Liquid overlaying improves somatic embryogenesis in <Emphasis Type="Italic">Catharanthus roseus</Emphasis>

Somatic embryos were induced from in vitro germinating seed-hypocotyls of Catharanthus roseus. The process of embryogenesis has been categorized into a few distinct stages (induction, proliferation, maturation and germination) in which liquid overlaying at varying levels 0 ml (T₀), 0.25 ml (T₁), 0.5 ml (T₂)_, 0.75 ml (T₃) and 1.0 ml (T₄) was applied on solid medium. It was found that liquid overlaying improved proliferation; maturation, germination of embryos in C. roseus. In proliferation stage, particularly in T₂, torpedo embryo number increased significantly (i.e. 129.6%) as compared to control. Liquid overlaying (T₂, T₃ and T₄) also improved embryo maturation and showed early germination even in maturation medium. It also accelerated normal embryo germination frequency particularly in treatment with T₂ and shortened ‘embryo—plantlet’ recovery time. Biochemical analyses revealed more proline, protein and amino acid with increasing level of liquid overlaying as it improved embryo induction, development and faster germination.