Effects of Controlled Deterioration and Osmoconditioning on Germination and Nuclear Replication in Seeds of Pepper (Capsicum annuum L.)

Unaged and controlled deteriorated (45 °C for 4, 6 or 10 d) samples of a pepper seed lot were subjected to osmoconditioning in PEG at osmotic potentials of −11 and −1·5 MPa for 6, 10 or 14 d. The effect of osmoconditioning on nuclear replication activity was examined using flow cytometry. Priming of unaged seeds always induced nuclei of embryo root tips to enter the synthetic phase. In accordance with our previous findings the amount of induced nuclear replication activity was higher after priming at the lowest osmotic potential. Under the same osmotic potential the amount of priming-induced replication was correlated with the length of priming treatment and its efficiency in improving seed performance. However, the 14 d treatment at −1·5 MPa was as effective on seed performance as the 6 d treatment at −1·1 MPa, which induced higher numbers of nuclei to enter the synthetic phase. Osmoconditioning on controlled deteriorated seeds had different effects on seed germination depending on the degree of seed deterioration. Under the same osmotic treatment, the amount of priming-induced DNA synthesis was lower than in unaged seeds or was not induced at all. The activation of nuclear replication by osmoconditioning, therefore, appears influenced by the level of seed deterioration. In less deteriorated seeds (45 °C for 4 d), 14 d priming at −1·1 MPa caused shortening of mean germination time compared with unaged seeds, but was less effective in inducing nuclear replication. The effect of the length and osmotic potential of priming on nuclear replication and the role of molecular processes, other than DNA synthesis, in improving seed performance are discussed.