nutrient that increases the thermal resistance of plants in greenhouses

raise humidity to decrease VPD. Refer to a VPD chart. you'll read lots of different suggestions of what it should be at various life stages but 1,0 - 1,5 should be a safe range. if the temps are too high you may have to live with 1,5 as humidity can only do so much before it too is a potential risk. look into improving exhuast or circulation.. something to make it all more efficient and knock 1-2 C off your temps. some small improvement may be enough.

A couple of teekee torches can help raise the temps a little.

I find that both silica and kelp can help plants be stronger, build immunity and resist temperature and humidity extremes. As a bonus, kelp can help condition the soil and increase the beneficial microbes, which in turn boosts the plant’s overall growth. Good luck 👍