Studies on Flowering Induction and Quantification of Gibberellins in Calocedrus formosana Florin.

• Main Authors: Jeng-Der Chung, 鍾振德
• Other Authors: Shing-Rong Kuo
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/65232842694634698393

博士 === 國立臺灣大學 === 森林學研究所 === 89 === This study is to promote the flowering in Calocedrus formosana by cultural practices, GA3 application, and re-establishment of clonal orchards at new sites. Changes of gibberellines concentration in grafts with different flowering performances were analyzed. Clonal orchards of C. formosana located at Tsuyunshan (1100 m in elevation) and Tashueshan (1500 m in elevation) in the central part of Taiwan have not been found to flower(established in 1974). Two approaches were conducted to promote flowering of these orchards. One was using cultural practices such as root pruning, branch thinning and bark girdling, and GA3 application on these orchards. The other was to graft the scions collected from these orchards and planted these grafts at new sites. The results revealed that these two approaches were effective in promoting flowering in C. formosana. GA3 application could promote more than 80% of 23-year-old grafts flowering. The re-established orchards flowered in three continuous yeas since the next year after planting. Although all clones flowered, variation of flower-bud formation was found. Clones could be divided into good and poor flowering types. GA3 is an effective factor to promote C. formosana flowering. However, the flowering response was significantly different between good and poor flowering clones. Extracts from the buds of two typed clones were chromatographed through RP-C18 and Nucleosil column and analyzed by GC-MS. Gibberellines were identified and quantified. The amount of GA1 and GA3 derived from good flowering clone samples collected at the first and third week were 920 and 1200 ng.g-1dw, and 436 and 600 ng.g-1dw, respectively. Whereas those from poor flowering clone were 1100 and 1312 ng.g-1dw, and 1118 and 826 ng.g-1dw, respectively. Minimal GA20 at both two timing of GA3 treated samples were detected. It presumed that GA1 was transformed from GA20 and GA20 was transformed from GA3. GA3 untreated samples from both good and poor clones could not found any types of gibberellines, suggesting that GA1 is the key type of gibberellines that promote C. formosana flowering. Minimal GA24 was detected in the GA3 treated samples. The dissertation is structured in four chapters. The topic of the first chapter is “Effect of cultural practices and gibberellins A3 on flowering of C. formaosan grafts”. The second chapter is “Preliminary of promoting flowering and seeding in Re-established clonal seed orchards of C. formosana”. The third chapter is “Effect of gibberellin A3 treatment on flowering response in different clones of C. formosana”. The fourth chapter is “Identification and quantification of gibberellin transformation and dosage changes in good and poor flowering clone of C. formosana grafts.”