1 Institute of Plant Nutrition (330), Hohenheim University, Fruwirthstr. 20, 70593 Stuttgart, Germany & National Institute of Agricultural Science and Technology, RDA, Suwon, 441-707, Republic of Korea
| 2 Leibniz Institute of Vegetable and Ornamental Crops, 14979 Grossbeeren, Germany & Plant Nutrition Institute of Crop Sciences, Humboldt University Berlin, 10115 Berlin, Germany
A nutrient film technique (NFT) culture system was developed to allow nursery production of arbuscular mycorrhizal horticultural crops. This would benefit horticultural production and allow for uncomplicated production of mycorrhizal hyphae. Roots of lettuce (Lactuca sativa var. capitata) plants were highly colonized by the arbuscular mycorrhizal fungus, Glomus mosseae (BEG 107) after 4 weeks in the NFT system, following an initial phase of five weeks in inoculated in Perlite substrate. In the NFT system, a thin layer of glass beads was used to provide solid support for plant and fungus growth and nutrient solution was supplied intermittently (15 min, six times per day). A modified nutrient solution (80 μm P) was used and was replaced with fresh solution every 3 days. A significantly higher dry weight was found for the mycorrhizal versus the nonmycorrhizal lettuce plants in Perlite during the precolonization period. The root colonization rate was also high at rates up to 80 μm P supply. On the NFT system, growth differences between mycorrhizal and nonmycorrhizal plants were less than in Perlite. However, root colonization rate was not reduced during the NFT culture period. In this system, high amounts of fungal biomass were produced. This would allow the determination of metal and other nutrient concentrations in fungal hyphae. Furthermore, we found large amounts of external fungal hyphae surrounding the root surface. As much as 130 mg fungal biomass were collected per culture plate (three plants). Therefore, we suggest that this modified NFT culture system would be suitable for fungal biomass production on a large scale with a view to additional aeration by intermittent nutrient supply, optimum P supply, and a use of glass beads as support materials. Furthermore, bulk inoculum composition with a mixture of spores, colonized roots, and hyphae grown in soilless media by the modified NFT system might be a useful way to mass-produce mycorrhizal crops and inoculum for commercial horticultural purposes.
Plant nutritionist and corresponding author. Current address: Division of Organic Farming Technology, National Institute of Agricultural Science and Technology, RDA, Suwon, 441-707, Republic of Korea; e-mail firstname.lastname@example.org.