IMPORTANCE OF THE IRON CHELATE FORMULA FOR MICROPROPAGATION OF ROSA-HYBRIDA L MONEYWAY

In vitro propagation of the rose rootstock 'Moneyway' was investigated on the following media: Murashige and Skoog (MS), Quoirin and Lepoivr e (QL) and Woody Plant (WP). Growth, which was measured as length of s hoots after a 6-week period, was faster on MS and QL than on WP, In sp ite of the better growth, chlorosis of newly formed leaves occurred fr om the third week on and was correlated with a lower chlorophyll conte nt of shoots. Replacement of FeEDTA by FeEDDHA in QL and MS resulted i n the development of green shoots for more than 3 months. The occurren ce of chlorosis was not pH directed since the pH of QL with FeEDTA or FeEDDHA had not changed after 6 weeks of growth. Addition of the light absorbing dye fast yellow 9 to QL with FeEDTA also resulted in green shoots with a higher chlorophyll content. It is suggested that FeEDDHA is a more photostable chelate than FeEDTA, resulting in a higher avai lability of iron for the rose shoots. The impact of the iron chelate f ormula on the micropropagation of plant species that are susceptible t o iron deficiency is discussed.