Cryo-stress in pine seeds

The rapid decrease in seed viability requires new storage methods. Conventional cryopreservation /storage methods have been widely used by researchers for seed survival studies. In this study, optimum protocols were determined and investigations made on the successful cryo-storage of the three pines (P. pinea, P. pseudostrobus and P. caribaea). The results show that (i) moisture content of orthodox seeds, in pines, especially P. pinea seeds is not a major determinant of survival; (ii) pre-storage treatments (stepwise freezing treatments) proved to be the best optimum protocols as compared to the conventional plunge in liquid nitrogen; (iii) leakage in P. caribaea seeds did not indicate any stressing of those seeds whilst in P. pinea seeds leakage appeared to be a stress marker; and (iv) orthodox seeds or embryos can be cryopreserved at 5 -13 % moisture contents, whilst storage between moisture contents of 15 -26 % or more will be lethal, as shown by differential scanning calorimetry (DSC) studies on P. pinea embryos in this study.