Study on callogenesis and organogenesis in local cultivars of rice (Oryza sativa L.)

Callogenesis and organogenesis studies were carried out for three important cultivars of rice i.e.,basmati-370,dr-82 and ir-6. 2,4-d @ 2.0 mg l -1 on ms medium proved to be the best for callus formation in all cultivars. maximum callus was produced by dr-82 followed by basmati-370 and irri-6,respectively. in order to get maximum regeneration frequency,different factors (age of calli and addition of ga3 in regeneration medium) were optimized. different concentrations and combinations of hormones i.e.,naa 1.0 mg l -1,bap 2.0-5.0 mg l -1 and ga3 0.5 mg l -1 or kinetin 0.5- 2.0 mg l -1 were used on ms medium. calli were shifted to different regeneration media to evaluate the plant regeneration frequency in tested rice cultivars as an interaction with all the cultivars. basmati- 370 showed regeneration efficiency (40.0%) on rm3 (naa 1.0 mg l -1 + bap 5.0 mg l -1 + ga3 0.5 mg l -1) while 80.0% and 65.0% was observed on the same medium in dr-82 and irri-6,respectively. maximum plant regeneration as a whole on different regeneration media was noted in irri-6,followed by dr-82 and basmati-370,respectively. it was also observed that 25 days old calli had more plantlet formation as compared to 17,21 and 29 days old calli. among the rice cultivars response of different calli ages on regeneration efficiency was of the order of dr-82>irri- 6>basmati-370. maximum regeneration frequency and multiple shoot formation were observed on medium containing ga3 in addition to bap and naa from 25 days old calli.