Nitrogen content, nitrate reductase activity, and biomass of kimpul (Xanthosoma sagittifolium) on shade and nitrogen fertilizer variation - CHOIRUL LATIFA, ISNAINI; Department of Biology, Faculty of Mathematics and Natural Sciences, Sebelas Maret University, Surakarta 57126, Central Java, Indonesia. Jl. Ir. Sutami 36a, Surakarta 57126. Tel./Fax.: +62-271-663375 (Ã¢â‚¬Å“Bioscience CommunityÃ¢â‚¬Â, School of Graduates, Sebelas Maret University, Surakarta, 2009)