The rice plant is an annual seed plant which is cultivated for its edible seeds. It belongs to the grass family, Gramineae, and has the characteristics of the grass species such as long and narrow leaves, shoots with swollen nodes and small flowers. Growth cycle of rice The growth cycle of the rice plant starts with the seed. The growth duration of a rice plant depends on the variety of the rice plant and the environment. It usually lasts for about 3-6 months. During this growth period the rice plant passes through three distinctive phases: vegetative phase, reproductive phase and ripening phase.
The vegetative phase In the vegetative phase the seed that is sown sprouts into a seedling. This phase can be subdivided into three stages: germination, early seedling growth and tillering or stem development. During this phase the seed germinates with the roots growing downwards into the soil and the seedling appearing above the ground. Leaves begin to appear at regular intervals and the plant reaches a height of about 3 to 4 ft. In the tillering stage shoots begin to grow from the stem. The reproductive phase
In the reproductive phase there is an elongation of the stem or culm which increases the height of the plant, reduction of tillers, emergence of the last leaf known as the flag leaf followed by booting, heading, and flowering. ( International Rice Research Institute (IRRI), 2007) This phase usually lasts for about 35 days. The plant begins to flower once the flag leaf is produced. It is in this phase that the panicle emerges. Panicle is the topmost shoot of the rice plant and it is this part that produces grains. The reproductive organs of the flowers develop here.
The flower head or the spike as it is commonly known as produces about hundred to hundred and fifty small flowers. As the panicle develops there is a swelling of the sheath of the flag leaf. This swelling is known as the booting stage. In the next stage known as the heading stage, the panicle emerges out of the out of the sheath. This is followed by the flowering stage when the anthers of the spikes present in the panicle come out and shed their pollen. It is at this time that fertilization takes place. Ripening Phase In this phase the rice seeds formed after fertilization ripen. This process lasts for about 30 days.
The ripening phase again has three stages: milky grain stage, dough grain stage and mature grain stage. The color and texture of the grain helps us to identify the stages. In the milky grain stage the rice seed is still in liquid form and white in color and the outer covering of the grain is green in color. In the dough grain stage the liquid hardens a little and is as hard as dough. The color of the outer grain cover is yellow. In the mature grain stage the rice grain is fully developed and hard. The outer covering in this stage is white in color and the grain is completely ripe and ready to be harvested. Conclusion
In conclusion it can be said that the rice plant is an annual seed plant belonging to the grass family. During its life cycle which is less than five months it passes through three growth phases: 1) Vegetative phase when there is increase in plant height, tillering and growth of leaves 2) Reproductive phase when there is elongation of the stem, decrease in tillering, appearance of the flag leaf and flowering 3) Ripening phase in which growth of the grain takes place. References International Rice Research Institute (IRRI), 2007, Frequently asked questions? Retrieved from http://www. irri. org/about/faq. asp on August 13