Chromatogram of tannin for fifteen different genotypes for greater yam. i Tannin standard 20 ppm, ii NGY-1, iii NGY-2, iv NGY-3, v NGY-4, vi NGY-5, vii NGY-6, viii NGY-7, ix NGY-8, x NGY-9, xi NGY-10, xii NGY-11, xiii NGY-12, xiv NGY-13, xv NGY-14, xvi Da-199