Optimization of in vitro culture in Tetra, Nemaguard and GF677 clonal rootstocks

According to problems caused by application of non-uniform seedling rootstocks in stone fruit trees orchards، the use of uniform and consistent rootstocks with these trees is essential. For determination of the best culture medium، explants of apical and lateral buds of Tetra، Nemaguard and G 677 rootstocks were prepared. Explants were placed in modified MS، WPM and Knop media each containing 0. 6 mg/l BAP and 0. 01mg/l NAA in mid-Spring and after disinfection. This research was carried out as factorial experiment in a completely randomized design with four replicates and four observations per each replication. Tetra، GF677 and Nemaguard rootstocks produced the highest of plantlet number respectively. Nemaguard rootstock did not show any proliferation in Knop medium and Nemaguard explants showed chlorosis on this medium. This medium caused chlorosis in produced plantlets of Tetra explants. Explants of every three rootstocks were produced the highest plantlet number and length in MS modified medium. Therefore، combinations of plant growth regulators were evaluated in this medium. Three different combinations were evaluated. Among different combinations of plant growth regulators (0. 8 and 1 mg/l BAP and 0. 1 and 0. 5 mg/l NAA)، the highest plantlet number and length were produced in MS medium containing 0. 6mg/l BAP and 0. 01mg/l NAA. Increase of plant growth regulators concentrations led to vitrification and callus production in GF677 rootstock. The highest root number and rooting percent were achieved in modified MS medium containing 1 mg/l NAA and explants of Tetra rootstock produced the highest root number and length.