DrJynx86answered grow question 5 years ago Seems like they're really under watered, you have 10 liter pots, should be watering with at least 1 liter and seeing some runoff at the bottom.
With this temperatures, you might need to water them twice a day, once when you start the lights, and then once at the afternoons/evenings, you will notice the soil gets really dirty even after watering the same day in the morning.
When I had the 600w sodium before switching to leds, on summer I had days with 34-37 C, and needed to water three times a day!
You will see, they are droopy, you water them, in 5-15 minutes they will be amazing. Learn to detect the droopiness and keep them watered and happy!