Washingtonia robusta growth analysis

[Dave in Warrington]

.... but there's only 5 hours of dusk / dark now Axel so is most of the growth in, what is probably the warmest 12 hours of the 24, between 13:00 and 01:00 and it appears to be growing at night

[Axel]

It's just the way palms grow, they collect the light and daytemps and process everything into growth during night, something to do with stomata and all that. That's not to say there is zero growth during day, but most is at night. Look at Dave's measurement, of 17 mm only 4 mm has been archieved from early morning till afternoon.

[Axel]

Dave, it's a real eyeopener for me to see that soiltemps are not leading the process, since the same soiltemps are measured with very differnt growth. It really seems to be about the means and i still think they influence the toplayer on a daily basis, at 30cm the effects of airtemps level off imo. It would be intesting to see fluctuations at 15cm, my geuss is they jump up and down with the mean.

[weve]

Axel and Dave, as I understand it (and assuming I'm remembering correctly from Uni) plants grow mainly at night because there are two distinct reactions involved in photosynthesis, the light and dark reactions, and it is the dark reaction that releases the stored energy from the chlorophyll molecule and faciltates growth.

Light energy accelerates the electrons of the chlorophyll molecule during the day and they 'jump shells'. Then at night, in the absence of light, enzymes are produced which kicks off the dark reaction, the electrons loose energy and return to their original state and shells releasing their energy which powers the production of sugars and therefore growth. So, as Axel quite rightly said, basically the daytime is spent just 'collecting' the energy and this energy is used mainly during the night. It is the two different reactions involved in the photosynthetic process that's the reason behind it.

Its of course far more complicated than that, but I didn't fully understand all the details of the extremely complex biochemistry even when at Uni

Knowing the theory tho', doesn't actually help me to grow my plants alas! Just thought I'd explain the reason and mechanism behind 'night-growth'

cheers

EDIT I know none of us are taking a botany exam. (Thank Goodnesss ) so this doesn't really matter, but for the sake of absolute accurancy, after checking up on the web, it seems current knowledge (bear in mind mine is over 35 years out of date) states that the 'dark' reaction can take place in the presence of light as well as when its dark But it seems some types of plant (but not all) store all the energy up during the day and then use it mainly at night as described in my original post,

[Dave Brown]

Growth measurement is much more difficult than you might think. The standard method os to mark a spear and measure it compared to a full grown petiole, but on my washie you risk death of a thousand cuts getting into the crown. I have been measuring a young petiole against a full grown petiole, however this is proving not to be accurate as the growth patten changes in high summer light. The petioles are 50% shorter from May to July than those in October

What this means is the the palm grows more leaves with less mm of actual growth in the summer months. So... how do we measure this ... I'm not sure that I can. The growing point is way above head height and protected by the crown of leaves.

[eddie]

found this:

http://forums.gardenweb.com/forums/load ... 19106.html

scroll a bit down, there's a nice set of pictures of Washi's at various ages in their natural climate

[Dave in Warrington]

Interesting growth photos and especially like the weeds in the 'sidewalk'

[fgtbell]

There's a good article here that may shed some light on it.

Remember the "limiting factor" applies with plants. For example if water is in short supply, this will slow or halt growth. Same for food, temperature, sunlight etc. So, if your palm is nice and warm but hasn't got enough nutrients at the root, then it won't budge.

[daftbanana]

Well, I have no scientific evidence to offer but what I can tell you is that my multi-stemmer in a pot on the patio is growing faster than my Trachys, Phoenix canariensis_CIDP and Butia right now.

[eddie]

What effects does watering have one the growth? Do you water your Washi a lot?

It never rains in southern california.....

LA gets only 12 to 24 inches of rain a year, average is 14.77 inch according to http://www.wrh.noaa.gov/lox/climate/climate_intro.php

I wonder, here in the polder groundwater is already found at 1 to 1.5 meters deep. Maybe the roots are already touching the water so i don't need to water anymore?

[Exotic Life]

Dave,

Just curious, how many leafes produced your Washingtonia so far since it started to grow? Mine is growing very fast during this warm july so far, also because the high night temperatures I think.

Robbin

[Dave Brown]

I have had to abandon measuring growth by petiole marks as it is just not reliable enough. What I have found is that as light levels rise the petioles are shorter by up to 50% in May, June and July, compared to October, November. Every year this gives the palm a flat topped appearance in summer, if the winter leaves are left on, with what appears a massive height increase in August to November, but it is the petioles lengthening rather than the palm gaining height.

Also it is not just light levels that alter petiole length, as they got very short in May, but have lengthened again in July 2010. This would suggest high light coupled with cool to warm gives short, compact petioles, but high light with high heat, or low light with cool to warm lengthens them

The bottom line is you can't measure growth by comparing marks on leaves or petioles.

What I have done this summer is count the number of days between fans opening, which measures how many leaves regardless of petiole length. What this has shown is that in high temps with max around 28-32C a fan opens roughlty every 6 days, giving 5 leaves a month, but in cooler weather around low 20s it is nearer 10 days per fan, or 3 leaves per month. However, what this means is that a daily growth rate is not measurable so not as easy to tell exactly what conditions cause best growth.

Eddie, LA may only have 12 to 24 inches of rain, but Washinftonia naturally grow in burrancos where the ground would remain wetter for longer as the water from the mountains seeps down towards the sea. I don't know if the actual rain falling in the area they grow would be sufficient. I certainly water mine with no ill effect

Robbin I have 12 leaves opened so far since the last frosts damaged the leaf tips. 8 since the beginning of June. It laso has 2 to 3 spears at any one time.

Here in March and again in July

Edit: added better July pic

[Exotic Life]

Dave,

Fun to read your story about the petiole length, last week I was thinking the same thing. After a nice seat in the garden and enjoy my Washingtonia my thoughts where hmm does it looks like the last new leafes has much longer petioles or is it just because I want to see things what's not there, but not giving it more attention after that, and now I read similair things from your side.

12 is not a bad count right? Because you where thinking the growth rate would be slower because it was coming above the wall and miss the microclimate. Don't have count my leafes yet, and don't even cut the damaged leafes away from last winter. I hope to do that this weekend or next week, and doing a count to, but specially during the first weeks of July with a average maximum temperature from 28C it was growing very fast!

Robbin