Question for our Chemists

[orchid-man]

Over the last few months I have been buying flasks, that's OK,but what to do with the medium that is left in the flask.
Anyway I have been putting it on a Dendrobium Cassiope which is growing in full sun.The nobile type are not ones for being grown in full sun,the leaves will not take it and go bright yellow or worst.So what color are the leaves of my dendrobium,but a nice lush looking green.!
To get back to the flask medium,I was talking to the nursery that I bought them from and was advised that they were putting sugar (sucrose- table sugar) into the mix.Having done my research I find that sugar is glucose and fructose linked by one bond to form C12H22O11.This chemical bond is bot hard to break,
question -Will being put through an Autoclave break the bond?
If the bond is broken,what does each of the two different sugars do for the plant,appart from Carbon.

As the plant that has been getting the sugar and is looking like it is and all the other plants around it are yellow as,what is the sugar doing for the plant ?

I hope these questions make sense.

[Becky15349]

Trithfully, this is a form of sugar that is not in a usable form for the plant...and as for it being denatured in the autoclave, that is possible, but again, would onlly break down into its indivuduall elements... In all honesty, I feel like when people add sugar to their mixes, its really just a habit..they assume sugar is good for the plants, but don't understand that table sugar isn't the same form of sugar that plants need. To make a long story short, IMHO, table sugar is useless in agar mixes...at least, that was one of the fundamental lesson we learned in tissue culture lab. The goal of agar is to provide nutrients to the plant for them to create sugars they can use...giving them sugar outright isn't going to help them much bc its in the wrong form.
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[pavel]

The nobile type are not ones for being grown in full sun,the leaves will not take it and go bright yellow or worst.So what color are the leaves of my dendrobium,but a nice lush looking green.!
I hope these questions make sense.

Murray, I had a nobile type a number of years back that I used to put outside in the summer where it received unobstructed afternoon sun from 1 -4:00 pm -- the hottest part of the day. It too stayed a nice lush green .... I just had to water it frequently (pretty much kept it lightly moist). Did quite well for me for a number of years then one winter it just up and died.

Truthfully, this is a form of sugar that is not in a usable form for the plant...bc its in the wrong form.
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Really? Hmmm, that truly surprises me, Becky, since glucose is one of the products of photosynthesis. I would have thought that the plant would have been able to take up this sugar form and utilize it even as it utilizes the glucose that it makes itself during the synth. process. Curious, wonder why it wouldn't............

Well if that's the case, Murray, perhaps either the plant is making use of other elements of the agar or perhaps beneficial fungi or bacteria living amongst the roots are using it and producing some byproduct beneficial to the orchid. Course could just be coincidence too I suppose.