Abstract:
A total of forty Sri Lankan traditional rice varieties (Oryza sativa L) were examined for their callus induction, growth and regeneration ability at Laboratory of Agricultural Biology, Faculty of Agriculture,
University of Ruhuna. Surface sterilized rice seeds (caryopses) were cultured on four different callus
induction media supplemented with 1.5, 2.5, 3mg/l 2,4 – dichlorophenoxy acetic acid (2,4-D) and 0.1 mg/
l 6 – benzyladenine (BA) on Murashige and Skoog’s (MS) basal medium. Proliferated calli were regenerated on 4 different regeneration media supplemented with 1.5, 2, 2.5, 3mg/l BA with 0.1 mg/l naphthaleneacetic acid (NAA). Eighty seven point five % of rice cultivars were able to produce callus on callus induction medium and among them 12.5 % of rice cultivars regenerated shoots. 100% callus induction was recorded by 75% of tested rice cultivars on 2.5mg/l 2,4-D supplemented to MS basal medium while the callus induction percentages were 30% and 32.5% in 1.5mg/l 2,4-D and 3mg/l 2,4-D supplemented media respectively.
Callus growth of rice cultivars showed significant difference with the cultivar and medium. By the 4th
week of callus induction maximum diameter (> 2cm) of callus recorded by rice cultivar Herath on 2.5
mg/l 2,4-D + 0.1mg/l BA + MS basal medium. The regeneration ability of rice cultivars varied from 0 %
to 100% while the highest regeneration was recorded in rice cultivar Herath on regeneration medium
supplemented with 2.5mg/l BA and 0.1mg/l NAA. Callus induction varied from 0% - 100% and significantly high callus formation was offered in Dik wee, Herath, Pachchai Perumal and Rathu wee. Sudu bala wee, Kahata wee (long grain), Sudu heenati, Kahata samba and Muthumala failed to initiate callus on any of the medium. Significantly highest shoot regeneration percentage was found in Herath (100%) while Mas samba, Seedevi, Dostara heenati and Rathel were also categorized in to the same DMRT (Duncan's Multiple Range Test) group with Herath. The highest number of shoots (8 shoots/callus) was recorded in Herath compared to other varieties (0.1- 8 per explant). There was a significant interaction between callus induction medium and rice cultivar as well as regeneration medium and rice cultivar.
