Influence of light intensity and photoperiod on frost-hardiness development in Douglas-fir seedlings

Effect of light intensity and photoperiod on frost-hardiness development in 2-year-old Douglas-fir seedlings was studied using an electrical conductivity method to assess stem hardiness. Hardiness increased with light intensity to 1000 ft-c at 7.5 °C, under both 8-h and 16-h photoperiods, after about 8 weeks. This response suggested photosynthesis was necessary for rapid hardening, as also did the more rapid hardening obtained under continuous light at 40 ft-c, compared with 8-h photoperiods of the same intensity. By contrast, short photoperiods enhanced the rate of hardening at a light intensity of 3000 ft-c and 500 ft-c (after 7 weeks), compared with long photoperiods. After 7 weeks plants under short photoperiods with supplementary red light hardened like plants under long photoperiods, but after 10 weeks this effect of red light was no longer apparent. Far-red light did not produce any effect. Evidently a certain amount of photosynthesis must be carried out by Douglas-fir seedlings for rapid development of hardiness, but, with sufficient light for this to occur, short photoperiods hasten hardening.

Download Full-text

LIGHT-STIMULATED LEAF GROWTH ON INTACT AND EXCISED BEAN PLANTS (PHASEOLUS VULGARIS L.) III. EFFECT OF LIGHT INTENSITY

Israel Journal of Plant Sciences ◽

10.1080/07929978.1999.10676778 ◽

1999 ◽

Vol 47 (4) ◽

pp. 231-236

Author(s):

Shimon Lavee ◽

Elizabeth Van Volkenburgh ◽

Robert Cleland E.

Keyword(s):

Light Intensity ◽

Leaf Growth ◽

Energy Requirement ◽

Red Light ◽

Continuous Light ◽

Leaf Expansion ◽

Minimal Amount ◽

Light Intensities ◽

Bean Plants ◽

Effect Of Light

The effect of light intensity on primary bean leaf unfolding and elongation was studied with intact and excised 10-day-old plants grown under red light. Continuous light of 40 μmol; m−2S−1 was enough to induce maximal leaf expansion both on intact and excised bean plants. Lower light intensities had a partial effect. The growth rate during the first 24 h in light was linearly related to light intensity up to 130 μmol; m−2S−1, although this light intensity was already supra-optimal for final leaf size. The minimal amount of light energy needed for full leaf expansion was about 15 mol photons m−2. The mode of light application, level of intensity, and irradiance duration were not critical when the total energy requirement was fulfilled. Under insufficient light applications for full leaf expansion, interrupted irradiance and longer low light intensity application induced leaf elongation more efficiently. Generally, the effect of different white light intensities on primary bean leaf expansion was the same on both intact and excised red-light-grown plants.

Download Full-text

Determination of frost hardiness of Eucalyptus using the electrical conductivity of diffusate in conjunction with a freezing chamber

Canadian Journal of Forest Research ◽

10.1139/x88-086 ◽

1988 ◽

Vol 18 (5) ◽

pp. 595-600 ◽

Cited By ~ 18

Author(s):

P. M. Hallam ◽

W. N. Tibbits

Keyword(s):

Electrical Conductivity ◽

Frost Hardiness ◽

Lethal Temperature ◽

Conductivity Method ◽

Water Conductivity ◽

Leaf Discs ◽

Significant Difference ◽

Maximum Conductivity ◽

Electrical Conductivity Method

An electrical conductivity method for determining frost hardiness of tissue discs punched from Eucalyptus leaves is described. Samples were exposed to convective heat loss in an air-filled chamber. Rates of cooling and desired frost temperatures were electronically controlled and maintained. Supercooling of tissue was effectively eliminated by addition of small amounts of AgI and water. Conductivity of diffusate was measured as a means of quantifying tissue damage following frost. Relative conductivity was determined with reference to subsequent measurements following heating the discs to 70 °C which resulted in maximum conductivity. Exposure of leaf discs to temperatures below the lethal temperature for these species (<−10 °C) resulted in similar maximum conductivity readings. The technique is evaluated to assess its potential to distinguish small differences in frost hardiness caused by genotype and environment. For both E. delegatensis and E. nitens there was no significant difference in frost hardiness expressed in terms of mean lethal temperature when comparing leaf discs with frosting whole seedlings.

Download Full-text

Survival of coastal and interior Douglas fir seedlings after storage at different temperatures, and effectiveness of cold storage in satisfying chilling requirements

Canadian Journal of Forest Research ◽

10.1139/x77-018 ◽

1977 ◽

Vol 7 (1) ◽

pp. 125-131 ◽

Cited By ~ 7

Author(s):

R. van den Driessche

Keyword(s):

Cold Storage ◽

Douglas Fir ◽

Chilling Requirement ◽

Conductivity Method ◽

Relative Growth ◽

Different Temperatures ◽

Survival And Growth ◽

Bud Flushing ◽

Lower Temperature ◽

Electrical Conductivity Method

Survival and growth of coastal and interior provenances of 2-0 Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), after storage for 16 weeks at different temperatures, were examined in two experiments. In the first experiment, plants of two coastal and two interior provenances were grown under three sets of environmental conditions. These provided non-hardy, partially hardy, and hardy stock of each provenance for storage at 2, −5, and −9 °C. Survival, after 8 weeks poststorage growth in the greenhouse, showed that no provenances survived storage well in a non-hardy condition, and that coastal provenances only stored well at 2 °C. Even interior provenances did not store well at −9 °C.In the second experiment plants of four coastal and four interior provenances were lifted on 10 November and again on 8 December for storage at 2 and −2 °C. Survival and stem relative growth rate measurements, made after plants had been allowed 8 weeks poststorage growth in the greenhouse, showed that 2 °C was less deleterious than −2 °C, and that coastal provenances were less tolerant of the lower temperature. Plants stored on 10 November showed better survival than those stored on 8 December, and there was no clear relationship between stem hardiness, measured by an electrical conductivity method, and survival after storage.In a third experiment, two coastal provenances of 2-0 Douglas fir were used to compare the effect of cold storage at 2 °C with exposure of heeled-in stock to open nursery conditions in satisfying the chilling requirement for bud flushing. Flushing of previously unchilled stock, which had been cold-stored for 12 weeks, occurred as rapidly as flushing of similar stock heeled-in in the open nursery for the same period.

Download Full-text

Axillary Budbreak in a Cut Rose Crop as Influenced by Light Intensity and Red:far-red Ratio at Bud Level

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.139.2.131 ◽

2014 ◽

Vol 139 (2) ◽

pp. 131-138 ◽

Cited By ~ 4

Author(s):

A. Maaike Wubs ◽

Ep Heuvelink ◽

Leo F.M. Marcelis ◽

Gerhard H. Buck-Sorlin ◽

Jan Vos

Keyword(s):

Light Intensity ◽

Incident Light ◽

Red Light ◽

Axillary Buds ◽

Light Spectrum ◽

Correlative Inhibition ◽

Whole Plants ◽

Positive Effect ◽

Cut Rose ◽

Effect Of Light

When flower-bearing shoots in cut rose (Rosa ×hybrida) are harvested, a varying number of repressed axillary buds on the shoot remainder start to grow into new shoots (budbreak). Earlier experiments indicated that light reaching the bud affected the number of budbreaks. In all these studies, whole plants were illuminated with different light intensities or light spectra. The aim of this article is to disentangle the effects of light intensity and light spectrum, in this case red:far-red ratio, at the level of the buds on budbreak in a rose crop. Three experiments were conducted in which light intensity and red:far-red ratio at the level of the buds were independently varied, whereas intensity and red:far-red ratio of incident light on the crop were not changed. Light intensity and red:far-red ratio at the position of the buds were quantified and related to budbreak on the shoot remainders. Removal of vertical shoots increased light intensity and red:far-red ratio as well as budbreak (1.9 budbreaks per shoot remainder compared with 0.4 budbreaks when five vertical shoots were present). No vertical shoots and red light-absorbing shading paper over the plant base mimicked the effect of vertical shoots with respect to light intensity and red:far-red ratio, but budbreak (1.0 budbreaks) was intermediate compared with treatments with and without shoots. This suggested that the presence of shoots exerts an inhibiting effect on budbreak through both effects on light at the bud and correlative inhibition. When plants had no vertical shoots and light intensity and red:far-red ratio at bud level were changed by neutral and red light-absorbing shading paper, there was a positive effect of light intensity on budbreak (0.3 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Combinations of high and low light intensity with high and low red:far-red ratio on axillary buds showed that there was a positive effect of light intensity on budbreak (0.5 more budbreaks per shoot remainder) and no effect of red:far-red ratio. Our study reveals that when light intensity and red:far-red ratio received by the plant are similar but differ at bud level, budbreak was affected by light intensity and not by red:far-red ratio.

Download Full-text

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100103565 ◽

1988 ◽

Vol 46 ◽

pp. 300-301

Author(s):

C. S. Bricker ◽

S. R. Barnum ◽

B. Huang ◽

J. G. Jaworskl

Keyword(s):

Fatty Acid ◽

Light Intensity ◽

Acid Content ◽

Fatty Acid Content ◽

Anabaena Variabilis ◽

Chloroplast Envelope ◽

Major Constituent ◽

Filamentous Cyanobacterium ◽

Photosynthetic Membrane ◽

Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

Download Full-text