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-   -   Growing leaf lettuce in tropical climate (http://www.hydroponicsonline.com/forums/showthread.php?t=2056)

Tropica 08-07-2011 04:03 PM

Growing leaf lettuce in tropical climate
I grow leaf lettuce in temperatures over 80 F and I have no problem with bolting. My nutrient supplier informed me that it is especially formulated for our situation. I understand that two components are not use compared to the usual nurient list. I am curious to know which ones. Does anyone have an idea what these are?

jamromhem 08-07-2011 04:15 PM

I think more information might be needed.. What nutrients are you using? Being able to look at the contents of the nutrients you use might be a better way for us to understand what is in it that might be different from other nutrients.

Tropica 08-07-2011 04:18 PM

I understand it has something to do with ammonium

jamromhem 08-07-2011 05:44 PM

There seems to be evidence to support that. The trick will be finding the right levels to help you. Also cooling your res will play a huge part in keeping the from bolting.

The influence of an additional supply of ammonium to a nitrate containing hydroponic solution on the mineral nutrition of greenhouse rose plants (Rosa hybrida cv. ‘Lambada’) has been investigated. The effect on NPK uptake, mineral contents in roots and leaves as well as nitrate reductase (NR) and glutamine synthetase (GS) activities were examined. The addition of ammonium in a nutrient solution containing nitrate produced a total nitrogen uptake increase during shoot elongation, while in the absence of ammonium, nitrate uptake was lower during shoot elongation. Adding ammonium to the hydroponics solution caused an increase of potassium uptake while ammonium absorption was constant. Phosphate uptake was always higher in combined nitrate plus ammonium treatment, likewise in this treatment the most relevant effect on plant mineral content was the increase of P concentration in the roots. In both treatments with or without NH+4, free nitrate was notably higher in the roots than in leaves, indicating that nitrate reduction in rose plants takes place mainly in the leaves. NR activity in the leaves was higher when ammonium was present, whereas the root GS activity was similar in both treatments. The influence of ammonium on phosphate uptake and the subsequent effects on transport of other ions and enzymatic activities are discussed.

(N) is primary to plant growth. Plants convert nitrogen to make proteins essential to new cell growth. Nitrogen is mainly responsible for leaf and stem growth as well as overall size and vigor. Nitrogen moves easily to active young buds, shoots and leaves and slower to older leaves. Deficiency signs show first in older leaves. They turn a pale yellow and may die. New growth becomes weak and spindly. An abundance of nitrogen will cause soft, weak growth and even delay flower and fruit production if it is allowed to accumulate.

Tropica 08-09-2011 12:05 PM

Thank you jamromhem for your input. As for now I am not seeing any evidence of any signs nitrogen deficiency. I will keep an eye on them and look for any signs you mentioned.

jamromhem 08-09-2011 02:43 PM

well the introduction of amoniom will cause a surplus of (N) and will cause the growth to be soft and weak.. It might explain some of the soggy feeling lettuce you sometimes get in grocerie stores.. I would also be concerned about a shortened shelf life if the plant is softer.

You may have a good balance to ammonium to prevent the surplus from getting too strong to cause the mooshy lettuce. But when you harvest if you can let us know if there is a shelf life problem

Tropica 08-20-2011 09:07 AM

1 Attachment(s)
Thank you for your reaction, but as I read it I thought there was a misunderstanding. Maybe I was not quiet clear but the nutrient solution I am using has as far as I understood no ammonium in it further more I work with a pH of 7 - 8. When the pH is lower the growth is slower. The only problem I really have is cooling the nutrtion to below 30 Celsius as it is often more the 35 Celsius. My lettuce is not soft nor do I have a problem with shelf life as it stays very good when kept cool.
I am very interested to know if there are brands of hydroponic nutrients with no ammonium an no ureum and where I can find these.

I added a picture.

jamromhem 08-20-2011 09:38 AM

I think in most cases they are not uesd too much in hydroponic nutrients. Amonium is not readily obsorbed from plants to my understanding and takes enzymes to break down into a useable for for the plants.

Most commercial hydroponic solutions tend to use nitrates rather than other forms. You will usually only find ammonium and ureum in organic hydroponic solutions as they also contain the enzymes that let these things be usable.

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