摘要:

Terminal shoot growth and bud formation in striped maple (Acerpensylvanicum) were followed both in vigorous and suppressed forest trees and in suppressed trees grown in the greenhouse and garden under 10 light intensities from 6 to 82% of solar radiation in the open. All buds contained (1) a pair of preformed early leaves that grew rapidly and (2) a pair of rudimentary primordia that became either bud scales in suppressed trees, after abortion of the blade, or a second pair of leaves in vigorous or released trees. The fate of the rudimentary primordia could be regulated by light intensity. They formed bud scales at 6% light or leaves at about 18% light. Maximum height growth and leaf pair formation occurred at 30–60% solar radiation in the open, although the first internode was longest under the lowest light. When leaf production stopped, bud formation was similar in vigorous and suppressed trees. The inner and outer bud scales and the pair of preformed early leaves were produced at 2- to 4-week intervals. The rudimentary primordia were not formed until after an interval of 8–12 weeks, in late summer near the end of bud formation.

ISSN:0045-5067    

DOI:10.1139/x77-001

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

not available

ISSN:0045-5067    

DOI:10.1139/x77-002

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Forest temperature for 50% kill (LT50) of female buds as determined by laboratory freezing tests in 1973–1975 ranged between −19 and −23 °C for five clones from mid-December to early March. Hardiness then decreased at 1.6 °C per week to an LT50of −6.5 °C by the time of first bud swelling in late April. Throughout flowering, LTMremained at −4.5 and LTio at −2.7 °C. Male and vegetative buds were respectively about 1.5 and 4 °C hardier. Preliminary frost protection requirements have been defined so as to ensure 90% female bud survival on 80% of the clones.

ISSN:0045-5067    

DOI:10.1139/x77-003

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Some theory and observations are presented on the factors governing the start and spread of crown fire in conifer forests. Crown fires are classified in three ways according to the degree of dependence of the crown phase of the fire on the ground surface phase. The crown fuel is pictured as a layer of uniform bulk density and height above ground. Simple criteria are presented for the initiation of crown combustion and for the minimum rates of spread and heat transfer into the crown combustion zone at which the crown fire will spread. The theory is partially supported by some observations in four kinds of conifer forest.

ISSN:0045-5067    

DOI:10.1139/x77-004

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Seed collected from 30 stands of black spruce, 15 upland and 15 lowland, was tested by germination, nursery performance at two nurseries, and field planting at three locations; results were measured to the 5th and 10th year after planting.Significant differences (seed size, germination, seedling size, survival, and height growth) were found between the three geographical locations: Cochrane, Geraldton, and Thunder Bay. Only very minor differences were found between upland and lowland types. Strong significant differences were found between individual collection stands, indicating that superior stands for seed collection could be located and preserved.

ISSN:0045-5067    

DOI:10.1139/x77-005

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Growth-room studies were made to determine both, alone and combined, the pathogenicity of the nematodeXiphinemabakeriWilliams and the fungusCylindrocarpondestructans(Zinnsm.) Scholten to Douglas-fir [Pseudotsugamenziesii(Mirb.) Franco] seedlings. Inoculations with 20, 40, and 60X.bakerinematodes per seedling resulted in nematode population increases and development of typical corky root disease symptoms.Cylindrocarpondestructanswas not pathogenic to seedlings; no consistent synergistic effects were detected when inoculations were made with the nematode and fungus together. It was concluded thatX.bakeriis the 'primary' pathogen in corky root etiology.

ISSN:0045-5067    

DOI:10.1139/x77-006

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Year-to-year, geographical, and local variations in foliar concentrations of crude fat, nitrogen, total sugars, and starch and in foliar caloric value were determined for maturing, current-year needles of balsam fir (AbiesbalsameaL.). All except geographical variations proved to be statistically significant. Seasonal trends of chemical concentrations in maturing needles were in agreement with previous findings.Much of the variation in foliar caloric value could be explained by changes in foliar concentration of crude fat.Year-to-year changes in foliar nutrients may influence spruce budworm population dynamics.

ISSN:0045-5067    

DOI:10.1139/x77-007

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The distribution of sapwood and heartwood was analyzed at three different height levels inAbiesgrandisinfested and non-infested with balsam woolly aphid. In non-infested trees, there was a highly significant regression between percentage heartwood age and disk age and a less significant regression between percentage heartwood area and disk area. Aphid infestation increased both the number of annual rings of heartwood and the heartwood area. The amount of heartwood in the infested trees was highly variable and dependent upon the degree of aphid infestation. Phenolic composition ofA.grandiswas similar to western hemlock, with heartwood containing matairesinol, hydroxymatairesinol, conidendrin, and an unknown phenolic glucoside. Sapwood contained several leucoanthocyanidins. Aphid infestation did not alter the phenolic composition of the heartwood, but it did cause the occurrence of a new phenolic in the sapwood. The possible causes of the increased amounts of heartwood in infested trees are discussed.

ISSN:0045-5067    

DOI:10.1139/x77-008

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

After 3 years in the field, survival, date of shoot growth initiation, and total height of 15 provenances planted at three locations indicate moderate to large provenances effects. Relative provenance performance varied among locations for survival and total height but not for flushing date. Regression and correlation analyses indicated that both the temperature and moisture regimes at seed origin have acted as selective forces on the native population. Time of shoot growth initiation has been mainly influenced by the temperature regime, while total height was generally related to the moisture regime. Survival was not associated with any of the climatic variables used in the study.

ISSN:0045-5067    

DOI:10.1139/x77-009

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Evidence is presented suggesting the occurrence of cyclic adenosine 3′,5′-monophosphate (cAMP) and adenyl cyclase activity in loblolly pine (PinustaedaL.) callus cultures grown aseptically on a defined medium. The presence of enzymes in the callus capable of catalyzing cAMP hydrolysis also was detected. Adenosine was the most stable product resulting from cAMP hydrolysis. A direct relationship was found between apparent cAMP concentration and the rate of fresh weight increase of dark-grown callus during a 6-week passage.

ISSN:0045-5067    

DOI:10.1139/x77-010

出版商:NRC Research Press    

年代:1977

数据来源: NRC