Objective The study was carried out to understand the effects of drought stress on photosynthesis and leaf tissue structure of Litsea coreana Levl. var. lanuginosa cutting seedlings.

Method Three-year-old L. coreana Levl. var. lanuginosa cutting seedlings were used as experimental materials, and 4 drought stress treatments were set: CK (soil volume water holding capacity of 39.6%), mild drought(soil volume water holding capacity of 29.2%), moderate drought(soil volume water holding capacity of 19.5%), and severe drought (soil volume water holding capacity of 9.7%). The effects of drought stress on photosynthesis and leaf tissue structure of cutting seedlings of L. coreana Levl. var. lanuginosa were studied by analyzing the diurnal changes of net photosynthetic rate, the correlation between gas exchange parameters and environmental factors and the leaf transverse tissue structure.

Result Under severe drought, the "photosynthetic siesta"of Litsea coreana Levl. var. lanuginosa cutting seedlings was obvious, with over 2 hours. The average net photosynthetic rate of photosynthesis was 1.9712 μmol/m²·s, the photosynthetic capacity was low, and the photosynthetic rate correlation coefficient of relative humidity of leaf surface and net photosynthetic rate was -0.462, therefore, it is necessary to increase the air moisture and lower the temperature to maintain the normal photosynthetic physiology of the leaves. Under moderate drought, the total amount of chlorophyll in the cutting seedlings of L. coreana Levl. var. lanuginosa was higher(1.25 mg/L), which could respond to drought stress. With the increase of drought degree, leaf stomatal conductance decreased. Leaf stomatal conductance under moderate and severe drought stress was about 0.03mol/m²·s, which seriously affected its water use and gas exchange. The tissue structure of seedling leaves was also changing, the thickness of the upper epidermis became thinner, the palisade tissue became thicker, and the spongy tissue became thinner.

Conclusion Drought stress can reduce the photosynthesis of L. coreana Levl. var. lanuginosa cutting seedlings, and it also changes the leaf tissue structure. The correlation between photosynthesis capacity and leaf tissue structure changes under drought stress needs to be further studied.