Changes in some physiological properties during the growth and development of cauliflowers, Brassica oleracea var. botrytis

Growth in length of the cauliflowers sown on July 11 in glass house was slow until the period of the flower bud differentiation (Sept. 28), and after that period rapid growth took place. Water content and specific gravity of the tissue powder of the leaf blade and the petiole increased obviously at the time of the flower bud differentiation. Cor-rected concentration indices of the expressed cell sap (cell sap concentration determined by the re-fractometric method×water content then existing in plant) of the leaf blade and the petiole varied in parallel with the concentration of the aqueous ex-tract of the tissue powder. These values increased accompanied with the growth of the plant, their maximum values being at the period of the flower bud differentiation and thereafter these values de-creased. It is presumed that these physiological changes observed in the period of the flower bud differentiation may be associated with the flower ripening of the plant. Electrical specific conducti-vity of the cell sap and that of aqueous extract ofthe tissue powder of the leaf blade and the petiole were high in the early growing stage, and decreas-ed gradually with the development of abortive floral organs. On the changes by leaf order, of these values such as the corrected concentration indices of the expressed sap, and the concentration of the aqueous extract of the tissue powder, it was observed that the higher the position of the leaf was, the higher the values were until the flower bud differentiated in two portions of the leaves, and after the dif-ferentiation these tendencies were not observed. Such changes of these values by the leaf order were remarkable in the early growing stage, but it was inconspicuous in the period of the formation of abortive floral organs. The higher the position of the leaf was, the lower the values of the electri-cal specific conductivity of the cell sap and that of the aqueous extract of the tissue powder and the change of these values was marked in the period of the flower bud differentiation.