Abstract:Injurious electrolyte leakage (IL) from wheat leaves after 30 minutes heat stress increased along with the increase of temperature. The relationship between IL and injurious temperature was closely fitted with an exponential curve. But when the temperature exceeded a critical point, the curve suddenly turned steep and the temperature coefficient (Q10) increased to tens or even hundreds of times what was before. The critical temperature was largely equal to or slightly higher than the killing temperature. After adequate heat acclimation, both the killing temperature and the temperature at which the electrolyte leakage came to 50% (IT50) were apparently increased. After the temperature decreased to normal range, the acclimation effects were disappeared in a few days.