| Huanghuaihai is the second largest area of soybean cultivation in China.With increasing use of agricultural machine,soil compaction has become ever more serious in this area,which is one of the main obstacles for increase and stabling soybean production.This study analyzed the root characteristics of twenty-three varieties deriving from two local soybeans(Binhai Dabaihua and Juxuan23),to investigate their evolution law of root under uncompacted conditions.And the study compared their biological characters of above-ground and root between compacted and uncompacted conditions,to select the soybean varieties that can resisted to compaction,then to further analyze the reasons for these varieties to resist soil compaction.Form the study,we found that(1)Youbian 30,Kefeng 6,Zhonghuang 13 and Zhonghuang 37,which cultivated in the north of the Yellow River,had significantly difference in root characteristics under uncompacted condition.The length of main root,maximum width and dry weight of root of the four varieties increased significantly with the increase of cultivated years.Yudou 22,Wansu 01-15,Wansu 2156,Shangdou 1201,Shangdou 1310,and Zheng1307,which cultivated in the south of the Yellow River,had a significant increase in the number of lateral roots,the number of fibrous roots and the root area with the increase of cultivated years.The ten varieties cultivated in the region of Yellow River all derived from Binhai Dabaihua.Yidupingdinghuang,Fengshouhuang,Ludou 4,Ludou 11,Hedou 13,Shanning 16 and Shanning 21 derived from Juxuan 23,also had a significant difference in root characteristics.The maximum width,area and density of root,number of lateral roots,and main root length of the seven varieties,which cultivated in Shandong,increase significantly with the increase of cultivated years.There were two common points of root evolution in the three cultivated areas.One was expanding the growth space by increase maximum width,main root length,the other was increasing the contact area between the root system and the soil by increase the number of lateral roots and the number of fibrous roots.(2)In 20-40 cm layer,soil bulk density increased after rolling by agricultural machine.And soil penetration resistance under compaction conditions in this layer increased 65.6% than which in uncompacting condition.Under compaction condition,there were 80% varieties with lower emergence rate and plant height,70%varieties with more main stem nodes,60% varieties with higher stem thickness and aboveground biomass,90% varieties with lower length of main root,60% varieties with more side angle,maximum width and area of root.The other root traits,such as side root number,root tip number and diameter,root density and root dry weight,were different in different varieties.(3)There were 10 varieties,including Shangcaiercaopingdingshi,YiduPingdinghuang,Wenfeng 7,Jidou 8,Ludou 11,Jindou 25,Jidou 12,Zheng 92116,Hedou 13 and Jidou 17,that assumed no reduce in yield between compacting and uncompacting conditions.All the 10 varieties were plant dwarfing,stem widening and no reduction in the number of main stem nodes and biomass in the above-ground biological traits.Some of the 10 varieties ensured the absorption of soil nutrients and maintained underground and above-ground biomass by increasing the maximum root width,root area,and expanding the root level Space,while theother varieties ensured the stable yield of crops by increasing the number of lateral roots and the number of root tips.These changes in biological characters of above-ground and root were the reasons for the 10 varieties to resist soil compaction.This study had initially grasped the succession law of soybean root characteristics in Huanghuaihai area,the root characteristics under compaction conditions,and the mechanism of compaction resistant varieties,which provided data support and theoretical basis for soybean breeding under the mechanized production conditions in the new era. |
PDF Full Text Request