The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates ...The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.展开更多
The growth periods(GPs, from planting/emergence to reproductive stage 8(R8) of soybean cultivars vary in different ecological regions, especially in China with a very complex soybean cropping system. In this study, a ...The growth periods(GPs, from planting/emergence to reproductive stage 8(R8) of soybean cultivars vary in different ecological regions, especially in China with a very complex soybean cropping system. In this study, a 3-yr experimental study was undertaken in three geographical locations of China from 2008 to 2010, including the Northeast(40.66–45.85°N), Huang-Huai(34.75–38.04°N) and southern(22.82–30.60°N) eco-regions with about 250 accessions in each region to clarify the classification of maturity group(MG) and identify the cultivars with stable GP to increase the knowledge about the GP distribution of soybean cultivars in China. GPs of soybean cultivars in different eco-regions were significant different with a gradual decrease from 115–125 d in the Northeast part to the 85–100 d in the southern part of China. The geographical location was the major factor for GP of cultivars from the Northeast, while the year of planting was the major factor affecting the stability of GPs in Huang-Huai summer and southern summer soybean. AMMI2(additive main effects and multiplicativeinteraction)-Biplot analysis showed that the GPs of soybean cultivars from the Northeast eco-region have a comparatively satisfactory environmental stability. Moreover, soybean cultivars with moderate GP/MG and stable environment adaptability in different eco-regions were identified based on the linear regression and AMMI analysis, which was important for the accurate classification of soybean MGs in future. Taken together, our results reflected the genetic diversity, geographical distribution and environmental stability of the Chinese soybean GP trait. Soybean cultivars with stable GP for various Chinese eco-regions would be beneficial for Chinese soybean genetic improvement, varietal introduction, exchange, and soybean breeding program for wide adaptability.展开更多
in this paper, 4N-HCLAIA method was adopted to conduct digestive tests in young female and male Dongtian F1 red deer (Cervus elaphus) of rearing seperatefy in growth period and mixed raising in weaning period in Harbi...in this paper, 4N-HCLAIA method was adopted to conduct digestive tests in young female and male Dongtian F1 red deer (Cervus elaphus) of rearing seperatefy in growth period and mixed raising in weaning period in Harbin Specialty Research Institute. Results indicated that digestive rate of crude protein and crude fiber were 95.35% and 73.68% respectively when rational protein content was 26.8% in growth period. Digestive rate was not significantly different between female and male(P>0.05)i During weaning period, When rational crude protein content is 22.06%, digestive rate of crude protein and crude fiber were 93.05% and 63.96%, respectively. The tests suggest that higher rational protein can be effective in accelerating groWth of young Dongtian F1 red deer during growth period and weaning period(before 10 months old).展开更多
Xuzishu 8 is a new cultivated sweetpotato with high anthocyanidin content.The growth period affects its tuber traits and quality.In this study,the changes in sweetpotato shape,number of tubers per plant,rate of big an...Xuzishu 8 is a new cultivated sweetpotato with high anthocyanidin content.The growth period affects its tuber traits and quality.In this study,the changes in sweetpotato shape,number of tubers per plant,rate of big and medium tubers,yield,anthocyanin content and starch content of Xuzishu 8 were investigated under 12 growth periods from 78 to 188 d.The results showed that various traits of Xuzishu 8 were significantly different between different growth periods.The rate of large and medium tubers,the fresh sweetpotato yield,the starch content and the anthocyanin yield increased gradually with the extension of the growth period.The length/width ratio of sweetpotato tubers,the rate of small tubers and the contents of reducing sugar and soluble sugar decreased with the prolongation of the growth period.The correlation analysis showed that the fresh sweetpotato yield was in significant or extremely significant positive correlation with the number of tubers per plant,rate of big and medium tubers,dry matter content,dry yield and starch content.The 148-day growth period treatment exhibited the highest number of tubers per plant,the highest fresh sweetpotato yield and anthocyanin yield reaching 3 927 and 4.25 kg/667 m^2,respectively,as well as the rate of large and medium tubers up to 90%.Therefore,the tubers had good marketability and eating quality.展开更多
Under the background of global climate change,we analyze the change tendency of average temperature and amount of precipitation influencing the corn's growth period. The results show that from March to August,the ...Under the background of global climate change,we analyze the change tendency of average temperature and amount of precipitation influencing the corn's growth period. The results show that from March to August,the monthly temperatures show an upward trend,but the rise is different in different months,and the maximum temperature rise is in May. Precipitation in different months has different trends. Climate change brings about favorable conditions at high altitudes in Fengjie,reduces production due to the temperature drop after the beginning of autumn,and increases the pressure on the corn supply.展开更多
[Objective]The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [Method]Based on daily precipitation data at Shijiaz...[Objective]The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [Method]Based on daily precipitation data at Shijiazhuang meteorological station in recent 51 years,average rainfall during growth periods of the 9 kinds of conventional crops was obtained. Precipitation tendency during growth periods of the 9 kinds of conventional crops in plain area before Taihang Mountains was analyzed by Mann-Kendall nonparametric test. [Result]Seen from rainfall during growth periods of the different crops,rainfall was the least during the growth period of winter wheat,followed by summer corn. Rainfall during growth periods of the cotton,oil plant,vegetable,fruit tree,potato,rice and legumes was more. Under different guaranteed rates,precipitation change also had difference. Rainfall change during growth periods of the wheat and corn was bigger,and rainfall change during growth period of the rice was smaller. Change degree of the precipitation during growth periods of the cotton,oil plant,vegetable,fruit tree and legumes was equivalent,while precipitation change during growth period of the potato was the biggest. Seen from change tendency of the precipitation during growth periods of the different crops,precipitation in the growth period of winter wheat was increasing at a speed of 0. 62 mm /a. However,precipitation in growth periods of the other crops had a decreasing tendency. Precipitation in the growth periods of summer corn and legumes decreased at the same speed which was 2. 11 mm /a,while precipitation in growth periods of the cotton,oil plant,vegetable,fruit tree,potato and rice decreased insignificantly. [Conclusion] The study laid foundation for determination of the agricultural irrigation water and provided theoretical reference for regional agricultural water-saving.展开更多
[Objective]The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the middle and southern part of Ningxia. [Method] Through Takahashi's evaporation e...[Objective]The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the middle and southern part of Ningxia. [Method] Through Takahashi's evaporation equation,linear trend analysis,Mann - Kendall,Lepage,wavelet analysis,the characteristics of available precipitation and its abnormal characteristics during its growth period in Ningxia were analyzed based on monthly precipitation ( March - September) ,temperature,and NCAR/NCEP reanalysis data in 9 observation stations from 1961 to 2010. [Result] In recent 50 years,the available precipitation during the growth period of crops in central drought area and south hilly area varied a lot,more in the south and less in the north. The available precipitation in these two areas was reducing and varied a lot in different ages. The available precipitation was less in the middle drought region after 1970s and in the southern hilly region after 1990s and the available precipitation in middle drought area changed significantly. The available precipitation in the two areas appeared in July,August,and September,above 76% of general growth period, while that in March,April and May was 14% lower than that in growth period. No abrupt changes in central drought area and south hilly area. There were the periods of 5 -7 a and 2 -3 a oscillations in the middle drought region,2 -3 a and 10 -12 a oscillations in the southern hilly region. There were negative anomaly field at 500hPa height in high-precipitation years between the Baikal and the China's northwestern,and there were positive anomaly field in low-precipitation years. [Conclusion]The study provided reference for the reasonable utilization of available water resources in central and south Ningxia.展开更多
Owing to the complexity and variability of global climate,the study of extreme events to ensure food security is particularly critical.The standardized precipitation requirement index(SPRI)and chilling injury index(I_...Owing to the complexity and variability of global climate,the study of extreme events to ensure food security is particularly critical.The standardized precipitation requirement index(SPRI)and chilling injury index(I_(Ci))were introduced using data from agrometeorological stations on the Songliao Plain between 1981 and 2020 to identify the spatial and temporal variability of drought,waterlogging,and low-temperature cold damage during various maize growth periods.Compound drought and low-temperature cold damage events(CDLEs)and compound waterlogging and low-temperature cold damage events(CWLEs)were then identified.To measure the intensity of compound events,the compound drought and low-temperature cold damage magnitude index(CDLMI),and compound waterlogging and low-temperature cold damage magnitude index(CWLMI)were constructed by fitting marginal distributions.Finally,the effects of extreme events of various intensities on maize output were examined.The findings demonstrate that:(1)There were significant differences in the temporal trends of the SPRI and ICiduring different maize growth periods.Drought predominated in the middle growth period(MP),waterlogging predominated in the early growth period(EP)and late growth period(LP),and both drought and waterlogging tended to increase in intensity and frequency.The frequency of low-temperature cold damage showed a decreasing trend in all periods.(2)The CDLMI and CWLMI can effectively determine the intensity of CDLEs and CWLEs in the study area;these CDLEs and CWLEs had higher intensity and frequency in the late growth period.(3)Compared to single events,maize relative meteorological yield had a more significant negative correlation with the CDLMI and CWLMI.展开更多
Dynamic acquisition of crop morphology is beneficial to real-time variable decision of precise spraying operations in fields.However,the existing spraying quantity regulation has high tolerance on the statistical char...Dynamic acquisition of crop morphology is beneficial to real-time variable decision of precise spraying operations in fields.However,the existing spraying quantity regulation has high tolerance on the statistical characteristics of regional morphology,so expensive LiDAR and ultrasonic radar can’t make full use of their high accuracy,and can reduce decision speed because of too much detail of branches and leaves.Therefore,designing a novel recognition system embedded machine learning with low-cost monocular vision is more feasible,especially in China,where the agricultural implements are medium sizes and cost-sensitive.In addition,we found that the growth period of crops is an important reference index for guiding spraying.So,taking cotton as a case study,a cotton morphology acquisition by a single camera is established,and a cotton growth period recognition algorithm based on Convolution Neural Network(CNN)is proposed in this paper.Through the optimization process based on confusion matrix and recognition efficiency,an optimized CNN model structure is determined from 9 different model structures,and its reliability was verified by changing training sets and test sets many times based on the idea of kfold test.The accuracy,precision,recall,F1-score and recognition speed of this CNN model are 93.27%,95.39%,94.31%,94.76%and 71.46 ms per image,respectively.In addition,compared with the performance of VGG16 and AlexNet,the convolution neural network model proposed in this paper has better performance.Finally,in order to verify the reliability of the designed recognition system and the feasibility of the spray decision-making algorithm based on CNN,spraying deposition experiments were carried out with 3 different growthperiods of cotton.The experiments’results validate that after the optimal spray parameters were applied at different growth periods respectively,the average optimum index in 3 growth periods was 42.29%,which was increased up to 62.24%than the operations without distinguishing growth periods.展开更多
Experiments were conducted to examine the effects of salinity fluctuation on the intermolt period and growth of Fenneropenaeus chi- nensis with an initial body weight of (0.553 2±0.000 1)g (mean plus or minus SE)...Experiments were conducted to examine the effects of salinity fluctuation on the intermolt period and growth of Fenneropenaeus chi- nensis with an initial body weight of (0.553 2±0.000 1)g (mean plus or minus SE). The salinity (S0) of the control treatment is 30 throughout the experiment, while the treatments S2, S4, S7 and S10 are subjected to different salinity fluctuations, and the ranges are 2, 4, 7 and 10, respectively. After a 30-day feeding trial, the longest and the shortest intermolt periods of the shrimp occur under Treatments S10 and S2, respectively (difference 37.14%). The special growth rates (SGR) of the shrimp under the five treatments are ranked as S7> S4> S2> S10> S0, and the SGR of the shrimp under Treatment S0 is lower than that under Treatments S4 and S7 by 22.36% and 28.11%, respectively (P< 0.05). The minimal feed intake (FI) of the experimental animals occurs in Treatment S0 (84.04% and 88.54% of that under Treatments S4 and S7, respectively) (P< 0.05). There are no significant differences in the food conversion efficiency (FCE) of the shrimp under the five treatments (P> 0.05).展开更多
Deprivation is an environmental experience that organisms are continually exposed to. However, few studies analyze deprivation effects on the consumption pattern during the post-deprivation period systematically. The ...Deprivation is an environmental experience that organisms are continually exposed to. However, few studies analyze deprivation effects on the consumption pattern during the post-deprivation period systematically. The aim of this study was to evaluate the deprivation effect on feeding pattern, growth rate and body weight during post-deprivation. Sixteen albino rats (3 months old at the beginning of the experiment) were exposed to 72-hour total food deprivation every 15 days. Food and water were freely available during non-deprivation periods. Rats completed three cycles comprised by a free access period followed by food deprivation. Once deprivation was removed, food and water consumption increased and then decreased, while body weight was recovered. Growth rate increased after every deprivation period and reached similar levels to those presented by the control group. Depriving rats from one commodity (i.e., food) cause them to restrain their consumption of the other freely available commodity (i.e., water). Results confirm that food deprivation modifies growth rate, water and food consumption. Additionally, during post-deprivation period, differences between males and females were not registered.展开更多
Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land ...Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land area to the area of the city X1(%), green coverage ratio of the built up area X2(%), the ratio of personnel involved in the secondary industry X3(%), the GDP per capita X4(×104)and other 43 indicators, by relying on the relevant data from China Urban Statistical Yearbook(2008), applying SPSS statistical software and by applying the Factor Analysis and Regression Analysis. The results show that the factors which affect the city growth have four major groups, namely economic and institutional factors, location factors, environmental factors and social cultural services and functions. Among the factors which affect Chinese city growth, the general budgetary expenditures and the general budgetary revenues of local public finance are the most important factors. The general budgetary expenditures of local finance, the general budgetary revenues, the lands of urban construction and other 12 factors obtained by gradually excluding method can be used to present the coefficient of city growth.展开更多
This article is concerned with a mathematical model of tumor growth governed by 2<sup>nd</sup> order diffusion equation . The source of mitotic inhibitor is almost periodic and time-dependent within the ti...This article is concerned with a mathematical model of tumor growth governed by 2<sup>nd</sup> order diffusion equation . The source of mitotic inhibitor is almost periodic and time-dependent within the tissue. The system is set up with the initial condition C(r, 0) = C<sub>0</sub>(r) and Robin type inhomogeneous boundary condition . Under certain conditions we show that there exists a unique solution for this model which is almost periodic.展开更多
基金Supported by the National Key Research and Development Program of China(2017YFD0300302)the earmarked fund for China Agriculture Research System(CARS-02-25)+1 种基金the Science and Technology Program of the Sixth Division of Xinjiang Production and Construction Corps in China(1703)the Agricultural Science and Technology Innovation Project of the Chinese Academy of Agricultural Sciences.
文摘The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.
基金supported by the Program of Accurate Identification and Display of Soybean Germplasm, China (NB08-2130315-(25-31)-06, NB07-2130315-(25-30)-06, NB06-070401-(22-27)-05), NB2010-2130315-25-05)the National Crop Germplasm Platform, Ministry of Agriculture and Ministry of Science and Technology, China (2012-004, 2014-004)
文摘The growth periods(GPs, from planting/emergence to reproductive stage 8(R8) of soybean cultivars vary in different ecological regions, especially in China with a very complex soybean cropping system. In this study, a 3-yr experimental study was undertaken in three geographical locations of China from 2008 to 2010, including the Northeast(40.66–45.85°N), Huang-Huai(34.75–38.04°N) and southern(22.82–30.60°N) eco-regions with about 250 accessions in each region to clarify the classification of maturity group(MG) and identify the cultivars with stable GP to increase the knowledge about the GP distribution of soybean cultivars in China. GPs of soybean cultivars in different eco-regions were significant different with a gradual decrease from 115–125 d in the Northeast part to the 85–100 d in the southern part of China. The geographical location was the major factor for GP of cultivars from the Northeast, while the year of planting was the major factor affecting the stability of GPs in Huang-Huai summer and southern summer soybean. AMMI2(additive main effects and multiplicativeinteraction)-Biplot analysis showed that the GPs of soybean cultivars from the Northeast eco-region have a comparatively satisfactory environmental stability. Moreover, soybean cultivars with moderate GP/MG and stable environment adaptability in different eco-regions were identified based on the linear regression and AMMI analysis, which was important for the accurate classification of soybean MGs in future. Taken together, our results reflected the genetic diversity, geographical distribution and environmental stability of the Chinese soybean GP trait. Soybean cultivars with stable GP for various Chinese eco-regions would be beneficial for Chinese soybean genetic improvement, varietal introduction, exchange, and soybean breeding program for wide adaptability.
文摘in this paper, 4N-HCLAIA method was adopted to conduct digestive tests in young female and male Dongtian F1 red deer (Cervus elaphus) of rearing seperatefy in growth period and mixed raising in weaning period in Harbin Specialty Research Institute. Results indicated that digestive rate of crude protein and crude fiber were 95.35% and 73.68% respectively when rational protein content was 26.8% in growth period. Digestive rate was not significantly different between female and male(P>0.05)i During weaning period, When rational crude protein content is 22.06%, digestive rate of crude protein and crude fiber were 93.05% and 63.96%, respectively. The tests suggest that higher rational protein can be effective in accelerating groWth of young Dongtian F1 red deer during growth period and weaning period(before 10 months old).
基金Supported by Jiangsu Agricultural Science and Technology Independent Innovation Fund [CX(17)2023]Earmarked Fund for China Agriculture Research System(CARS-10)"333 Project"of Jiangsu Province(BRA2016265)
文摘Xuzishu 8 is a new cultivated sweetpotato with high anthocyanidin content.The growth period affects its tuber traits and quality.In this study,the changes in sweetpotato shape,number of tubers per plant,rate of big and medium tubers,yield,anthocyanin content and starch content of Xuzishu 8 were investigated under 12 growth periods from 78 to 188 d.The results showed that various traits of Xuzishu 8 were significantly different between different growth periods.The rate of large and medium tubers,the fresh sweetpotato yield,the starch content and the anthocyanin yield increased gradually with the extension of the growth period.The length/width ratio of sweetpotato tubers,the rate of small tubers and the contents of reducing sugar and soluble sugar decreased with the prolongation of the growth period.The correlation analysis showed that the fresh sweetpotato yield was in significant or extremely significant positive correlation with the number of tubers per plant,rate of big and medium tubers,dry matter content,dry yield and starch content.The 148-day growth period treatment exhibited the highest number of tubers per plant,the highest fresh sweetpotato yield and anthocyanin yield reaching 3 927 and 4.25 kg/667 m^2,respectively,as well as the rate of large and medium tubers up to 90%.Therefore,the tubers had good marketability and eating quality.
基金Supported by Chongqing Municipal Frontiers and Application Base Research Program(cstc2014jcyj A20002)Chongqing Municipal Key Laboratory of Institutions of Higher Education(WEPKL2013MS-10)+4 种基金Chongqing Three Georges University Key Project(14ZD15)Wanzhou District Soft Science Project(201404009)Chongqing Three Georges University Key Project(14ZD15)Wanzhou District Soft Science Project(201404009)Chongqing Three Georges University Innovation Planning Project for University Students(2014-56)
文摘Under the background of global climate change,we analyze the change tendency of average temperature and amount of precipitation influencing the corn's growth period. The results show that from March to August,the monthly temperatures show an upward trend,but the rise is different in different months,and the maximum temperature rise is in May. Precipitation in different months has different trends. Climate change brings about favorable conditions at high altitudes in Fengjie,reduces production due to the temperature drop after the beginning of autumn,and increases the pressure on the corn supply.
基金Supported by National Science and Technology Support Plan Item, China ( 2007BAD69B09)Soft Science Research Plan Project in Hebei Province,China (10457204D-30,114572124)
文摘[Objective]The aim was to study change tendency of the precipitation resource during growth period of the conventional crops in plain area before Taihang Mountains. [Method]Based on daily precipitation data at Shijiazhuang meteorological station in recent 51 years,average rainfall during growth periods of the 9 kinds of conventional crops was obtained. Precipitation tendency during growth periods of the 9 kinds of conventional crops in plain area before Taihang Mountains was analyzed by Mann-Kendall nonparametric test. [Result]Seen from rainfall during growth periods of the different crops,rainfall was the least during the growth period of winter wheat,followed by summer corn. Rainfall during growth periods of the cotton,oil plant,vegetable,fruit tree,potato,rice and legumes was more. Under different guaranteed rates,precipitation change also had difference. Rainfall change during growth periods of the wheat and corn was bigger,and rainfall change during growth period of the rice was smaller. Change degree of the precipitation during growth periods of the cotton,oil plant,vegetable,fruit tree and legumes was equivalent,while precipitation change during growth period of the potato was the biggest. Seen from change tendency of the precipitation during growth periods of the different crops,precipitation in the growth period of winter wheat was increasing at a speed of 0. 62 mm /a. However,precipitation in growth periods of the other crops had a decreasing tendency. Precipitation in the growth periods of summer corn and legumes decreased at the same speed which was 2. 11 mm /a,while precipitation in growth periods of the cotton,oil plant,vegetable,fruit tree,potato and rice decreased insignificantly. [Conclusion] The study laid foundation for determination of the agricultural irrigation water and provided theoretical reference for regional agricultural water-saving.
基金Supported by National Natural Foundation Program (40965008 ) Special Foundation of Meteorology in China Meteorological Administration (CCSF2011-26)
文摘[Objective]The aim was to study the available precipitation and its abnormal characteristics during the growth period of crops in the middle and southern part of Ningxia. [Method] Through Takahashi's evaporation equation,linear trend analysis,Mann - Kendall,Lepage,wavelet analysis,the characteristics of available precipitation and its abnormal characteristics during its growth period in Ningxia were analyzed based on monthly precipitation ( March - September) ,temperature,and NCAR/NCEP reanalysis data in 9 observation stations from 1961 to 2010. [Result] In recent 50 years,the available precipitation during the growth period of crops in central drought area and south hilly area varied a lot,more in the south and less in the north. The available precipitation in these two areas was reducing and varied a lot in different ages. The available precipitation was less in the middle drought region after 1970s and in the southern hilly region after 1990s and the available precipitation in middle drought area changed significantly. The available precipitation in the two areas appeared in July,August,and September,above 76% of general growth period, while that in March,April and May was 14% lower than that in growth period. No abrupt changes in central drought area and south hilly area. There were the periods of 5 -7 a and 2 -3 a oscillations in the middle drought region,2 -3 a and 10 -12 a oscillations in the southern hilly region. There were negative anomaly field at 500hPa height in high-precipitation years between the Baikal and the China's northwestern,and there were positive anomaly field in low-precipitation years. [Conclusion]The study provided reference for the reasonable utilization of available water resources in central and south Ningxia.
基金supported by the National K&D Program of China(2022YFD2300201)the National Natural Science Foundation of China(U21A2040)+4 种基金the Major Science and Technology Program of Jilin Province(YDZJ202303CGZH023)the National Natural Science Foundation of China(42077443)the Science and Technology Development Planning of Jilin Province(20210203153SF)the Key Scientific and Technology Research and Development Program of Jilin Province(20200403065 SF)the Construction Project of the Science and Technology Innovation Center(20210502008ZP).
文摘Owing to the complexity and variability of global climate,the study of extreme events to ensure food security is particularly critical.The standardized precipitation requirement index(SPRI)and chilling injury index(I_(Ci))were introduced using data from agrometeorological stations on the Songliao Plain between 1981 and 2020 to identify the spatial and temporal variability of drought,waterlogging,and low-temperature cold damage during various maize growth periods.Compound drought and low-temperature cold damage events(CDLEs)and compound waterlogging and low-temperature cold damage events(CWLEs)were then identified.To measure the intensity of compound events,the compound drought and low-temperature cold damage magnitude index(CDLMI),and compound waterlogging and low-temperature cold damage magnitude index(CWLMI)were constructed by fitting marginal distributions.Finally,the effects of extreme events of various intensities on maize output were examined.The findings demonstrate that:(1)There were significant differences in the temporal trends of the SPRI and ICiduring different maize growth periods.Drought predominated in the middle growth period(MP),waterlogging predominated in the early growth period(EP)and late growth period(LP),and both drought and waterlogging tended to increase in intensity and frequency.The frequency of low-temperature cold damage showed a decreasing trend in all periods.(2)The CDLMI and CWLMI can effectively determine the intensity of CDLEs and CWLEs in the study area;these CDLEs and CWLEs had higher intensity and frequency in the late growth period.(3)Compared to single events,maize relative meteorological yield had a more significant negative correlation with the CDLMI and CWLMI.
基金supported by National Natural Science Foundation of China(51475278)China Shandong Province Agricultural Machinery Equipment Research and Development Innovation Project(2018YF002)+2 种基金China Natural Science Foundation of Shandong Province(ZR2019PC024)China Scientific Research and Development Projects of Universities in Shandong Province(J18KA128)China and the Funds of Shandong‘Double Tops’Program(SYL2017XTTD14),China.
文摘Dynamic acquisition of crop morphology is beneficial to real-time variable decision of precise spraying operations in fields.However,the existing spraying quantity regulation has high tolerance on the statistical characteristics of regional morphology,so expensive LiDAR and ultrasonic radar can’t make full use of their high accuracy,and can reduce decision speed because of too much detail of branches and leaves.Therefore,designing a novel recognition system embedded machine learning with low-cost monocular vision is more feasible,especially in China,where the agricultural implements are medium sizes and cost-sensitive.In addition,we found that the growth period of crops is an important reference index for guiding spraying.So,taking cotton as a case study,a cotton morphology acquisition by a single camera is established,and a cotton growth period recognition algorithm based on Convolution Neural Network(CNN)is proposed in this paper.Through the optimization process based on confusion matrix and recognition efficiency,an optimized CNN model structure is determined from 9 different model structures,and its reliability was verified by changing training sets and test sets many times based on the idea of kfold test.The accuracy,precision,recall,F1-score and recognition speed of this CNN model are 93.27%,95.39%,94.31%,94.76%and 71.46 ms per image,respectively.In addition,compared with the performance of VGG16 and AlexNet,the convolution neural network model proposed in this paper has better performance.Finally,in order to verify the reliability of the designed recognition system and the feasibility of the spray decision-making algorithm based on CNN,spraying deposition experiments were carried out with 3 different growthperiods of cotton.The experiments’results validate that after the optimal spray parameters were applied at different growth periods respectively,the average optimum index in 3 growth periods was 42.29%,which was increased up to 62.24%than the operations without distinguishing growth periods.
文摘Experiments were conducted to examine the effects of salinity fluctuation on the intermolt period and growth of Fenneropenaeus chi- nensis with an initial body weight of (0.553 2±0.000 1)g (mean plus or minus SE). The salinity (S0) of the control treatment is 30 throughout the experiment, while the treatments S2, S4, S7 and S10 are subjected to different salinity fluctuations, and the ranges are 2, 4, 7 and 10, respectively. After a 30-day feeding trial, the longest and the shortest intermolt periods of the shrimp occur under Treatments S10 and S2, respectively (difference 37.14%). The special growth rates (SGR) of the shrimp under the five treatments are ranked as S7> S4> S2> S10> S0, and the SGR of the shrimp under Treatment S0 is lower than that under Treatments S4 and S7 by 22.36% and 28.11%, respectively (P< 0.05). The minimal feed intake (FI) of the experimental animals occurs in Treatment S0 (84.04% and 88.54% of that under Treatments S4 and S7, respectively) (P< 0.05). There are no significant differences in the food conversion efficiency (FCE) of the shrimp under the five treatments (P> 0.05).
文摘Deprivation is an environmental experience that organisms are continually exposed to. However, few studies analyze deprivation effects on the consumption pattern during the post-deprivation period systematically. The aim of this study was to evaluate the deprivation effect on feeding pattern, growth rate and body weight during post-deprivation. Sixteen albino rats (3 months old at the beginning of the experiment) were exposed to 72-hour total food deprivation every 15 days. Food and water were freely available during non-deprivation periods. Rats completed three cycles comprised by a free access period followed by food deprivation. Once deprivation was removed, food and water consumption increased and then decreased, while body weight was recovered. Growth rate increased after every deprivation period and reached similar levels to those presented by the control group. Depriving rats from one commodity (i.e., food) cause them to restrain their consumption of the other freely available commodity (i.e., water). Results confirm that food deprivation modifies growth rate, water and food consumption. Additionally, during post-deprivation period, differences between males and females were not registered.
基金Supported by National Natural Science Foundation of China(40771064)Plan for Person with ability of Chinese Ministry of Education in 21 Century& Lanzhou University Foundation for Personwith Ability
文摘Based on the definition of the concept of city growth, the paper mainly discussed the factors which impact the growth of Chinese cities in the transitional period by selecting the proportion of city construction land area to the area of the city X1(%), green coverage ratio of the built up area X2(%), the ratio of personnel involved in the secondary industry X3(%), the GDP per capita X4(×104)and other 43 indicators, by relying on the relevant data from China Urban Statistical Yearbook(2008), applying SPSS statistical software and by applying the Factor Analysis and Regression Analysis. The results show that the factors which affect the city growth have four major groups, namely economic and institutional factors, location factors, environmental factors and social cultural services and functions. Among the factors which affect Chinese city growth, the general budgetary expenditures and the general budgetary revenues of local public finance are the most important factors. The general budgetary expenditures of local finance, the general budgetary revenues, the lands of urban construction and other 12 factors obtained by gradually excluding method can be used to present the coefficient of city growth.
文摘This article is concerned with a mathematical model of tumor growth governed by 2<sup>nd</sup> order diffusion equation . The source of mitotic inhibitor is almost periodic and time-dependent within the tissue. The system is set up with the initial condition C(r, 0) = C<sub>0</sub>(r) and Robin type inhomogeneous boundary condition . Under certain conditions we show that there exists a unique solution for this model which is almost periodic.
