Development of arbuscular mycorrhizal spore production in hydroponic culture on leaf lettuce (Lactuca sativar var crispa L.)

Abstract

This study aimed to assess the suitability of a nutrient liquid solution for the production of Glomus verruculosum on leaf lettuce, a highly-colonized horticultural crop that is a host of arbuscular mycorrhizal (AM) fungi for inoculum production. A hydroponic culture was developed to allow nursery production of an AM horticultural crop. A suitable host of leaf lettuce cultivars was selected by an initial experiment. The red-leaf variety was found to be the best host because it exhibit maximum amount of root infection. In a second experiment, 2 nutrient media; modified Long Ashton (LANS) and modified Hoagland medium (HNS) were compared for culturing AM fungi on leaf lettuce. After a pre-culture period of 4 weeks with 50 spores in sand substrate, the plants initially infected with AM fungi and irrigated with both LANS and HNS were not significantly different. At 4 weeks after transplanting in the hydroponic culture, the total percentage of root colonization was found to be significantly greater in HNS medium than in LANS medium. In a third experiment, 4 nutrient media (solution-I, solution-II, solution-III and solution-IV) of HNS were used to compare root colonization, plant growth and spore production. The solution was changed every week by a deep water culture technique. At harvest time, plants in a solution-I with containing of NO 3 - as the N source and insoluble Ca 3PO 4 and CaSO 4.2H 2O had a higher percentage of mycorrhizal colonization and spore population than those using other nutrient media.