IntroductionSeeds of most woody-plant species are dormant when fully ripe; germination and seedling formation assumes breaking of this dormancy. Preservation of seed viability by proper conservation generally does not contribute to dormancy breaking.After storage, seeds can be as dormant as they were before storage was started. However, whether dormancy is broken before, during or after storage -breaking of dormancy and conservation of seeds should not be regarded separately. Seedling production is not possible from dormant seeds if both dormancy and the tendency to lose viability are not dealt with by proper treatments. We cannot discuss conservation of seeds leaving their dormancy aside. Storage of non-dormant seeds is, except for 'recalcitrant' seeds, much easier.
Recent trends in seed physiologyIn the last few decades, intensive work has been conducted to understand better ! I would like to express my thanks to Prof. S Lewak, lnsti ! some basic facts and processes occurring during the development of seeds when they are still on the mother plant and later, after separation from it, in the period be- (Lewak et aG, 1975;Lewak and Rudnicki, 1977;Esashi et al., 1979;Roos, 1980;Pradet, 1982;K6hler and Hecker, 1985). (Tyszkiewicz, 1949;Rohmeder, 1951Rohmeder, , 1953Holmes and Buszewicz, 1956; Sch6nborn, 1964;Buszewicz, 1967;Vlase, 1969;Machanicek, 1973;Suszka, 1974; Muller, 1975, 1977;Bonner, 1978;Suszka and Tylkowski, 1980;Suszka and Kluczyriska, 1980; Muller and Bonnet-Masimbert, 1985;Muller, 1986;Bonner and Vozzo, 1987;Suszka, 1982Suszka, , 1988Wang, 1982) (Nelubov, 1925;Piskarev, 1937;Flemion, 1938;Krzeszkiewicz, 1939;Tyszkiewicz, 1939;Lakon, 1950;Lakon and Bulat, 1952;Bulat and Lindenbein, 1961 ), methods of X-ray testing (Simak, 1957;Simak and Kamra, 1963;Belcher, 1974;Chavagnat, 1984), studies on frost tolerance of seeds in connection with their hydration level (Zakhariev and Tsonev, 1958; Sch6nborn, 1964) and studies on the mutual interactions between various thermal conditions causing germination or induction of a new dormancy in seeds (Haut, 1938; Barton, 1931, 1953;Nikolaeva, 1967Nikolaeva, , 1977Suszka, 1976;Edwards, 1986 Presowing treatment of dormant 'orthodox' seeds without any medium (naked stratification) (Fig. 1 (Edwards, 1982(Edwards, , 1986 or of fruit tree species from the subfamilies Pomoidae and Prunoidae of the Rosaceae family (Crocker and Barton, 1931;Haut, 1932;Stepanov, 1955;Visser, 1956;Decourtye and Brian, 1967;Kaminski and Rom, 1973 (Suszka, 1975