为了探明四川盆地东南部气象因子对杂交中稻产量的影响,并提出相应的丰产技术对策。2015年和2016年,以2个杂交中稻品种II优602和旌优127为材料,在5个播种期和高氮低密与低氮高密2种栽培方式下,研究了四川盆地东南部气象因子对杂交中稻...为了探明四川盆地东南部气象因子对杂交中稻产量的影响,并提出相应的丰产技术对策。2015年和2016年,以2个杂交中稻品种II优602和旌优127为材料,在5个播种期和高氮低密与低氮高密2种栽培方式下,研究了四川盆地东南部气象因子对杂交中稻产量的影响。结果表明,随着播种期推迟,平均全生育期从148.13 d逐渐缩短到123.25 d,缩短了14.77%;气象因子对水稻全生育期的影响主要在营养生长期,生殖生长期受其影响较小。年度间、栽培方式间、品种间稻谷产量差异均不显著;随着播种期推迟,稻谷产量呈下降趋势,从3月5日的8507.76 kg hm^(-2)下降到5月24日的6251.01 kg hm^(-2),降低了26.53%。播种–移栽、移栽–拔节、营养生长的日数和全生育期日数分别与穗粒数和产量呈极显著正相关。气象因子对产量的影响在不同年份和不同品种间的表现不一致:优质稻旌优1272015年的结实率、千粒重和产量分别与齐穗–成熟的日平均气温呈极显著正相关,分别与拔节–齐穗的日照时数呈显著负相关;2016年的穗粒数、产量分别与播种—移栽日最高气温、移栽—拔节的日平均气温呈极显著负相关。高产品种II优602,2015年的有效穗、千粒重和产量分别与移栽—拔节的降雨量呈显著或极显著负相关,2016年的穗粒数和产量分别与移栽–拔节的日最高气温呈显著或极显著负相关,结实率、千粒重和产量分别与拔节–齐穗的日平均相对湿度呈显著正相关。生产上一季中稻模式的最佳播种期在3月5日至3月25日,而中稻-再生稻模式则在3月5日至3月25日期间尽可能早播,以利于提高再生稻安全齐穗保证率。展开更多
Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Re...Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Reserve. Although the typhoon disturbance occurred more than two decades ago, the effects of the typhoon still remain within the study area. Few studies have focused on mapping and assessing disturbances across broad spatial and temporal scales. For this study, we first generated a map of forest composition prior to the typhoon disturbance, which served as a baseline data for the extraction of disturbed area. Then, the Disturbance Index(DI) method was tested for mapping the extent and magnitude of disturbance in the study area by applying a Tasseled Cap transformation to the Landsat imagery. The Landsatbased DI method estimated that an area of 13,764.78 ha of forest was disturbed by the typhoon. Based on visual assessments, these results correspond closely with the reference map derived from ground surveys. These results also revealed the influence of local topographic features on the distribution of windthrow areas. Windthrow areas were more pronounced inareas with elevations ranging from 1,000 to 2,000 m, slopes of less than 10 degrees, and southwestern to northwestern aspects. In addition, the relatively long(25 years) post-typhoon recovery period assessed by this study provided a more comprehensive analysis of the dynamics of forest recovery processes over time. Windthrow areas did not recover immediately after the typhoon, likely due to forest management practices enacted at the time. So far, forest recovery has proceeded more rapidly at elevations below 1,400 m, particularly on western slopes within the study area. Finally, a time series of DI values within the study period suggests a secondary disturbance may have occurred between 2000 and 2001.展开更多
The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics...The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.展开更多
Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective ...Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective forest fire management.To reveal biogeoclimatic and anthropogenic influences,this study introduced a geographical detector model to quantitatively examine the effects of multiple individual factors and their combinations on spatial patterns of fire occurrence in the Greater Khingan Mountains between 1980 and 2009.The geographical detector computes the explanatory power(q value)to measure the connection between driving factors and spatial distributions of fire occurrence.Kernel density estimation revealed the spatial variability of fire occurrence which was impacted by bandwidth.30 km might be the optimal bandwidth in this study.The biogeoclimatic and anthropogenic effects were explored using topography,climate,vegetation,and human activity factors as proxies.Our results indicated that solar radiation had the most influence on the spatial pattern of fire occurrence in the study area.Meanwhile,Normalized Difference Vegetation Index,temperature,wind speed,and vegetation type were determined as the major driving factors.For various groups of driving factors,climate variables were the dominant factors for the density of fire occurrence,while vegetation exerted a strong influence.The interactions between the driving factors had a more significant impact than a single factor.Individually,the factors in the topography and human activity groups exhibited weaker influences.However,their effects were enhanced when combined with climate and vegetation factors.This study improves our understanding of various driving factors and their combined influences on fire occurrences of the study area in a spatial context.The findings of this study verify that the geographical detector is applicable in revealing the driving factors of fire occurrence.展开更多
Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at diff...Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at different yield levels(medium yielding site(MYS)Luzhou City and high yielding site(HYS)Deyang City had not been described.Field experiments with hybrid rice Rongyou1015 were conducted to study the effects of two plant densities.High plant density(HD),low plant density(LD)and four N rates(without N,N_(0);a recommended N rate of 195 kg•hm^(-2),N_(CK);a 23%reduction in N rate,N_(-23%);a 46%reduction in N rate,N_(-46%)on yield attributes,grain yield,TNU and NUE of hybrid rice were studied under different yield levels in 2016-2017.The results showed that the grain yield and NUE of hybrid rice in response to plant density and N rate varied with yield levels.For MYS,reducing N rate by 46%result in significantly lower grain yield at LD treatment;whereas at HD treatment the grain yield of hybrid rice under N_(-46%) and N_(CK) were equal.For HYS,reducing N rate by 46% result in significantly lower grain yield regardless of low plant density and high plant density;however,a reduction in N rate by 23%increased grain yield,AE_(N) by 36%,PFP_(N) by 31% and RE_(N) by 11% over N_(CK) at HD treatment.Higher grain yield of hybrid rice under the combination of HD with low N rate was attributable to improvement in spikelets per panicle and harvest index.The results suggested that high plant density with low N rate might be an effective approach to improve grain yield and NUE in rice production,but reduction in N application rate was determined,according to yield levels.展开更多
目的:通过生物信息学软件分析和预测在人骨肉瘤中能够靶向结合Gab2的miRNA。方法:首先通过生物信息学软件mir Walk 2. 0预测可以靶向结合Gab2的miRNA,然后用miRanda得到Gab2-miRNA的热力学稳定性评分和序列保守性评分。并通过人骨肉瘤mi...目的:通过生物信息学软件分析和预测在人骨肉瘤中能够靶向结合Gab2的miRNA。方法:首先通过生物信息学软件mir Walk 2. 0预测可以靶向结合Gab2的miRNA,然后用miRanda得到Gab2-miRNA的热力学稳定性评分和序列保守性评分。并通过人骨肉瘤miRNA芯片GSE70367得到在人骨肉瘤中差异表达的miRNA。在生物信息学软件打分较高的miRNA中选出差异表达的miRNA,从而选出人骨肉瘤中能与Gab2结合的特异性最强,稳定性最高的miRNA。结果:mir Walk 2. 0预测有22个miRNA可与Gab2靶向结合;其中,miR-1236-3p、miR-218-5p与Gab2结合的稳定性和特异性最好;在人骨肉瘤中差异表达的miRNA有184个,而miR-218-5p的表达也存在差异性,并且表达下调。结论:在人骨肉瘤中miR-218-5p可能靶向结合于Gab2,Gab2是miR-218-5p的靶基因。展开更多
文摘为了探明四川盆地东南部气象因子对杂交中稻产量的影响,并提出相应的丰产技术对策。2015年和2016年,以2个杂交中稻品种II优602和旌优127为材料,在5个播种期和高氮低密与低氮高密2种栽培方式下,研究了四川盆地东南部气象因子对杂交中稻产量的影响。结果表明,随着播种期推迟,平均全生育期从148.13 d逐渐缩短到123.25 d,缩短了14.77%;气象因子对水稻全生育期的影响主要在营养生长期,生殖生长期受其影响较小。年度间、栽培方式间、品种间稻谷产量差异均不显著;随着播种期推迟,稻谷产量呈下降趋势,从3月5日的8507.76 kg hm^(-2)下降到5月24日的6251.01 kg hm^(-2),降低了26.53%。播种–移栽、移栽–拔节、营养生长的日数和全生育期日数分别与穗粒数和产量呈极显著正相关。气象因子对产量的影响在不同年份和不同品种间的表现不一致:优质稻旌优1272015年的结实率、千粒重和产量分别与齐穗–成熟的日平均气温呈极显著正相关,分别与拔节–齐穗的日照时数呈显著负相关;2016年的穗粒数、产量分别与播种—移栽日最高气温、移栽—拔节的日平均气温呈极显著负相关。高产品种II优602,2015年的有效穗、千粒重和产量分别与移栽—拔节的降雨量呈显著或极显著负相关,2016年的穗粒数和产量分别与移栽–拔节的日最高气温呈显著或极显著负相关,结实率、千粒重和产量分别与拔节–齐穗的日平均相对湿度呈显著正相关。生产上一季中稻模式的最佳播种期在3月5日至3月25日,而中稻-再生稻模式则在3月5日至3月25日期间尽可能早播,以利于提高再生稻安全齐穗保证率。
基金sponsored by the "State Key Laboratory of Resources and Environmental Information System" and the "Fundamental Research Funds for the Central Universities" (No. 11SSXT134)
文摘Monitoring forest disturbances is important for understanding changes in ecosystems. The 1986 Typhoon Vera was a serious disturbance that severely impacted the forest ecosystems of Changbai Mountain National Nature Reserve. Although the typhoon disturbance occurred more than two decades ago, the effects of the typhoon still remain within the study area. Few studies have focused on mapping and assessing disturbances across broad spatial and temporal scales. For this study, we first generated a map of forest composition prior to the typhoon disturbance, which served as a baseline data for the extraction of disturbed area. Then, the Disturbance Index(DI) method was tested for mapping the extent and magnitude of disturbance in the study area by applying a Tasseled Cap transformation to the Landsat imagery. The Landsatbased DI method estimated that an area of 13,764.78 ha of forest was disturbed by the typhoon. Based on visual assessments, these results correspond closely with the reference map derived from ground surveys. These results also revealed the influence of local topographic features on the distribution of windthrow areas. Windthrow areas were more pronounced inareas with elevations ranging from 1,000 to 2,000 m, slopes of less than 10 degrees, and southwestern to northwestern aspects. In addition, the relatively long(25 years) post-typhoon recovery period assessed by this study provided a more comprehensive analysis of the dynamics of forest recovery processes over time. Windthrow areas did not recover immediately after the typhoon, likely due to forest management practices enacted at the time. So far, forest recovery has proceeded more rapidly at elevations below 1,400 m, particularly on western slopes within the study area. Finally, a time series of DI values within the study period suggests a secondary disturbance may have occurred between 2000 and 2001.
基金supported by the Special Fund of National Seismological Bureau, China (Grant No. 201208005)the National Natural Science Foundation of China (Grant No. 41171072)the National Grand Fundamental Research 973 Program of China (Grant No. 2009CB426305)
基金supported by the National Natural Science Foundation of China (Grant No. 41601438 and 41571078)the Fundamental Research Funds for the Central Universities (Grant No.2412016KJ026)the Foundation of the Education Department of Jilin Province in the 13~(th) Five-Year project (Grant No. JJKH20170916KJ)
文摘The Changbai Mountains and the Appalachian Mountains have similar spatial contexts.The elevation,latitude,and moisture gradients of both mountain ranges offer regional insight for investigating the vegetation dynamics in eastern Eurasia and eastern North America.We determined and compared the spatial patterns and temporal trends in the normalized difference vegetation index(NDVI)in the Changbai Mountains and the Appalachian Mountains using time series data from the Global Inventory Modeling and Mapping Studies 3^(rd) generation dataset from 1982 to 2013.The spatial pattern of NDVI in the Changbai Mountains exhibited fragmentation,whereas NDVI in the Appalachian Mountains decreased from south to north.The vegetation dynamics in the Changbai Mountains had an insignificant trend at the regional scale,whereas the dynamics in the Appalachian Mountains had a significant increasing trend.NDVI increased in 55% of the area of the Changbai Mountains and in 95% of the area of the Appalachian Mountains.The peak NDVI occurred one month later in the Changbai Mountains than in the Appalachian Mountains.The results revealed a significant increase in NDVI in autumn in both mountain ranges.The climatic trend in the Changbai Mountains included warming and decreased precipitation,and whereas that in the Appalachian Mountains included significant warming and increased precipitation.Positive and negative correlations existed between NDVI and temperature and precipitation,respectively,in both mountain ranges.Particularly,the spring temperature and NDVI exhibited a significant positive correlation in both mountain ranges.The results of this study suggest that human actives caused the differences in the spatial patterns of NDVI and that various characteristics of climate change and intensity of human actives dominated the differences in the NDVI trends between the Changbai Mountains and the Appalachian Mountains.Additionally,the vegetation dynamics of both mountain ranges were not identical to those in previous broader-scale studies.
基金funded by the National Natural Science Foundation of China(Grant No.41601438)Fundamental Research Funds for the Central Universities(Grant NO.2412019FZ002)。
文摘Fire is an important disturbance in terms of forest management.A comprehensive understanding of the relationships between the spatial distribution of fire occurrence and its driving factors are critical for effective forest fire management.To reveal biogeoclimatic and anthropogenic influences,this study introduced a geographical detector model to quantitatively examine the effects of multiple individual factors and their combinations on spatial patterns of fire occurrence in the Greater Khingan Mountains between 1980 and 2009.The geographical detector computes the explanatory power(q value)to measure the connection between driving factors and spatial distributions of fire occurrence.Kernel density estimation revealed the spatial variability of fire occurrence which was impacted by bandwidth.30 km might be the optimal bandwidth in this study.The biogeoclimatic and anthropogenic effects were explored using topography,climate,vegetation,and human activity factors as proxies.Our results indicated that solar radiation had the most influence on the spatial pattern of fire occurrence in the study area.Meanwhile,Normalized Difference Vegetation Index,temperature,wind speed,and vegetation type were determined as the major driving factors.For various groups of driving factors,climate variables were the dominant factors for the density of fire occurrence,while vegetation exerted a strong influence.The interactions between the driving factors had a more significant impact than a single factor.Individually,the factors in the topography and human activity groups exhibited weaker influences.However,their effects were enhanced when combined with climate and vegetation factors.This study improves our understanding of various driving factors and their combined influences on fire occurrences of the study area in a spatial context.The findings of this study verify that the geographical detector is applicable in revealing the driving factors of fire occurrence.
基金Supported by Earmarked Fund for Modern Agro-industry Technology of China(CARS-01-25)National Key Research and Development Program of China(2017YFD0301705)Foundation of Youth Science Program of Sichuan Agricultural Sciences Academy(2019QNJJ-020)。
文摘Increased plant density with low N rate was a recommended strategy to increase grain yield and N use efficiency(NUE);however,grain yield,NUE and the total N uptake(TNU)responses of hybrid rice to this strategy at different yield levels(medium yielding site(MYS)Luzhou City and high yielding site(HYS)Deyang City had not been described.Field experiments with hybrid rice Rongyou1015 were conducted to study the effects of two plant densities.High plant density(HD),low plant density(LD)and four N rates(without N,N_(0);a recommended N rate of 195 kg•hm^(-2),N_(CK);a 23%reduction in N rate,N_(-23%);a 46%reduction in N rate,N_(-46%)on yield attributes,grain yield,TNU and NUE of hybrid rice were studied under different yield levels in 2016-2017.The results showed that the grain yield and NUE of hybrid rice in response to plant density and N rate varied with yield levels.For MYS,reducing N rate by 46%result in significantly lower grain yield at LD treatment;whereas at HD treatment the grain yield of hybrid rice under N_(-46%) and N_(CK) were equal.For HYS,reducing N rate by 46% result in significantly lower grain yield regardless of low plant density and high plant density;however,a reduction in N rate by 23%increased grain yield,AE_(N) by 36%,PFP_(N) by 31% and RE_(N) by 11% over N_(CK) at HD treatment.Higher grain yield of hybrid rice under the combination of HD with low N rate was attributable to improvement in spikelets per panicle and harvest index.The results suggested that high plant density with low N rate might be an effective approach to improve grain yield and NUE in rice production,but reduction in N application rate was determined,according to yield levels.
文摘目的:通过生物信息学软件分析和预测在人骨肉瘤中能够靶向结合Gab2的miRNA。方法:首先通过生物信息学软件mir Walk 2. 0预测可以靶向结合Gab2的miRNA,然后用miRanda得到Gab2-miRNA的热力学稳定性评分和序列保守性评分。并通过人骨肉瘤miRNA芯片GSE70367得到在人骨肉瘤中差异表达的miRNA。在生物信息学软件打分较高的miRNA中选出差异表达的miRNA,从而选出人骨肉瘤中能与Gab2结合的特异性最强,稳定性最高的miRNA。结果:mir Walk 2. 0预测有22个miRNA可与Gab2靶向结合;其中,miR-1236-3p、miR-218-5p与Gab2结合的稳定性和特异性最好;在人骨肉瘤中差异表达的miRNA有184个,而miR-218-5p的表达也存在差异性,并且表达下调。结论:在人骨肉瘤中miR-218-5p可能靶向结合于Gab2,Gab2是miR-218-5p的靶基因。
