ABSORPTION, TRANSLOCATION AND ASSIMILATION OF ^<16>N AND ^<45>Ca IN SOME VERGETABLE CROPS

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The absorption and translocation of Ca were measured after ^<45>Ca was supplied to either surface of lamina, the stem, the node, fruits, and the roots of the water-cultured tomato plants. We found that : 1) When Ca was supplied to either surface of the lamina, it was well absorbed and translocated only to the distal end in the applied leaf. Ca was not translocated to other plant organs such as roots, stem, upper leaves or shoot apices. 2) When supplied at the stem, absprption and translocation to the upper part of the plant was detected more for Ca than P.3) When supplied at the node, the amount of Ca absorbed and translocated was the largest in comparison with other plant organs and portions, and absorbed Ca was well translocated to the top portion of the plant and immediately above the supplied leaf. 4) Ca supplied at the fruit was well absorbed and distributed to the inner parts. 5) Ca supplied at the root was translocated to all parts of the plant. 6) The absorption and the translocation of Ca in leaves and fruits were monitored by the autoradiography.In the N study, at first, urea as N source for tomato seedlings was compared with nitrate and ammonium under different N concentration, solution pH, solution temperature, and nickel concentration. Then, the absorption, translocation, and assimilation of urea were compared with those of nitrate and ammonium at different growth stage of water-cultured tomato plants. The absorption, translocation, and assimilation of urea supplied by foliar application were also compared with those of nitrate and ammonium by using ^<15>N as a tracer.