Effects of drought stress and rehydration on chlorophyll fluorescence characteristics in Fragaria×ananassa Duch

Water deficiency is a limiting factor for plant growth and development because it can severely affect a wide range of physiological processes such as photosynthesis in plants. Chlorophyll fluorescence assays provide a rapid and noninvasive means to study the behavior of plant photosynthetic systems under drought stress. This study was conducted to characterize the drought stress induced changes in chlorophyll fluorescence parameters in strawberry,Fragaria ananassa Duch. cv. Toyonoka. Plants were treated with four different soil water levels,75% (CK),55% (T1),35% (T2),and 15% (T3) (ratio of relative water content to maximum moisture capacity in field). After 14 days of drought stress,plants were slowly rehydrated Chlorophyll fluorescence parameters were measured. The results showed that the maximal fluorescence (Fm),light energy transformation efficiency of PSII (Fv/Fm),actual photochemical efficiency of PSII during illumination (Yield),photochemical quenching coefficient (qP) declined fluorescence parameters with decreasing soil water content. A significant difference in the chlorophyll was found among different treatments (P0.05). Damages in the plants treated with low or moderate drought stress could rapidly recover after rehydration. However,damage recovery in the plants under the severe drought stress and control differed significantly (P0.05) after rehydration.