Variation in aromatic rice (Oryza sativa L. var. Khao Dawk Mali 105) derived from tissue culture
1994
Porntip Cheewasesthatham
Embryos of aromatic rice (Oryza sativa L.) variety Khao Dawk Mali 105 cultured on MS medium supplemented with 2 mg/1 2, 4-D and 300 mg/l casein hydrolysate for 4 weeks under light condition produced the high percentage of callus formation (96.3 %). The callus produced was also largest in the size (9.4 mm). The calli dehydrated by placing in the petridish for 7 days before transferring to regenerating medium could regenerate into shoots at the higher frequency than calli cultured on regenerating medium without dehydration. There were 2 kinds of medium suitable for plant regeneration. The first medium was MS suplemented with 1 mg/1 IAA and 4 mg/1 BA which induced the highest percentage of calli forming shoots (45.8 %) and each callus produced 7.9 shoots. Another medium was MA supplemented with 1 mg/l IAA, 4 mg/l BA and 1 g/l yeast extract which induced the high percentage of calli forming shoots (45.5 %) and each callus produced the highest number of shoots (average 8.7 shoots). Regenerated R1 plants from embryo-derived calli showed variation in various agronomic characters. There were the number of days to flowering, plant height, number of tillers and panicles per plant, percentage of seed fertility and seed weight. Chlorophyll mutation was also found among the R1 plants such as albino and striata. R2 progenies showed variation in agronomic characters similar to R1 plants. Some lines of the R2 progenies segregated into photoperiod sensitive and insensitive plants. The photoperiod insensitive plants flowered when they reached the maximum vegetative growth stage without the influence of short daylength. Most of the lines of R2 progenies including control plants were photoperiod sensitive. They flowered after the stimulation of short daylength. Chlorophyll mutation was recovered among the R2 progenies such as albino, xantha and striata.
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