Study On Genetic Improvement Effect Of Density Tolerance And Lodging Resistance Of Reid Group Germplasm In Maize

Corn is the most important food crop in China,in feed,chemical,food and other fields of corn demand continues to rise,China has become a corn importer.In the limited arable land area to further improve the yield,only through genetic improvement,breeding good new varieties,to meet the demand of increasing corn yield year by year.It is an effective measure to cultivate density-tolerant varieties to improve maize yield,but with the increase of planting density,lodging also increases,which leads to the decrease of yield and quality.In this study,J05-1,J05-20 and J05-48 were genetically improved from HCL301 and M03 inbred lines.Using Reid group density-resistant inbred lines HCL301 and M03 and their improved lines J05-1,J05-20 and J05-48,backbone line PH6WC as female parent,non-Reid group backbone inbred lines M5972,F0147Z,PH4CV,J1185,PH5AD,J1845 and J1899 as male parent.The yield and lodging resistance related traits of 42 cross combinations(6×7)were studied at densities of 60,000 plants/hm~2,75,000 plants/hm~2 and 90,000plants/hm2.The results were as follows.1.The analysis of heterosis showed that heterosis was common among 42 cross combinations,and the hybrid Z33(J1845/J05-20)had the highest heterosis in yield per plant at 75,000 plants/hm~2 and 90,000 plants/hm~2,indicating that the hybrid Z33was superior to other combinations in density tolerance and lodging resistance.The improved line J05-20 is easy to produce high-yield and density-resistant combinations,and has potential in density-resistant and lodging resistance.2.3 Lodging resistance under different densities showed that the combination Z32 and Z33 showed good performance in stem pulling force under three densities.In terms of stem crushing strength,the combinations Z16,Z12 and Z4 showed better performance.In puncture intensity,combination Z19 showed better performance.In stem diameter,Z16,Z18 and Z17 showed better performance.In terms of spike height coefficient,combination Z5 and Z1 performed well.3.The analysis of general combining ability(GCA)showed that the modified lines J05-1 and J05-20 had higher GCA effects on 100 grain weight,yield per plant and grain number per row under three densities.The general combining ability effect values of stem pulling force and stem crushing strength were higher in the improved line J05-48,which indicated that J05-1 and J05-20 had the potential to be combined with high-yield combinations,and the improved line J05-48 had the potential to be combined with lodging resistance combinations.4.According to the special combining ability effect values of the traits related to density and lodging resistance at three densities,the improved lines J05-20,J05-1 and J05-48 have the potential of density and lodging resistance and can be used as optional parents in the combination of high yield and high density and lodging resistance hybrid combinations.