Construction Of Evaluation Index System For Spring Maize Varieties With Tolerance To Density Planting And Suitable For Machine Harvesting

With the requirements of the development of the corn industry,the requirements for the dense planting and mechanical harvestability of corn varieties have become an important research direction.Constructing an evaluation index system for corn tolerant to dense planting and suitable for machine harvest is a prerequisite for realizing the mechanization of corn production and promoting the increase of corn production and efficiency.This study was conducted in Puding County,Anshun City,Guizhou Province,Dejiang County,Tongren City,Xingren City,Bijie City,Qixingguan District,Bijie City,and Weining County,Bijie City,Guizhou Province from 2018 to 2020.The two-factor split zone design of density and variety is adopted.The main treatment is density and the side treatment is corn varieties.Through comprehensive evaluation of the characteristics of different spring corn varieties tolerant to dense planting and suitable for machine harvesting,principal component analysis,correlation analysis,gray correlation analysis,etc.Methods.The evaluation indexes of spring maize varieties tolerant to dense planting and suitable for machine harvest were screened,the weights and thresholds of each index were determined,a comprehensive evaluation method was proposed,and an evaluation index system for spring maize varieties tolerant to dense planting and suitable for machine harvest was established.he selection and breeding of varieties that are resistant to dense planting and suitable for machine harvest provide a more systematic and complete scientific basis.Below are key research findings:1.Using principal component(PCA)combined function value(Norm)analysis,19 indicators were screened out of 34 indicators to construct an evaluation index system for spring corn tolerant to dense planting and suitable for machine harvest,including the indicators of density tolerant:the third section above ground is thick,Ear position height,dry weight per stem length,third section of maturity,yield per plant,empty stalk rate,lodging and inverted rate;suitable harvest index:grain moisture content,bract moisture content,broken rate,Impurity rate,total loss rate,ear height uniformity,grain top surface crushing strength;high yield indicators:yield,thousand-grain weight,number of grains per ear,growth period,number of effective ears.2.The comparative analysis of the results of determining the weight of each indicator by the common factor variance method,correlation coefficient method,gray correlation method,and entropy weight method shows that the correlation coefficient method and common factor variance method can highlight the relative importance of the indicators and the weights are more accurate.Using the principle of minimum information entropy,the two weights are combined to obtain the final weight of each indicator.Yield per plant,grain moisture content,bract moisture content,fragmentation rate,impurity rate,and number of grains per spike are the core indicators of the system.When evaluating whether spring maize varieties are tolerant to dense planting and suitable for machine harvest,the first consideration should be the suitability of machine harvest,followed by dense planting resistance,and finally high yield.3.The K-S test was used to test all the indicators,and the results showed that all the indicators except for the lodging rate,empty bar rate,and ear height uniformity obey normal distribution.Using t-distribution interval estimation,the 95%confidence interval of each index is obtained.Among them,ear height,grain moisture content,bract moisture content,broken rate,impurity rate,total loss rate,and growth period are reverse indicators,and the upper confidence limit of the 95%confidence interval is taken as the critical threshold of the indicator;the rest of the indicators are positive.Take the lower confidence limit of the 95%confidence interval as the critical threshold of the indicator,and finally get the threshold of each indicator.4.Use fuzzy comprehensive evaluation method,the principal component analysis method and the gray correlation method are used to comprehensively evaluate each variety,and the KENDALL-W coordination coefficient method is used to check the consistency of the evaluation results of the three methods.The results show that the three evaluation methods can be used as spring.The evaluation method in the index system of corn tolerance to dense planting and suitable for machine harvest.The evaluation results obtained by the fuzzy comprehensive evaluation method and the gray correlation method have a repeat rate of 70%;the principal component analysis method,the fuzzy comprehensive evaluation method,and the gray correlation method have a repeat rate of 60%.The fuzzy comprehensive evaluation method and the gray correlation method have greater correlation,and the evaluation effect is better than the principal component method.In the fuzzy comprehensive evaluation method,the obtained evaluation results vary between 36.6-71.94,while the gray correlation method evaluation results vary between 44.42-68.9.The fuzzy comprehensive evaluation method has a greater variation and highlights the variety.The characteristics of tolerance to dense planting and suitable for machine harvest can be better applied to the objective evaluation of varieties.5.Using the constructed evaluation indicators for dense planting and suitable for machine harvesting and fuzzy comprehensive evaluation methods,a comprehensive evaluation of each tested variety in Guizhou Anshun from 2018 to 2019 was carried out,and the evaluation results obtained were significantly correlated with field performance.Xianyu 1171,Xinzhongyu 801,Zhenghong 507,Jinyu 838,Xingyu No.3,and Huaxing Dan 88 were selected as the first choices for dense planting and machine harvesting in Guizhou.