Leaf chlorophyll fluorescence can show if cucumber plants are stressed by too much light. Short bursts of high light cause temporary loss of fluorescence, but longer exposure leads to permanent damage. Even short periods of intense light can harm the plants. The damage is mainly on the part of the plant that helps with photosynthesis. Low light-grown leaves can recover better from this stress compared to leaves grown in sunlight. Monitoring chlorophyll fluorescence can quickly tell if plants are being harmed by too much light.