Relationships between Stem Pitting Occurrences and Flowering, Yield and Fruit Quality in Hyuganatsu that Influence Citrus Tristeza Virus Infection

Abstract

The relationships between stem pitting (SP) and flowering, yield, and fruit quality that influence citrus tristeza virus (CTV) infection were investigated in Hyuganatsu (Citrus tamurana hort. ex Tanaka), a key item for citrus cultivation in the Shizuoka Prefecture Izu region. SP tended to increase over the investigated period. Positive correlations were observed between SP and the number of flowers and soluble solid content. On the other hand, negative correlations were observed between SP and the harvested fruit number, yield, and fruit weight. Following these results, the number of flowers in Hyuganatsu rose with an increase in SP occurrences, but yields decreased due to increased physiological fruit drop and smaller a fruit size. Of the five CTV genotypes tested, Hyuganatsu trees infected with T3 genotypes showed an increase in SP occurrences. These observations indicate that T3 infection affects the yield reduction of Hyuganatsu. A negative correlation was observed between SP occurrences and yield, and so SP occurrences can be used as a diagnostic indicator of yield reduction in Hyuganatsu.