Plants, growth

Plants grow by converting sugars produced by photosynthesis into other carbohydrates that are sturdy and structurally robust. The rate of plant growth therefore depends on the rate at which sugars can be formed through photosynthesis. 

The basic metabolic pathway for photosynthetic sugar formation is called the Calvin cycle carbon dioxide is enzymatically added to an acceptor molecule and then converted into two 3-carbon sugar molecules with the help of photochemically generated ATP and NADPH (Tiaz and Zeiger, 1998). Plants that use this mechanism exclusively are called C3 plants. 

Some plants possess an additional metabolic pathway to concentrate carbon dioxide before it enters the Calvin cycle. These are called C4 plants because of the 4-carbon molecules that are formed as intermediates. C4 plants comprise about 1% of plant species and 5% of the Earth s plant biomass. They have higher photosynthetic efficiency than do C3 plants. C4 plants are found in habitats with high daytime temperatures and intense sunlight. They also have an advantage in dry climates because their leaf stomata do not have to be as open to admit CO2 as those for C3 plants. Open stomata allow loss of water to the atmosphere. 

The C4 pathway seans to have evolved many times as an example of convergent evolution. Thus, there are few gross physical features distinguishing C4 plants from C3 plants. A few examples of C4 plants are 

The top group isolates the C4 pathways in different portions of their leaves the bottom group separates the C4 pathways in time. 

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C12H20O4. M.p. 165°C. A plant growth hormone, which is produced in damaged plant tissue, and on diffusing into adjacent intact tissue cells stimulates them to divide. Traumatic acid has been isolated from the pods of green beans. 

The greatest demand for potash has been in its use for fertilizers. Potassium is an essential constituent for plant growth and is found in most soils. 

Recently, however, new interest has developed due to their chemotherapeutic and bacteriostatic usefulness in animal husbandry. They also have been patented as herbicides and plant-growth-regulating agents. 

COLORANTSFORFOOD,DRUGS,COSTffiTICSANDTffiDICALDEVICES] (Void) -plant growth regulators for [GROWTH REGULATIONS - PLANT] (Vol 12)... 

Growth rate dispersion Growth regulator, plant Growth regulators... 

Plant growth regulators Plant gum exudates Plant layout... 

At atmospheric pressure and at its melting point, urea decomposes to ammonia, biuret (1), cyanuric acid (qv) (2), ammelide (3), and triuret (4). Biuret is the main and least desirable by-product present in commercial urea. An excessive amount (>wt%) of biuret in fertiliser-grade urea is detrimental to plant growth. 

Environmental impact studies on NE have been performed. Although undiluted NE inhibits seed growth, no effect on plant growth was observed when exposed to 6, 000 ppm-min of NE and only minor effects were observed at the 60, 000 ppm-min exposure level (41). Exposure of microbial populations to 25% NE in air for seven hours showed normal growth. NE is not an o2one-depleting gas (20). 

The ideal plant growth regulator should leave no harmful persistent residue in a finished product or crop and the paradigm compounds are ones that have high specific activity, are target specific, and are environmentally biodegradable. 

Fig. 2. Natural product derivative plant growth regulators. See Table 1.

Ethylene. Ethylene [74-85-1/, (7) is considered to be one of the principal plant growth regulators in the natural products family. However,... 

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