Hello all, seems like a few people have been breathing a little too much co2 lately and are getting a little light-headed as a result! (wink) Our greenhouse site (max. of 18 acres under glass, usually 14 acres used solely for plants) used to supplement co2 at night (houses vented during the day even in winter so co2 wouldn't help) to try and get increased growth. We have a wide mix of house types from loose double poly hoop type houses, polycarbonate sides with loose plastic tops, to hard sided glass topped old houses. I believe our horticultural consultant or some literature passed around the greenhouse community stated to us that if you could control factors at night (no venting) then co2 could help for a short-term crop with quick turnover. The only problem we were told was that the plant would 'get used to it', so the growth would stabilize again at the rate it was before the increase. So, continued growth wasn't possible and continued introduction of co2 was wasteful of the natural gas unless we needed the heat in the house anyway. Most of our crops were/are around for longer than the most beneficial time, we were venting at night during warm times so it wasn't really feasible. Many of our houses were very leaky anyway and most of the plants were up on benches with relatively dead air underneath the benches so the gas wasn't where the plants were, and air was leaking out and in at many spots, so it was very wasteful. Fuel is extremely costly, so all of the co2 makers were removed except for where they were needed for supplemental heating. Seems like in these conditions, orchids of some types in closed environments could see a boost for a little while if they were in a closed area, but then it seems that the boost would stop. Maybe there is some other effect with orchids (?) where if they have gotten a jump start from the co2, they may continue via inertia if there is enough other things being taken in to the plant so that they are happy... it seems alot like what happens when a person is training at high altitude - their body makes more red blood cells to get more oxygen, the athlete goes back down in elevation and they have a boost in stamina and all that from the increased oxygen and red blood cells. The body then decreases the red blood cell production and eventually the extra boost is worn off.
'controlling for' certain factors just means that you know exactly what each thing in a tested system is, and when you change one thing while the other things are stable, you can tell if the one changed factor is responsible for any reaction. Many different factors could be limiting and causing a slow down of growth. There are a few good reasons why growth may slow down in winter, and it may or may not have anything to do with co2. In our production houses growth often can slow down mainly because of the much decreased light, and the fact that the high temperatures reached during the day are much lower in winter than in summer. Also if venting is needed in winter because of it getting too warm, the air coming in is much cooler and can shock the plant, making it slow down greatly. Also a big factor is that often the water being put on the plants is much cooler in winter than summer, so exposure and evaporation really cools the plant down. If your pots are cooler in winter and the roots are alot cooler than in the summer season then the plant can slow down greatly as well. If there is a much slower metabolism in the plant because of lower temps and less light, it won't matter so much if the co2 is low, because the plant doesn't need as much anyways. If you can get the pot temp, leaf temp, air temp, light amount, all other things the same in winter as in summer except for the venting (air exchange possibly creating a co2 deficit), then you have controlled the conditions to know if sealing up the house is responsible for slowing the plants down. You would have to know also what the co2 levels were day and night in summer and in winter, and then you would know if it were co2 loss/growth reduction. It doesn't matter if you are a 'pro' or an 'amateur' these things can be tested the same by both (well I don't know how to test for co2 though there is a box in one of our large ranges that says 'co2 sensor' on it that is hooked to a computer; don't have any idea if there is a cheap or portable sensor for home use. Iris and Tony wrote: >CO2 must have some effect. I breathe on my orchids every day, and some of >them bloom. >Iris >I hope you are controlling for your breath. Is that two breaths per orchid? Or three? I breath on mine too and have a good percentage that bloom during the winter. Even so I feel sure (how un-scientific is it to 'feel') that additional CO2 during the winter would result in even better flowering. Happy growing >Tony I think there is contradictory testimony here! You would think that 'breathing on your orchids' would make them grow and flower better, but for some reason when I hover over my plants waiting for them to open up the buds, or to make some flowers, they don't cooperate and either blast the buds or don't flower at all ; ) ........... maybe I need some listerine, or it's that whole 'the watched pot never boils', thing (smile) . I find that many of my plants do bloom in the summer, and that is when I am usually outside taking native orchid pictures and not watching over them so much, so maybe my plants are shy. happy that my paphinia cristata plant now has a very large and wild looking open flower that is larger than the plant itself... coool! happy thanksgiving, charles -- charles ufford oriskany, ny usa _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
