摘要:

Previous investigations have shown different growth and root/shoot ratio increases of beech seedlings(Fagus sylvatica)with increased light intensity. In the present investigation both light intensity and soil water content were regulated on four levels in a factorial experiment. At the highest level of soil water content the seedling growth increased linearly with light intensity while the root/shoot ratio decreased with light intensity. At low levels of soil water content both the growth and root/shoot ratio slightly increased with increased light. The soil water content was also affected by the light intensity indicating that the soil water content may have caused unobserved effects in responding to increased light in previous investigations. It is concluded that both light intensity and soil water content should be quantified or manipulated even if only the effect of one of the two growth factors are investigated.

ISSN:0282-7581    

DOI:10.1080/02827589409382846

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effects of root pruning and stem injections of gibberellin A 4/7 (GA) on flowering and cone harvest were studied in three maturePicea abies(L.) Karst. seed orchards. The trials were split into two consecutive years, two in the summer of 1988, the third in summer 1989. Both years could be regarded as good years for natural induction of flowering. No effects were found on male flowering, whereas female flowering was enhanced by root pruning in two trials and by GA injections in one. No interaction effects on either male or female flowering were detected. In two trials, an approximately three‐fold increase in number of cones per tree was obtained after root pruning and GA injections, which is a commercially acceptable increase.

ISSN:0282-7581    

DOI:10.1080/02827589409382847

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Abortion of seed cones and production of full seeds have been recorded in an indoor‐potted Norway spruce (Picea abies(L.) Karst.) seed orchard at Biri nursery in Norway. Seed cone buds aborted their normal development at much higher frequencies (22–45%) inside isolation bags than in an open‐air (4–12%) greenhouse environment. The grafts had been induced to flower the year prior to seed cone development. Treatment with gibberellin A4/7in conjunction with heat reduced the proportion of aborted, isolated flowers (13%) compared to treatment with heat alone (22%) in a clonally balanced material. The production of full seeds per cone increased from 3 in 1987 to 50 in 1991. The full seed production is discussed in relation to methods and timing of pollen forcing. It is anticipated that 1 kg of seeds could be produced annually in a 1250 m2greenhouse.

ISSN:0282-7581    

DOI:10.1080/02827589409382848

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Potted grafts, made from scions of more than 50‐year‐old Norway spruce trees(Picea abies(L.) Karst.), were induced to flower in several experiments by heat‐ and gibberellin A4/7(GA) treatments in an acrylic greenhouse at Biri nursery in Norway. The grafts were treated when they were 1.5–3 m tall, 4–8 years after grafting. GA alone (spray and injection) enhanced female flowering, especially in combination with heat. Heat alone was ineffective; few grafts formed seed cone buds. Low amounts of GA (0.5–2 mg per graft) could enhance female flowering in previously treated grafts (retreatment), but only a slight response to 2 mg GA was found among previously untreated grafts. Heat alone induced profuse male flowering, GA + heat did not further enhance the male response, and GA alone did not induce formation of pollen cone buds. The highest male scores were found for early and long heat treatments (LHT) which started when shoots were elongated to 25–60% of final length and ended at least one week after termination of shoot elongation. Late and short heat treatment (SHT), starting from 86–95% elongation and ending on the same date as LHT, gave significantly fewer pollen cone buds than LHT in each experiment. If heat treatments started early (20–30% elongation), but terminated before or at time of shoot growth cessation (95–100%), no pollen cones were formed. GA could be phytotoxic, especially after spraying, but also when high amounts of GA were injected (40 mg). Good female flowering and low levels of needle damage were found when 2–10 mg GA was injected. The possibility of regulating sex expression in Norway spruce is discussed.

ISSN:0282-7581    

DOI:10.1080/02827589409382849

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Endogenous gibberellin A1(GA1), GA3, GA4and GA9were quantitated in elongating shoots of Norway spruce[Picea abies(L.) Karst.] grafts with a good or a poor flowering history. The grafts were grown either in a natural environment outdoors, cool and wet (CW) treatment, or in a greenhouse with elevated temperatures and controlled drought stress, hot and dry (HD) treatment. The GAs were quantitated by gas chromatography‐mass spectrometry selected ion monitoring (GC‐MS SIM) using deuterated GA1, GA3, GA4and GA9as internal standards. Terminal shoots from the second whorl of branches were harvested at 76%, 86% and 96% shoot elongation for the CW treated grafts and at 90% and 99% shoot elongation for the HD treated grafts. The content of GAs in the CW grafts was highest during most rapid shoot elongation, GA9being the dominant GA. The levels decreased as shoot elongation ceased. This was also noted for GA‐content in shoots of the HD treated grafts. A comparison of the GA‐amounts at ca. 96% of total shoot elongation for the CW treated grafts and ca. 99% of total shoot elongation for the HD treated grafts revealed that shoots of the good flowering clone had a higher content of GA9and a lower content of GA, and GA3. When comparing the HD treated and CW treated grafts, the shoots of HD treated grafts contained higher concentrations of GA9but lower concentrations of GA, and GA3. Calculating the ratios between [GA9] and [GA1] resulted in a ratio of 12.5 and 36.6 for the good flowering clone grown outdoors and in greenhouse, respectively. The same ratios were for the poor flowering clone 1.45 and 3.8 when grown outdoors and in greenhouse, respectively. A higher ratio may indicate a higher capacity of synthezise the importance of flowering GA4from GA9and a lower conversion of GA4to GA1, thereby favouring the diffentiation to reproductive buds.

ISSN:0282-7581    

DOI:10.1080/02827589409382850

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Various herbicides (glyphosate, sethoxydim, pendimethalin, chlorthiamid, dichlobenil, ter‐buthylazine) as well as particle board mulch and a cover crop (clover,Trifolium repens)were compared during the first two post‐planting years as weed control means in a silver birch (Betula pendula)plantation established on agricultural soil in southern Finland. Chlorthiamid, dichlobenil and terbuthylazine exhibited good weed control for two years and also increased the height growth of the seedlings by 40–50 cm and much greater relative increase in leaf area and volume as compared to untreated control plots. Weed control had a significant effect on the foliar nutrient concentrations of birch, particularly that of N. As the amount of weed vegetation increased, foliar N, P (second year), K, Cu and B decreased and, respectively, foliar P (first year), Ca and Mg increased. Vegetation control also had a great indirect influence on the state of health of the seedlings. Incidences of vole damage and bark necrosis disease were associated with a high cover‐percentage of weeds, particularly of clover which is much favoured by voles. Particle board mulch seemed to increase vole damage by providing shelter for the voles. The competition by weeds for nutrients, and probably also for water, was much more important than their competition for light. Use of mulch and a cover crop did not reduce root competition as effectively as did the best herbicides.

ISSN:0282-7581    

DOI:10.1080/02827589409382851

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Initial growth of released Scots pine(Pinus sylvestrisL.) advance reproduction in nine stands dominated by Scots pine was studied in north Sweden. In each stand, one 40 × 40 m plot was established for each of four different intensities of overstorey removal: 0% (control), 60%, 85%, and 100%. Seedings were monitored on one 18 × 8 m sub‐plot at the centre of each plot for two growing seasons following overstorey treatment. Only undeformed seedlings, uninjured before treatment and during the study period, were considered. In the second growing season, needle lengths and number of laterals increased or tended to increase compared to the control for all treatments. Compared to the control, leading annual shoot lengths for all treatments initially tended to decrease (seedlings > 10.0 cm), but increased or tended to increase (all seedlings) during the second growing season. It is concluded that seedling performance generally improved with increasing basal area removal.

ISSN:0282-7581    

DOI:10.1080/02827589409382852

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Damage to planted conifer seedings was assessed and numbers of adult pine weevils(Hylobius abietis)were estimated after cutting of a mixed conifer stand to form shelterwoods of eight different densities. Untreated and insecticide treated seedlings ofPicea abiesandPinus sylvestriswere included in the experiments.

ISSN:0282-7581    

DOI:10.1080/02827589409382853

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The role of the resin‐top disease caused byPeridermium piniin volume and value losses to Scots pine (Pinus sylvestrisL.) was surveyed in two heavily infected stands in northern Finland. Of the Scots pines, 26% were infected by the disease.Peridermium pinicaused 2% volume losses to saw timber trees and 3% volume losses to pulpwood trees in the stem‐lesion class and 10% and 14% in the dead‐top class, respectively. The disease caused saw timber volume losses to saw timber trees of 34% and 22% in the stem‐lesion and dead‐top class, respectively. However, saw timber volume losses increased the pulpwood volume in both disease classes. The disease reduced the marketing value of saw timber trees and pulpwood trees by 18% and 3% in the stem‐lesion class and by 15% and 14% in the dead‐top class.

ISSN:0282-7581    

DOI:10.1080/02827589409382854

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In a field experiment the influence of different girdling patterns like wide girdling, longitudinal debarking, debarking with one or several bridges, narrow girdling and bark crushing on resin soaked wood formation (lightwood) inPinus sylvestrisL. trees was investigated. Four years after treatment the concentrations of total extractives and resin acids were measured. It is shown that treatment methods differently affected concentrations of total extractives and resin acids. Longitudinal debarking with a wide bridge and debarking with several narrow bridges were the most successful methods for lightwood induction.

ISSN:0282-7581    

DOI:10.1080/02827589409382855

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor