Effects of Mycorrhizal Fungi on Rosa Multiflora 'Brooks 56' Understock

by Fred T. Davies, Jr.

Asexually propagated rooted cuttings of Rosa multiflora 'Brooks 56' were grown in 15 cm. clay pots containing sterilized media of 1 mineral soil: 1 sand (v/v) or 1 bark: 1 sand (v/v) inoculated with VA mycorrhizal fungi [Glomus mosseae (Nicol. and Gerd.) and G. fasciculatus (Thaxt. sensu Gerd.) Ger. and Trappe] (VAM) or left as noninoculated controls. Slow release fertilizer (18N-6P-12K) at rates of 1.2 or 4.2 kg/m3 were incorporated into the container media. After 180 days plants were evaluated for shoot and root fresh and dry weight, length of longest and second longest axillary shoots, number of lateral brakes, and stem cutting fresh and dry weight. Greatest growth responses occured at highest fertility of 4.2 kg/m3. Combination bark: sand media was superior to mineral soil: san media. At 1.2 kg/m3, VAM plants in bark: sand media had greatest effect on all growth parameters except the length of the longest shoot and number of new lateral brakes. At the highest fertility rate of 4.2 kg/m2, greatest growth responses occurred with mycorrhizal colonized plants in barkL sand media.

Acta Horticulturae 189. 1986