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Germany

The past days we´ve had some alternating weather conditions, sometimes cool and wet, and then again warm for a couple of days. My daily measurements indicated that, upon weather having cooled down, the pumpkins kept growing at good rate for another one or two days before growth rate dropped. Then, when it had warmed up again, pumpkins seemed to require an induction period of one or two days before they reached their initial growth rate. Did others also observe this phenomenon, which I call FRUIT GROWTH HYSTERESIS? Is this just a phenomenon caused by cool pumpkins (it might take a while before they cooled down, and also takes a while before they reach higher temperatures when days are warmer), or does light have a much more important influence (so that "warm" pumpkins in greenhouses would show the same behavior when there are some cloudy days to drop growth rate after the second dark day and recover to high speed after an induction period of one or two sunny days)?

8/5/2011 5:53:15 AM

Netherlands

I have observed the same here. Interesting is that I have an LG in the same greenhouse which responds directly to heat/sunlight changes.
During a nice day and the night afterwards, the LG grew up to 2" per 24 hours more than on an overcast day (with almost the same temperature).
On the days the LG picked up, the AG slowed down and when the LG slowed down, the AG grew faster. It does seem to me that the AG responds somewhere between 24-48 hours later, while an LG responds pretty much right away.

8/5/2011 7:07:44 AM

Germany

Thank you Brad for that comment. In addition to temperature ups and downs the factor sunlight also seems to contribute to this phenomenon.

8/8/2011 3:14:24 PM