Effect of Media and Photoperiod on Embryogenic and Organogenic Callus Induction from Mature Seed in Oryza sativa L.

Rice is the staple food for billions of people and a source of income for hundreds of millions. This food security crop production needs to be improved to face the projected demands of the exponentially augmenting world’s population and overcome biotic and abiotic stress in the fields. Optimized in vitro culture protocols are a prerequisite to genetic engineering which appears to be the best potential way to improve the rice plant. In this study, ‘Nerica 3’ and ‘Nerica L36’ seeds were in vitro culture tested into 4 media (m1-4), in dark and photoperiod environments. The percentage of callus induction was calculated and callus weight was recorded. Results show that callus induction was influenced by variety × environment and medium × environment interactions, with a strong influence of the environment used. ‘Nerica 3’ showed the highest mean (88.25%) callus induction after six weeks of incubation on different media. m1 and m2 media showed greater mean callus induction (more than 86%). Higher callus induction came from m1 (82% and 91%) and m2 (81% and 93%) media, while lower rates came from m3 (73%) and m4 (69%) media for embryogenic and organogenic calli respectively. Culturing the explant in dark environment to produce embryogenic callus, resulted in greater callus weight for ‘Nerica 3’ (1.03 g) and ‘Nerica L36’ (0.79 g). This study is a contribution to the rice plant genetic improvement by proposing protocols for somatic embryogenesis of two Nerica rice varieties.