พัฒนาการทางลำต้นและการออกดอกในรอบปีของต้นศรีตรัง

Abstract

Jacaranda Jacaranda filicifolia) is a flowering tree mascot of Prince of Songkla University (PSU). To study the production of Jacaranda as ornamental pot plant, the experiment was arranged in 2 parts as followed; 1) flowering phenological changes and developments in Jacaranda trees and 2) flower induction of Jacaranda grown in pots by canopy manipulating and applying growth retardant. In the first experiment, results showed that phenological changes in leaf flushing and flowering times in Jacaranda were exhibited seasonal differences in strong relationships with minimum temperature and relative humidity. The majority of flowering in Jacaranda occurred during January to April (summer), and there was a small number of trees began to flower again during September to November (rainy). The relationship between flowering percentage and tree size was also observed. Furthermore, an inflorescence of J. filicifolia consists of perfect flower with cymose panicle or thyrsus. Also, Indeterminate and determinate inflorescences are known as thyrsus. Due to the change of developmental stages of the flower according to its botanical characteristics, the freshly-identified flower was classified into four developmental stages: (1) sprout to green bud; (II) green to purple flower bud; (III) purple corolla tube; and (IV) full flowering to initial fruiting. The last experiment, results showed that the flowering percentage was statistically different as it resulted in a higher number of primary branch per plant due to canopy size control. Trunk diameter, canopy width and tree height was significantly reduced and new shoot growth was also reduced by application of PBZ. Furthermore, the abundance of flowers was affected by PBZ treatment with three increasing dosages (400-800 mg/L), which resulted in the highest values for percentage of plant flowering, number of flowers per inflorescence and number of florets per inflorescence. This study can be recommended that variation in the quantity of flowering and flowering time related to seasonal climate, trunk size and canopy manipulation. Floral initiation of Jacaranda by PBZ treatment as potential ornamental flowering in potted plants was the most suitable to obtain profuse flowering.