Abstract:

The study aims to explore the effects of temperature under different stress durations on chlorophyll content and chlorophyll fluorescence in five varieties of ornamental peach leaves, and compare the heat resistance in ornamental peaches. Changes in chlorophyll content and chlorophyll fluorescence parameters of ornamental peach leaves after different treatments were measured, and the heat resistance of different varieties of ornamental peaches was compared using principal component analysis and fuzzy comprehensive evaluation method. The results showed that with the prolongation of heat stress duration and the gradual increase in temperature, the chlorophyll content in the leaves of the five varieties of ornamental peaches decreased, Fo value increased, and Fm and Fv/Fm values decreased; ABS/RC, TR_o/RC, DI_o/RC, and ET_o/RC all increased; φP_o, φ_o, and φE_o first gradually increased and then decreased rapidly, with φD_o reaching the maximum value before leaf inactivation, and decreasing rapidly to approach zero after inactivation. When the temperature was below 43℃, the treatment duration had no obvious effect on leaf structure and function; when the temperature was around or above 43℃, both short-term and long-term high temperatures would cause irreversible damage to the leaf cell membrane system, the structure of photosystem II reaction center, and its electron transfer chain. This indicates that changes in chlorophyll content and chlorophyll fluorescence parameters in ornamental peaches are mainly related to the stress temperature. Different varieties of ornamental peaches have varying heat resistance, the heat resistance of Amygdalus perscia ‘Yingchun’ is the strongest and A. perscia ‘Mantianhong’ is the lowest.

Key words: ornamental peach, heat stress, chlorophyll, chlorophyll fluorescence, heat resistance