Effect of pruning on flowering of Rhododendron simsii Planch.

摘要

The lack of management of wild rhododendrons, which led to biennial bloom, had seriously reduced their ornamental values. To overcome biennial flowering, Rhododendron simsii had been pruned to various degrees. The results indicated that pruning of wild azalea plants had significantly affected on its growth and flowering in the following year. Removing deceased flowers promoted new branch growth by 5 folds. The new branch length was 12.2 cm under thinning cut. If pruning heavily, the new growth was much longer, to 40 cm. Number of branches per square meter reduced as pruning methods from light to heavy. Deadhead treatment yielded 603 branches per square meter, while control treatment sprouted 408. Both deadhead and thinning cut had significant higher number of branches than control. However, cut-back of plants significantly decreased the number of branches. Only 25 branches were counted from heavy pruning treatment. Total new growth had similar trend of number of branches. Thinning cut had most of growth to 5,843 cm. Thinning cut had much better bloom than any other treatment, with 64.6 flower clusters and 68.5 flowering branches. Deadhead produced 64.6 flower clusters and 60.8 flowering branches. Both treatments produced significant higher numbers of flowers, no statistical difference was found between them. Medium cut-back and heavy pruning did not produce any flower. Management practices of wild Rhodedendron simsii could promote growth and flowering and overcome biennial flowering phenomena. Both thinning cut and deadhead in May are recommended.