Effect of water stress on chlorophyll fluorescence in leaves of tea plant (Camellia sinensis)

The effects of water stress on the chlorophyll fluorescence parameters in the leaves of Tieguanyin and Fudingdabai-cha tea cultivars were investigated.The results show that under water stress,the minimal fluorescence(Fo) of tea plants increases significantly,while the maximal fluorescence(Fm),variable fluorescence(Fv),light energy transformation efficiency of PS Ⅱ(Fv/Fm) and activity potential of PSⅡ(Fv/Fo) decrease markedly,suggesting that PS Ⅱ reaction center is destroyed by water stress.Photochemical reaction rate(Prate),fluorescence increment time(T1/2) and electron transport rate(ETR) decrease,leading to increased thermal dissipation rate(Drate),non-photochemical quenching(qN) and relative limitation of photosynthesis(LPFD),but obviously decreased photochemical quenching(qP) and actual photochemical efficiency of PSⅡ(Yield).The tea cultivar Tieguanyin has stronger stress tolerance and higher PSⅡ photochemical efficiency than Fudingdabaicha.