The Response Of Different Maize Hybrids To Planting Density

To study the response and evolution of growth period structure,plant type trait structure,photosynthetic efficiency trait structure and grain yield trait structure of main single crosses of maize at different densities in different periods,which can provide traits for designing single crosses suitable for high density planting.Selected reference.This experiment selected 12 large-area varieties in China from 1980 s to 2010 s,including Zhongdan No.2,Sidan19,Shendan No.7,Danyu13,Yudan 13,Nongda 108,Zhengdan 958,and Shandan 20.Xianyu 335,Demeiya No.3,DK516,Huamei No.1,conducted two-year four-point experimental research in Northeast China(Shenyang Shenyang and Jilin Gongzhuling)and Huanghuaihai District(Shijiazhuang and Henan Xinxiang)in 2017-2018.The aim of this study is to:(1)the growth period structure,plant type trait structure,photosynthetic efficiency trait structure and grain yield trait structure of typical hybrids of different ages under the same planting density(4000,6000,8000,10000 plants/667 m2)The evolution law;(2)the growth period structure,plant type trait structure,photosynthetic efficiency trait structure and grain yield trait structure of the same hybrid or the same age hybrids under four planting densities;(3)According to the growth period structure The evolution of plant type trait structure,photosynthetic efficiency trait structure and grain yield trait structure,and the selection index of single crosses suitable for high density planting were proposed.The main findings are as follows:(1)With the increase of density,the growth period of 1980 s corn hybrids gradually extended.The plant type was compact and then compact and compact.The plant height and ear height increased first and then decreased,chlorophyll content decreased first and then increased,and the yield gradually decreased.1990 s With the increase of density,the growth of maize hybrids first increased and then decreased.The plant type was first compact,then loose and compact,and the plant height and ear height increased first and then decreased.The chlorophyll content increased first,then decreased and then increased,and the yield gradually decreased.With the increase of density,the growth period of 2000 s corn hybrids gradually extended,the plant type was first compact and then loose,the chlorophyll content increased first,then decreased and then increased,and the yield gradually decreased.The growth of 2010 s maize hybrids gradually increased with the increase of density.The plant type was first compact and loose,the plant height gradually decreased,the ear height increased and stabilized,the chlorophyll content decreased gradually,and the yield increased first and then decreased.(2)At the density of 4000-6000 plants/667m2,with the increase of planting density,the growth period of 1980 s hybrids was prolonged,the plant type became compact,the chlorophyll content decreased,and the yield decreased;the growth period of 1990 s and 2000 s hybrids was extended,plant type It became compact,the content of chlorophyll decreased,and the yield decreased.The growth period of hybrids in 2010 s was prolonged,the plant type became loose,the chlorophyll content increased,and the yield increased.At the density of 6000-8000 plants/667m2,with the increase of planting density,1980 s and The growth period of the 1990 s hybrids was prolonged,the plant type became loose,the chlorophyll content decreased,and the yield decreased.The growth period of the hybrids of 2000 s and 2010 s was prolonged,the plant type became compact,the chlorophyll content decreased,and the yield decreased;at the density of 8000-10000 plants/667m2 With the increase of planting density,the growth period of 1980 s and 1990 s hybrids was prolonged,the plant type became compact,the chlorophyll content increased,and the yield decreased.The growth period of 2000 s hybrids prolonged,the plant type deteriorated,the chlorophyll content increased,and the yield decreased.The growth period of the 2010 s hybrids was prolonged,the plant type was worse,the chlorophyll content was decreased,and the yield was decreased.(3)With the change of age,the yield of corn hybrids has been significantly improved,but due to the different chronological characteristics,the yield of hybrids in each era is affected by different traits.The yield of hybrids in 1980 s was mainly restricted by growth period,ear row number and seed yield.Chlorophyll content,ear length and grain number were good.The yield of 1990 s hybrids was mainly restricted by chlorophyll content,water content during harvest and bulk density.The number of rows and rows of grain performed well;the yield of 2000 s hybrids was mainly restricted by the lodging rate,the fold rate,the length of the panicle,the leaf phase value,the ear diameter,the ear row number and the 100-grain weight.The yield of the 2010 s hybrid was mainly affected.The ear diameter,the number of rows,the number of rows,the weight of 100-grain weight,the growth period,the lodging rate,the lodging rate,and the water content and seeding rate during the harvest period performed well.Combined with the results of correlation analysis,it can be seen that during the replacement of maize hybrids in China,the traits of the panicles,especially the 100-grain weight,the number of rows and the number of rows,have the greatest impact on yield,and with the increase of planting density,this effect gradually increase.