Effect of vesicular—arbuscular mycorrhizae on growth of Chrysanthemum morifolium Ramat

Benefits of inoculation with the mycorrhizal fungus Glomus fasciculatus (Thaxter) Gerd. Trappe, on growth of Chrysanthemum morifolium ‘Circus’ were determined for varied conditions of N fertilization (375, 1500 or 3000 kg N/ha/year) and irradiance (6 or 800 μE m^?2s^?1) during lighting long-day treatments. High N fertilization combined with high level of irradiance produced the most mycorrhizal infection. Mycorrhizal infection generally increased C. morifolium height, especially with continuation of long-day lighting to 8 weeks. Mycorrhizae also improved flower, stem and root dry weight for most treatments, particularly the 1500 or 3000 kg N/ha/year fertilization rate and 4- or 8-week long-day light treatments. Although mycorrhizal inoculation increased C. morifolium growth most under extended long-day treatments, only the 2-week duration night lighting resulted in commercially acceptable plant size.