Prediction of germination and vigour in naturally aged commercially available seed lots of cabbage (Brassica oleracea var. capitata) using the bulk conductivity method

The potential for the electrical conductivity of seed soak water (EC) to predict the germination of cabbage seeds before and after controlled deterioration (CD), an ageing-based vigour test, was examined. The normal germination of naturally aged cabbage seed from commercial sources ranged from 6% to 92% for 11 lots of the white cultivar Yalova 1 and from 61% to 99% for 5 lots of the red cultivar Möhrenkopf. The EC (4 x 100 seeds, each in 40 ml deionised water) after 24 hours was inversely and closely related to normal germination, with R values of 0.85 (11 white cultivar lots) and 0.97 (5 red cultivar lots). CD tests at 20% moisture content (mc) for 24 hours at 45°C (CD20) and at 10% mc at 50°C for 2, 4 and 6 days (CD10) also revealed vigour differences. A significant negative correlation between the initial EC (before CD) of all lots and their CD germination resulted from the large range in initial germination. However, the correlations between initial EC and germination after CD were extremely low for the six lots of the white cultivar with >75% normal germination. EC after CD was closely related to total germination after CD20 and, although less so, after CD10 (2 days), indicating that because of the wide range of germinations the dominant influence on EC was the level of germination and not the vigour of the germinable seeds. The same observations were made after CD10 for 2, 4 and 6 days. The potential of EC as a rapid test to predict normal laboratory germination and germination after the CD test is discussed.