Impact of Terminal Bud Quality on the Growth of Different Growth Forms of Seedlings in Tropical Secondary Forest

Health condition and replacement time of terminal bud were selected as quality indexes of regenerated seedlings in 3 different growth forms to analyze their impact on seedling height and ground diameter. The results showed that quality of terminal bud was related to the seedling growth, the regenerated seedlings with healthy terminal buds but no replacement experienced the largest growth amount and slight damage of terminal bud or one replacement stimulated growth of ground diameter. Multiple replacements of terminal bud would reduce seedling quality and influence its growth. Exploration of the quality characters of seedlings helped to know the dynamic features of early seedling growth, and provided theoretical support for the tending operation to improve quality of natural tropical forest.

An Efficient Plant Regeneration System for Different Explants of Rare and Endangered Plants in Mussaenda anomala

To establish an efficient regeneration method for the rare and endangered plant Mussaenda anomala to address problems regarding its reproductive obstacles and scarce populations.In this study,the terminal buds,axillary buds,stem segments with two axillary buds,stem segments with two axillary buds and one terminal bud,and leaves of M.anomala were used as explants.The effects of different explants and disinfection methods,plant growth regulators and substrates on plant regeneration were explored.The following results were obtained:(1)The terminal bud was a suitable explant for M.anomala tissue culture,and the disinfection method utilized was treatment with 0.2%HgCl2 for 8 min.(2)Initiate medium:MS basic medium supplemented with 0.5 mg/L 6-BA and 0.2 mg/L IBA for the high germination rate(100%)and the maximum bud height(1.70 cm)of the terminal bud.(3)Proliferation medium:MS basic medium supplemented with 3.0 mg/L 6-BA and 0.2 mg/L IBA for a high proliferation rate(96%)and proliferation time(6.0)of terminal buds.(4)Proliferation medium supplemented with 0.7 mg/L GA3 significantly increased the bud heights of multiple buds.(5)Rooting medium:MS basic medium supplemented with 0.5 mg/L IBA and 0.5 mg/L IAA for a high rooting rate(88%),root number(12.0)and root length(5.07 cm).(6)The optimal substrate for seedling acclimation and transplanting was perlite:vermiculite(1:1),which resulted in the highest survival rate(97%)and plant height(5.89 cm),as well as better growth potential for seedlings.The surfaces of M.anomala explants are densely covered with trichome,which increased the difficulty of disinfection;the plant growth regulators directly affected the growth and development in the regeneration process of M.anomala,and the substrate significantly affected the survival rate and height growth for seedling acclimation.

Temperature Characteristics of Dormancy Development of Terminal and Lateral Buds in Paulownia

In order to probe the death reason of terminal buds and carry out trunk extension by using lateralbuds, the temperature characteristics of dormancy development of terminal and lateral buds in Paulowniatomentosa p. fortunei 33 were investigated by raising cutting branches on different date at 25 ℃ and 15 ℃.The results were as follows: ①The death reason of terminal buds and the first pair of lateral buds was itselfecological adapting strategy, not the injury of early frost and freezing; ②The lateral buds 2, 3 and 4 hadobtained the feature of winter dormancy, and could survive from cold winter, and widen its possible temperaturerange of sprouting to lower temperature by experiencing winter chilling; ③The lateral buds 2, 3 and 4 couldsprout at the same time in spring, but it was difficult to sprout for other lateral buds; ④The sprouting ofupper lateral buds could restrict the sprouting of lower lateral buds at 25 ℃, but not at 15 ℃.