. Botany, with agricultural applications. Botany. FACTORS INFLUENCING PHOTOSYNTHESIS 259 combustion, and all oxidation processes in maintaining the supply of carbon dioxide for photosynthesis. Roughly estimated, 150 square meters of leaf area will use up in one summer all of the carbon dioxide which an average man produces through respira- tion in one year. When one considers that the amount of carbon dioxide in the air is only about per cent, that is, about 3 parts in 10,000 parts of air, it is surpris- ing that plants can make sugar as rapidly as they do. Sometimes, as around cities wit
. Botany, with agricultural applications. Botany. FACTORS INFLUENCING PHOTOSYNTHESIS 259 combustion, and all oxidation processes in maintaining the supply of carbon dioxide for photosynthesis. Roughly estimated, 150 square meters of leaf area will use up in one summer all of the carbon dioxide which an average man produces through respira- tion in one year. When one considers that the amount of carbon dioxide in the air is only about per cent, that is, about 3 parts in 10,000 parts of air, it is surpris- ing that plants can make sugar as rapidly as they do. Sometimes, as around cities with many factories, the per cent of carbon dioxide may be a little higher but it is always exceedingly low. Of course carbon dioxide is present in solution in the soil water; but it is easily demonstrated that this carbon dioxide is of practically no help to plants in photosynthesis. To compensate for the limited amount of carbon dioxide, it is obvious that leaves need broad surfaces and a thorough distribution of chlorophyll, so that their absorbing surface may be large. However, with all of these adjust- ments of the plant, it has been demonstrated that the normal supply of carbon dioxide is often insufficient for the maximum showing the effect amount of photosynthesis; for some plants, photosynthesis of dos- when surrounded by air in which the amount of carbon dioxide is increased up to 1 per cent, show a corresponding rise in were closed by covering photosynthetic activity. the epidermis with vase- Since stomata are the openings through line, thus filling the which carbon dioxide enters the leaf, their ^to^^ta and excluding » , , J, J ,, carbon dioxide, number per area oi leaf suriace and the extent to which they are open affect the amount of this gas that reaches the mesophyll. That photosynthesis is inhibited when stomata are closed is demonstrated by the experiment shown in Figure 236. The experiment shows the necessity of keeping the stomata free from dust and other bodi
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbotany, bookyear1920
