Growth characteristics and nutrient depletion of Miscanthus x ogiformis Honda 'Giganteus' suspension cultures

The growth characteristics and nutrient depletion in suspension cultures of Miscanthus x ogiformis Honda 'Giganteus' grown in media containing either Murashige and Skoog or N6 basal nutrient salts were studied during a culture period of 15 days. Proline was added to both media in concentrations from 0 to 300 mM. The fresh and dry weights of the suspension aggregates and the concentrations of ammonium, nitrate, proline and sugar remaining in the medium were measured at different points in time during the culture period. The results showed an almost total depletion of ammonium but a limited nitrate depletion of only 15 mM in both media. Proline at 12.5 to 50 mM was totally depleted during the culture period whereas approximately half the concentration remained in media with 100 to 300 mM proline. Higher fresh weight increases were obtained by the proline additions to the N6 as compared to the MS suspension cultures. Sucrose was hydrolysed into its monosaccharide components in the culture medium. Glucose was depleted faster than fructose indicating a preference for glucose as a carbohydrate source of the M. x ogiformis cultures. The high water uptake by the suspension aggregates 12 to 15 days after subculture indicate that the cultures should be subcultured more frequently to prevent the formation of nonembryogenic cells in the cultures.