Photoinhibituion is caused by excess light energy to photosynthesis, which increased under drought condition. To clarify the relationship between susceptibility of photoinhibition and species-specific drought tolerance, we measured predawn water potential, gas exchange rate and Fv/Fm after exposing strong light on drying potted saplings of three deciduous species ; Sorbus alnifolia, Carpinus tschonoskii and Betula platyphylla var. japonica, and compared them with leaf mass per area (LMA) and wood density, which are indices of drought tolerance, and hydraulic conductivity. B. platyphylla, whose LMA and wood density were the lowest, showed decreased gas exchange rate and high susceptibility of photoinhibition during drought. S. alnifolia, whose LMA and wood density were the highest, showed sustained gas exchange rate and the least susceptibility to high irradiance even under drought condition. This species also showed the highest leaf-specific hydraulic conductivity than other two species. C. tschonoskii showed similar LMA but higher wood density than B. platyphylla, leading maintained gas exchange rate and less susceptibility of photoinhibition. These results indicated that susceptibility of photoinhibition is associated with species-specific drought tolerance and corresponding control of gas exchange rate by stomata under drought condition.
The invasive red-necked longhorn beetle, Aromia bungii, has been recently reported from the Aichi and Saitama Prefectures in Japan. The beetle invasion has been affecting cherry cultivars Prunus×yedoensis ‘Somei-Yoshino’ and plum trees Prunus mume. Irreversible damages to cherry trees have been reported from the Saitana Prefecture. The red-necked longhorn beetle is a primary pest, and the larvae bore holes through both inner bark and xylem. In Saitama, A. bungii population had begun to disperse beyond the initially detected areas. Intensive management during the stage of population establishment in areas at risk may help to successfully eradicate populations in newly colonized habitats. Immediate actions, involving systematic management of A. bungii, are necessary to eradicate this invasive species.