Kingrow1
Well-Known Member
The seed has two primary startch stores in the endosperm and cotyledons. Organelles in the cotyledon exist of startch, protein and lipids to facilitate the energy requirements of germination up until the formation of chlorophyll which is a nutrient dependant process. As the cotyledons unfold and turn green they begin to function as a leaf and provider of energy.
Once the germination process is triggered it takes a few days before another process prompts the conversion of available startch from storage organells to basic glucosides of sugar. At this point the sugar levels rapidly rise for a duration of between three to four days and then fall again as growth exponetially increases and storage exhausts.
One could say that shortly before and for a short period of time after a seed breaks the surface it is flooded with sugar, like a barrel with a tap at the base turned on and then after a few days inevitablly run dry.
As root growth relies on certain sugars transported from the leaves there is an inevitable flow from the leaf source to the root sink. A common question is where do potatos get their startch from?... from the leaves in the form of basic sugars. This basic transport is heavily reliant on the sink root matching the sugar storage sources of the cotyledons, any negative tropism or growth will result in a build up just above the casparian strip and then back up the hypocotyl/stem eventually leading to the petioles and lower cotyledon surfaces. A small imbalance might just trigger a small strip of excess sugar just above the divide between the root and hypocotyl/stem.
As it increased to a maximun after 72 to 96 hours, now a decrease is seen as startch stores exhaust and nutrient dependant chlorophyll energy processes become the main source of energy and source to sink relationship. At this point, as the cotyledons unfold, loose thir lobed apperance and thin out into a leaf to support the plant as it grows its next set of leaves (often called true leaves) we can see this storage depleted.
A side mention to the endosperm contained in the sac surrounding the seed of which its root radicle must puncture through at the second stage of germination after the imbiment of water. This holds startch of basic forms and feeds the plant briefly until it dries in the air or is seperated by the forces as the seedling pushes up towards the surface of the soil.
Linked to the rise and fall of sugar and certain imbalances in growth we might see a purple discolouration from the hypocotyl/stem upwards
even as far as the lower surfaces of the cotyledons. Certain flavanoids form from basic chemicals via their conjunction with sugars, anthocyanin is one such pigment although there are others and set against a unique biosystem of regulators. If the root or plant as a whole suffers stress then anthocyanin will start to form at the casparian strip upwards.
This initially is not detrimental to seedling growth and is short term until the stem greens up and sugar levels fall, generally after the initial 72 - 96 hour increase. One factor against this is that sometimes the negative factors which caused the initial sugar and anthocyanin increase will thus cause futher root and plant problems and the build up of anthocyanin may never dissapear and even worse increase past the stage of decrease (72 - 96 hours).
It is commonly seen that a purple stem or band at germination, even purple cotyledon undersides soon dissapates after a few days. Some can even watch the stem turn green from the top cotyledons down to the base. This purple to green in a short period is no worry as highlighted but a completley green seedling at germination would show that the harmony of the sugar to root growth rate was a more harmonious one but not necessarially better in terms of final dry mass and growth.
These systems alone are easy to see but can be mimicked by pathogens, drought, flooding and certain other stressors.
A overview of purple stems in early germination linked to sugar startch storage in cotyledons by an enthusiast, me!
Once the germination process is triggered it takes a few days before another process prompts the conversion of available startch from storage organells to basic glucosides of sugar. At this point the sugar levels rapidly rise for a duration of between three to four days and then fall again as growth exponetially increases and storage exhausts.
One could say that shortly before and for a short period of time after a seed breaks the surface it is flooded with sugar, like a barrel with a tap at the base turned on and then after a few days inevitablly run dry.
As root growth relies on certain sugars transported from the leaves there is an inevitable flow from the leaf source to the root sink. A common question is where do potatos get their startch from?... from the leaves in the form of basic sugars. This basic transport is heavily reliant on the sink root matching the sugar storage sources of the cotyledons, any negative tropism or growth will result in a build up just above the casparian strip and then back up the hypocotyl/stem eventually leading to the petioles and lower cotyledon surfaces. A small imbalance might just trigger a small strip of excess sugar just above the divide between the root and hypocotyl/stem.
As it increased to a maximun after 72 to 96 hours, now a decrease is seen as startch stores exhaust and nutrient dependant chlorophyll energy processes become the main source of energy and source to sink relationship. At this point, as the cotyledons unfold, loose thir lobed apperance and thin out into a leaf to support the plant as it grows its next set of leaves (often called true leaves) we can see this storage depleted.
A side mention to the endosperm contained in the sac surrounding the seed of which its root radicle must puncture through at the second stage of germination after the imbiment of water. This holds startch of basic forms and feeds the plant briefly until it dries in the air or is seperated by the forces as the seedling pushes up towards the surface of the soil.
Linked to the rise and fall of sugar and certain imbalances in growth we might see a purple discolouration from the hypocotyl/stem upwards
even as far as the lower surfaces of the cotyledons. Certain flavanoids form from basic chemicals via their conjunction with sugars, anthocyanin is one such pigment although there are others and set against a unique biosystem of regulators. If the root or plant as a whole suffers stress then anthocyanin will start to form at the casparian strip upwards.
This initially is not detrimental to seedling growth and is short term until the stem greens up and sugar levels fall, generally after the initial 72 - 96 hour increase. One factor against this is that sometimes the negative factors which caused the initial sugar and anthocyanin increase will thus cause futher root and plant problems and the build up of anthocyanin may never dissapear and even worse increase past the stage of decrease (72 - 96 hours).
It is commonly seen that a purple stem or band at germination, even purple cotyledon undersides soon dissapates after a few days. Some can even watch the stem turn green from the top cotyledons down to the base. This purple to green in a short period is no worry as highlighted but a completley green seedling at germination would show that the harmony of the sugar to root growth rate was a more harmonious one but not necessarially better in terms of final dry mass and growth.
These systems alone are easy to see but can be mimicked by pathogens, drought, flooding and certain other stressors.
A overview of purple stems in early germination linked to sugar startch storage in cotyledons by an enthusiast, me!
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