[Effects of high temperature stress on net photosynthetic rate and photosystem II activity in Citrus]
Related Experiment Video
Updated: Sep 20, 2026

High Throughput Image-Based Phenotyping for Determining Morphological and Physiological Responses to Single and Combined Stresses in Potato
Published on: June 7, 2024
Yanping Guo1, Huifen Zhou, Guanghui Zeng
1Department of Horticulture, Zhejiang University, Hangzhou 310029, China. ypguo@zju.edu.cn
Abstract:
Table ADC-225-MK3 CO2 gas analyzer and PAM-2000 portable fluorescence measurement system were used to measure the net photosynthetic rate (Pn), initial fluorescence (Fo), maximal photochemical efficiency of PS II (Fv/Fm) and electron transport rate (ETR) of satsuma mandarin (Citrus unshiu Marc.) and navel orange (C. sinensis Osbeck) leaves. The results showed that exposure of citrus plants to high temperature (38-40 degrees C) led to a lowering of Pn, Fv/Fm, and ETR, whereas Fo increased. After exposure to high temperature for 25 days, compared with normal temperature (25 degrees C), the Pn of satsuma mandarin and navel orange leaves decreased by 55.6% and 39.8%, Fv/Fm decreased by 22.0% and 6.7% and ETR reduced by 55.0% and 41.5%, respectively. On the other hand, Fo increased 113.8% and 14.9%, respectively. With subsequent transfer to the 25 degrees C culture room for 10 days, Pn, Fv/Fm, Fo and ETR recovered significantly. These results demonstrated that the reduction of Pn in Citrus was related to the inactivation of PSII reaction center.
Related Concept Videos
Responses to Heat and Cold Stress
Responses to Salt Stress
Adaptations that Reduce Water Loss
Regulation of Transpiration by Stomata
Effects of Temperature on Free Energy
Photosystem I
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...

