522 



L. ZUFA 



Figure 3. Rooted white pine needle fascicles. 



Cuttings rooted in small plastic containers are a very useful method 

 of vegetative propagation. The cuttings planted in tubes showed better 

 survival and root development. The better survival of cuttings may be 

 attributed to the isolation of parasites and saprophytes which destroy 

 the weakened cuttings. While the root system of cuttings planted in 

 open flats or rooting beds is usually unbalanced, consisting of one long 

 horizontal side-root, the cuttings rooted in tubes developed a well- 

 balanced root system consisting of several vertically oriented roots 

 (Figs. 1 and 2). This is one of the greatest advantages of rooting in 

 tubes. Other advantages of this method are that the tubes require less 

 space and that the cuttings and needle fascicles planted in tubes can 

 be checked, moved or outplanted anytime without risk of breaking the roots 

 or losing the plant. 



Significant within population differences in rooting were found in 

 the majority of cases. Patton and Riker (1958b) also found distinct 

 differences in rooting ability of white pine clones. Establishing 

 individuals with superior rooting ability could be of great importance 

 for the development of white pine clones. 



Significant differences in rooting ability were found between the 

 two P. griffithii x stvobus populations of the same age. A significant 

 variation in rooting ability apparently existed between the rest of the 

 P. griffithii x stvobus populations, as well as between the P. stvobus 

 populations in the experiments. A statistical comparison of their rooting 

 ability could not be made because of the differences in age which might 

 also have been an influencing factor. 



Not much is known about the rooting ability of different white pine 

 species and their interspecific hybrids. This problem is worth 



