Vernalization of spinach. (I)

Abstract

(1) In the present paper, effects of the following treatments on the reproductive development of “King of Denmark”, a variety of spinach, were studied. (a) Vernalization with 1±1°C. (b) Combination of vernalization and long-day treatment (17 hrs.) supplemented with artificial illumination. (2) Vernalization (for 10, 20, 30 and 40 days) was promotive for the seedstalk elongation of spinach in its earlier stage of growth in proportion to the duration of the treatment. (3) In the growing period in a green house from November to next June in Kyoto, with the coming of long-days of spring, the plants grown from non-vernalized seeds were accelerated to elongate their seedstalks, nullifying their handicap by the lack of vernalization. Of the time of flowering and fruiting, it was hard to find any significant differences between plants vernalized and non-vernalized. (4) Under natural short-day condition (October_??_December), plants vernalized for 0, 15 and 30 days, after they expanded the 3rd. leaf, were exposed to artificial long-day (17 hrs.) for 0, 5, 10 and 20 days. Of these, the only plot which flowered by the end of December was the combination of 30-day vernalization and 20-day long-day (V-30, LD-20). In the other plots, the elongation of seedstalk was remarkable in proportion to the duration of long-day treatment and/or vernalization. (5) With the seedstalk elongation in spinach, it is presumed that at least to a certain degree, a reciprocal quantitative compensation exists between the effects of long-day and vernalization,