Morphological changes in rice panicle development; a review of literature
1986
Xu, X.B. | Vergara, B.S.
The panicle is a modified racemose branching inflorescence consisting of the panicle axis and primary branches. It extends from the neck node to the degenerated growing point. As many as three secondary branches form on the lower part of each primary branch. The secondary branches usually have three spikelets. The first sign of panicle initiation is the appearance of the first-bract primordium. The order of branch primordium development differs from that of spikelet primordium development. The differentiation and development of primary and secondary branch primordia is acropetal while the sequence of primary or secondary branch development is basipetal. Within any branch, the sequence of spikelet primordia development is acropetal except the topmost spikelet which develops the fastest. The sequence of flowering on a panicle is generally basipetal. Flowering and grain filling follow the same order. The upper branches dominate the lower ones. The topmost and lowest spikelets in each branch are dominating. Going up the branch the metabolic dominance seems to decrease, hence the second spikelet from the top is the most dominated. The dominant spikelets produce heavier grains and have less chance of sterility. Pollen grain development has been used to identify the stage of panicle development. Various stages were reported as a result of difference in methods used to observe pollen development. Spikelet development on a panicle is not synchronous, therefore, the most representative spikelet - the III-2 spikelet-should be used. The panicle distance is the most widely used indirect method of showing the development of the pollen grains
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