The variables included rupture disc pressures (1,100 psi), distance from rupture disk to macrocarrier (6 cm), type of micro carrier (gold), size of micro carrier (1.0 μm diameter of gold particles), number of bombardments per Petri plate (1), precipitating agent of ackage the bullets (0.1 M Spermidine and 2.5 M CaCl2). After bombardment, scutella were kept on
medium supplemented with 0.4 M mannitol for 16 h then transferred to induction medium without mannitol.
The Experiment designs two controls: gold bombardment (without exogenous gene) and no bombardment.