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内容記述 |
Calcium (Ca) deficiency symptoms, such as blossom-end rot, often occur in fruits due to weak transpiration. It has been generally believed that Ca is primarily transported through the xylem via transpiration flow, with limited redistribution through the phloem. To elucidate the mechanism of Ca transport to tomato fruit, we performed real-time monitoring using radioactive Ca (45Ca) and a compact positron multi-probe system. A 45Ca solution was injected directly into the main stem either in the daytime or at night, and its radioactivity was monitored by detectors placed on the stem, pedicel, and petiole. The arrival order of 45Ca depended on distance from the injection site, without an apparent day–night difference. Time Activity-Curve profiles were classified into two patterns: (1) decline after a peak, (2) continuous increase or stable. Pattern (1) was likely observed in the main stem close to the injection site, and pattern (2) in the distal or terminal parts, suggesting successful detection of the spatiotemporal movement of 45Ca from the main stem to the distal parts. We will discuss the dynamics of 45Ca together with the proportions of mobile and immobile 45Ca in each plant part. |
