Uncapped centre Fickou, 18, picked up an ankle injury in a Heineken Cup game this month.
Winger Plante, who has never played for France, won the French championship with Perpignan.
France, who finished last year's Six Nations in a disappointing fourth place in coach Philippe Saint-Andre's first competition in charge, visit Italy on Feb. 3 and host defending champions Wales at Stade de France the following week.
The squad will be trimmed to 23 players before the opening game.
Forwards: Vincent Debaty, Thomas Domingo, Yannick Forestier, Benjamin Kayser, Guilhem Guirado, Dimitri Szarzewski, David Attoub, Luc Ducalcon, Nicolas Mas, Yoann Maestri, Pascal Pape (captain), Jocelino Suta, Romain Taofifenua, Damien Chouly, Thierry Dusautoir, Wenceslas Laurey, Yannick Nyanga, Fulgence Ouedraogo, Louis Picamoles.
Backs: Maxime Machenaud, Morgan Parra, Frederic Michalak, Francois Trinh-Duc, Mathieu Bastareaud, Jean-Marcellin Buttin, Vincent Clerc, Brice Dulin, Benjamin Fall, Adrien Plante, Wesley Fofana, Florian Fritz, Yoann Huget, Maxime Mermoz.