Effects of some plant growth regulators and light on callus induction and explants browning in date palm (Phoenix dactylifera L.) in vitro leaves culture

The present study was carried out to evaluate the effects of light and plant growth regulators on callus induction and explant browning in date palm cultivar, estameran in in vitro condition. the explants were pretreated by an antioxidant combination (100 mgl^-1 citric acid and 150 mgl^-1 ascorbic acid) for 3 days in 5 °c. then, the leaf explants were cultured in murashige and skoog medium (ms) with 3 gl^-1 of activated charcoal, 75 mgl^-1 citric acid and 75 mgl^-1 ascorbic acid, for 14 days. after that, explants cultured in callogenesis medium were supplemented with 12 different levels of plant growth regulators including 2,4-d (0 and 5 mgl^-1), tdz (0 and 5 mgl^-1), and bap at three concentrations (0, 5, and 10 mgl^-1), and two incubation conditions (light condition and absolute darkness). the number of explants that induced callus and browning was recorded after six months. results indicated that 2,4-d and bap increased browning and this was exacerbated under light condition. highest callus induction was achieved in medium supplemented with 5 mgl^-1 bap or with 5 mgl^-1 tdz. this experiment showed that low concentrations of cytokinin induced callus in date palm in vitro leave culture and callus induction increased in darkness.