Variation in sex ratio and flowering traits in backcross hybrid populations between ornamental ‘Jiangshanjiao’ and male Actinidia chinensis Planch

A population of interspecific ‘Jiangshanjiao’ (Actinidia chinensis Planch×A. eriantha Benth) and male A. chinensis Planch hybrids was used in this study. Sex ratio and flowering traits were investigated in the spring of 2012, 2013, and 2016, respectively. The sex ratio of female to male progeny was lower than 1:1, which means there are more male than female plants in the hybrid population. The basic petal color of the progeny was red, but a subtle segregation of color distribution, color depth, and red color types were observed in the population. Clustering analysis using extracted parameters with CMYK mode showed four sub-clusters, among which two groups of hybrids were consistent with scarlet and violet petal phenotypes, respectively. The early flowering season, flowering duration, flower diameter, flower number, and petal number per flower were found to have wide variations, and changed with investigation year. The average time span between the first and the last early flowering season of the hybrids was 14 d. Average proportion of the hybrids in the early flowering season reached a maximum of 25.5% in the population. Flowering duration of the population in 2016 was the longest, with 47.4% of hybrids blooming for 10-13 d, but was the shortest in 2013, with 55.2% of hybrids blooming for 3-5 d. A few progenies had larger flowers and more petals per flower or more flowers per inflorescence. There were 21 combination types of petal-flower-inflorescence number in the hybrid population.