Detection of Photosynthetic Performance of Stipa bungeana Seedlings under Climatic Change using Chlorophyll Fluorescence Imaging

Xiliang Song,Guangsheng Zhou,Yuhui Wang,Xiaomin Lv,Zhenzhu Xu

doi:10.3389/fpls.2015.01254

Abstract

In this study, the impact of future climate change on photosynthetic efficiency as well as energy partitioning in the Stipa bungeana was investigated by using chlorophyll fluorescence imaging (CFI) technique. Two thermal regimes (room temperature, T0: 23.0/17.0°C; High temperature, T6: 29.0/23.0°C) and three water conditions (Control, W0; Water deficit, W−30; excess precipitation, W+30) were set up in artificial control chambers. The results showed that excess precipitation had no significant effect on chlorophyll fluorescence parameters, while water deficit decreased the maximal quantum yield of photosystem II (PSII) photochemistry for the dark-adapted state (Fv/Fm) by 16.7%, with no large change in maximal quantum yield of PSII photochemistry for the light-adapted state (FV′/FM′) and coefficient of the photochemical quenching (qP) at T0 condition. Under T6 condition, high temperature offset the negative effect of water deficit on Fv/Fm and enhanced the positive effect of excess precipitation on Fv/Fm, Fv′/Fm′, and qP, the values of which all increased. This indicates that the temperature higher by 6°C will be beneficial to the photosynthetic performance of S. bungeana. Spatial changes of photosynthetic performance were monitored in three areas of interest (AOIs) located on the bottom, middle and upper position of leaf. Chlorophyll fluorescence images (Fv/Fm, actual quantum yield of PSII photochemistry for the light-adapted state (ΦPSII), quantum yield of non-regulated energy dissipation for the light-adapted state (ΦNO) at T0 condition, and ΦPSII at T6 condition) showed a large spatial variation, with greater value of ΦNO and lower values of Fv/Fm and ΦPSII in the upper position of leaves. Moreover, there was a closer relationship between ΦPSII and ΦNO, suggesting that the energy dissipation by non-regulated quenching mechanisms played a dominant role in the yield of PSII photochemistry. It was also found that, among all measured fluorescence parameters, the Fv/Fm ratio was most sensitive to precipitation change at T0, while ΦPSII was the most sensitive indicator at T6.

Highlights

High temperature and water stress as abiotic stress factors will limit plant growth and reduce crop productivity (Boyer, 1982; Wahid et al, 2007), and they always occur simultaneously in that high temperature increases both evaporation and potential evapotranspiration and exacerbates the negative influence of water deficit (Machado and Paulsen, 2001; Osório et al, 2011)
The results indicate that (1) excess precipitation had no effect on S. bungeana at room temperature; (2) S. bungeana suffered from water deficit, and water stress inhibited plant’s ability in thermal energy dissipation (Zivcak et al, 2014)
Our results showed that S. bungeana has strong ability in protecting photosynthetic apparatus against the photoinhibitory damage from drought, and a 6◦C higher temperature could offset the negative effect of water deficit to a certain extent

Summary

Introduction

High temperature and water stress as abiotic stress factors will limit plant growth and reduce crop productivity (Boyer, 1982; Wahid et al, 2007), and they always occur simultaneously in that high temperature increases both evaporation and potential evapotranspiration and exacerbates the negative influence of water deficit (Machado and Paulsen, 2001; Osório et al, 2011). Plant photosynthetic apparatus appears to be highly resistant to water deficit (Giardi et al, 1996; Petsas and Grammatikopoulos, 2009; Zivcak et al, 2014), temperature rising can change the response of photosynthesis to water stress (Chaves et al, 2002). When water and heat stress occur simultaneously, water stress may impose a certain effect on the photosynthesis together with temperature through oxidative damage (Chaves et al, 2002). On this basis, the inhibitory effect and damage on photosynthesis can be studied when the two stresses coexist, even at a low light intensity

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Conclusion