Effect of Short-Time High-Temperature Treatment on the Photosynthetic Performance of Different Heat-Tolerant Grapevine Cultivars.

To explore the photosynthetic response of short-term high-temperature treatments to the leaves of different grape varieties (Shenyue and Shenfeng), we performed 45°C treatments on annual potted grapes in an artificial climate chamber to simulate the summer high-temperature period. We measured the rapid A-Ci response curve, 1,5-ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity and chlorophyll a fluorescence. Photosynthetic performance-related parameters of grapevine leaves were found to be adversely affected by high temperature; the maximum rates of carboxylation of Rubisco and ribulose diphosphate regeneration and Rubisco activity were all significantly reduced. The JI of the JIP-test curve disappeared under high-temperature treatment, and the K peak appeared, indicating that the oxygen-evolving complex (OEC) had been destroyed. Principal component analysis showed that PSII activity (F /F , DF , φ , ABS/RC) was greatly affected by high temperature. It was also found that the Rubisco activity and OEC destruction strength were greater in one of the cultivars, and we were able to determine heat resistance based on the phenotype and photosynthetic performance. It can be seen from the above that Shenyue leaves have higher heat tolerance and stronger photosynthetic performance than Shenfeng leaves. This shows that photosynthetic performance is strongly correlated with a grapevine's tolerance to abiotic stress.