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Dimka
Sundewist
During that time, the seeds detect prolonged conditions suitable for growth.
Hormones are released, the seed shell is broken and the growth begins.
Light is not necessary (at least I don't think so) until the seed breaks. Then it is needed for the new plant to determine which way is up and down (where the light is is up, so leaves go that way (up), no light - the plant is confused and grows wherever it happens to go). Then it is needed for photosynthesis and growth.
No light = white plants (no chlorophyll), poor growth. Roots will still go down though because of gravity and the medium.
That's what I think... if i remember correctly...
Hormones are released, the seed shell is broken and the growth begins.
Light is not necessary (at least I don't think so) until the seed breaks. Then it is needed for the new plant to determine which way is up and down (where the light is is up, so leaves go that way (up), no light - the plant is confused and grows wherever it happens to go). Then it is needed for photosynthesis and growth.
No light = white plants (no chlorophyll), poor growth. Roots will still go down though because of gravity and the medium.
That's what I think... if i remember correctly...
Dimka
Sundewist
jimscott
Tropical Fish Enthusiast
Depending on the species light is necessary for germination. If you read the Ellison studies on Sarracenia seed germination only the seeds receiving a photoperiod germinated. The seeds kept in the dark did not germinate. I posted links to online versions of these studies early in the Sarracenia section.
To insure the hisghest rate of survival seeds are not going to germinate until minimums of temperature, moisture and (for some) light levels.
The general rule seems to be higher humidity and warmer temperatures facilitate germination. That's why there are so many propagation kits with humidity domes and heat pads. The seedling heating pad I have has a chart of optimal soil temperatures for many popular garden plants (tomatoes, onions, lettuce, various flowers).
There are exceptions of course. The Drosera capillaris "long arm" seeds I have tend not to germinate in high humidity and do better uncovered.
To insure the hisghest rate of survival seeds are not going to germinate until minimums of temperature, moisture and (for some) light levels.
The general rule seems to be higher humidity and warmer temperatures facilitate germination. That's why there are so many propagation kits with humidity domes and heat pads. The seedling heating pad I have has a chart of optimal soil temperatures for many popular garden plants (tomatoes, onions, lettuce, various flowers).
There are exceptions of course. The Drosera capillaris "long arm" seeds I have tend not to germinate in high humidity and do better uncovered.
jimscott
Tropical Fish Enthusiast
I have the humidity and temp thing going, for sure. They are all in pots, open tray, with plastic cups on top, by the window. The window allows the sun to created a mini-greenhouse effect and the cups are moist with dew. But then they decrease their temps when the sun isn't shining. But that's like nature, right?
Dimka
Sundewist
That is sarra seeds. I honestly do not think light is that necessary for drosera.
The point of cold germination (in the fridge) is to simulate winter. Cold, dark, moist (just like under the snow). After they are taken out, it is like the spring after the winter, seeds feel it and start growing. Of course some will grow without it too, but less seeds will germinate because they are waiting for the winter.
I think the photo period has something to do with heat. Since sunlight transmits heat via radiation, and seeds have no photosensitive parts on the outside. Maybe they respond to prolonged heat then? As light time increases, they are in warm temps for longer, meaning the summer is coming. And when these conditions last long enough, that means it is time to grow since spring/summer is here.
The point of cold germination (in the fridge) is to simulate winter. Cold, dark, moist (just like under the snow). After they are taken out, it is like the spring after the winter, seeds feel it and start growing. Of course some will grow without it too, but less seeds will germinate because they are waiting for the winter.
I think the photo period has something to do with heat. Since sunlight transmits heat via radiation, and seeds have no photosensitive parts on the outside. Maybe they respond to prolonged heat then? As light time increases, they are in warm temps for longer, meaning the summer is coming. And when these conditions last long enough, that means it is time to grow since spring/summer is here.
jimscott
Tropical Fish Enthusiast
Dimka
Sundewist
I don't think so. Its probably that the heat lasts long enough for their liking and they pop out.
Or you can divide your seeds into 2 batches and try out both methods.
I got a mix of seeds recently and they supposedly have a lot of different species there (I bet its just intermedia and binata judging by the look of them lol) both temperate and not. So I divided them and put one part in the fridge and another on a windowsill. I suppose in a month something will pop out
Or you can divide your seeds into 2 batches and try out both methods.
I got a mix of seeds recently and they supposedly have a lot of different species there (I bet its just intermedia and binata judging by the look of them lol) both temperate and not. So I divided them and put one part in the fridge and another on a windowsill. I suppose in a month something will pop out
jimscott
Tropical Fish Enthusiast
Water temperature that the pots sit partially in is ~95 F. The Grolite is on for ~15 hours per day. That just sprouted a D. harmeyerorum. I would kill for the D. ordensis seeds to do anything! I wonder if the spatulatas, glanduligera, intermedia, and capensis would respond better than just "room temp".
Dimka
Sundewist
jimscott
Tropical Fish Enthusiast
http://www.sciencedirect.com/scienc...serid=10&md5=94bd388c774ab2e81868c78f22d35132
Seed dormancy-breaking and germination requirements of Drosera anglica, an insectivorous species of the Northern Hemisphere
Carol C. Baskin, Milbergc, Lars Anderssond and Jerry M. Baskina
Acta Oecologica
Volume 22, Issue 1, January-February 2001, Pages 1-8
Abstract
Seeds of Drosera anglica collected in Sweden were dormant at maturity in late summer, and dormancy break occurred during cold stratification. Stratified seeds required light for germination, but light had to be given after temperatures were high enough to be favorable for germination. Seeds stratified in darkness at 5/1 °C and incubated in light at 12/12 h daily temperature regimes of 15/6, 20/10 and 25/15 °C germinated slower and to a significantly lower percentage at each temperature regime than those stratified in light and incubated in light. Length of the stratification period required before seeds would germinate to high percentages depended on (1) whether seeds were in light or in darkness during stratification and during the subsequent incubation period, and (2) the temperature regime during incubation. Seeds collected in 1999 germinated to 4, 24 and 92 % in light at 15/6, 20/10 and 25/15 °C, respectively, after 2 weeks of stratification in light. Seeds stratified in light for 18 weeks and incubated in light at 15/6, 20/10 and 25/15 °C germinated to 87, 95 and 100 %, respectively, while those stratified in darkness for 18 weeks and incubated in light germinated to 6, 82 and 91 %, respectively. Seeds collected from the same site in 1998 and 1999, stratified in light at 5/1 °C and incubated in light at 15/6 °C germinated to 22 and 87 %, respectively, indicating year-to-year variation in degree of dormancy. As dormancy break occurred, the minimum temperature for germination decreased. Thus, seed dormancy is broken in nature by cold stratification during winter, and by spring, seeds are capable of germinating at low habitat temperatures, if they are exposed to light.(emphasis mine)
Seed dormancy and the control of germination
William E. Finch-Savage and Gerhard Leubner-Metzger
http://www.seedbiology.de/pdf/Tansley-review-dormancy2006.pdf
It is widely accepted that temperature regulates both dormancy and germination and that light regulates germination; however, it is a matter of debate whether light is also a regulator of dormancy (Bewley & Black, 1994; Vleeshouwers et al., 1995; Casal & Sanchez, 1998; Pons, 2000; Baskin & Baskin, 2004; Fenner & Thompson, 2005; Kucera et al., 2005). Light has been considered both to stimulate germination (e.g. Vleeshouwers et al., 1995) and to terminate dormancy (e.g. Benech-Arnold et al., 2000; Batlla et al., 2004). To some extent, this depends on where one chooses to draw the line between the processes of dormancy and germination. In this review, we have used the definition above, that dormancy is a seed characteristic that defines the conditions required for germination, and therefore any cue that widens the environmental requirements for germination should be regarded as a dormancy release factor. Following this argument, exposure to light changes the seed so that it can germinate in darkness and is therefore the last step in the dormancy-breaking process, rather than the first step in the germination process (Bewley & Black, 1994; Pons, 2000; Leubner-Metzger, 2003). This light effect (red light via phytochrome) can also be reversed in some cases by far-red light, until the seed is committed to the process of germination (Casal & Sanchez, 1998; Sanchez & Mella, 2004). In seeds with coat dormancy, it is thought that light and gibberellins (GA) can both release (coat) dormancy and promote germination (e.g. Casal & Sanchez, 1998; Leubner-Metzger & Meins, 2001; Leubner-Metzger, 2001; Sanchez & Mella, 2004; Kucera et al., 2005).
A wide range of factors can therefore alter dormancy in PD seeds. However, there is an important distinction in the seed response to these factors. (1) There are factors that are related to slow seasonal change. These factors (e.g. temperature) are integrated over time to alter the depth of dormancy, and the sensitivity to other factors (e.g. light). (2) There are other factors that indicate in a more immediate way that conditions are suitable for germination (e.g. light), which could be considered to terminate dormancy and therefore induce germination. Each of these factors therefore removes successive blocks to germination, but this process usually needs to be carried out in a set order for it to work, i.e. in the process described light must come last to be effective. There is recent evidence from global transcriptional analysis of dormant states that the successive blocks are associated with both quantitative and qualitative changes in gene expression programmes (Cadman et al., 2006 and pers. comm.).
See also The Seed Biology Place
Seed Germination
Seed Dormancy 1
Seed Dormancy 2
Seed dormancy-breaking and germination requirements of Drosera anglica, an insectivorous species of the Northern Hemisphere
Carol C. Baskin, Milbergc, Lars Anderssond and Jerry M. Baskina
Acta Oecologica
Volume 22, Issue 1, January-February 2001, Pages 1-8
Abstract
Seeds of Drosera anglica collected in Sweden were dormant at maturity in late summer, and dormancy break occurred during cold stratification. Stratified seeds required light for germination, but light had to be given after temperatures were high enough to be favorable for germination. Seeds stratified in darkness at 5/1 °C and incubated in light at 12/12 h daily temperature regimes of 15/6, 20/10 and 25/15 °C germinated slower and to a significantly lower percentage at each temperature regime than those stratified in light and incubated in light. Length of the stratification period required before seeds would germinate to high percentages depended on (1) whether seeds were in light or in darkness during stratification and during the subsequent incubation period, and (2) the temperature regime during incubation. Seeds collected in 1999 germinated to 4, 24 and 92 % in light at 15/6, 20/10 and 25/15 °C, respectively, after 2 weeks of stratification in light. Seeds stratified in light for 18 weeks and incubated in light at 15/6, 20/10 and 25/15 °C germinated to 87, 95 and 100 %, respectively, while those stratified in darkness for 18 weeks and incubated in light germinated to 6, 82 and 91 %, respectively. Seeds collected from the same site in 1998 and 1999, stratified in light at 5/1 °C and incubated in light at 15/6 °C germinated to 22 and 87 %, respectively, indicating year-to-year variation in degree of dormancy. As dormancy break occurred, the minimum temperature for germination decreased. Thus, seed dormancy is broken in nature by cold stratification during winter, and by spring, seeds are capable of germinating at low habitat temperatures, if they are exposed to light.(emphasis mine)
Seed dormancy and the control of germination
William E. Finch-Savage and Gerhard Leubner-Metzger
http://www.seedbiology.de/pdf/Tansley-review-dormancy2006.pdf
It is widely accepted that temperature regulates both dormancy and germination and that light regulates germination; however, it is a matter of debate whether light is also a regulator of dormancy (Bewley & Black, 1994; Vleeshouwers et al., 1995; Casal & Sanchez, 1998; Pons, 2000; Baskin & Baskin, 2004; Fenner & Thompson, 2005; Kucera et al., 2005). Light has been considered both to stimulate germination (e.g. Vleeshouwers et al., 1995) and to terminate dormancy (e.g. Benech-Arnold et al., 2000; Batlla et al., 2004). To some extent, this depends on where one chooses to draw the line between the processes of dormancy and germination. In this review, we have used the definition above, that dormancy is a seed characteristic that defines the conditions required for germination, and therefore any cue that widens the environmental requirements for germination should be regarded as a dormancy release factor. Following this argument, exposure to light changes the seed so that it can germinate in darkness and is therefore the last step in the dormancy-breaking process, rather than the first step in the germination process (Bewley & Black, 1994; Pons, 2000; Leubner-Metzger, 2003). This light effect (red light via phytochrome) can also be reversed in some cases by far-red light, until the seed is committed to the process of germination (Casal & Sanchez, 1998; Sanchez & Mella, 2004). In seeds with coat dormancy, it is thought that light and gibberellins (GA) can both release (coat) dormancy and promote germination (e.g. Casal & Sanchez, 1998; Leubner-Metzger & Meins, 2001; Leubner-Metzger, 2001; Sanchez & Mella, 2004; Kucera et al., 2005).
A wide range of factors can therefore alter dormancy in PD seeds. However, there is an important distinction in the seed response to these factors. (1) There are factors that are related to slow seasonal change. These factors (e.g. temperature) are integrated over time to alter the depth of dormancy, and the sensitivity to other factors (e.g. light). (2) There are other factors that indicate in a more immediate way that conditions are suitable for germination (e.g. light), which could be considered to terminate dormancy and therefore induce germination. Each of these factors therefore removes successive blocks to germination, but this process usually needs to be carried out in a set order for it to work, i.e. in the process described light must come last to be effective. There is recent evidence from global transcriptional analysis of dormant states that the successive blocks are associated with both quantitative and qualitative changes in gene expression programmes (Cadman et al., 2006 and pers. comm.).
See also The Seed Biology Place
Seed Germination
Seed Dormancy 1
Seed Dormancy 2
Dimka
Sundewist
Cool. I still don't get how light affects them. Seed shell has no photosensitive parts, so how does it improve germination? Who knows? Maybe its like a microwave effect or something?
Its interesting... I think I'll take botany sometime just out of interest... when I see the light in my educational tunnel
Its interesting... I think I'll take botany sometime just out of interest... when I see the light in my educational tunnel
jimscott
Tropical Fish Enthusiast
Dimka
Sundewist
jimscott
Tropical Fish Enthusiast
Dimka
Sundewist
