Response of Different Salts as Alternative Nitrogen Source for Ginger (Zingiber officinal rosc.) In Vitro Regeneration

In Ethiopia, ginger is mainly produced in southern parts of the country specifically in some districts of Wolayta and Kambata Tambaro administrative zones. Its production is being challenged primarily due to bacterial wilt disease eruption as of 2012 production season. Use of disease free tissue culture generated seed rhizome as part of integrated management was considered as best option to reduce the disease impact. On the other hand, major media components like ammonium nitrate are not available for large scale in vitro propagation. To enhance disease free ginger in vitro propagation; experiment was designed with the aim to select alternative sources of nitrogen to replace unavailable ammonium nitrate due to its explosive nature and safety issue. Three nitrogen salts at different level were evaluated as part of MS medium for in vitro regeneration of Volvo ginger cultivar. Three alternative salts tasted (NH₄Cl KNO₃ and urea) were observed as potential replacements of NH₄NO₃ in MS medium supplemented with 2.0 mg/l BAP and 1.0 mg/l Kinetin. The highest mean shoot number (9.33) of shoots from media containing 1.0 g/l NH₄Cl followed by mediums containing 1.9 g/l KNO₃ and 4.5 g/l urea with record of mean shoot numbers 7.33 and 7.00 respectively. Whereas, the lowest explants survival and proliferation was observed on medium containing 2.0 g/l and 1.65 g/l NH₄Cl. Root formation and survival after acclimatization were also affected negatively at elevated levels of NH₄Cl. The highest mean number of roots was observed on medium supplemented with 1.0 g/l NH₄Cl followed by normal MS media. In contrary, the lowest root number (4) was observed on medium containing 2.0 g/l NH₄Cl. Survival after acclimatization was found to be 98% for plants derived from medium containing 4.5 and 1.9 g/l urea and KNO₃ respectively followed by 95% for plants derived from medium containing 1.0 g/l NH₄Cl. This experiment revealed that the three nitrogen salts can be used as nitrogen source. But urea (3 g/l to 4.5 g/l) was the first option for ginger in vitro propagation which ensures availability and low cost tissue culture technique.