Her leafs died, why?

Okay. I've read your diary. Few things mate. With your high temp. Your plants co2 intake will be very high. And its suffering under that plastic bottles. With such high heat you have to have air movement over the leafs. The cotyledons are dying this early. Is not normal. Its signs your plant is struggling. As I said if your outside temp is that high. Now think of a plastic dom. (Like sitting in a car that's been sitting in the sun for hrs with no ac) in this case. She's sweating her bollox off. She needs as much air movement over her stomatas on a molecular level. Co2/o2 bubbles need exchanging on that level As your plant has layers of stomata and needs constant exchanging. I know all about this as I'm growing with co2 in 32-35c that's air temp. Leaf temp is a lot lower. LVPD. As I've many fans that blow air over. Think of them as vents. They need to be hitting peak conditions. At 32c and above them vents are closed, no photosynthesis and that's your outside temp with plastic dom. I don't know how much its used. But, ditch it completely. In that level of temp if you live near woods your ambient co2 level will be low,,as everything green will be working hard to clean your area. So, you need to take advantage. It'll still work hard as you need 29+c for extra co2 intake. Good Growing