michbich's trivia

[michbich]

So after reading Beam's coin thread, seeing that we are all brilliant minds here on AO and since it's my birthday. I want to ask you guys 2 questions about vegetation. To wich one of them, a PhD prefessor in vegetation couldn't even answer.

I will start with the warm-up question:

Do tropical plants have those anual circles to tell it's age?

The tuffy and extremely theoretical:

Let's say you're in a spaceship with no gravity. You have a perfectly round volume of earth, that is perfectly watered, perfectly aired, perfect lighting all arround. The sphere of earth is floating in the spaceship. If there is a seed perfectly in the middle of it, would it grow or not? If so, where?

I only have the answer for the first question, the second one is up for debate. I would like your thought on it since it has been bugging me for years...yes, i have no life

[BiNumber3]

i would think the direction the seed sprouts and breaks earth will depend on the seed's orientation. Root growth is affected on Earth by gravity, so in that ball the roots might go wild n the ball will become fully rooted.

[Army]

If the plant produces bark, it will have growth rings. The rings are the growth level reached for that particular wet season. Thick rings mean plenty of water for good growth. Thin rings mean drought years. The divider rings are the growth accumulated during winter "hibernation". Most people equate tropical with palm trees, which are more of a fern and not a real tree. Very fibreous and lacking bark, palms do not have growth rings. The outer bark-like layer is composed of the old and dead leaves (a palm frond is actually a single leaf).

Roots will sense water, and send shoots out to collect it. Gravity would not have any effect on this. Notice the many plants that are attached to cliff faces, and growing sideways. Plants have been grown in space successfully. The MiR station had a tiny garden.

[neppo1345]

1. yes

2. yes

[bstc]

1. yes

2. yes

You're wrong.

[domeplz]

You're wrong.

no you!

[michbich]

If the plant produces bark, it will have growth rings. The rings are the growth level reached for that particular wet season. Thick rings mean plenty of water for good growth. Thin rings mean drought years. The divider rings are the growth accumulated during winter "hibernation". Most people equate tropical with palm trees, which are more of a fern and not a real tree. Very fibreous and lacking bark, palms do not have growth rings. The outer bark-like layer is composed of the old and dead leaves (a palm frond is actually a single leaf).

Roots will sense water, and send shoots out to collect it. Gravity would not have any effect on this. Notice the many plants that are attached to cliff faces, and growing sideways. Plants have been grown in space successfully. The MiR station had a tiny garden.

You are entirely correct on the first one, bark trees will have rain season rings and "trees" like palms will have none. On the second one, i will have to argue a little. Plants have "gravity sensors" and "heat sensors" in there germination phase to determine in wich direction it must grow before reaching the surface. So the orientation of the seed is not a factor.

I do admit that the plant would have no problem to grow in space if it has already germinated. My theories: it would germinate in every direction until it hits surface, or that the germination process will simply not activate and the seed will remain dormante.

[Beemer]

My theories: it would germinate in every direction until it hits surface, or that the germination process will simply not activate and the seed will remain dormante.

Hmmmm Whats the seed. I can grow a seed with out earth. I would guess the direction might be random or every depending on the seed. If it didnt remain dormant, I would also guess it would die trying looking for the light. Might want to try NASA.

[Army]

Seed orientation means nothing. A plant is genetically programmed to seek water and light. The roots will search for water, and the plant will respond to light and Co2. Gravity means nothing as has been proven by the Mir and the old SkyLab.

French growth test on the ISS: notice the plant has gone "up" and the roots "down", despite zero gravity. The curly root is a zero gravity oddity.


Wheat grown on Shuttle:


MiR experiment:


Take note that all roots are "down" and the plant is reaching for light. In zero gravity, plant orientation remains normal.

[Swampy]

Seed orientation means nothing. A plant is genetically programmed to seek water and light. The roots will search for water, and the plant will respond to light and Co2. Gravity means nothing as has been proven by the Mir and the old SkyLab.

French growth test on the ISS: notice the plant has gone "up" and the roots "down", despite zero gravity. The curly root is a zero gravity oddity.

Take note that all roots are "down" and the plant is reaching for light. In zero gravity, plant orientation remains normal.

Army those look like hydroponic plants which is a different field of study within agronomy. Actually fun fact Walt Disney is one of the country's leaders in both horticulture and hydroponics. Your right that roots grow either down and out and leaves and stems grow up and out. Roots really don't grow down, a taproot will grow down but most root growth is in the first 32 inches of soil and spread out seeking water, oxygen, and nutrients. A taproot really isn't used much other than support, and deep water if it can find it.

On palm trees they are Monocots, they have a different vascular system then other trees, thus they won't have growth rings(some other Monocots are grass). Most trees have actually 5 layers of rings, (from outside in)Bark, Phloem, Cambium, (Live)Xylem, Heartwood (Dead Xylem). You get your growth rings from counting live and dead xylem.

Assuming that culture practices where followed where soil condition, watering, seed depth, and light are all followed. Then it would grow. Bulb plants are a little bit easier to explain but seeds pretty much act the same way (They drastically differ in culture but their growth is pretty similar) With bulbs there is a top and a bottom to a bulb, obviously roots grow out of the bottom and the stem and leaves grow from the top (Notice if your tulips don't grow after planting them they are probably upside down, remember pointed side up) Seeds pretty much act the same but really don't care if planted up side down, mostly because the proper seed depth is only about 2 to 3 times the diameter of the seed.

Gravity doesn't effect a plants growth, even though its a constant force on a plant, it is not need for plant growth. Plants foliage will always grow towards the light not towards the lesser of the gravity (Don't get confused with Green Ash Fraxinus pennsylvanica with there Re-curving issue, that is just the habit of the plant not a effect of gravity). Sucker growth on trees, in response to over pruning or disease a tree will shoot up branches to regain lost foliage, will pretty much always grow geotrophically in fact I have never came across sucker growth that are not geotrophic.



With the tropic question. It depends on you species of tree your looking at. Trees grow in whats called the growing season, not the wet or rain season.