| Southwest mountain corn area is the third largest corn producing area in China,but the yield is lower than the national average and the product quality is poor.The frequent occurrence of seasonal drought has become the main factor restricting the development of corn in southwest China.Selecting and promoting drought-resistant varieties is an effective way to reduce the losses caused by drought,and studying the advantages of drought-resistant hybrids in the corn seedling period and the correlation with parenthood can provide a reference for drought-resistant breeding of corn.Therefore,this study mainly evaluates the application potential of the 34 new combinations from the aspects of high yield,quality and drought resistance,and studies the drought-resistance of its parenthood and the advantages of drought-resistant hybrids in the corn seedling period,and discusses the correlation between drought resistance of seedlings and its parenthood,which is of important practical guidance significance.Its main findings are as follows:1.The high yield of 34 new combinations: based on the data of each new combination participating in the Sichuan regional trial,it is concluded that 20 new combinations have a higher yield than that of the reference variety,among which the increase of more than 10%are ZH606,Zhenghong507 and ZH755,with specific increase of 12.80%,12.59% and11.00% respectively;4 new combinations such as GR401 and Ruiyu 612 were found to increase by 8-10%;8 new combinations such as ZH431 and ZH412 were increased by5-8%.The above results show that they have a high yield and great potential to increase yield.2.Commodity quality performance of 34 new combinations: Except for Zhenghong509,the grain weight of the other 33 new combinations all exceeds the national standard National First-Grade Standard for maize quality(GB1353-2018).About this indicator,7 new combinations,including ZH756,ZH777 and ZH719 exceed 780g/L;and 7new combinations,including GR7568,ZH717 and ZH737 exceed 760g/L;The 34 combinations all reached the first-class standard for forage quality(GB / T17890-2008),indicating that these new combinations have excellent commodity quality and forage quality and good overall quality.3.Drought-resistant performance of maize hybrid combination: The drought-resistant evaluation of 34 new combinations and 11 approved varieties was carried out in this study.The drought stress was carried out by using 20% PEG-6000 solution during the germination period and the seedling period.We mainly study7 indicators,such as germination rate and germination energy in the germination period while 9 indicators,such as plant height and root-shoot ratio in the seedling period.By using main component analysis and membership function method for the analysis of drought resistance in the germination and seedling periods,and the study of drought resistance performance in the 2periods,we discuss the comprehensive drought resistance of their germination seedling stage.The main results are:(1)According to the resistance performance of the germination stage,the test hybrid combination can be divided into 4 categories: Class I contains Ruiyu617 and ZH008,belonging to the strong drought-resistant type;ClassⅡcontains 16 combinations,such as GR609,ZH700 and zhenghong006,belonging to the drought-resistant type;Class Ⅲ contains 23 combinations,including Ruiyu13,GR401 and Zhenghong507,belonging to the medium drought-resistant type;Class IV includes ZH719,ZH709 and other 2 combinations,belonging to the drought-sensitive type.In addition,there are 22 combinations performed stronger drought-resistance than reference variety Zhongdan808 during the germination period,7 combinations were stronger than the southwest maize national area test control species Zhongyu335 combination.(2)According to the drought-resistant performance of the seedling period,the hybrid combination can be divided into 3 categories: Class I contains 9 maize combinations,such as ZH733,Zhongyu335,which are drought-resistant;Class Ⅱ contains 34 maize combinations,such as ZH729 and Zhenghong412;which are medium drought-resistance;Class Ⅲ are drought-sensitive,including ZH606 and Zhenghong510.(3)The drought resistance of the two stages of comprehensive germination and seedling period can be divided into 3categories,Category I is a strong drought-resistant combination,there are 14 combinations,such as Ruiyu617;CategoryⅡ is the medium drought-resistant combination,there are 28 combinations,such as ZH669;Category Ⅲ is drought-sensitive combination,there are 3combinations,such as ZH719.It has been shown that in production practice,it is more practical and instructive to evaluate the drought resistance of the germination and seedling periods of maize hybrid.4.Drought-resistant performance of parents in the seedling stage: In this study,54 maize inbred lines were used as materials,using 20% PEG-6000 solution to carry out drought stress in the seedling period,and examined 9 indicators such as plant height and root-shoot ratio.Through the main component analysis and screening indicators,the comprehensive drought-resistant value D is calculated by the sub-functional function method,and their drought resistance is evaluated and clustered according to the D value.The main results are: 7 inbred lines,such as K186,K123,and Zheng58 are classified as one category,belonging to the drought-resistant inbred lines;25 inbred lines,such as K121,K182,and Chang7-2,are classified as medium drought-resistant;20 inbred lines,such as K101 and G2490,are classified as drought-sensitive inbred line.The results of the study can provide a reference basis for the use of these inbred lines in the drought-resistant breeding of maize.5.The performance of drought-resistant heterosis in maize seedling period: This experiment analyzes the drought-resistant heterosis of maize seedling period with 43 maize hybrid combinations and their corresponding parenthood as materials,and the results show that,which 12 combinations have positive transgressive heterosis,18 combinations have positive mid-parent heterosis.If we take Zhongyu335 as reference variety,only ZH733 showed positive control advantage;if we take Zhongdan808 for reference,13 combinations showed positive control advantage.6.The correlation of drought resistance of mazie hybrid combination and inbred lines in seedling stage: This experiment analyzed the correlation of drought resistance of inbred lines with maize hybrid combination and control advantages in seedling stage with 43 maize hybrid combination and their corresponding parents as materials.The result shows that the correlation between maize hybrid combination drought resistance and comparison heterosis is consistent with the female parent,male parent,high value parent,low-value parent and mid-parent,and the correlation coefficients are-0.064,0.078,0.031,0.019 and0.030,none of them reach standard levels.It showed that there was no obvious correlation between drought resistance in the maize hybrid seedling period and the drought resistance of the control hybrids and the drought resistance of the inbred line,and in breeding practice,the drought resistance of hybrids could not be predicted simply on the basis of inbird line drought resistance.7.Application potential of 34 new combinations: According to comprehensive analysis of high yield,quality and drought resistance,the application potential of the 12 new combinations,including Ruiyu617,Ruiyu612,ZH507,Zhenghong613,Zhenghong412,Zhenghong431,Zhenghong419,ZH411,ZH633,ZH680,ZH755 and GR401,these is large.It is proposed to further strengthen pilot research,laying a solid foundation for quick promotion and application. |
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