Analysis of genetic tendency of fruit characters in hybrid progenies of Passiflora edulis f. flavicarpa Deg.

Abstract:【Objective】In order to provide theoretical basis for breeding new varieties of yellow passion fruit, the inheritance tendency of the fruit appearance and main quality traits of the hybrid progeny of yellow passion fruit was studied. The genetic tendency of the fruit shape index, edible rate and solidity acid ratio of hybrid progenies was clarified based on the characteristics of universality and irregularity of separation of hybrid progenies.【Methods】In this study, the large yellow passion fruit tree was used as female parent (The fruit is large, oval, high acidic with, thin skin and high edible rate) and small yellow passion fruit tree was used as male parent (The fruit is small, round and high in soluble solid content). The seeds obtained by hybridization were sown, cultivated and managed in the field. The mature fruits of 200 hybrid progenies and parents were randomly selected as materials. The transverse and longitudinal diameter of fruits were measured with Vernier caliper, and the fruit shape index was calculated. The single fruit weight and rind weight of fruits were weighed with electronic balance, and the edible rate of fruit was calculated. The soluble solid content and total acid content of fruits were measured with sugar acid instrument (ATAGO PAL-BX / ACID1), and the solidity-acid ratio was calculat-ed.【Results】The coefficients of variation of fruit traits in hybrid progenies were 5.04%-30.63%, and the coefficient of variation of solidity-acid ratio was the highest. The coefficient of variation of other traits was over 15% except for the transverse diameter, longitudinal diameter, fruit shape index, edible rate and soluble solids content, which had high genetic diversity. Their coefficients of variation of the solidity- acid ratio, total acids content, single fruit weight and rind weight were 30.63% , 23.43% , 22.63% and 21.45%, respectively. The longitudinal diameter of hybrid progenies tended to be the mid value of the parents, with an average of 7.38 cm. The transverse diameter and single fruit weight of the hybrid progenies showed superiority over the female parent. Among them, the fruit transverse diameter of 1.50% of the hybrid progenies was longer than that of the female parent, and the single fruit weight of 3.00% of the hybrid progenies was larger than that of the female parent. The fruit shape index, edible rate and total acid exhibited the tendency to exceed the female parent, and the proportion over female parent traits were 19.00%, 91.00% and 28.50% respectively. The soluble solid content showed the tendency to surpass the male parent. The standard deviation of the fruit weight and fruit shape index was small and concentrated, and their genetic trend was consistent, but the standard deviation of the solidity acid ratio was large and the coefficient of variation was high, which led to the high degree of dispersion of genetic trend in hybrid progenies. Correlation analysis showed that the single fruit weight were highly, significantly and positively correlated with the fruit longitudinal diameter and transverse diameter; the rind weight were highly, significantly and positively correlated with the fruit longitudinal diameter, transverse diameter and single fruit weight; The edible rate highly, significantly and positively correlated with the fruit longitudinal diameter and single fruit weight, but it was significantly and negatively correlated with the rind weight. According to the cluster analysis of soluble solids content and total acids content, 202 samples could be divided into three categories (group similar to female parent, female parent group and male parent group) when the cluster distance was 10. The female parent group is the largest, includes 97 hybrid progenies and female parent, accounting for 48.50% of the total samples. The characteristics were biased towards the female parent, with low soluble solid content and high total acid content.【Conclusion】There were obvious genetic tendency and heterosis among hybrid progenies. The transverse diameter, fruit shape index, single fruit weight, edible rate, soluble solids content and total acids content of hybrid progenies showed the tendency to exceed those of the parent with high value. However, the fruit shape index, rind weight, soluble solids content and solidity-acid ratio of hybrid progenies showed the tendency to be inferior to those of the parent with low value The soluble solids content and total acids content of the hybrid progenies were greatly affected by the characteristics of the female. The fruits of the hybrid progenies with high edible rate were oval and heavier. Two excellent individual plants of No. 6-4-27 and No. 6-12-65 were selected from the hybrid population.