Tag: plant growth and development

Phytochrome is responsible for absorption of red and far red light it is involved in red-far red light interconversion. Phytochrome is a photoreceptor, a pigment that plants use to detect light. It is sensitive to light in the red and far red region of the visible spectrum.

Photoblastic seeds require wavelength in the range of 660nm for the germination of seeds. Out of the two forms of phytochrome, Pr form absorbs light of 660nm wavelngth. It stimulates germination.

Seed germination requires sufficient amount of P$ _pr$fr. P$ _r$ is synthesized by germinating seeds and is converted to P$ _pr$ when exposed to red light. However, when  seeds are exposed to far-red light, they will not germinate as P$ _r$ is converted to P$ _r$.

Rate of plant growth and development depend upon various factors including temperature surrounding the plant. Each plant has a specific temperature range for optimum growth. The temperature affects plant growth processes such as photosynthesis, respiration, transpiration, protein synthesis, etc. In general, temperature range for plant growth is 0$^o$C to 35$^o$C. However, optimal day and night temperature range varies for plant growth.

In chloroplasts, the main pigment present is chlorophyll which is green in color. Growth of plant is affected by the different wavelengths of light as pigments in chloroplasts absorb different wavelengths of light for photosynthesis. White light is a mixture of many wavelengths of colors. Chlorophyll will absorb energies from all visible light except green. Hence exposing white light to a green plants will result in the fastest rate of photosynthesis which in turn result in fastest growth. Hence, optimum growth occurs in white light followed by blue or red.

A carbon-to-nitrogen ratio is a ratio of carbon to the nitrogen in a plant. In general, a high C/N ratio produces a high acid content and low methane production. In plants young tissues have less C/N ratio. Plants with high C/N ratio have more mechanical tissues and larger root system.

Photosynthesis requires light between 400 and 700 nm. Blue light promotes vegetative growth. Red and far-red promotes stem elongation. Red and blue light promotes flowering. Photoperiodism is best seen in red light as chlorophyll strongly absorbs red light and carries out photosynthesis. Hence, red light stimulates plant growth.