Flowering and Growth of Adonis amurensis as Influenced by Temperature and Photosynthetic Photon Flux Density

This study was carried out to investigate the effects of daylength, temperature, and photosynthetic photon flux density (PPFD) on the flowering, growth and dormancy induction in Adonis amurensis. Flowering was not affected by daylength. Aerial shoots ceased to grow, withered away and entered into dormancy irrespective of daylength. The number of days to flowering was significantly shortened as temperature or PPFD increased. Shoot length and leaf area significantly decreased as temperature and PPFD increased; however, root growth was promoted by increasing temperature and PPFD, resulting in decreasing of T/R ratio, except at 30/20 degrees C. Aerial shoots withered away and entered dormancy 45 days after treatment at high temperature over 25/15 degrees C, and it was accelerated by high PPFD. Leaf temperature increased as growing temperature increased, but it was lower than air temperature. However, water use efficiency decreased as temperature and PPFD increased. Based on these results, we could recommend 15/5 or 20/10 degrees C with 100 mu mol.m(-2).s(-1) among treatment to promote flowering and continuous growth without dormancy induction in A. amurensis. High temperature over 25/15 degrees C also could be used for promoting the flowering of A. amurensis, but it could not be recommended as it shortened flower longevity significantly. High temperature over 25/15 degrees C might be the primary factor for inducing dormancy of A. amurensis.