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 3 different regeneration media supplemented with 1.5, 2, 2.5, 3
mg/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 2.5 mg/l 2,4-D MS
basal medium while the callus induction percentages were 30% and 32.5% in
1.5 mg/l 2,4-D and 3 mg/l 2,4-D media, respectively. The callus growth of rice
cultivars showed significant difference with the cultivar and with the
medium. By the 4th week of callus induction the maximum diameter of the
callus recorded by rice cultivar Herath on 2.5 mg/l 2,4-D with 0.1 mg/l BA MS
basal medium. The regeneration ability of rice cultivars were varied from 0 %
to 100% while the highest regeneration was recorded in rice cultivar Herath
on regeneration medium supplemented with 2.5 mg/l BA and 0.1 mg/l NAA.
Callus induction % were varied from 0% - 100% while Dik wee, Herath,
Pachchai Perumal and Rathu wee were observed significantly highest callus
formation. Sudu bala wee, Kahata wee (long grain), Sudu heenati, Kahata samba and
Muthumala failed to initiate callus on any of the medium. The 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 Suduru Samba. The highest
number of shoots (8 shoots/callus) was recorded in Sudhu samba compared to
other varieties (0.1-8per explant). There was a significant interaction
between callus induction medium and rice cultivar as well as regeneration
medium and rice cultivar.
