Study on Heat Resistance of Peony Using Photosynthetic Indexes and Rapid Fluorescence Kinetics

Abstract

To investigate the effects of high-temperature stress on the chlorophyll fluorescence induction kinetics of peony and to determine indicators for the rapid screening of varieties responding to high temperatures, three four-year-old peony variety, ‘Fengdanbai’, ‘Huhong’, and ‘Yinhongqiaodui’, were selected as materials. The photosynthetic curves (Pn-PAR) and fast chlorophyll fluorescence curves (OJIP curves) of peony leaves were measured at different times under high-temperature stress conditions (40 °C), the changes in the photosynthetic characteristics of different peony varieties under high-temperature stress were analyzed, and the heat tolerance of peony was evaluated. The results showed that ‘Huhong’ grew well within 16 days, while all of the other varieties showed obvious wilting at 6–9 days. High temperatures damaged the structure and function of the photosystem of peony leaves, indicating that the maximum net photosynthetic rate (Pnmax), apparent quantum efficiency (AQE), maximum photochemical efficiency (Fv/Fm), and photosynthetic performance index (PIABS) all tended to decrease under high-temperature stress, while the rate of closing the PS II reaction center (Mo) and the absorption per reaction center (ABS/RC), the capture (TRo/RC), and the dissipation (Dio/RC) of light energy per reaction center showed an overall increasing trend. The ability to cope with high-temperature stress differed among varieties, and the heat tolerance was determined to be in the descending order of ‘Fengdanbai’ < ‘Yinhongqiaodui’ < ‘Huhong’. The correlation analysis among the parameters and the analysis of the morphological change patterns in peony leaves concluded that PIABS, Dio/RC, and Mo could be used as indicators of peony tolerance to high-temperature stress. The results of the study can provide a basis for the screening of heat-tolerant peony species and peony heat defense in the Jiangnan area.

Effects of High Temperature Stress on the Physiological and Biochemical Characteristics of Paeonia ostii

“…However, peony cultivars resistant to high temperature stress have a relatively low degree of time inhibition under high temperature stress and can maintain relatively high PSII actual light energy conversion efficiency [14]. Ji et al [15,16] investigated the changes in photosynthetic characteristics of P. ostii under high temperature stress and found that high temperature damaged the photosynthetic capacity and photosynthetic mechanism of peony leaves. At the same time, some studies have shown that exogenous additives can alleviate the photosynthetic characteristics of peonies under high temperature stress [17][18][19][20][21].…”

Effect of nitrogen application on enhancing high-temperature stress tolerance of tomato plants during the flowering and fruiting stage

“…High temperature (HT) has adverse effects on photosynthesis, such as significantly reducing the maximum net photosynthetic rate ( P Nmax ), apparent quantum efficiency (AQE), and light-compensation point (LCP), and significantly increasing the light-saturation point (LSP) ( Djanaguiraman et al., 2020 ; Li et al., 2023 ). Previous studies demonstrated that gas exchange and photosynthesis had marked reduction under HT stress due to the inhibition of chloroplast and photosystem II (PSII) activity ( Salvucci and Crafts-Brandner, 2004 ; Allakhverdiev et al., 2008 ).…”

Performance Evaluation of New Table Grape Varieties under High Light Intensity Conditions Based on the Photosynthetic and Chlorophyll Fluorescence Characteristics

“…In a separate study, it was discovered that heat stress has a pronounced impact on the chlorophyll fluorescence properties of Rhododendron leaves [16]. Some studies including peony plants revealed that high-temperature stress directly influences chlorophyll fluorescence induction kinetics [17]. The direct impact of heat stress on plant fluorescence activity suggests its potential use as an indicator of heat stress [18].…”