Abstract
The nitrate absorption and the nitrate assimilation by excised organs of seed embryos of Vigna sesquipedalis grown in the dark were investi-gated. The most vigorous absorption was found in radicle, especially aged 4 days when lateral roots appeared. As for nitrate assimilation in the dark, plumule and radicle showed strong activity, and hypocotyl relatively weak one. The nitrate assimilation in these organs kept pace with the oxygen respiration, and under anaerobic conditions the as-similation was greatly diminished.
In cotyledon absorbed nitrate was converted into nitrite, but not further. The nitrite production decreased as the age of tissue progressed, when a greater part of the nitrite accumulated in the tissue was put out into medium. In the early stage of germination the cotyledon tissue was found to have cytochromes of coli-type (a1, b), and in the later stage that of subtilis-type (a, b, c). A possiblity was pointed out that nitrate may serve as a terminal hydrogen-acceptor in the cotyledon tissue at least in the earlier stage of germination.
The author wishes to express her gratitude to Assist. Prof. Dr. Yukito Oota under whose cordial guidance the present investigation was carried out. Thanks are also due to Prof. Dr. Takeshi Mori who has made valuable counsels and encouragement during the course of this study.
