Effect of cultivar, nitrogen nutrition and cultivating system of Chrysanthemum mother plants on cutting yield, nitrogen concentration, and subsequent rooting of cuttings

Cuttings of chrysanthemum mother plants (Dendranthema Grandiflorum-Hybrids) were grown and the influence of cultivar ('Puma', 'Cassa'), cultivation system (peat substrate, hydroponic) and nitrogen supply (deficient, adequate, high) was investigated on cutting yield (number per mother plant and fresh mass per cutting), nitrogen concentration of cutting dry mass and rooting behaviour of cuttings (root number and length per cutting). After 21 cutting harvests an adequate nitrogen fertilization of chrysanthemum mother plants appropriate to the actual demand (peat substrate: 1.5 to 2 g N *m(-2) * week(-1); hydroponic: 100 to 120 mg N * l(-1)) yielded the highest number of cuttings per mother plant (29 to 33) and the highest fresh mass per cutting (1.13 to 1.50 g). The rooting of chrysanthemum cuttings could be enhanced up to the highest nitrogen fertilization level under adequate lighting conditions (natural radiation in greenhouse in spring and early summer). In the hydroponic cultivation system cuttings revealed significantly higher dry mass nitrogen concentrations (7.83 % N) compared to the highest nitrogen supply in pear substrate cultivation (5.84 % N). However, this was not associated with a higher number of roots. In contrast, the root length of hydroponic cuttings was significantly enhanced with high nitrogen supply. High nitrogen supply promoted rooting in both systems but with the disadvantage of increasing the risk of gaseous nitrogen losses and unwanted salt accumulation in the rooting zone. This led to hardened cuttings of a visually poorer quality, reduced cutting fresh mass and increased dry matter content. Therefore, nitrogen dosage per area and the time unit should be adjusted to the fluctuating uptake requirements of the mother plants. Our results indicate that this is the only way to achieve both maximum yield and optimal quality in cutting production. However, precise determination of the fluctuating nitrogen demand of mother plants requires further research.