Forstliche Genressourcen - Nachhaltige Waldbewirtschaftung
Blühbonitur in Vogelkirschen-Klonensamenplantagen (Flowering bonitur in Prunus avium clonal seed orchards)
Forest seed orchards are plantations of genetically valuable individuals of distinct tree species that serve the production of reproductive material. With respect to a constant high genetic quality of the seed production in a seed orchard, it is required that each tree has to make a reasonably steady contribution over the years to the seed crop. Moreover, each tree must act relatively stable as seed and pollen parent, and finally it is necessary that all trees are capable in being in blossom and recombining at the same time. These prerequisites are also considered in the administrative regulations for the approval of basic material for forest reproductive material. Any seed crop in clonal seed orchards being followed by trading, harvesting reproductive material is permitted by law exclusively in case that at least half of the clones present were in blossom sufficiently and at the same time. Thus blossoming may be fairly easily discerned for seed cropping, but determining a synchronic course of the blossom is more complex.
In order to get an insight in the blossoming process of wild cherry (Prunus avium L.) clones growing in the two Rhineland-Palatinatian conservation seed orchards Lauterecken and Saarburg, a phenotypic study on this subject was carried out in early spring 1998. Seed orchard Lauterecken includes 148 clones in 10-12 replicate blocks which originate from occurrences growing in elevations up to 400 m a.s.l. (altitudinal zones plain and colline), while in seed orchard Saarburg graftings of 93 clones are planted in 10 replications from occurrences in the kolline and submontaneous elevation zones above 400 m a.s.l. For this study three ramets per clone were analyzed for the qualitative trait "flushing status of the blossoms" (closed, unfolding, unfolded) in connection with the quantitative trait "amount of blossoms on the tree" (amount less than 1/3 of full blossom; 1/3 to 2/3 of full blossom; more than 2/3 of full blossom; and full blossom in 4-day-intervals.
It can be concluded from the results obtained that the clones present in the two seed orchards differ more or less in view of the date of the start of blossoming as well as in the duration of blossoming. However, what is most important, an overlapping period of time was observed when more than ¾ of the clones were in blossom. Thus pollination and fertilization of most of the blossoms is guaranteed. Even this study is the only one performed so far for these seed orchards and the examination was carried out by random sampling, it is basically confirmed that both wild cherry seed orchards agree with the regulations by law to be allowed to harvest seed crops here.