Isolation and Screening of Mycorrhizal Fungi from Citrus Nurseries and Orchards and Inoculation Studies

Abstract

The selection of the most effective arbuscular mycorrhizal (AM) fungi for growth enhancement of citrus cultivars used as rootstocks was the first step toward development of an AM inoculation system in citrus nurseries in Spain. AM fungi were isolated from citrus nurseries and orchards in the major citrus-growing areas of eastern Spain. The most common AM fungi found in citrus soils belonged to Glomus species, and G. mosseae (Nicol. & Gerd.) Gerdemann & Trappe and G. intraradices Schenck & Smith were the AM fungi most frequently associated with citrus roots. The most effective fungus for growth enhancement of citrus rootstocks was G. intraradices. Significant differences in mycorrhizal dependency among rootstocks were confirmed. Sour orange (Citrus aurantium L.) and Cleopatra mandarin (C. reshni L.) were more dependent than Troyer citrange [C. sinensis (L.) Obs. × Poncirus trifoliata (L.) Raf.] and Swingle citrumelo (C. paradisi Macf. × P. trifoliata). Moreover, several inoculation systems for plant production were evaluated for their effectiveness in promoting root colonization of the rootstock cultivars.