seedlings unable to shed coat, lose seed leaves

[brian]

I have noticed this happening with certain types of tropical seedlings.  A strong root emerges and digs into the soil, the seed is lifted into the air as the seed leaves begin growing, but the seed coat is never shed and the seed leaves die.  Luckily, because these tropical seeds are fat and full of energy, they tend to eventually grow new leaves and carry on fine.  I saw this happen to every single durian seed I sprouted, and now I see it has happened to every kepel seedling.  I remember that sugar apples had similar issues but not as severe, they usually got enough of their seed leaves out that the tips would simply die and drop the seed shell, and the leaves could open.

Is this normal?  Environmental?

[Daintree]

I have had the same problem with some of my seeds. 
Once it comes up and I can see that the cotyledons cannot emerge from the hard seed coat, I just take a pair of pliers and crack the seed.  The smaller the seed, the smaller the pliers.  I have even done it with tomatoes that can't drop the outer husk of the seed.
All you want to do is crack it hard enough to cause the outer shell to split slightly.  The seedling can usually do the rest of the work.

Cheers,
Carolyn

[elouicious]

This is an interesting technique carolyn-

I have always had poor results with trying to remove the seed but have had better luck when it is done after the seedling has formed its first set of leaves

I recently lost an Ambelania acida seedling to this-

[driftwood]

spritzing the seedling and letting it dry repeatedly is a way to get it to open naturally. I think while sometimes its just luck of the draw that too much moisture in the soil can cause this seed coat to get stuck. it's something that happens to many seeds and not just tropicals

[brian]

I had tried Daintree's approach but I tend to end up accidentally twisting the seed and damaging the seedling further when I try to crack them.   

I am thinking I will start scoring the edges before germinating next time.  For hard seed coats I usually score randomly but I think focusing on the edges will help.

[Jamesther]

I think your seeds are just getting dry to fast.
I would try a humidity dome or tent.

[brian]

In the most recent batch, the kepel seeds, the seeds remained almost entirely underground the whole time and very moist soil.  I don't think that was the issue for that batch.  It seems the emerged root had pulled the seed quite far under the soil, and the seed leaves never even reached above the soil line.

[Jamesther]

I always just press tropical fruit seeds onto the soil. Never covering them. I had 100% germination with keel seeds sent from Oscar at fruitlovers. The seeds get lifted into the air before the leaves open.