Flowering in ‘Honeycrisp’ Apple Shows That Spurs Are Semiautonomous Organs

Irregular flowering and biennial bearing are challenging in many apple ( Malus × domestica ) cultivars such as Honeycrisp. Apple is influenced by factors including crop load, fruit weight, seed number, bourse shoot length. However, it unclear how these exert their control. We investigated ‘Honeycrisp’ whether flower formation regulated locally within the spur or if under control of whole tree system. Treatments consisting 30 to 240 per with one two were applied, length, resulting measured. In 2013, was affected number tree, interaction, lower total loads, spurs had fewer flowers than those a single fruit. 2014, few formed regardless treatment. unaffected on single-fruited but inhibition correlated weight. fruit, inhibited higher numbers weight no effect flowering. Our data suggest that both within-spur characteristics contribute local formation. Therefore, can be considered semiautonomous organs because appears related depletion resources spurs, systematically tree. The main associated spur, spur. contrast previous reports, our show seeds do not play direct role regulating