Phenology and flowering of the clove tree, an irregular bearing spice crop
Irregularity of flowering of the clove tree (Syzygium aromaticum) is an important issue for this perennial crop in Madagascar and in the other producing countries. This species is poorly studied and the factors determining flowering are not known. Inflorescences are produced by the terminal buds and field observations suggest that flowering is partly related to architectural factors, as it has been shown for fruit crops such as apple and mango. The aim of this work was to describe vegetative and reproductive growth and development of the clove tree, and to explore the relationships between vegetative traits and flowering. Three studies have been carried out. First, vegetative and reproductive phenological stages have been defined, based on morphological characteristics, shape, color, texture, and, when possible, on discontinuities of these characteristics. Second, leaf area expansion has been measured in winter and in summer from early phenological stage to leaf maturity. Third, vegetative traits related to morphology and phenology have been recorded on flowering and non-flowering axes in order to identify if flowering could be related to specific vegetative traits. Nine and eight phenological stages have been described for vegetative and reproductive development, respectively. Leaf area expansion followed a sigmoid shape. Leaf area expansion rate was related to leaf phenological stage and was affected by the season. It was higher in summer than in winter and was surprisingly low for a tropical tree. Morphological and phenological differences were observed between flowering and non-flowering axes. In particular, a growth arrest seemed to be necessary, but not sufficient, for flowering.
Razakaratrimo, J.T., Jahiel, M., Jeannoda, V. and Normand, F. (2018). Phenology and flowering of the clove tree, an irregular bearing spice crop. Acta Hortic. 1228, 369-376
leaf expansion, morphology, phenological stage, Syzygium aromaticum, vegetative growth