宁海白×大房枇杷F_(1)杂交群体果实性状的相关性及遗传分析

Correlation and genetic analysis of fruit traits in F_(1) hybrid population of loquat generated from Ninghaibai×Dafang

【目的】探究枇杷果实重要性状的遗传倾向以及果实性状间的相关关系,以期为枇杷杂交育种的亲本选配提供参考。【方法】对宁海白与大房杂交产生的130株F_(1)杂种后代的7个果实重要性状进行调查以及相关性分析。【结果】调查的7个果实性状均呈正态分布,其中果肉厚度、果实横径、果实质量、果实纵径等4个性状表现出趋低遗传倾向;种子数、种子质量、可溶性固形物含量3个性状表现出趋高遗传倾向。相关性分析显示,果实质量与其他6个性状均呈极显著相关,而通径分析显示,果实横径、种子质量、果肉厚度、果实纵径、种子数是影响果实质量的主要因素,其中果实横径和种子质量对果实质量的影响最大,而种子数的影响最小。【结论】7个果实重要性状均为数量性状,其中果肉厚度、果实横径、果实质量、果实纵径遗传倾向趋于趋低遗传,种子数、种子质量、可溶性固形物含量为趋高遗传;果实横径和种子质量是影响果实质量的关键性状。

【Objective】This paper aimed to complement the correlation genetic analysis of the important traits of loquat(Eriobotrya japonica Lindl.)fruits in the F1 population generated from the white flesh cultivar Ninghaibai crossed with the yellow flesh cultivar Dafang in order to provide the reference for the parent selection and seedling screening in loquat breeding.【Methods】A total of 130 plants of F_(1) hybrid population of Ninghaibai×Dafang were used as experimental materials.The samples were collected at the maturity stage from May to June in 2020,and 30 fruits were randomly selected from the middle and upper part of the crown of each tree.The longitudinal diameter,transverse diameter and pulp thickness of the fruits were measured with digital display vernier caliper.The Fruit weight and seed weight were measured with electronic balance(1/100).Soluble solid content(TSS)in fruit flesh was determined by ATAGO handheld digital refractometer.The number of seeds was also recorded.Excel2016 was used to organize data and draw tables.IBM SPSS Statistics 25.0 was used to test normality,draw frequency histogram and perform correlation analysis.【Results】The results of genetic analysis showed that the seven important fruit traits were normally distributed.The average values of fruit weight,fruit longitudinal diameter,fruit transverse diameter and fruit flesh thickness were lower than the mid-parent value or even lower than the low parental value.The genetic transmission ability was between 90.40%-96.46%,all lower than 100%,and the dominant rate was all negative.The heterosis was not significant,the genetic tendency was small,and most of the hybrid offspring showed the phenomenon of character decline.The decline in flesh thickness was the most serious,73.08%were thinner than the low parent and 11.54%were thicker than the high parent.Although fruit weight,fruit longitudinal diameter and fruit transverse diameter showed a genetic tendency to be lower,the high parental rate was 24.62%to 33.08%.The average values of TSS,seed weight,seed number were higher than that of high value,genetic heritability were higher than 100%and between 102.26 and 121.23%.Heterotic rate showed strong heterotic,genetic tendency represented as high genetic predisposition.Among them,the heterotic rates of seed weight and seed number reached 21.23%and 15.20%,showing the most significant heterosis performance.The results of correlation analysis showed that the fruit weight was positively correlated with the vertical diameter,horizontal diameter,flesh thickness,seed weight and seed number,but negatively related to TSS.Through stepwise regression analysis,the optimal multiple linear regression equation for fruit weight was expressed as:Y=-41.861+0.317 X1+0.795 X2+2.975 X3+2.208 X5-0.879 X6(Y=fruit weight,X1=fruit longitudinal diameter,X2=fruit transverse diameter,X3=flesh thickness,X5=seed weight,X6=seed number;R=0.991,R2=0.981,e=0.138),which indicated that the fruit longitudinal diameter,fruit transverse diameter,flesh thickness,seed weight and seed number were the main factors affecting fruit weight.Path analysis results showed that the fruit transverse diameter,fruit longitudinal diameter,flesh thickness,seed weight and seed number were the important traits that affected fruit weight.The order of simple correlation coefficient between five traits and fruit weight was the fruit transverse diameter(0.974)>seed weight(0.859)>flesh thickness(0.847)>longitudinal diameter(0.820)>seed number(0.323).The order of direct path coefficient between five traits was the seed weight(0.383)>transverse diameter(0.338)>flesh thickness(0.227)>longitudinal diameter(0.136)>seed number(-0.070).The order of decision coefficient was the fruit transverse diameter(0.544)>seed weight(0.511)>flesh thickness(0.393)>longitudinal diameter(0.204)>seed number(-0.050).【Conclusion】The fruit weight,fruit transverse diameter,fruit longitudinal diameter,flesh thickness,TSS,seed weight and seed number were all quantitative traits controlled by multiple genes.Among them,the genetic tendency of the fruit weight,fruit transverse diameter,fruit longitudinal diameter and flesh thickness tended to be smaller,while the genetic tendency of the TSS,seed weight and seed number tended to be higher.The fruit weight was significantly positively correlated with the longitudinal diameter,transverse diameter,flesh thickness,seed weight and seed number,but negatively correlated with the TSS.In conclusion,the longitudinal diameter,transverse diameter,flesh thickness,seed weight and seed number are the main factors affecting fruit weight,among them the transverse diameter and seed weight had the greatest effect on fruit weight,whereas the seed number had the least effect.