The fertility of grafted forest pine wad observed and appraised on some of the oldest seed plantations of an overall area of 6,5 ha. The seed plantation in the Slapy forest area of the Zbraslav Forest Works, of the overall area of 2 ha, laid out in 1976-1977, was used for the determination of the number of cones in 1981, 1982 and 1983. In the Ledec forest area of the Ledec nad Saz. Forest Works the cone count was carried out on two sites of different area, laid out in 1973-1977 of an overall area of 3.5 ha, in 1982 and 1983; in 1984 the number of female flowers was ascertained. The appraisal by a simple variance analysis has shown that the differences in the number of cones among the individual clones are statistically significant in all investigated plantations over 9 years of age, although in some highly fertile plantations it applied also to grafted pines of 5 years of age. Extraordinarily high clone differences have been found in a similar appraisal in a plantation at the ages of 5 and 10 years with regard tothe number of female flowers. The ranking of the individual clones according to their fruit-bearing ability thus affords the possibility of finding the most and the least fertile clones which have preserved continuously their fron and back ranks respectively in cone production also in the years to follow. Therefore, such data on the mean annual fertility of the individual clones can be used both for the increase of the overall cone production and for the collection of secondary grafts for new, even more productive seed plantations. The paper points out also the importance of the responsible selection of sites for the plantations, particularly with reference to the possible occurrence of industrial exhalates from minor industrial works and local workshops which can, however sporadically, cause the dropping of needles and even the withering of whole trees. This fact only accentuates the significance of local investigations in the selection of sites for seed plantations. In connection with detailed analyses of flowering, which is characterized by the two-years period of cone maturing, the paper suggests also a specific method of branch cutting and crown forming of the grafted pines. Since in the grafted forest pines the shoots of the past 2-3 years do not practically bear flowers, it is possible to cut off the terminal and the two-years lateral branches, on older individuals the whole three-years increment, without reducing fertility.
