RETRACTED ARTICLE

Conductivity as a vigour test for Brassica species

RETRACTED ARTICLE

This paper has been retracted by the Chief Editor and Executive Committee of ISTA and should no longer be referred to in the scientific literature. (October 2010)

Seed vigour differences among Brassica seed lots have been previously demonstrated using the accelerated ageing test. However this test takes 10 days to complete whereas the conductivity test takes only 24h. The potential of the conductivity test to determine seed vigour differences among 26 high germinating (>91%) seed lots of five Brassica species was therefore investigated. Seed moisture content (SMC) was included as a test variable and the relationship between test results after 16 h of soaking and field emergence was assessed following three sowings at the same site. Conductivity differences occurred among seed lots of B. napus, B. oleraceae var. alboglabra, B. rapa var. pekinensis, and B. campestris, but not for B. rapa x B. campestris. Increasing the SMC to 8.5% before soaking reduced the variation among replicates of individual seed lots, and also reduced the conductivity values recorded when compared with results for seed lots tested at their initial SMCs (6.0 to 8.1%). Tetrazolium testing of three B. rapa x B. campestris seed lots demonstrated that slowly increasing SMC to 8.5% reduced the percentage of non-viable seeds, suggesting that imbibition damage was occurring when dry seeds were placed directly into water. Seed lot field emergence ranged from 6 to 92% depending on sowing time. Standard germination of all 26 seed lots was therefore not related to field emergence, but conductivity was for all three sowings (r² from −0.48* to −0.89** for non-adjusted SMC results and r² from −0.59** to −0.96** for adjusted SMC results). For two of the three sowings, this relationship was stronger for the adjusted SMC method.