Phenological Observations and Factor Analysis of ‘Flowering Disorder’ in Japanese Pears Cultivated in Greenhouses in the Asakura Area, Fukuoka Prefecture

Abstract

Characteristics of ‘Flowering disorder (erratic flowering)’ in greenhouse-cultivated Japanese pears were investigated from 2014 to 2017 in Fukuoka Prefecture. Trees with 30% or lower flowering rates showed decreases in the fruit number and an infer fruit size, and thus were categorized into the ‘severe’ grade of flowering disorder. We calculated the ‘severe grade tree rate’ as the proportion of trees with a severe grade to the total number of trees in each orchard. When the severe grade tree rate was averaged separately for the orchards without and with heating, the highest rate was 8.6% in 2017 and 16.6% in 2016, respectively. The severe grade tree rate was higher in ‘Kosui’ than ‘Hosui’. In 2016, the severe grade tree rate became lower in greenhouses with the start of vinyl covering of greenhouses. The results suggest that delayed endodormancy breaking is one of the causes of flowering disorder. They also suggest that flowering disorder in greenhouses is influenced by the endodormancy of flower buds.