Simulation of Photosynthetic Quantum Efficiency and Energy Distribution Analysis Reveals Differential Drought Response Strategies in Two (Drought-Resistant and -Susceptible) Sugarcane Cultivars

Dongsheng An; Baoshan Zhao; Yang Liu; Zhijun Xu; Ran Kong; Chengming Yan; Junbo Su

doi:10.3390/plants12051042

Simulation of Photosynthetic Quantum Efficiency and Energy Distribution Analysis Reveals Differential Drought Response Strategies in Two (Drought-Resistant and -Susceptible) Sugarcane Cultivars

Plants (Basel). 2023 Feb 24;12(5):1042. doi: 10.3390/plants12051042.

Authors

Dongsheng An^{1

2}, Baoshan Zhao^{1

2}, Yang Liu^{2

3}, Zhijun Xu², Ran Kong¹, Chengming Yan¹, Junbo Su¹

Affiliations

¹ South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang Experimental and Observation Station for National Long-Term Agricultural Green Development, Zhanjiang 524091, China.
² Zhanjing Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Zhanjiang 524013, China.
³ Jiaxing Vocational and Technical College, Jiaxing 314036, China.

Abstract

Selections of drought-tolerant cultivars and drought-stress diagnosis are important for sugarcane production under seasonal drought, which becomes a crucial factor causing sugarcane yield reduction. The main objective of this study was to investigate the differential drought-response strategies of drought-resistant ('ROC22') and -susceptible ('ROC16') sugarcane cultivars via photosynthetic quantum efficiency (Φ) simulation and analyze photosystem energy distribution. Five experiments were conducted to measure chlorophyll fluorescence parameters under different photothermal and natural drought conditions. The response model of Φ to photosynthetically active radiation (PAR), temperature (T), and the relative water content of the substrate (rSWC) was established for both cultivars. The results showed that the decreasing rate of Φ was higher at lower temperatures than at higher temperatures, with increasing PAR under well-watered conditions. The drought-stress indexes (ε_D) of both cultivars increased after rSWC decreased to the critical values of 40% and 29% for 'ROC22' and 'ROC16', respectively, indicating that the photosystem of 'ROC22' reacted more quickly than that of 'ROC16' to water deficit. An earlier response and higher capability of nonphotochemical quenching (NPQ) accompanied the slower and slighter increments of the yield for other energy losses (Φ_NO) for 'ROC22' (at day5, with a rSWC of 40%) compared with 'ROC16' (at day3, with a rSWC of 56%), indicating that a rapid decrease in water consumption and an increase in energy dissipation involved in delaying the photosystem injury could contribute to drought tolerance for sugarcane. In addition, the rSWC of 'ROC16' was lower than that of 'ROC22' throughout the drought treatment, suggesting that high water consumption might be adverse to drought tolerance of sugarcane. This model could be applied for drought-tolerance assessment or drought-stress diagnosis for sugarcane cultivars.

Keywords: chlorophyll fluorescence; energy dissipation; model; photoprotection; water consumption.

Abstract

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