Journal of the Japanese Society for Horticultural Science

Epandage de la potasse et de la chaux hydraulique par un jour de pluie au commencement de la croissance augmente considérablement le teur de sucre et d'amidon chez la pomme de terre et de la batate ayant accompagné l'augmentation de leur densité. L'épandage hâtif ne produit pas cet effet même à la forte dose.

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Good pollen germination and tube growth were obtained Jon 4/10 M sucrose plus 6 percent gelatine, in which the hydrogen-ion concentration was adjusted to PH 8.2. If crushed pistils from a plant were placed on the artificial medium of pollen from the same plant, both pollen germination and tube growth were inhibited. This fact appears to show that the inhibiting substance exists in the pistil of open flower.
The germination tests of pollen on the artificial media containing crushed pistils from buds, open flowers, and old flowers respectively proved that the inhibiting substance is secreted not at all or a little in the pistil of bud stage, while abundant at the flowering time, and that it is again decreased in the pistil of old flower. These results were fully in accord with those of pollination experiments (TATEBE 1937 _??_ and b).
An experiment to graft stigma upon style with the aid of gelatine (see YASUDA 1931) clearly indicated that-pollen germination and tube growth on the stigma are affected exclusiveiy by the character of the stigma, but not at all by that of the style. Consequently it seems that in the Japanese radish the inhibiting substance is chiefly secreted in the stigma. This fact was also corroborated by the results of experiments which the stigmas mutilated in bud stage were applied with their own pollen at the flowering time. these cases were superior in the percentage of pollen germination and that of emptied grains to the control.
Self-fertility was increased by rubbing the stigma with absorbent cotton wetted with distilled water.
The fact that the stigmas mutilated at the, time of anthesis increase self-fertility (TATEBE 1939), as well as the results of the germination tests of pollen on the artificial media containing separately fluid extracted from each part of the pistils indicated us that the inhibiting substance exists in the stigma, especially in the upper part of the stigma at the flowering time, and that it diffuses somewhat through the style into the ovary.
The addition of crushed pistils to the artifical media does not stimulate the pollen germination and tube growth of different strains.
The action of the inhibiting substance is still kept in the dry powder of the pistil.
The inhibiting substance is water-soluble, and diffuses through a thin layer of gelatine.

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