Wheat planted in temperate regions accounts for almost 40% of the world's total wheat production. The terminal thermal stress showed that aboveground biomass, grain number ㎡, flowering and maturity, thermal stability of membrane, photosynthesis of flag leaves, chlorophyll content, stomatal conductance and canopy temperature were greatly affected by thermal stress.

The chlorophyll content and related characters of photosynthesis, and the stability of thylakoid membrane at high temperature were also reported, indicating that chlorophyll fluorescence and membrane leakage may be practical methods to quantify the effect of heat resistance.

In order to solve the problem of thermal stress, most researchers focus on genome research to determine the characteristics of heat tolerance, but also known as cytoplasm, which can play an important role.

In addition to cytoplasmic male sterility, cytoplasm has been proved to affect the yield, grain quality, plant height, plant vitality, cold tolerance, heat tolerance, green retention and other agronomic traits of various crops.

Chloroplasts and mitochondria are sources of additional nuclear genes.

Roach and Woolf (1987) pointed out that plastids and mitochondria have small genomes, which can ovulate directly from the mother to the spring, resulting in maternal effect of cytoplasmic inheritance.

They also pointed out that the cytoplasmic genome is an independent nuclear genome, which affects the quantitative and quality traits of plants.