Feddes Repertorium 123 (2012) 1, 37 – 49 © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 0014-8962/12/102-0037 Research Paper Seasonal variation in the phytomass, chemical composition and nutritional value of Azolla filiculoides Lam. along the water courses in the Nile Delta, Egypt KAMAL H. SHALTOUT 1 ; THANAA M. EL-KOMI 1 & EBRAHEM M. EID *, 2 1 Botany Department, Faculty of Science, Tanta University, 31527 Tanta, Egypt 2 Botany Department, Faculty of Science, Kafr El-Sheikh University, 33516 Kafr El-Sheikh, Egypt Keywords: aquatic ferns, invasive species, nutritional value, phytomass, water courses * Corresponding author: Ebrahem M. Eid, Botany Department, Faculty of Science, Kafr El-Sheikh University, 33516 Kafr El-Sheikh, Egypt, Phone: 002 010 2264 8840; Fax: 002 047 3215175; E-mail: ebrahem.eid@sci.kfs.edu.eg Accepted for publication: September 6 th , 2012. DOI 10.1002/fedr.201200001 Abstract The present study aims to assess phenological be- haviour, phytomass production, chemical composi- tion and nutritional value of Azolla filiculoides in the water courses of the Nile Delta, Egypt. The sampling process was carried out seasonally using twenty-five plots (each of 1 × 1 m) distributed along 15 irriga- tion canals and 10 drainage canals in the study area. Sprouting of A. filiculoides had its maximum activity during winter, vegetative growth during spring and summer and withering during autumn. Maximum seasonal phytomass (285.2 g DW m –2 ) was found during spring. The annual mean was significantly higher in drainage canals (278.3 g DW m –2 ) than in irrigation canals (144.4 g DW m –2 ). The concentra- tions of Ca, Mg and Na in A. filiculoides from drain- age canals were significantly higher than in those from irrigation canals. Regarding the type of water courses, there were no significant differences in or- ganic contents and nutritive values between the ir- rigation and drainage canals. The analysis of growth characteristics indicated that A. filiculoides can grow quite well in drainage canals; its macronutrient (N, Ca, Mg, Na and Fe) contents are high enough to allow it to be used as a bio-fertilizer. On the other hand, A. filiculoides could be considered as a ‘nut- rients and heavy metals remover’ especially in drain- age canals for wastewater treatment if the plant is harvested during its maximum phytomass. As feed supplement for animals, this plant could be consid- ered as excellent forage because its high levels of carbohydrate, protein, crude fat, total digestible nut- rients and the lower crude fiber contents. 1 Introduction Azollaceae Wettst. is a monogeneric family with Azolla Lam. comprising six species with several varieties of aquatic ferns. Four of them (A. caroliniana Willd., A. filiculoides Lam., A. mexicana Presl and A. microphylla Kaulf.) are Neotropical and belong to subgenus Eua- zolla, while A. pinnata R.Br. and A. nilotica Decne. are Palaeotropical and belong to subge- nus Rhizosperma Meyen (EL-SAADAWI & DARWISH 1997). In Egypt, Azolla species were introduced and naturalized almost four decades ago (EL- SAADAWI & DARWISH 1997). The earliest known records of Azolla species were those reported from the rice fields around Qantara, Ismailia and Tanta (EL-HADIDI 1993a, b), which were identified as A. caroliniana and A. filicu-