ACCURACY OF SINAPINE LEAKAGE IN BRASSICA AS A METHOD TO DETECT SEED GERMINABILITY

Sinapine leakage has been developed to predict seed germinability on a single-seed basis in Brassica. The major source of errors in predicti ng seed germinability are false negatives (F-), i.e. the method predic ted a seed was germinable since the seed did not leak, and yet it did not germinate. The sinapine leakage index (SLI) was calculated to asse ss F- for any seed lot by dividing the number of non-germinable seeds that leaked by the total number of non-germinable seeds. The SLI for 1 3 lots including cabbage, cauliflower and broccoli (B. oleracea. L., C apitata, Botrytis and Italic groups, respectively) ranged from 0.2 to 0.91. Seed coat permeability, as measured by the time for 50% of heat killed seeds to leak, was correlated with SLI. Different staining patt erns were observed from the tetrazolium test performed only on the F- seeds and the most common staining was dead tissue on the axis. Theref ore, at least two factors are responsible for the presence of F- seeds : the seed coat restricted leakage from diffusing from the embryo to t he environment and the presence of dead tissues on the axis that direc tly affect germinability without greatly contributing to total leakage .