J Integr Plant Biol. ›› 1960, Vol. 9 ›› Issue (1): -.

• Research Articles •    

Studies in the Differentiation of the Shoot Apex of Rice I. Varietal Differences

Laboratory of Experimental Plant Morphology, Institute of Botany, Academia Sinica   

Abstract: 1. The differentiation of the shoot apex of rice is morphogenetically similar to that of other Graminae such as Kaoliang, millet, Italian millet etc. in which the inflorescence is a panicle. The differentiation of the shoot apex initiates by swelling and somewhat elongating. Then the papillae- like primordia of the branches of the first order appear acropetally. The appearence of the branch primordia of the second order follows soon. In the middle part of the inflorescence the branch primordia of the third order make their appearence in succession, while at both ends only the branch primordia of the second order are formed. The order of the differentiation occurs in the following sequence: 2 glumes which are greatly reduced in size, 2 sterile lemma, the fertile lemma, the palea, the stamens, and the pistil. 2. The morphological difference in the differentiation of the shoot apex of rice among the different varieties is not great. In the early stage there is only slighte difference in size. During the development of the flower, the characteristics of the varieties become prominent; for example, in the variety Hsiao Hung Mong the awn primordia appear at the time of the closing of the lemma and the palea. From the developmental point of view, there are great differences among the varieties: in the early maturing varieties, the stages of differentiation pass through faster than those in the late maturing varieties, and this may explain why the early maturing varieties possess smaller panicle and less grains per panicle. If the transplantation is carried out as early as possible, the period of the vegetative growth may be prolonged, and in turn, it is beneficial to the increase in the size of the panicle and the number of the grains. 3. Owing to the regularity of the differentiation of the shoot apex of rice, more branch primordia may be produced if the fertilizer is applied in advance of their appearance. The rate of the flower development may be promoted, if the fertilizer is applied during the differentiation of the flower organs.

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