Wstępne badania nad mrozoodpornością jodły pospolitej (Abies alba Mill.) w Górach Świętokrzyskich

Preliminary studies on frost−hardiness of the current year shoots of silver fir were conducted between the autumn of 1999 and the spring of 2000 on the 20−25 year old saplings, collected in 13 sample plots distributed throughout the Świętokrzyski National Park.The diffusion of electrolytes from shoots and needles kept in a freezer at the temperature of −33°C was analysed using the Dexter's (1932) method. The highest degree of frost−hardiness of shoots and needles was found in February. In spring the resistance to low temperatures declined faster in shoots than in needles.The investigations showed significant differences in the frost−hardiness of young silver firs from different sample plots

The influence of PPM upon the sterility of the in vitro cultures in European beech [Fagus sylvatica L.]

Investigations were conducted on the strongly infested by microbes embryos isolated from seed stratified in non-sterile conditions or from tree buds. The results showed, that PPM (Plant Preservative Mixture, produced by Plant Cell Technology, Inc.) was very useful for increasing the percentage of sterile cultures disinfected in a 5% solution of NaOCl. The best way of applying PPM turned out to be adding the substance directly to the growing medium. At the concentration of 2 or 4 cm3 x dm-3 of PPM there was an 30% increase in percentage of sterile of in vitro cultures developed from embryos and 70-80% of cultures developed from buds, as compared with the control without PPM. At the range of concentrations employed in this study, no negative effects of PPM upon the development and growth of callus were observed