Phenology and Morphology of Flower Bud Differentiation of Dexing Raspberry Bushes

  Objective  Phenology and morphology of flower bud differentiation were studied for information on flowering regulation as well as berry yield and quality improvements on Dexing raspberry bushes (Rubus chingii).

  Method  The plant phenology was observed in the field, and the morphogenesis of the flower bud differentiation examined under a microscope using paraffin section.

  Result  The entire plant growth was classified into sprouting, leaf extending, blooming, fruit developing, two-year-old branch withering, flower bud differentiating, leaf falling and dormant phases. The flower bud differentiation of the bushes occurred largely from August to mid-to-late November with 5 distinct periods. The buds were not differentiated in August and September, and calyx primordium began to differentiate in early October, petal primordium in mid-October, stamen primordium in early November, and pistil primordium in mid-November. The buds grew rapidly in the early stage and slowed down in the mid-to-late stage before reaching dormancy.

  Conclusion  Unlike other Rubus spp, Dexing raspberry completed its flower bud differentiation before dormancy. The significant correlation between the external morphology and interior structure during the differentiation stage provided an indicator for easy estimating the flowering of the plants.