Fujita K, Okada M, Lei K, Ito J, Ohkura K, Adu-Gyamfi J J, Mohapatra P K
Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-hiroshima, 739-8528, Japan.
J Exp Bot. 2003 Nov;54(392):2519-28. doi: 10.1093/jxb/erg273.
Tomato (Lycopersicon esculentum) plants were grown in liquid culture inside the greenhouse of Hiroshima University, Japan. At the first fruiting stage, P was withdrawn from the rooting medium for a period of 19 d and its effect was studied on photosynthesis, stomatal conductance, transpiration, partitioning of 13C and 15N, P contents of various organs, and changes in stem and fruit diameter of the plant in order to identify the mechanism of resource management on the part of the plant at low P. Compared to the control, P-deficiency treatment decreased biomass growth of all organs except the roots. The treatment also depressed leaf photosynthesis, stomatal conductance and diameter of fruit and stem after a lag period of about 1 week. The stem diameter of the plant shrank during daytime and expanded during the night; the adverse effect of P-deficiency on stem diameter change was more evident during the night than the day. The circadian rhythm in fluctuations of diameter was less manifested in the fruit compared with the stem. P-deficiency induced daytime shrinkage and reduced night expansion of fruit. However, within the plant, P-deficiency encouraged partitioning of 13C, 15N and P into the fruit at the cost of autotrophic organs such as leaves and the upper parts of the stem. The results were discussed in the light of a plausible effect of P-deficiency on water relations of the plant. It is concluded that, in spite of the preference in partitioning of C and N received within the plant parts, assimilate flow into the fruit is limited at low-P compared with the control, owing to the restriction in fruit expansion.
番茄（Lycopersicon esculentum）植株在日本广岛大学温室的液体培养中生长。在第一结果期，从生根培养基中去除磷19天，并研究其对光合作用、气孔导度、蒸腾作用、13C和15N分配、各器官磷含量以及植株茎和果实直径变化的影响，以确定低磷条件下植物资源管理的机制。与对照相比，缺磷处理降低了除根以外所有器官的生物量生长。该处理在约1周的滞后期后还抑制了叶片光合作用、气孔导度以及果实和茎的直径。植株茎直径白天收缩，夜间扩张；缺磷对茎直径变化的不利影响在夜间比白天更明显。与茎相比，果实直径波动的昼夜节律表现较弱。缺磷导致果实白天收缩，夜间扩张减少。然而，在植株内部，缺磷促使13C、15N和磷以叶片和茎上部等自养器官为代价向果实分配。根据缺磷对植物水分关系的可能影响对结果进行了讨论。得出的结论是，尽管植株各部分对碳和氮的分配存在偏好，但由于果实扩张受限，与对照相比，低磷条件下进入果实的同化物流量有限。
