Effects of 9-hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic acid (KODA) on lateral primordial formation in the apical flower buds of Japanese pear [Pyrus pyrifolia (Burm.f.) Nakai]

Generally, year-to-year maintenance of the apical buds on spurs of Japanese pear ‘Kosui’ [Pyrus pyrifolia (Burm.f.) Nakai] is difficult; hence, flower buds become blind buds after blooming, whereas bud maintenance in another Japanese pear cultivar, ‘Shinsei’, is easy. Therefore, the effects of 9-hydroxy-10-oxo-12(Z), 15(Z)-octadecadienoic acid (KODA) on the formation of lateral primordia (vegetative growing points and/or floral lateral inflorescences) in apical flower buds on spurs were compared in both Japanese pear cultivars. Application of KODA (10 μM) in early-July increased the number of lateral primordial in the apical flower buds of both ‘Shinsei’ and ‘Kosui’, whereas the effects of KODA on the number of lateral inflorescences were not stable in either cultivar. Nevertheless, KODA tended to push up bud differentiation and development in both cultivars, compared to control, i.e. towards an increase in vegetative growing points and/or floral lateral inflorescences. These results suggest that application of KODA in July increased the number of lateral primordia in flower buds on Japanese pear spurs, a result that could be useful for decreasing the number of blind buds and promoting stable fruit production especially in the ‘Kosui’ cultivar.

► The apical flower buds on Japanese pear ‘Kosui’ spurs often become blind. ► KODA application increases the number of lateral primordia in flower buds on spurs. ► KODA promotes bud differentiation and development. ► This finding could be quite useful for decreasing the number of blind buds.