抄録
The present investigation deals with the variation of onion scales in accordance with bulbing, especially its relationship to the constitution of scales and the variety or the size of bulb on “Imaiwase” and other 3 varieties.
(1) Each scale of onion in bulbing period showed so remarkable inhibitance in the growth of blade and so remarkable thickness in the leaf-sheath, that the period is morphologically distinguishable from the vegetative growing period.
The author hypothetically named that inner condition in bulbing period “bulbing phase” again-st vegetative growing phase.
(2) After the cells differentiated as those of blade, they are multiplicative and the blade continues to grow. The increase of number of leaves ceases at the bulbing period, but inner scales within the bulb continue to increase until the death of all leaves.
Break over is caused by the no blade scales, and it appers at bulbing period. They do not held the tops, so break over is able to indicate the harvest time.
(3) According to investigation of the scale cells at bulbing period, those number scarcely increase already in the thickness of about 1cm in length. Then the thickness of bulbs is caused solely by enlargement of cells in scales. The thickened part gradually progresses from outer scales to inner scales, and the outmost varies to film-likescale.
(4) Degree of bulbing decided by the vegetative growth until the bulbing begins and by the bulbing period or the speed of bulbing. The speed is affected by nutrient condition and the profoundity of bulbing phase.
(5) In consequence, in the bulbs sown in autu-mn, those of early varieties (for example Aichishiro) may become flat of “thick scaled type” and those of late varieties globe of “many scaled type”; the form of scales is recognizable to be a charac-teristic of variety.
(6) The plants of many leaves grow up to large bulbs and the inner vegetation point begins to develop into inner bulblet at ealy time, so that the larger the bulb, the less the outer scales, and the larger the bulb, the more the bulblet scales.
