Possible Use of 1-Naphtalene Acetic Acid (NAA) as a Flowering Accelerator of Satsuma Mandarin

摘要

The chemical control of flowering is an important problem in the citrus industry, and many chemicals have been studied. Among them, gibberellin, a remarkable flowering retardant in citrus, is the most popular. However, few chemicals are known to be citrus flowering accelerators. We tried 1-naphtalene acetic acid (NAA) as a flowering accelerator using 11 -year-old Satsuma mandarin trees (Citrus unshiu Marcow.' okitsuwase' ). NAA was applied at 220ppm in the whole tree from summer to the following spring, and the effect of NAA on the subsequent flowering on vegetative shoots was investigated. In parallel, the completion period of the floral evocation and the morphological development of lateral buds on vegetative shoots were investigated and related with the time of application. The results suggested that NAA applied after the floral differentiation does not affect flowering and that NAA, applied before the beginning of the floral evocation stage or just before the completion time of it, could be effective. The possible use of NAA for flowering enhancement is discussed in relation to an earlier report on Satsuma mandarin grown in a greenhouse.