EFFECTS OF CONTROLLED DETERIORATION AND OSMOCONDITIONING ON GERMINATION AND NUCLEAR REPLICATION IN SEEDS OF PEPPER (CAPSICUM-ANNUUM-L)

Unaged and controlled deteriorated (45 degrees C for 4, 6 or 10 d) sam ples of a pepper seed lot were subjected to osmoconditioning in PEG at osmotic potentials of -1.1 and -1.1 and -1.5 Pa for 6, 10 or 14d. The effect of osmoconditioning on nuclear replication activity was examin ed 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 activi ty 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 wa s as effective on seed performance as the 6 d treatment at -1.1 MPa, w hich induced higher numbers of nuclei to enter the synthetic phase. Os moconditioning on controlled deteriorated seeds had different effects on seed germination depending on the degree of seed deterioration. Und er the same osmotic treatment. the amount of priming induced DNA synth esis was lower than in unaged seeds or was not induced at all. The act ivation of nuclear replication by osmoconditioning, therefore, appears influenced by the level of seed deterioration. In less deteriorated s eeds (45 degrees C for 4 d), 14 d priming at -1.1 MPa caused shortenin g of mean germination time compared with unaged seeds. but was less ef fective in inducing nuclear replication. The effect of the length and osmotic potential of priming on nuclear replication and the role of mo lecular processes, other than DNA synthesis, in improving seed perform ance are discussed. (C) 1996 Annals of Botany Company.