Direct Shoot Bud Formation and Plantlet Regeneration from Culturing Leaf Discs of Neem (Azadirachta excelsa L.)

Abstract

Direct shoot bud formation and plantlet regeneration was induced from leaf discs of neem (Azadirachta excelsa (Jack) Jacobs) at various ages of development. The cultures were carried out in various kinds of media supplemented with various kinds and concentrations of plant growth regulators. Excised single shoots of more than 10 mm in length were rooted by different methods. The results revealed that leafdiscs from leaf at the age of 10-14 days after flushing gave shoot buds from 31 to 37 buds/disc on Murashige and Skoog (MS) medium containing 10 μM α-naphthaleneacetic acid (NAA) and 1 μM kinetin (KN). Among culture media tested, MS supplemented with plant growth regulator as mentioned above resulted in the best for shoot forming ability. Percentage of shoot bud formation was 92.7% and a number of shoot buds were 35/disc. Moreover, the number of shoot at length more than 10 mm ready for root induction obtained in MS was the highest, significant difference to other media. Addition of caseinhydrolysate at concentration of 500 mg/l increased total number of shoot and the number of shoot at length more than 10 mm to 52.2 and 5.5 shoots/leaf, respectively. In the case of root induction, half strength MS (1/2MS) together with 15 μM indole-1-butyric acid (IBA) alone provided 60% of shoots with roots. Complete plantlets could be successfully transferred to soil.