Analysis Of Lodging Resistance And Heterosis Of Maize Hybrids And Their Parents

Maize is one of the main food crops,and also an important feed and industrial raw material crop.Lodging is the main factor that restricts the improvement of maize yield per unit area,and also the main limiting factor for maize to achieving high yield,high efficiency and high quality production.Lodging could greatly reduces maize grain yield and increases the difficulty of mechanical harvesting,thus increasing the cost of maize planting.The key factor to solve the lodging problem is to improve the lodging resistance of maize stalks,and the lodging resistance of maize stalks is closely related to the content of lignin and cellulose.However,it is not clear how endogenous hormones regulate the synthesis and accumulation of lignin and cellulose during the development of maize stalks,thereby affecting the lodging resistance of maize stalks.And there are relatively few studies on the lodging resistance of maize hybrids and the physiological and genetic characteristics of parental inbred lines.Therefore,the research on the genetic mechanism of the physiological metabolism of maize stalks has become a key issue in the variety breeding of lodging resistance and high-yielding.In this paper,maize hybrids(F1)with different lodging resistance and their parents were selected as experimental materials.To study how endogenous hormones regulated the synthesis and accumulation of lignin and cellulose,and then affecting the lodging resistance of maize stalks.The heterosis for agronomic traits,stalk rind puncture strength(RPS),lignin,cellulose and related endogenous hormones between F1 hybrids with different lodging resistance and their parents were analyzed,to reveal the regulation of genetic characteristics on lodging resistance of maize hybrid stalks.The results could helpful for providing important reference for parents selection and improvement of maize varieties with high yield and lodging resistance.The main results are as follows:(1)Heterosis analysis of plant characters and stalk strength of different resistance maize hybridsThe plant height,ear height and center of gravity of maize hybrids were higher than their parents and showed higher heterosis,the heterosis of ear height was higher than plant height and ear height coefficient.Diameter,dry weight per unit internode length(DWUL)and puncture strength(RPS)of basal 3rd internode were affected by the interaction between parents,and the contribution of female inbred lines was greater.Their heterosis was positive exceeding male parent heterosis,negative mid-parent and exceeding female parent heterosis.The heterosis of plant height,ear height and center of gravity of KX3564 hybrids with stronger lodging resistance was lower than that of Xinyu 41(XY41)with weaker lodging resistance,while the heterosis of diameter,DWUL and RPS for basal 3rd internode was significantly higher than that of XY41.(2)Analysis of heterosis of structural compounds and endogenous hormones in stemsThe content of cellulose and lignin in basal internodes of hybrids was significantly lower than their female inbred lines and showing super-male heterosis,mid-parent heterosis both less than 10%.The contents of IAA and ABA were lower than those of their parents showed negative mid-parent heterosis and super-parent heterosis,and the heterosis index was low.The content of ZT showed positive mid-parent and super-parent heterosis,the heterosis index was high.(3)Regulation of endogenous hormones on the accumulation of structural compounds and the relationship between structural compounds and stem rind puncture strength.There was a significant positive correlation between lignin accumulation and puncture strength and cellulose accumulation in the third internode of maize stalk.IAA content was positively correlated with lignin and cellulose content,ABA content was negatively correlated with lignin and cellulose content,ZT was positively correlated with lignin accumulation,but not with cellulose content.Therefore,endogenous hormones in maize stalks could improved the lodging resistance of maize stalks by regulating the accumulation of structural chemicals.Heterosis performance of various shapes of maize hybrids:Plant height,ear height,ear position coefficient and endogenous hormone ZT were super-parental.The third internode diameter,DWUL,RPS,cellulose and lignin,endogenous hormones IAA and ABA were super-low parental.The lignin accumulation in the third section of the corn stalk base was significantly positively correlated with RPS and positively correlated with cellulose accumulation.There was a significant positive correlation between IAA and ZT and lignin accumulation.There was a significant negative correlation between ABA and lignin accumulation.There was a significant positive correlation between IAA and cellulose content,and there was a significant negative correlation between ABA and cellulose.