改变玉米田间种植模式是提高玉米单产的重要措施之一。本文在大田试验条件下,以耐密品种(郑单958)和中密品种(沈玉21)研究了三比空密疏密、大垄双行和等行距(CK)3种种植模式对春玉米产量形成及其生长发育特征的影响。结果表明,田间种植...改变玉米田间种植模式是提高玉米单产的重要措施之一。本文在大田试验条件下,以耐密品种(郑单958)和中密品种(沈玉21)研究了三比空密疏密、大垄双行和等行距(CK)3种种植模式对春玉米产量形成及其生长发育特征的影响。结果表明,田间种植形式的改变可以显著影响玉米群体产量及其生长发育特征。耐密品种以大垄双行种植模式为宜,可以增加玉米的株高、茎粗,提高叶面积和光能利用率,促进干物质积累,2年平均产量为8882.36 kg hm 2,比对照增加6.51%,增产的原因是百粒重和穗行数的显著提高;中密品种以大垄双行和三比空种植模式为宜,2种种植模式均可增加玉米的株高、茎粗,提高叶面积和光能利用率,促进干物质积累,且与耐密品种表现不同,2年平均产量分别为8294.58 kg hm 2和8188.30 kg hm 2,比对照增加21.36%和19.81%,增产的原因是行粒数的显著增加。因此,我们认为在辽西地区特定的自然条件下大垄双行是提高玉米单产的最佳种植模式。展开更多
Exactly measuring the degradation degree of ecosystems is the basis and precondition of restoring ecosystems. At present,degradation degree is usually analyzed qualitatively.In this paper,quantitative classification m...Exactly measuring the degradation degree of ecosystems is the basis and precondition of restoring ecosystems. At present,degradation degree is usually analyzed qualitatively.In this paper,quantitative classification method was used to study the degradation degree of ecosystem in hilly region of western Liaoning,which was measured by the degradation degree of habitat.The result shows that the habitat in the northern slope of mountains has been degraded to certain stage between shrubbery and pioneer tree forest,which provides theoretical basis for vegetation restoration practice. Moreover,the result is beneficial for studying the degradation degree of ecosystems in other regions or of other types.展开更多
We herein describe a partial postcranial skeleton of a sauropod dinosaur recovered from the Lower Cretaceous Jehol Group in the Beipiao area of western Liaoning Province, northeastern China. A suite of features it pos...We herein describe a partial postcranial skeleton of a sauropod dinosaur recovered from the Lower Cretaceous Jehol Group in the Beipiao area of western Liaoning Province, northeastern China. A suite of features it possesses, including the camellate internal structure of its presacral elements, the existence of pneumatocoels on the proximal ends of the dorsal ribs, and especially the medially deflected proximal portion of the femur, definitively establish the titanosauriform affinities of the specimen. It differs from other titanosauriforms in having a craniocaudally elongate coracoid with a squared cranioventral extreme and a long, smooth, and slightly convex acetabular edge of the pubis. It represents a new taxon, Dongbeititan dongi gen. et sp. nov. Comparative studies suggest that Dongbeititan is a basal titanosauriform, more derived than Euhelopus, Fusuisaurus, and Huanghetitan, but less derived than Gobititan and Jiutaisaurus. Dongbeititan represents the first sauropod dinosaur reported from the Lower Cretaceous Jehol Group of western Liaoning Province.展开更多
文摘改变玉米田间种植模式是提高玉米单产的重要措施之一。本文在大田试验条件下,以耐密品种(郑单958)和中密品种(沈玉21)研究了三比空密疏密、大垄双行和等行距(CK)3种种植模式对春玉米产量形成及其生长发育特征的影响。结果表明,田间种植形式的改变可以显著影响玉米群体产量及其生长发育特征。耐密品种以大垄双行种植模式为宜,可以增加玉米的株高、茎粗,提高叶面积和光能利用率,促进干物质积累,2年平均产量为8882.36 kg hm 2,比对照增加6.51%,增产的原因是百粒重和穗行数的显著提高;中密品种以大垄双行和三比空种植模式为宜,2种种植模式均可增加玉米的株高、茎粗,提高叶面积和光能利用率,促进干物质积累,且与耐密品种表现不同,2年平均产量分别为8294.58 kg hm 2和8188.30 kg hm 2,比对照增加21.36%和19.81%,增产的原因是行粒数的显著增加。因此,我们认为在辽西地区特定的自然条件下大垄双行是提高玉米单产的最佳种植模式。
文摘Exactly measuring the degradation degree of ecosystems is the basis and precondition of restoring ecosystems. At present,degradation degree is usually analyzed qualitatively.In this paper,quantitative classification method was used to study the degradation degree of ecosystem in hilly region of western Liaoning,which was measured by the degradation degree of habitat.The result shows that the habitat in the northern slope of mountains has been degraded to certain stage between shrubbery and pioneer tree forest,which provides theoretical basis for vegetation restoration practice. Moreover,the result is beneficial for studying the degradation degree of ecosystems in other regions or of other types.
基金Funding was provided by the Bureau of Dalian Science and Technology,the Ministry of Science and Technology of China(973 Project:2006CB701405)the National Natural Science Foundation of China(40672007)the Hundred Talents Project of the Ministry of Land and Resources of China.
文摘We herein describe a partial postcranial skeleton of a sauropod dinosaur recovered from the Lower Cretaceous Jehol Group in the Beipiao area of western Liaoning Province, northeastern China. A suite of features it possesses, including the camellate internal structure of its presacral elements, the existence of pneumatocoels on the proximal ends of the dorsal ribs, and especially the medially deflected proximal portion of the femur, definitively establish the titanosauriform affinities of the specimen. It differs from other titanosauriforms in having a craniocaudally elongate coracoid with a squared cranioventral extreme and a long, smooth, and slightly convex acetabular edge of the pubis. It represents a new taxon, Dongbeititan dongi gen. et sp. nov. Comparative studies suggest that Dongbeititan is a basal titanosauriform, more derived than Euhelopus, Fusuisaurus, and Huanghetitan, but less derived than Gobititan and Jiutaisaurus. Dongbeititan represents the first sauropod dinosaur reported from the Lower Cretaceous Jehol Group of western Liaoning Province.
