Phenology. Growth stages :

      Phenology is the study of events of lifecycle in plants and is influenced by physical actors like season, climate, soil, topography, etc.

                The entire lifecycle of a rice plant can be divided into three main phases:

Germination to emergence: 1^st leaf appears 3 DAS.

a) Vegetative phase: seed germination to panicle initiation, 60-70 DAS.

b) Reproductive phase: panicle initiation to flowering, 35 DAS.

c) Ripening phase: Flowering to full maturity, 30 DAS.

a) Vegetative phase (seed germination to panicle initiation ) 60-70 DAS

I) seedling stage :

• Leaf develops at the rate of one per 3-4 days.
• Upto the 5-leaf stage, the seedling becomes autotrophic.

ii) Transplating phase :

• Found only in transplanted rice but not in DSR.
• 20-25 days old seedlings are ready for transplanting
• Transplanting shock up to 5-10 days for development of secondary roots.

iii) Tillering stage :

• 35-40 DAS
• First tiller to maximum tillering stage
• up to tertiary tillers
• Some tiller dies and only effective tillers remain.

b) Reproductive phase (panicle initiation to flowering ) 35 days :

I) Panicle initiation stage: Flower primordium initiation at the tip of the growing shoot.

ii) Bolting stage :

• Also known as stem elongation or internode elongation stage.
• Production of auxin accelerates the growth of internodes.
• Panicle causes bulging in the leaf sheath.

iii) Heading stage :

• Also known as the panicle emergence stage.
• Panicle tip energizes out of the flag leaf sheath.
• Occurs 15 days after booting.

iv) Flowering stage :

• occurs 25 days after booting and 5 days after heading
• Lodicules become turgid pushing lemma and palea apart, thus opening the flower (anthesis) out for pollination
• After pollination, lemma and palea are closed.
• Pollination is followed by fertilization.

c) Ripening phase (flowering to full maturity), 25-30 DAS :

I) Milky stage :

• The content of caryopsis is first watery but later turns into white milky fluid which can be squeezed out.

ii) Dough stage :

• 2-3 week duration
• soft dough: 5-7 days
• hard dough: 5-7 days
• Greenish tint

iii) Maturity stage :

• Physiological maturity: max. Dry matter accumulation in the seed, and 80n % of grains in the panicle are matured.
• Harvesting maturity: Moisture content of the seed is reduced, and 90 % of grains in the panicle are matured.