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Reproductive biology of Pinus sylvestris L.: Seed yield, flower phenology, the response of young seedlings to GA(4/7), and developmental anatomy
Abstract
The Scotch pine (Pinus sylvestris L.) seed orchard at the University of Nebraska Agricultural Research and Development Center consists of 42 Eurasian clones replicated in 20 blocks. The orchard was established during 1971-1974 from trees selected in a range-wide provenance test. In 1985 and 1986 all cones were collected and kept separate for five replications of each tree. Yield for each clone was characterized by the number of cones produced per tree, the number of seed produced per cone, and the weight per seed. Each variable was evaluated for its potential use in a yield-improvement breeding program. From 1985-1987 strobili production was monitored from late April through May on all trees in the orchard to determine when staminate cone dehiscence and ovulate cone receptivity began for each clone. Although some clones consistently reached anthesis before or after others, non-synchronous flowering phenology was not an obvious cause of previously observed low seed production. Gibberellic acid (GA$\sb{4/7}$) in concentrations of 100, 200, 400 and 800 mg L$\sp{-1}$ was applied to 2-year-old Scotch pine seedlings over a period of 12 weeks. Some seedlings formed ovulate and/or staminate strobili, but there were no significant differences among treatments after one growing season. After a second season of treatments on the same trees, more ovulate strobili were produced than after one season, but not enough to distinguish differences among treatments. The developmental anatomy of ovulate strobili in mature buds was followed through the growing season to ascertain when reproductive differentiation was initiated. The long, conical buds characteristic of developing ovulate strobili were evident by 22 July, and the formation of bracts could be distinguished a week later. Development in mature buds was compared to development in the 2-year-old, GA$\sb{4/7}$ treated seedlings, but no ovulate strobili were detected in the seedling trees.
Subject Area
Botany|Forestry
Recommended Citation
Boes, Teresa Katherine, "Reproductive biology of Pinus sylvestris L.: Seed yield, flower phenology, the response of young seedlings to GA(4/7), and developmental anatomy" (1989). ETD collection for University of Nebraska-Lincoln. AAI9019556.
https://digitalcommons.unl.edu/dissertations/AAI9019556