In the whole process of growth, plants will be affected by various kinds of environmrntal stimuli, such as drought, salinity and high temperature, and so on. In the process of long-term evolution, plants have formed their own defe nse mechanisms against various biotic stresses and abiotic stresses. Drought stress, as a common abiotic stress in the north of C hina, can affect the growth and development of plants, and lead to the changes of morphology, physiology and chemistry. Disease damage is one of the fa...