Comprehensive Evaluation Of The Phenotype,Quality And Cold Resistance Of Introduced Pyrus In Inner Mongolia

In this study,140 germplasm resources of 18 pear varieties collected from Bayannur City Resource Garden were studied as research objects,and the germplasm resources of different varieties of pear were analyzed and evaluated from the aspects of phenotypic traits,fruit quality and cold resistance.It provides a theoretical basis for local selection and improvement of existing excellent pear varieties and the development of new varieties.The results are as follows:(1)Studies on 28 phenotypic traits of introduced pear varieties showed that the coefficient of variation between the quality and quantitative traits of the investigated pear germplasm resources ranged from 11.78% to 64.72% and 9.28 to 59.54%,and the diversity index range ranged between 0.22 and 1.33 and 0.35 and 1.53,respectively,indicating that Inner Mongolia pear germplasm resources have extremely rich phenotypic diversity.Eight principal components were extracted through principal component analysis,with characteristic values greater than 1,and the cumulative contribution rate was 74.58%,among which fruit morphology was the most important indicator leading to the difference in germplasm resources of different pear varieties.Q and R cluster analysis of the trait indicators of pear test materials,in which leaf length,leaf width,fruit longitudinal diameter and fruit transverse diameter were significantly different from other phenotypic traits,which proved that leaf morphology and fruit size could be used as important morphological indicators of pear germplasm resources.(2)The study on seven fruit quality indicators of 18 pear varieties showed that the fruit quality was significantly different in different pear varieties,with a coefficient of variation between 10.58% and 56.54%,among which the sugar acid ratio,titratable acid and stone ocyte content were all more than 50%,which can be used as the main index to evaluate pear fruit quality.The variation of soluble sugar in each pear variety was small but the variation of titratable acid and sugar ratio was large.When evaluation,the acidity reflected the sweet and sour taste of the fruit more than the sugar.According to the correlation analysis between phenotypic traits and fruit quality indicators,leaf size,density,fruit coloring degree and fruit point size can be used as important criteria to directly judge fruit quality.In the comprehensive ranking of fruit quality of 18 pear varieties,’Yuluxiang’ pear has the best performance.(3)Through the determination of five cold resistance indexes,it shows that with the decrease of temperature,the relative conductivity of branches of each variety increased;MDA showed an overall increasing trend;the enzyme activity of POD and SOD increased first and then decreased,while some varieties showed a down-up-down trend;the content of soluble protein generally increased or increased first and then decreased.According to the analysis of the correlation between phenotypic traits and cold resistance index,the annual skin hole density,leaf color status,fruit color and fruit point density can be considered as factors to reflect the cold resistance level of pear trees.In the 18 varieties ’Hanhong’ pear has the best in the comprehensive order of cold resistance.