Báo cáo lâm nghiệp: "Gibberellin A enhances flowering 4/7 of Picea glauca grafts in two consecutive years"

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Gibberellin A enhances flowering 4/7 of Picea glauca grafts in two consecutive years D.E. Riemenschneider R.A. Cecich 1 USDA-Forest Service, Columbia, MO 65211, and 2 Rhinelander, WI 54501 U.S.A. USDA-Forest Sf-rvice, Materials and Methods Introduction Trees that flower abundantly in one year Readers are referred to Cecich (1985) for details of the experimental design and treat- and then bear sparsely or not at all for ment procedures. The first GA applications 7 , 4 several years are said to show periodicity were made in 1982. In 1983, GA was again 4/7 of flowering. This infrequent, unpredictable sprayed on the same trees and branches on the flowering behavior has led to inefficient same dates. Length of the terminal shoot on all the treated and control lateral branches was seed collecting and seed orchard opera- measured in August 1983 and 1984. Ovulate tions. Therefore, treatments to alleviate and staminate strobili were counted in early such flowering problems in conifers have May 1983 and 1984. Flowering data were trans- been the subject of much recent experi- formed to log,, (x + 1) and evaluated by a com- mentation. bined analysis of variance and Duncan’s new multiple range test. Simple correlation coeffi- The mixture of gibberellins A and A 4 7 cients computed for the 1983 and 1984 were can increase flowering in conifers ) 4;7 (GA and branch length data. flowering if applied at the correct time, duration and concentration (Cecich, 1983; Marquard and Hanover, 1984; Pollard and Portlock, Results 1983). Except for Marquard and Hanover (1985), all experiments with GA have 4í7 been done on plants never previously flowering results for the 5 early- The 1983 treated. There have been no reports of flushing (EF) and 5 late-flushing (LF) white GA being applied to the same tree or 4i7 spruce clones have been published else- seedling, or even the same branches, in where (Cecich 1985), but treatment two consecutive years. Our paper reports means are summarized in Table I for the results of an experiment on Picea convenience of comparison with the 1984 glauca (Moench (Voss)) grafts in which mean results. In both years, the GA4!T ’7 , 4 GA was applied to the same branches treated branches on ramets of the EF and in two consecutive years in an attempt to LF clones produced significantly more ovulate and staminate strobili than periodic flowering. overcome
branches on their paired control ramets. In Discussion 1984, the LF clones again produced signi- ficantly more ovulate strobili than the EF This report is the first to describe the suc- clones. This was reversed for staminate cessful stimulation of male and female strobili; that is, the EF clones produced flowering in a conifer by consecutive more than the LF clones. annual treatments with GA4!7. The 1984 Spraying with GA in 1982 had no 4/7 results substantiated the 1983 observa- effect on lateral branch length of either the tions that the treated LF ramets produced EF or LF clones in 1983. However, in significantly more ovulate strobili than the 1984 the GA branches were -treated 4/7 treated EF ramets. In 1983, there was no about 25% shorter than the control difference in s!laminate strobilus produc- branches. The EF clones had a mean tion between EEF and LF clones but, in length of 185 mm for the controls and 1984, the EF clones produced significantly 141 mm for the GA branches. atca P -tr 4» more staminate strobili than the LF clones. The LF control !a!nets had an average In unpublished experiments, flowering was branch length of 217 mm, while the treat- promoted by G in both flushing types; n 4 A ed branches were 163 mm long. but the response was closely related to a Treated branches EF and LF clones common date (June 20), indicating a pos- on responded with significant increases in sible environmental control, or a larger flowering in 1983 and 1984 (Table I). than expected ’window’ for treatment Interactions were due to a change in application. Needles of the elongating magnitude of response, rather than to a branch tips in the EF families began to change in rank of the treatment combina- harden on June 13, 1 wk before the opti- tions. Clone x treatment interactions for treatment date. Needle harden- mum staminate strobilus production tP
treated branch length. If to determine the had used the experiments required are one number of years in which proposed index of 90% (Owens and Mol- significant a re- sponse can be elicited. der, 1977) or 75% (Marquard and Hano- ver, 1984) for GA application, the ’win- 4f7 dow’ would have been missed. Under these circumstances, calendar dates, References needle hardening and/or bud morphology may be preferred for scheduling treat- Cecich R.A. (1983) Flowering in a jack pine ments. seedling seed orchard increased by spraying These results suggest that periodic flow- with gibberellin A Can. J. For. Res. 13, 1056- - 4/7 in white spruce can be overcome ering 1062 with judicious spray application of GA 7’ 4f Cecich R.A. (1985) White spruce (Picea glau- ca) flowering in response to spray application of Furthermore, the lack of significant inter- gibberellin A Can. J. For. Res. 15, 170-174 - 7 , 4 actions for clone x treatment and clone x Marquard R.D. & Hanover J.W. (1984) Relation- year for ovulate strobili suggests that ship between gibberellin A concentration, 4n GA can be used to overcome clonal 4f7 time of treatment, and crown position on flow- variation in female flowering. However, ering of Picea glauca. Can. J. For. Res. 14, unequal representation of clones as pollen 547-553 parents, as exemplified by the strong Marquard R.D. & Hanover J.W. (1985) Floral response of Picea glauca to gibberellin A clone x treatment interaction, might be a 4/7’ naphthalene acetic acid, root pruning, and bien- possible concern for an orchard manager. nial treatment. Can. J. For. Res. 15, 743-746 Owens J.N. & Molder M. (1977) Bud develop- ment in Picea glauca. 11. Cone differentiation and early development. Can. J. Bot. 55, 2746- Conclusions 2760 Pollard D.F.W. & Portlock F.T. (1983) Timing and duration effects of gibberellin and fertilizer Although the present data are encour- treatment on strobilus production in young aging that year-to-year regularity in seed western hemlock. Can. For. Serv. Res. Notes 3, production can be achieved, additional 3-5