ICOM1 Abstract

ALVAREZ, I.F., J. PERA & J. PARLADE. IRTA, Dept. de Patologia Vegetal, Ctra. de Cabrils s/n, 08348 Cabrils (Barcelona), Spain. - Effect of mycorrhizal inoculation, hormone treatment and substrate disinfection on rooting, mycorrhiza development and growth of Douglas-fir cuttings Douglas-fir cuttings were taken from three-year-old mother plants and inserted in a substrate composed of peat and vermiculite (1:1, v:v) previously disinfected with either steam or methyl bromide. Two hormonal treatments were applied: 24 h dipping in L-exuberone or IBA mixed with talc powder. Inoculation of cuttings with vegetative inoculum of Laccaria bicolor S-238 N was established at insertion at the dose 1:20 (v:v, inoculum substrate). Inoculation with spores of Melanogaster ambiguus and Rhizopogon subareolatus were established two months after insertion at the dose of one million of spores per cutting. A treatment of non inoculated seedlings was also considered. After rooting, the mean percentage of mycorrhizal plants with each fungus for the whole experiment was 82 % for L. bicolor, 30% for R. subareolatus and 21% for M. ambiguus. Substrate disinfection with methyl bromide decreased significantly the number of rooted cuttings and the percentage of mycorrhizal plants with R. subareolatus (for both hormone treatments) and L. bicolor (only for exuberone). Inoculation with either L. bicolor and R. subareolatus significantly increased the percentage of rooted cuttings. No significant effects in growth were observed.