Phenotypic correlation analysis of Phalaenopsis reciprocal F₁ hybrids using SPSS and principal component analysis (PCA)

In the present study, we investigated the expression of traits in the progeny from reciprocal hybridization to improve the breeding efficiency of Phalaenopsis. We reciprocally hybridized Phalaenopsis ‘KS Little Gem’ (LG) (A) and Phalaenopsis ‘1747’ (B) (a Taiwanese cultivar). According to the Korea Seeds and Varieties Service (KSVS) guidelines, we cultivated 10, 13, 34, and 63 plants of ‘KS Little Gem’, ‘1747’, ‘1059’ (A×B), and ‘1076’ (B×A), respectively, and evaluated the performance of the hybrids to determine phenotypic correlation among traits. Correlation analysis revealed that there was a positive correlation between leaf thickness and flower longevity on the premise that a thicker leaf is associated with increased flower longevity. Phenotypic analysis of inflorescence factors in the reciprocal hybrids revealed no correlation between flower longevity and stalk length, number of florets, inflorescence length, pedicel length, and pedicel diameter; whereas there was negative correlation between the number of florets, pedicel length, and pedicel diameter. Although flower longevity was not correlated with flower length, flower width, sepal length, petal length, or petal width, it was negatively correlated with sepal width. Plots of the principal component analysis (PCA) scores indicated that ‘LG’ was least associated with ‘1747’, ‘1076’, and ‘1059’, which exhibited a high degree of overdominance (Figure 1A). The hybrids ‘1059’ and ‘1076’ – resulting from the cross between ‘LG’ and ‘1747’ – had intermediate characteristics. The PCA results revealed that flowering longevity was positively correlated with leaf thickness and negatively correlated with petal width. Our results suggest that to breed Phalaenopsis with a longer shelf life, plants with increased flower longevity should be used as the female parent, and leaf thickness and sepal width should be monitored to determine long flowering durations in the progeny lines.