Plant Growth and Development Test - 7

Cytokinin is added to culture medium to induce cell division and cell differentiation. If cytokine is not added to culture medium, there will be very little growth in culture.

If tobacco pith is cultured with minimal nutritive medium with more cytokinin than Auxin. The callus formation will take place, the callus develops buds first due to presence of excess of cytokinin.

Plant hormone 2 : 4-D and 2 : 4 :5 T have ability to kills the weeds in the crop field. Weeds are unwanted plants that grows along with crop plants and compete with crop for nutrient and water.

The major precursor of Auxin is most likely the amino acid Tryptophan.

However the tryptophan is possibly derived from the shikimic acid pathway.

Numerous enzymes would be utilized for Auxin alone. the ultimate precurser depends on how far you want to follow the production back.

The response of plants to periods of day/night is termed photoperiodism. The site of perception of light/dark duration is the leaves.

short-day (i.e.long-night) plants flower as days grow shorter (and nights grow longer) after 21 June in the northern hemisphere, which is during summer or fall.

Short-day plants flower when the night lengths exceed their critical photoperiod. They cannot flower under short nights or if a pulse of artificial light is shone on the plant for several minutes during the night; they require a continuous period of darkness before floral development can begin.

There are plants for which flowering is either quantitatively or qualitatively dependent on exposure to low temperature. This phenomenon is termed vernalisation.

A plant that requires a long period of darkness, is termed a "short day" (long night) plant. Short-day plants form flowers only when day length is less than about 12 hours. Many spring and fall flowering plants are short day plants,

In 1920, W. W. Garner and H. A. Allard published their discoveries on photoperiodism and felt it was the length of daylight that was critical, but it was later discovered that the length of the night was the controlling factor