Abstract
Decreasing water content interferes many metabolic processes of plants, and continued dehydration eventually causes death. Thus, assessing drought stress is important for management of landscaping trees. Although canopy temperature, canopy spectral reflectance or chlorophyll fluorescence have been previously studied as practical indicators of drought stress, accuracy improvement is needed. Therefore, we newly focused on delayed fluorescence, of which luminescence origin is different from chlorophyll fluorescence, and examined a method of assessing drought stress of trees. We conducted experiments that applied acute drought stress on leaves of Cerasus jamasakura (Sieb. ex Koidz.) H. Ohba var. jamasakura by a pressure chamber until water potential of − 3.0 MPa. As a result, it was shown that intensity of delayed fluorescence and ratio of two time-point delayed fluorescence had the strongest correlation with water potential between 0.1 − 2.0 sec and between 0.5 − 2.0 sec, respectively. These indicators of delayed fluorescence had stronger correlation with water potential and higher accuracy in estimating water potential than Fv/Fm that is a well-known indicator of photosynthesis function based on chlorophyll fluorescence. Although further studies with different species are necessary, this study indicated that delayed fluorescence can be an indicator of acute drought stress superior to chlorophyll fluorescence.
