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Thread: Nepenthes attenboroughii seeds germinated!

  1. #17

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    Flasker I think no one has mentioned the most important difference--osmolarity. If you think about the water in planting medium, it is relatively pure, maybe maxing out at 200 ppm tds. In contrast, the tc medium might have 30 g sugar, 6 g agar, and lets say 1.5 g salts. That water contains 37,500 ppm tds. So for the purposes of osmosis, these environments are very different. My own opinion is that this is the most likely explanation for differential results between soil and tc.

    Quote Originally Posted by flasker View Post
    I have no clue why Nepenthes seeds germinate in extro (no nutrient, only high humidity) faster than in vitro (complete nutrients) ?. It happens to me with other Nepenthes seeds (I sterilize seeds both in extro and intro). Do you have any idea, BigBella and Donh?

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    A few quick updates...





    More sprouts on the way.


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    Quote Originally Posted by mikewilder View Post
    Flasker I think no one has mentioned the most important difference--osmolarity. If you think about the water in planting medium, it is relatively pure, maybe maxing out at 200 ppm tds. In contrast, the tc medium might have 30 g sugar, 6 g agar, and lets say 1.5 g salts. That water contains 37,500 ppm tds. So for the purposes of osmosis, these environments are very different. My own opinion is that this is the most likely explanation for differential results between soil and tc.
    Osmolarity certainly plays some role; but what of its supposed deleterious effects? I have experienced in vitro and conventional germination within ten days of some Nepenthes, Drosera, and Darlingtonia; yet have also waited for months for some of those same plants -- which points more towards seed freshness; its general viability; or other factors not being considered. Also, considering that I average some twenty vessels per liter of prepared, diluted media (generally 1:5 to 1:3 concentrations and sucrose at about 2 percent), I'd suggest that the solute concentration can't be significantly higher than some of the standard, saturated peat-sand composts that I use.

    In addition, similar "either / or" results occurred with some 2011 photo-autotrophic cultures, where solute concentrations were kept far lower (sugars were not even included in the media); and where "normal" rates of gas exchange were obtained through vented lids . . .
    “Sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo . . ."

    -- Galileo "Biff" Galilei

  4. #20

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    idk if this applies to nepenthes but many plant seeds use differential dormancy and staggered germination to protect a seed crop from failing due to changes in growing conditions. some seeds will germinate faster than others when exposed to the same ideal germination conditions. doesnt explain why you would have all the seed ina batch take much longer but could explain why some seeds in a group just take much longer to geminate in vitro.

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    Quote Originally Posted by mikewilder View Post
    Flasker I think no one has mentioned the most important difference--osmolarity. If you think about the water in planting medium, it is relatively pure, maybe maxing out at 200 ppm tds. In contrast, the tc medium might have 30 g sugar, 6 g agar, and lets say 1.5 g salts. That water contains 37,500 ppm tds. So for the purposes of osmosis, these environments are very different. My own opinion is that this is the most likely explanation for differential results between soil and tc.
    Mikewilder,
    You may be right!!! Osmolarity is too high so seeds get less water -> germinate longer. I use 10 g sugar, 4 g agar and 1 g salts but it's still too high than ~ 0 ppm tds (distilled water). Seeds germinate well but take longer. It happened to me 3 times. I will try next time in vitro with coconut coir and distilled water only or with very diluted salts. However, some other seeds germinate very fast in normal media so it may depend on what kind of seeds. Anyway, Thanks !!! You're ingenious!!! Play with TC Mike ?

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    It's important to understand that I'm not claiming that osmolarity is the only relevant variable. I simply claimed that it was a relevant variable no one mentioned. It is my opinion that it is very relevant in explaining differential germination in pots vs test tubes, where the sower claims all other things (except humidity) are being held the same. It is a demonstrated fact that osmolarity differences are critical in getting many haploid cells to grow in vitro, for example. In general my experience is that seeds take longer in test tubes than in pots, though like just about any phenomenon in biology, exceptions can be found.

    It's not obvious to me how seed freshness or general viability explains differential results in pots versus in the test tube--please clarify David. Like 'God's will', "other factors not being considered" are always a possible explanation for any phenomenon in the universe. One of the nice features of my explanation is that it is testable.

    "I'd suggest that the solute concentration can't be significantly higher than some of the standard, saturated peat-sand composts that I use." This is an empirical claim that is easily tested with a tds meter. But I'm wagering you are wrong. 2% sucrose is 20,000 ppm, 1/3 strength MS or LS will be about 1500 ppm, 4 g agar is 4,000 ppm. Pour some water through your pots and see if it measures 25,500 ppm tds. If it does I'll mail you a big Heliamphora or do it as a Nasc auction, your choice. Let's find out--

    Quote Originally Posted by BigBella View Post
    Osmolarity certainly plays some role; but what of its supposed deleterious effects? I have experienced in vitro and conventional germination within ten days of some Nepenthes, Drosera, and Darlingtonia; yet have also waited for months for some of those same plants -- which points more towards seed freshness; its general viability; or other factors not being considered. Also, considering that I average some twenty vessels per liter of prepared, diluted media (generally 1:5 to 1:3 concentrations and sucrose at about 2 percent), I'd suggest that the solute concentration can't be significantly higher than some of the standard, saturated peat-sand composts that I use.

    In addition, similar "either / or" results occurred with some 2011 photo-autotrophic cultures, where solute concentrations were kept far lower (sugars were not even included in the media); and where "normal" rates of gas exchange were obtained through vented lids . . .

  7. #23
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    Quote Originally Posted by mikewilder View Post
    It's not obvious to me how seed freshness or general viability explains differential results in pots versus in the test tube--please clarify David. Like 'God's will', "other factors not being considered" are always a possible explanation for any phenomenon in the universe. One of the nice features of my explanation is that it is testable.

    "I'd suggest that the solute concentration can't be significantly higher than some of the standard, saturated peat-sand composts that I use." This is an empirical claim that is easily tested with a tds meter. But I'm wagering you are wrong. 2% sucrose is 20,000 ppm, 1/3 strength MS or LS will be about 1500 ppm, 4 g agar is 4,000 ppm. Pour some water through your pots and see if it measures 25,500 ppm tds. If it does I'll mail you a big Heliamphora or do it as a Nasc auction, your choice. Let's find out--
    When I had mentioned "general viability," the freshness of the seed -- especially Nepenthes -- plays an obvious and significant role in the rate and speed of germination in either form of media (whether they'll even sprout in compost or TC media at all); the genera being notorious for even having a low viability in the wild. The low-land species can have seed viability measured only in terms of weeks; while I have had highland seeds sprout after two years under refrigeration. Alternatively, I have had seed that I had personally collected that germinated within a couple of weeks in vitro, yet took eight to ten weeks in compost. I have found that the age of the seed to be a primary factor with either method. "Other factors" could include varying photoperiods; distance from lights; color temperature of said lights; temperature of the grow rooms; methods of seed sterilization; whether the TC vials were vented; whether the media was properly prepared, etc.

    Generally, seventy-five percent or more of my Nepenthes and Heliamphora seed germination occurred far more rapidly in vitro -- measured in terms of weeks; but there have been those occasional exceptions. The photo-autotrphic method has even been more successful.

    In terms of solute concentrations, I was thinking more of the peat "teas" that I had prepared in the past, not so much a three inch pot of peat and sand; and the TDS of that stuff (or, perhaps more properly, TSS), was quite high . . .
    Last edited by BigBella; 12-05-2012 at 12:55 AM.
    “Sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo . . ."

    -- Galileo "Biff" Galilei

  8. #24

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    The question was why DON and Flasker observed differential germination in pots and tubes. You yourself replied that:

    I have had both experiences -- where the seed germinated in vitro weeks before those in compost; and quite the opposite, even with both kept in the same environment, in terms of temperature and light.

    So you seem to agree that differential germination in the "genera" [sic] Nepenthes is typical or at least common, even where the environment is the "same" in terms of "temperature and light". But agreeing that it happens doesn't explain it.

    You proposed that since differential germination happens, but in unpredictable ways (sometimes tubes first, other times pots first), it's probably to be explained by seed freshness, viability, or anything other than osmolarity.

    I asked how freshness or viability could explain differential germination in pots and tubes. After all, whatever the age is, that's the age of all the seeds. If it's so important, you'd expect the same results in pots and tubes, because the age of the seeds is the same. Whether general viability is randomly or uniformly distributed in a seed packet, you wouldn't expect differential germination in pots and tubes, at least with reasonably large samples.

    So I'm sticking with what I said before--it's not obvious how these factors can explain the observed differential germination that we're trying to explain. Nobody was wondering whether age or viability determines whether a seed will sprout. That just goes without saying, doesn't it?

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