建立的单变量回归模型(R^(2)=0.01~0.72)预测精度总体上低于使用高斯过程回归(R^(2)=0.79~0.81)和偏最小二乘法(R^(2)=0.75~0.77)的模型。其中,GPR-BAT模型和PLSR-VIP模型都筛选出了对叶绿素敏感的R、G颜色特征参数;GPR模型的表现总体上优于PLSR模型,特别是在使用GPR-BAT优选颜色参数建模时表现最佳(R^(2)=0.81)。基于GPR-BAT优选颜色参数构建的GPR模型效果最佳,可准确估测银杏叶片叶绿素含量,为银杏生产的精确管理和监测银杏生长状况提供技术支撑。展开更多
明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,...明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,主区为浇水次数,设春浇一水(W1,拔节水)和春浇两水(W2,拔节水+开花水);副区为氮肥施用量,设N0、N1、N2、N3、N4和N5(0、60、120、180、240和300 kg hm^(-2))6个水平。结果表明,施氮量0~300 kg hm^(-2)时,不同降水年型春浇一水、春浇两水小麦产量随施氮量的增加均先增加后减少,产量最高值对应的施氮量均为240 kg hm^(-2)。施氮量120~300 kg hm^(-2)时,春浇两水处理产量显著高于春浇一水处理。水氮互作对小麦单位面积收获穗数的影响最大,其次是千粒重,对穗粒数的影响最小。施氮量0~300 kg hm^(-2)时,2017-2018年度(丰水年型),春浇两水小麦湿面筋含量、沉降值、吸水率、面团稳定时间、拉伸能量、最大拉伸阻力平均值均高于春浇一水,而2018-2019、2019-2020年度(干旱年型)则相反:春浇一水高于春浇两水。不同降水年型春浇一水、春浇两水小麦湿面筋含量和沉降值随施氮量的增加先增加后减少或逐渐增加,二者最大值对应的施氮量为240 kg hm^(-2)或300 kg hm^(-2);稳定时间、拉伸能量和最大拉伸阻力随施氮量的增加均先增加后减少,施氮量240 kg hm^(-2)时达到最大值。不同降水年型强筋优质小麦师栾02-1生育期春浇两水、施氮量240 kg hm^(-2)时,籽粒产量和加工品质表现最佳。展开更多
水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇...水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH_(4)^(+)-N、NO_(3)^(-)-N含量以及参与自养硝化的AOA amo A和AOB amo A基因拷贝数均有显著差异。无乙炔培养7 d后,NO_(3)^(-)-N含量显著增加,而NH_(4)^(+)-N含量显著降低,AOA amo A和AOB amo A的基因丰度显著增加。添加乙炔后,NO_(3)^(-)-N、NH_(4)^(+)-N含量基本保持恒定,AOA amo A和AOB amo A基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH_(4)^(+)-N含量、AOB amo A、NO_(3)^(-)-N-C_(2)H_(2)、AOA amo A可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%~80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%~86%;仅40%WHC下,氮纯养分量300和525 kg·hm^(-2)处理以异养硝化为主,占总硝化速率的61%~77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。展开更多
By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For t...By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For the time history of the vertical force, the computational fluid dynamics(CFD) results match the experimental data much better than the classical potential-flow theories due to the consideration of the viscosity, turbulence, surface tension, gravity, and compressibility. The results show that the position of peak pressure on ellipse shifts from the spray root to the bottom of ellipse at a critical time. The critical time changes with the geometry and Froude number. By studying the vertical force, the ellipse water entry process can be divided into the initial and late stages based on the critical dimensionless time of about 0.1. The geometry of the ellipse plays a dominant role in the initial stage, while the Froude number is more important in the late stage of entry. The classical Wagner theory is extended to the ellipse water entry, and the predicted maximum value of vertical force coefficient in the initial stage is 4?a/b that matches the CFD results very well, where a and b are the horizontal axis and vertical axis of the ellipse parallel and perpendicular to the initial calm water surface, respectively.展开更多
基金the National Key Research and Development Program of China(2021YFD1200700)the National Natural Science Foundation of China(32272076)+1 种基金the Hainan Provincial Science and Technology Plan Sanya Yazhou Bay Science and Technology City Joint Project(320LH011)the Inner Mongolia Foundation for the Conversion of Scientific and Technological Achievements(2021CG0026).
文摘Water and nitrogen fertilization are the key factors limiting maize productivity.The genetic basis of interactions between maize genotype,water,and nitrogen is unclear.A recombinant inbred line(RIL)maize population was evaluated for seven yield and five agronomic traits under four water and nitrogen conditions:water stress and low nitrogen,water stress and high nitrogen,well-watered and low nitrogen,and well-watered and high nitrogen.Respectively eight,six,and six traits varied in response to genotype–water interactions,genotype–nitrogen interactions,and genotype–water–nitrogen interactions.Using a linkage map consisting of 896 single-nucleotide polymorphism markers and multipleenvironmental quantitative-trait locus(QTL)mapping,we identified 31 QTL,including 12 for genotype–water–nitrogen interaction,across the four treatments.A set of 8060 genes were differentially expressed among treatments.Integrating genetic analysis,gene co-expression,and functional annotation revealed two candidate genes controlling genotype–water–nitrogen interactions,affecting both leaf width and grain yield.Genes involved in abscisic acid biosynthesis and bZIP,NAC,and WRKY transcription factors participated in maize response to water and nitrogen conditions.These results represent a step toward understanding the genetic regulatory network of maize that responds to water and nitrogen stress and provide a theoretical basis for the genetic improvement of both water-and nitrogen-use efficiency.
基金financially supported by the National Key Research and Development Program of China (Grant No. 2019YFC1407700)。
文摘Recent damages to the box-like structures caused by wave slamming have made it necessary to study the impact problems of this kind of structure. This paper showed findings from numerical simulations of the rigid/elastic structures, aiming to gain insights into the characteristics of the problem. The results of the rigid cases showed the significance of air compressibility during the impact process, while the slamming phenomena became quite different without the effect. In the elastic cases, the trapped air made the structure vibrate at frequencies much smaller than its eigenfrequencies. Besides, the structural deformation made it easy for the trapped air to escape outwards, which weakened the air cushioning effect, especially at high impact velocities. The above analysis gives the results when the structural symmetry axis was vertical to the water(vertical impacts). In addition, the results were given when the axis was oblique to the water(oblique impacts). Compared with the vertical cases, the impact phenomena and structural response showed asymmetry. This work used the computational fluid dynamics(CFD) method to describe fluid motion and the finite element method(FEM) for the deformable structure. A two-way coupling approach was used to deal with the fluid-structure interaction in the elastic cases.
基金supported by the National Natural Science Foundation of China(30030090) Jiangsu Key Project of Science and Technology(BE2001331).
文摘The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.
基金This research was supported by the National Key Research and Development Program of China(No.2017YFD0301106)the National Natural Science Foundation of China(Nos.31871553 and 31601258).
文摘Knowledge of the interactive effects of water and nitrogen(N)on physio-chemical traits of maize(Zea mays L.)helps to optimize water and N management and improve productivity.A split-plot experiment was conducted with three soil water conditions(severe drought,moderate drought,and fully water supply referring to 45%-55%,65%-75%,and 85%-95%field capacity,respectively)and four N application rates(N0,N150,N240,and N330 referring to 0,150,240,330 kg N ha^(-1)respectively)under drip fertigation in 2014 and 2015 in the Huang-Huai-Hai Plain of China.The results indicated that drought stress inhibited physiological activity of plants(leaf relative water content,root bleeding sap,and net photosynthetic rate),resulting in low dry matter accumulation after silking,yield,and N uptake,whereas increased WUE and NUE.N application rates over than 150 kg ha^(-1)aggravated the inhibition of physiological activity under severe drought condition,while it was offset under moderate drought condition.High N application rates(N330)still revealed negative effects under moderate drought condition,as it did not consistently enhance plant physiological activity and significantly reduced N uptake as compared to the N240 treatment.With fully water supply,increasing N application rates synergistically enhanced physiological activity,promoted dry matter accumulation after silking,and increased yield,WUE,and N uptake.Although the N240 treatment reduced yield by 5.4%in average,it saved 27.3%N under full water supply condition as compared with N330 treatment.The results indicated that N regulated growth of maize in aspects of physiological traits,dry matter accumulation,and yield as well as water and N use was depended on soil water status.The appropriate N application rates for maize production was 150 kg ha^(-1)under moderate drought or 240 kg ha^(-1)under fully water supply under drip fertigation,and high N supply(>150 kg ha^(-1))should be avoided under severe drought condition.
文摘叶绿素含量是植物生长状况的重要指标。传统的测量叶绿素的方法费时费力,会对植物造成损伤。近年来,数字图像处理技术在估测植物叶绿素含量方向上取得了较好的进展,但针对银杏等经济林木的研究依旧偏少。以不同水氮互作条件下的2年生银杏幼苗为研究对象,使用数字扫描仪采集银杏幼苗叶片图像,利用数字图像技术构建颜色特征参数,结合相关性分析初筛出对叶绿素显著相关的颜色特征参数,并进一步基于高斯过程回归(gaussian process regression, GPR)和偏最小二乘回归(partial least squares regression, PLSR)优选建模中最为重要的颜色特征参数,建立基于银杏叶片颜色特征参数的叶绿素含量估测模型。结果表明,叶绿素含量随着施氮水平和水分处理水平的上升总体上呈现逐渐提高而后缓慢下降的趋势。基于单一颜色参数建立的单变量回归模型(R^(2)=0.01~0.72)预测精度总体上低于使用高斯过程回归(R^(2)=0.79~0.81)和偏最小二乘法(R^(2)=0.75~0.77)的模型。其中,GPR-BAT模型和PLSR-VIP模型都筛选出了对叶绿素敏感的R、G颜色特征参数;GPR模型的表现总体上优于PLSR模型,特别是在使用GPR-BAT优选颜色参数建模时表现最佳(R^(2)=0.81)。基于GPR-BAT优选颜色参数构建的GPR模型效果最佳,可准确估测银杏叶片叶绿素含量,为银杏生产的精确管理和监测银杏生长状况提供技术支撑。
文摘明确不同水氮互作对强筋优质小麦师栾02-1产量和加工品质的影响,为强筋小麦生产中如何通过合理灌溉和优化氮肥施用量来实现协同提高籽粒产量和加工品质的目标提供理论依据。2017-2020年,大田条件下设置浇水次数和施氮量二因子裂区试验,主区为浇水次数,设春浇一水(W1,拔节水)和春浇两水(W2,拔节水+开花水);副区为氮肥施用量,设N0、N1、N2、N3、N4和N5(0、60、120、180、240和300 kg hm^(-2))6个水平。结果表明,施氮量0~300 kg hm^(-2)时,不同降水年型春浇一水、春浇两水小麦产量随施氮量的增加均先增加后减少,产量最高值对应的施氮量均为240 kg hm^(-2)。施氮量120~300 kg hm^(-2)时,春浇两水处理产量显著高于春浇一水处理。水氮互作对小麦单位面积收获穗数的影响最大,其次是千粒重,对穗粒数的影响最小。施氮量0~300 kg hm^(-2)时,2017-2018年度(丰水年型),春浇两水小麦湿面筋含量、沉降值、吸水率、面团稳定时间、拉伸能量、最大拉伸阻力平均值均高于春浇一水,而2018-2019、2019-2020年度(干旱年型)则相反:春浇一水高于春浇两水。不同降水年型春浇一水、春浇两水小麦湿面筋含量和沉降值随施氮量的增加先增加后减少或逐渐增加,二者最大值对应的施氮量为240 kg hm^(-2)或300 kg hm^(-2);稳定时间、拉伸能量和最大拉伸阻力随施氮量的增加均先增加后减少,施氮量240 kg hm^(-2)时达到最大值。不同降水年型强筋优质小麦师栾02-1生育期春浇两水、施氮量240 kg hm^(-2)时,籽粒产量和加工品质表现最佳。
文摘水氮措施影响设施土壤氮素的转化及硝化微生物活性,但水氮耦合对设施土壤自养和异养硝化作用差异的影响尚不明确。以连续8年设施水氮耦合田间定位试验土壤为研究对象,控制不同土壤田间持水量(WHC)(40%WHC、60%WHC和80%WHC)进行室内微宇宙培养试验,通过添加乙炔抑制剂抑制自养硝化途径,研究水氮耦合对设施土壤自养和异养硝化速率及参与自养硝化的氨氧化微生物的影响,分析氨氧化微生物氨氧化古细菌(AOA)和氨氧化细菌(AOB)对自养硝化作用的贡献。结果表明,水氮耦合下,不同硝化途径NH_(4)^(+)-N、NO_(3)^(-)-N含量以及参与自养硝化的AOA amo A和AOB amo A基因拷贝数均有显著差异。无乙炔培养7 d后,NO_(3)^(-)-N含量显著增加,而NH_(4)^(+)-N含量显著降低,AOA amo A和AOB amo A的基因丰度显著增加。添加乙炔后,NO_(3)^(-)-N、NH_(4)^(+)-N含量基本保持恒定,AOA amo A和AOB amo A基因丰度显著减少。水氮耦合显著影响自养和异养硝化速率,冗余分析(RDA)表明,NH_(4)^(+)-N含量、AOB amo A、NO_(3)^(-)-N-C_(2)H_(2)、AOA amo A可分别解释自养和异养硝化速率变异的68.9%、34.9%、32.8%和24.4%。设施土壤存在自养硝化和异养硝化两种途径,60%~80%WHC各施氮处理均以自养硝化为主,占总硝化速率的65%~86%;仅40%WHC下,氮纯养分量300和525 kg·hm^(-2)处理以异养硝化为主,占总硝化速率的61%~77%。AOB和AOA共同驱动自养硝化,且AOB贡献更大。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11302015,11272034)
文摘By using the finite volume method with volume of fluid model and global dynamic mesh technique, the effects of Froude number and geometry on the water entry process of a 2-D ellipse are investigated numerically. For the time history of the vertical force, the computational fluid dynamics(CFD) results match the experimental data much better than the classical potential-flow theories due to the consideration of the viscosity, turbulence, surface tension, gravity, and compressibility. The results show that the position of peak pressure on ellipse shifts from the spray root to the bottom of ellipse at a critical time. The critical time changes with the geometry and Froude number. By studying the vertical force, the ellipse water entry process can be divided into the initial and late stages based on the critical dimensionless time of about 0.1. The geometry of the ellipse plays a dominant role in the initial stage, while the Froude number is more important in the late stage of entry. The classical Wagner theory is extended to the ellipse water entry, and the predicted maximum value of vertical force coefficient in the initial stage is 4?a/b that matches the CFD results very well, where a and b are the horizontal axis and vertical axis of the ellipse parallel and perpendicular to the initial calm water surface, respectively.