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3.4.1. Source of food for growth The growth of the coleoptile and subsequent leaves is largely dependent on the seed reserves which are nutrients accumulated in the endosperm. When a seed germinates and grows in the dark, it continues to grow until the tip of the fourth leaf emerges. The seedling grows first by using food from the endosperm of seed. As the seedling gets older, it depends more o..

3.3.4. Temperature Germination involves numerous enzymatically controlled processes of catabolism and anabolism and hence is highly responsive to temperature. The cardinal temperatures-maximum, optimum, minimum- for germination of most crop seeds are essentially those of normal vegetative growth. The maximal and minimal temperatures are those temperatures that just permit germination whereas th..

3.3.3. Air The respiration is sharply accelerated with the start of water uptake in the seed ready for germination. In the seed with high activity and fast gemination rate, the respiration increases with the water absorption. And the oxygen consumption also increases. Germination requires high levels of O2 unless respiration associated with it is by fermentation. Most species respond best to th..

3.3.2. Water Germination starts when the seed absorbs water, starts to swell and the radicle or coleoptile emerges from the geminating embryo. Uptake of water is the first need for gemination. Germination may take two or more days depending upon the incubation temperature and dormancy of the seeds. The Germination process may be subdivided into imbibition, activation, and postgermination. Under..

3.3.1. Germination Germination starts with the growth of embryos. It is defined as the time when the embryo splits the outer membrane of seeds and part of the tissue appears. Another view is that gemination is defined as the time when the normal growth of next generation plants can be established. When the rice seed begins to germinate, the basal part of the lemma swells gradually. The embryo i..

3.2.3. Ripening phase The ripening phase may be subdivided into three stages which are milky grain, dough grain, and mature grain stage. The ripening phase from flowering to maturity lasts for 25 to 35 days regardless of variety. In low temperature areas, ripening may last for 45 to 60 days. Ripening actually stars when the individual grain starts to harden. The rice grain develops after fertil..

3.2.2. Reproductive phase The reproductive phase may be subdivided into three stages which are panicle initiation, internode elongation, and heading stage. The length of the reproductive phase are generally constant for most varieties. The phase is approximately 35 days. The initiation of the panicle primordium at the tip of the growing shoot marks the reproductive phase. Panicle initiation occ..

3.2.1. Vegetative phase The vegetative phase may be subdivided into fore stages which are germination, seedling, transplanting, and tillering stage. The length of vegetative phase deffers according to the varieties.The germination stage starts when the seed absorbs water and starts to swell and the radicle or coleoptile emerges from the gemination. The seedling stage starts at seedling emergenc..

3.1. Life cycle of the rice plant The life cycle of the rice plant begins with the fertilization and subsequent development of the embryonic plant. In rice culture, the life cycle generally starts when the embryonic plant germinates into a seedling. The seedling grows into a mature plant and produces the seeds for the next generation. In the tropics, rice varieties complete their life cycle wit..

2.8. Grain The grain is the ripened overy with the lemma and palea. The rice hull includes the lemma and palea and thier associated structures such as the sterile lemmas, rachilla, and the awn. The dehulled rice grain is called brown rice due to its brownish pericarp.The pericaro which is fibrous and has varied thickness, envelopes the caryopsis. The aleurone layer, which encloses the endosperm..