Phytochrome Manipulation:- Growing Cannabis quicker

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. Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. It also regulates other responses including the germination of seeds, elongation of seedlings, the size, shape and number of leaves, the synthesis of chlorophyll, and the straightening of the epicotyl or hypocotyl hook of dicot seedlings. It is found in the leaves of most plants. Phytochromes are characterised by a red/far-red photochromicity. Photochromic pigments change their "colour" (spectral absorbance properties) upon light absorption. In the case of phytochrome the ground state is Pr, the r indicating that it absorbs red light particularly strongly. The absorbance maximum is a sharp peak 650–670 nm, so concentrated phytochrome solutions look turquoise-blue to the human eye. But once a red photon has been absorbed, the pigment undergoes a rapid conformational change to form the Pfr state. Here fr indicates that now not red but far-red (also called "near infra-red"; 705–740 nm) is preferentially absorbed. This shift in absorbance is apparent to the human eye as a slightly more greenish colour. When Pfr absorbs far-red light it is converted back to Pr. Hence, red light makes Pfr, far-red light makes Pr. In plants at least Pfr is the physiologically active or "signalling" state. Using a light in the 650-670nm range will put the phytochrome into it's signalling state (or for our particular plant it will keep the plant in veg.) Even if you gave a plant 12/12 if you had a 660nm light source of suitable intensity the plant would stay in veg mode. The intensity of light needed to keep in veg especially since the change of state from Pr to Pfr is near instantaneous means that pulsing a low wattage 660nm light will extend the day for minimal electricity costs. How useful to a ganja grower is debatable but you could start plants in a conservatory in March and use this to extend the day. normal cfl's contain enough 660nm to work no special lamps are needed. This is extremely useful for other crops though. Phototropism is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth and response to a light stimulus.

The Growth and functioning of leaves, proceedings of a symposium held prior to the thirteenth International Botanical Congress at the University of Sydney, 18-20 August 1981

Developmental regulation of plant gene expression

Life, The Science of Biology

Biology of plants

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