Growth Rhythms of Two-year-old Cutting-propagated Seedlings of Rhododendron taipaoense

To better conserve and utilize wild Rhododendron taipaoense,resources,the seedling height and ground diameter of two-year-old seedlings were monitored continuously for one year. The monthly growth dynamics and their relationship with environmental factors were analyzed. The results showed that the annual increments of seedling height and diameter followed a typical “slow-fast-slow”(S-shaped)trend,with the average total growth of 8. 01 cm in height and 1. 53 cm in diameter. Monthly height growth exhibited a significant bimodal seasonal pattern,whereas diameter growth displayed a single peak. And the principal growing periods were spring and summer(height peak in April and August) and summer(diameter peak in August),respectively. Height growth was significantly positively correlated with precipitation,but the diameter growth was significantly positively correlated with air temperature and sunshine duration. Overall,the growth of Rhododendron taipaoense exists markedly seasonal,and these findings provide a theoretical basis for its cultivation and management.