Andini, U. R. ., Hot Setiado and Siregar, L. A. M. . (1) “The Effect of Vernalization on the Appearance of Local Amaryllis (Hippeastrum sp.) Plants in the Land of Karo and West Sumatera”, Jurnal Online PERTANIAN TROPIK, 6(1), pp. 24- 33. doi: 10.32734/jpt.v6i1.3036.