Pale green leaves?

I'm growing two chestnut trees indoors right now. One of them, the one that came out of the ground earlier, right now has six leaves, the last two still developing, but what concerns me is that these last two leaves are paler in color around the middle, and only darker around their veins. This is the tree that I accidentally broke the bottom of it's root when I was transplanting it. The other tree, wich came out later, is already taller and has much larger leaves than this one, it's growing perfectly healthy and fine.

Does anyone have any suggestions as to what causes this?
Thanks.

 

Hi when you have seedlings you can have diffrences in leaf colour & shape and form, it just could be light or its hungry
If possible can you give a bit more background history size of pot and the soil they are growing in , if you have damaged a root that may be the cause, but since its growing should be ok , and why are you growing indoors and not out ?? at this time of year



Spruce

 

Thanks for the fast reply Spruce.

I first planted them both in smaller pots, thought it was going to be enough, but after watching a video on how planting is done, I got concerned that the pots will be too small. The older one, the one with the smaller growth and the pale green new leaves already had a root system, I tried to pull the whole soil out but it fell apart, and the root's tip at the bottom, about half a centimeter long broke off. I planted it into a larger pot, 20 cm in height and about 15-16 cm in diameter. I think I remember giving the seedling earth from one of the pots that was meant for a tree that was killed by the weather, but I added lots of new earth to it too thereafter. It eventually sprouted from the ground and grew leaves, but lately it seemed to have slowed down, and the newest two leaves have that pale color to them, only being green near the veins. The other tree had purely the new soil given to it, it sprouted from he ground one month later and it already outgrew the older one.
The reason they are outdoors is because I planted them back in the middle of december when I found these two sprouting out of the nuts, and here in my country the outside temperature is still just barely above zero, I'd only dare put them out once the temperature rises.