To establish a mass micropropagation procedure for Cephalotus follicularis, the effects of varying the strengths of solid Murashige and Skoog (MS) medium were investigated using subcultured shoot explants. After a 60-day primary culture from root mass, the regenerated shoot explants were subcultured every 60 days in solid MS medium. To facilitate shoot proliferation, liquid MS medium was applied with or without exogenous auxin and cytokinin. Our results demonstrate that shoot proliferation and survival of C. follicularis is most effective in modified MS (MMS) medium containing one-fifth or one-tenth strength macronutrients and full-strength micronutrients. Successful shoot proliferation and development of C. follicularis explants were obtained in one-fifth or one-tenth modified liquid MS medium without auxin and cytokinin or with addition of 5 μM indole 3-acetic acid/1 μM N6-benzyladenine for 45 days. The liquid medium consistently produced more explants than the solid medium and shortened the culturing time. Plantlets cultured in hormone-free one-fifth MMS medium developed greater root systems. Using the liquid culture we established, vigorous plants with extensive roots were obtained within 4 months. Plant survival in the greenhouse reached 100%.
Chia-Yun Ko, Tsai-Yun Lin, Chin-Wen Ho and Jei-Fu Shaw
Ren-Huang Wang, Yu-Mei Hsu, Duane P. Bartholomew, Subbiyan Maruthasalam and Chin-Ho Lin
In Taiwan, the major yield constraint in pineapple cultivation is natural flowering, which occurs when daylengths are shorter and nights are cooler. This natural (precocious) flowering increases the cost of cultivation and reduces the percentage of fruits of marketable size. Two field experiments were conducted to evaluate the inhibitory potential of aviglycine [(S)-trans-2-amino-4-(2 aminoethoxy)-3-butenoic acid hydrochloride, AVG] on natural flowering of ‘Tainon 17’ pineapple plants during the 2003 to 2004 and 2004 to 2005 cropping seasons. In the 2003 to 2004 season, bolting in the control exceeded 80% on 2 Mar. 2004, whereas no bolting was observed in the treatments. Inhibition of bolting by aviglycine (AVG) was dependent on the concentration and frequency of application. Bolting was less than 40% when plants were treated in Nov. and Dec. 2003 with 500 mg·L−1 of AVG four times at 15-day intervals or with five applications made at 10-day intervals. For the 2004 to 2005 season, bolting of plants treated with 250 or 375 mg·L−1 AVG was delayed 4 weeks relative to the control, whereas bolting was delayed 7 weeks by four or five applications of 500 mg·L−1 of AVG applied at 10- or 15-day intervals. Both experiments showed that four to five applications of 500 mg·L−1 of AVG at 10- or 15-day intervals delayed inflorescence emergence relative to the control for the duration of the treatments. We assume control was maintained for 1 to 2 weeks after treatments stopped. Based on these results, the date AVG treatments stop can be used to estimate the duration of delay in flowering. AVG inhibits ethylene biosynthesis and has the potential to be effectively used to delay or completely control the problem of precocious flowering and associated crop losses in pineapple.
Ching-San Kuan, Chih-Wen Yu, Mei-Li Lin, Hsin-Tszu Hsu, Duane P. Bartholomew and Chin-Ho Lin
Natural flowering of pineapple is a serious problem for commercial growers of pineapple because it disrupts fruiting schedules, decreases harvesting efficiency and increases costs, and may reduce the percentage of marketable fruit. Aviglycine ([S]-trans-2-amino-4-(2 aminoethoxy)-3-butenoic acid hydrochloride), an inhibitor of ethylene biosynthesis, was applied as a foliar spray to evaluate its potential to prevent natural flowering in 1-year-old `Tainon 18' pineapple. Two experiments were conducted between 10 Oct. and 10 Apr. during the 2001-02 and 2002-03 production seasons. For the 2001-02 season, single or double applications of aviglycine at 100 mg L-1 had no significant effect on natural flowering. A double application of aviglycine at 500 mg L-1 first applied on 9 Nov. reduced flowering from 95.0% in the control to 51.3% when evaluated on 25 Feb. 2002. In the 2002-03 production season, triple applications of aviglycine applied at 20-day intervals beginning on 10 Nov. 2002 significantly reduced natural flowering when evaluated on 28 Mar. 2003. There was 95.8% flowering in the control, 64.6% with 250 and 375 mg L-1 aviglycine, and 50% with 500 mg L-1 aviglycine. Aviglycine has the potential to partially control precocious flowering of pineapple, which will reduce crop losses associated with such flowering.