利用植物生長調節劑誘導番木瓜體內、體外腋芽與組織培養幼苗生長及發育

番木瓜 (Carica papaya L.) 為世界主要熱帶水果之一，擁有高產、營養豐富及週年結果的特性，目前多以實生苗行栽培（一穴三株），再篩選兩性株。此模式造成人力成本增加、肥料的浪費及生長空間的競爭。組織培養可以大量繁殖優良基因遺傳性狀且全兩性株的番木瓜種苗，顯著提高栽培效率。本試驗以番木瓜‘台農2號’苗齡4個月之實生苗作為體內腋芽誘導材料，結果顯示不同濃度組合的BA及GA3在處理植株兩週後，對短腋芽 (< 40.0 mm) 及長腋芽 (≥ 40.0 mm) 有交感效應，其中 (2,220 µM BA + 289 µM GA3) 處理2週後，可產生最多短腋芽（9.1 ± 0.4）， (444 µM BA + 866 µM GA3) 可產生最多長腋芽（8.4 ± 0.9）。此兩處理可用作番木瓜體內誘導腋芽配方，以採取最多的組織培養材料。體外腋芽以 (1 µM BA + 3 µM GA3) 處理後3個月，可得總腋芽數18.0 ± 0.5，與各處理達顯著性差異，此處理腋芽的葉片沒發生玻璃質化。以 (1 µM BA + 3 µM GA3) 處理培植體一個月，再繼代培養於不含植物生長調節劑的培養基中，可有效降低培植體的癒傷組織發生率，另添加1 g L-1活性炭培養四個月後，則可提高培植體生長抽長且具頂芽優勢的腋芽數（1.9 ± 0.2），同時使培植體保持更高的顏色指數及更高的生物量合成效率，乾鮮重比顯著最大 (10.50 ± 0.31%) 。將誘導形成之腋芽培植體以不同濃度IBA進行發根處理， 15 µM IBA處理組在處理後第6週達100%發根率，根數達9.7 ± 2.1，平均根長為23.93 ± 8.84 mm，然而各處理組均有80%左右的癒傷組織發生率。處理後第11週，10 µM IBA處理組植株高度達26.66 ± 16.45 mm與各處理達顯著性差異，同時也有平均最多葉片數（3.87 ± 1.32）及平均最低癒傷組織大小 (16.68 ± 1.09 mm）。以15 µM IBA處理一週後，將培植體定植在不同發根介質的培養基內，3週後結果顯示水耕海綿介質處理組平均植株高度達24.74 ± 3.48 mm及葉片數為6.7 ± 0.8，0.7%洋菜介質則培植體高度僅17.46 ± 3.72 mm及葉片數4.3 ± 1.4。處理後4週，水耕海綿及洋菜介質中發根的培植體，在根數、地上部乾鮮重及地下部乾鮮重都沒有顯著差異，但在地下部乾鮮重比方面，則以水耕海綿的9.01 ± 0.32%顯著較高。本試驗對番木瓜組織培養進行腋芽增殖系統的建立，結果顯示以 (444 µM BA + 866 µM GA3) 對番木瓜體內及 (1 µM BA + 3 µM GA3) 對體外有最佳腋芽誘導效率，而在瓶內則需以不含生長調節劑且添加活性炭的培養基進行交替培養，以降低癒傷組織的發生率及提高腋芽生長並恢復頂芽優勢。在發根處理方面，以15 µM IBA處理1週後，繼代培養到以水耕海綿作為固定介質的培養基內，擁有最好的培植體生長狀況，在繼代3週後，便可對培植體進行馴化及出瓶。

關鍵字

體內腋芽誘導；瓶內增殖；發根；發根介質；活性炭；植物生長調節劑

並列摘要

Papaya (Carica papaya L.) is currently one of the major tropical fruit in the world. It is often characterized by high yields, enrich with vitamins and year-round production. Seed propagation in cultivation required 3 seeds per unit and culled to one hermaphrodite plant when they reached reproductive growth period. This method will increase labor cost, waste of fertilizer and competition of growing space. Tissue culture can mass propagate elite genotype from known sex of papaya seedling, thus increase cultivation efficiency. This experiment used 4 months old ‘Tainung 2’ papaya seedlings to induce axillary bud with different plant growth regulator treatment (PGR). Result showed two weeks after combination of different concentration of 6-benzylaminopurine (BA) and gibberellic acid (GA3) treatment showed significant interaction between this two PGR for inducing short axillary bud (< 40 mm) and long axillary bud (≥ 40 mm), where as treatment with (2,220 µM BA + 289 µM GA3) induced most short axillary bud (9.1 ± 0.4) and (444 µM BA + 866 µM GA3) induced most long axillary bud (8.4 ± 0.9). This combination could be use for in vivo axillary bud induction for material of in vivo experiment, as well as the ratio combination will be used in papaya in vitro axillary bud induction. In vitro multiplication using (1 µM BA + 3 µM GA3) and (5 µM BA + 1 µM GA3) induced significantly higher average long shoot (> 10 mm) than control, which is 3.3 ± 0.2 and 3.2 ± 0.7 shoots after 3 months of treatment. (1 µM BA + 3 µM GA3) induced significantly highest total shoot number (18.0 ± 0.5) without vitrification on leaf. Treatment with (1 µM BA + 3 µM GA3) for 1 month and subculture to medium with PGR could effectively reduce callus production rate, while addition of 1 g L-1 activated charcoal and cultured for 4 months could increase number of elongated axillary shoot per plantlet (1.9 ± 0.2), at the same time maintained higher green color index and had better biomass production rate, with significant highest dry weight (DW) to fresh weight (FW) ratio of 10.50 ± 0.31%. Rooting induction using indole-3-butyric acid (IBA) on shoot with shoot length above 5 mm successfully produced rooting after 3 weeks. Treatment with 15 µM IBA achieved rooting rate of 100% after 6 weeks of treatment with average 9.7 ± 2.1 roots per shoot and average root length 23.93 ± 8.84 mm. Treatments showed averagely 80% induction of callus. Eleven weeks after IBA treatment, 10 µM treatment produced significantly highest plantlet with average height 26.66 ± 16.45 mm, highest number of leaf number (3.9 ± 1.3) and smallest callus width (16.68 ± 1.09 mm). Shoots treated with 15 µM of IBA then subculture to different rooting media showed highest plantlet height (24.74 ± 3.48 mm) and leaf number (6.7 ± 0.8) for hydroponic sponge as rooting media after 3 weeks, while 0.7% agar as rooting media produced plantlet height of 17.46 ± 3.72 mm with 4.3 ± 1.4 leaf numbers. After 4 weeks of treatment, plantlet growth in hydroponic sponge and agar were indifferent in root number, shoot FW and DW, root FW and DW, but hydroponic sponge treatment showed significant higher in root DW to FW ratio (9.01 ± 0.32%). This experiment goal was to establish papaya in vitro axillary shoot multiplication system, result of this study showed (444 µM BA + 866 µM GA3) treatment for in vivo and (1 µM BA + 3 µM GA3) treatment for in vitro could achieved highest axillary bud induction rate. In conclusion, the in vitro cultivation system on culture medium with PGR and with alternate cultivation on medium without PGR while supplement of activated charcoal, could reduce callus production rate and increase axillary bud growth to restore apical dominance, then prepare the axillary shoot for rooting treatment of 15 µM IBA for 1 weeks and subculture to medium without PGR and plus use of the hydroponic sponge as supporting media. After 3 weeks of subculture, plantlets are ready for acclimatization and reestablishment in soil.