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Reproductive Phase
• Stage 4 - Panicle initiation to booting: The initiation of the panicle primordium at the tip of the
growing shoot marks the start of the reproductive phase. The panicle primordium becomes visible to the naked eye about 10 days after initiation. At this stage, 3 leaves will still emerge before the panicle finally emerges. In short-duration varieties, the panicle becomes visible as a white feathery cone 1.0- 1.5 mm long. It occurs first in the main culm and then in tillers where it emerges in uneven pattern.
It can be seen by dissecting the stem. As the panicle continues to develop, the spikelets become
distinguishable. The young panicle increases in size and its upward extension inside the flag leaf sheath causes the leaf sheath bulge. This bulging of the flag leaf sheath is called booting. Booting is most likely to occur first in the main culm. At booting, senescence (aging and dying) of leaves and nonbearing tillers are noticeable at the base of the plant .
• Stage 5 - Heading: Heading is marked by the emergence of the panicle tip from the flag leaf
sheath. The panicle continues to emerge until it partially or completely protrudes from the sheath
.
• Stage 6 - Flowering: It begins when anthers protrude from the spikelet and then fertilization takes place. At flowering, the florets open, the anthers protrude from the flower glumes because of stamen elongation, and the pollen is shed. The florets then close. The pollen falls on the pistil, thereby fertilizing the egg. The pistil is the feathery structure through which the pollen tube of the germinating pollen (round, dark structures in this illustration) will extend into the ovary. The flowering process continues until most of the spikelets in the panicle are in bloom. From left to right, this frame shows anthesis or flowering at the top of the panicle, 1st day after heading; anthesis at the middle of the panicle, 2nd day after heading; anthesis at the lower third of the panicle, 3rd day after heading.Flowering occurs a day after heading. Generally, the florets open in the morning. It takes about 7 days for all spikelets in a panicle to open. At flowering, 3-5 leaves are still active.The tillers of this rice plant have been separated at the start of flowering and grouped into bearing and non bearing tillers
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