Effects of different growth regulators, nutrient media, gelling agents and carbohydrate sources on shoot multiplication of Pyrus glabra Boiss

Fars province is one of the natural habitats of Pyrus glabra Boiss. in Iran. Fruit harvesting, deforestation, expansion of agriculture and overgrazing during recent years has threatened the wild pear forests and imposed detrimental effects on their natural regeneration. Therefore, investigation on propagation of P. glabra for afforestation is needed. This research was carried out to study the effects of different growth regulators, nutrient media, gelling agents, and carbohydrate sources on shoot multiplication of P. glabra. Shoot tips and nodal segments of In Vitro propagated shoots originated from seeds and current season growth shoots of selected trees were used as explants. Two concentrations of 0.8 or 1.0 mgl-1 BA and 0.01 mgl-1 IBA were optimum for shoot multiplication. Addition of GA3 to nutrient medium had negative significant effects on shoot fresh weight of explants. Main shoot length of explants cultured on Murashige and Skoog (MS) medium was significantly longer than those cultured on woody plant medium (WPM) and Driver Kuniyuki walnut (DKW) (half strength macronutrients) medium. Quality and morphology of shoots produced on DKW medium were better than other nutrient media. Explants cultured on media containing sucrose or glucose did not show any significant differences for measured growth indices, but both of them were significantly better than those cultured on the media containing fructose. Media solidified with Phytagel were significantly better than those solidified with Difco Bacto agar for shoot fresh weight. The quality of shoots produced on media solidified with Phytagel was better than those on media solidified with Difco Bacto agar.