Studia Forestalia Suecica

ODC 174.7 Picea abies 181.521: 165.4 (455) T h e female and male flowering frequency >*'ere studied in a clone frial o j Picea abies at Roskar nine kilonzeters north-east of Stockholm. During 1971 the e s t m ~ i o n in time of pollen shedding and fenzale receptivity was recorded follo~ving daily esurnination of individual strobili. T h e data obtained revealed a great variation in fenlale as well as male flowering Detn.eeiz the clones. Only a part of this variation could be atfributed f o differencer in height of the clones. Great yearly variations in flowering o f individual grafts were noticed. Based on the flo7vering freq~~erzcy as well as the pollen shedding and fenzale receptivity during each day, the expected contribution o f the different clones to the o f J ~ p r i n g was calculated. According to the calculations four o f the clones contributed 55 per cent o f the genec to rhe offspring. Many 166) o f the 190 theoretically portible co~nbinatiorzs among the 20 clones occurred in a lower frequencj than 0.1 per cent. T h e consequence5 of the data obtained for the genetic composifiorz of the seed orchard progeny were discursed. Ms. recei~ed 2nd July 1973