EFFECTS OF ROOTING PERIOD, CLUMP SIZE, AND GROWTH MEDIUM ON SUGARCANE PLANTLETS IN MICROPROPAGATION DURING AND AFTER TRANSFORMATION TO PHOTOAUTOTROPHY

摘要

Experiments were conducted to improve the conditions for growth of sugarcane (Saccharum spp.) plantlets during and after transformation to photoautotrophy. The experimental treatments included different rooting periods, media, and clump sizes. Photomixotrophic (sugar-containing medium) and photoautotrophic (sugar-free medium) cultures were also compared. The presence of roots was concluded to be essential for plantlet survival during transformation from photomixotrophic to photoautotrophic culture. Six-week rooted plantlets were fully capable of surviving photoautotrophic conditions after transfer whereas three- and four-week rooting periods were insufficient. The test of clump size during transformation to photoautotrophy showed that two plantlets per clump resulted in the highest growth, but insignificantly so, when tested against four plantlets per clump and individual plantlets. Comparison of different sugarless medium types for the photoautotrophic growth of plantlets showed that liquid Murashige and Skoog (MS) medium had the highest growth among other liquid media tested but the differences were not statistically significant. Similarly, gelled MS medium gave insignificantly higher growth rates when compared with liquid MS media. Liquid MS medium was concluded to be suitable for photoautotrophic growth of sugarcane plantlet cultures. The experiments of this study achieved photoautotrophic cultures growing in weight and in number of plantlets, though at a much slower rate than for photomixotrophic cultures. This study is the first time photoautotrophic multiplication of any plant has been demonstrated in micropropagation and further optimization of culture conditions is needed.