IMPROVEMENT OF INDICA RICE (ORYZA-SATIVA L.) IN-VITRO REGENERATION EFFICIENCY FROM CALLUS MEDIATED BY STRESS

Plant regeneration frequency and average number of plant per callus si gnificantly enhanced in Indica rice callus maintained under the stimul atory effect of stressing conditions. Culture on high sucrose concentr ation for one week before regeneration, increasing gelling agent conce ntrations in the regeneration medium above the recommended levels, or blotting on filter paper for drastically reducing callus water content prior regeneration lead to significant improvements of regeneration e fficiency from callus, although no selection of embryogenic clusters w as performed. The simple procedures described in this paper provide an alternative for improving regeneration capacity in other rice cultiva rs and recalcitrant cereal species for in vitro regeneration of whole plants.