Pine seedlings turning white

[czaczaja]

I've recently put my pine seedlings outside for better air circulation than in the greenhouse. It looks like the first set of needles is turning white whereas the newer set looks healthy. They have not been subjected to frost and the soil is well draining. Any ideas?

 

[Wires_Guy_wires]

Sometimes when light intensity increases, some plants exhibit chlorotic behavior.
It could be that, or natural shedding of spent needles.

 

[Shibui]

Possible sunburn on leaves that were not sun hardy. This happens when plants are suddenly shifted from shade to sun.
Provided the emerging leaves are OK there's no problem. New leaves will be adapted to the light conditions they emerge into.

 

[czaczaja]

Thanks guys, makes me feel bit better now. Hope they survive the winter.