J Integr Plant Biol. ›› 1964, Vol. 12 ›› Issue (4): -.

• Research Articles •    

Accumulation and Mobilization of Starch During the Differentiation of the Shoot Apex and their Correlation to the Development of the Spikelets in Wheat

Chien Ling-cheng   

Abstract: The accumulation and mobilization of starch during the differentiation of the shoot apex and the morphogenesis of fructiferous organs of the wheat have been investigated with the PAS reaction method. The results obtained in this study are briefly summarized as follows: 1. Before the elongation of the shoot apex, the starch is mainly accumulated in the cells of tillering nodes; in the shoot apex, only small quantities of starch have been observed in a few cells of the central region of corpus. 2. The starch deposit increases more and more with the differentiation of the shoot apex and the development of the young spike. Unequal distributions of the starch deposit occur, soon after the elongation of the shoot apex, in different parts of the young spike, namely, the starch content in the middle part is more than that in the upper part or in the basal part. This phenomenon becomes more prominent with the further development of the young spike. The distribution of the starch deposit in different parts of the young spike is in close correlation with the development of the spikelets, as it is well known that the spikelets in the middle part of the spike generally develop better than those in the upper and basal parts. 3. The starch content varies also in different florets of a spikelet, according to their location. For instance, the starch content of the florets in the basal part of the spikelet is more than that of the florets in the upper part. This is also correlated with the developmental conditions of the florets, the basal ones of which gain further development and the upper ones usually degenerate. 4. During the course of organogenesis of the shoot apex, the starch deposit region always closely follows the meristematic region, and the mobilization of the accumulated starch seems to be always directed to the newly formed and rapidly growing organs. 5. The basal spikelets of a spike or the upper florets of a spikelet in which only few starch grains are present, usually degenerate under unfavourable conditions (as drought). Experimental results of this study showed that if optimum irrigation was applied before degeneration occurs, the starch content of these spikelets and florets increased prominently, thereby further development of the above mentioned organs was ensured and the rate of fructification increased. 6. The author believes that the development of the spikelets and the florets of wheat essentially depends on the sufficient quantity of carbohydrates accumulated in these organs.

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