So how can these factors have an effect on the rate of photosynthesis? Lets start off with the light intensity. When the light intensity is poor, there is a shortage of ATP and NADPH, as these are products from the light dependent reactions. Without these products the light independent reactions can't occur as glycerate 3-phosphate cannot be reduced. Therefore a shortage of these products will limit the rate of photosynthesis. When the carbon dioxide concentration is low, the amount of glycerate 3-phosphate produced is limited as carbon dioxide is needed for its production and therefore the rate of photosynthesis is affected. Finally, many enzymes are involved during the process of photosynthesis. At low temperatures these enzymes work slower. At high temperatures the enzymes no longer work effectively. This affects the rate of the reactions in the Calvin cycle and therefore the rate of photosynthesis will be affected.
Residual insecticide sprays:These products remain on the plant for a period of one week or more (see product label for recommended treatment intervals). Keep in mind that insecticides kill predators and parasitic wasps as well as aphids, and can make aphid problems worse if used carelessly. Avoid spraying insecticides when possible to preserve these natural enemies of aphids, and to maintain a good long-term strategy for aphid management.
Alternatively, we can calculate the global production of humanfood. The annual grain harvest in the early and mid-1980s hasbeen about 1.7 Pg (FAO 1983, USDA 1984), about two-thirds ofwhich (1.1 Pg) is intended for direct human consumption and aboutone-third for livestock feed. The water content of harvestedgrain averages about 20% (Spedding et al. 1981), so the annualamount of dry material produced for human consumption is about0.85 Pg. People also eat nongrain materials, which account forroughly an additional 0.3 Pg in dry material (FAO 1982). Overall,this gives about 1.15 Pg of plant material harvested annually,compared with 0.76 Pg for direct human consumption. Thus, about0.39 Pg (34%) of the human food harvest from plants appears to bewasted or lost to pests or postharvest spoilage. This estimate ishigh but not out of line with other estimates (e.g., FAO 1984).We have not included this lost material in our estimate of theNPP used directly by humans.
As aphids feed, they inject saliva into their host plant which helps digest the sap. The pre-digested sap is sucked up by fine needle-like mouthparts of the aphid. A large portion of this undigested material is excreted through the anus of the aphid, a waste product called honeydew. Honeydew is often described as a "clear, sticky liquid that rains down from trees." It is a sugar rich material that attracts ants, yellowjackets (especially during late summer and fall), and other insects that feed on it. Honeydew will coat bark, leaves, and objects beneath the plant, including car windshields and lawn furniture, leaving a sticky mess.
Let nature takes its course. Typically aphid problems are managed by their natural enemies and diseases. Because of their high reproductive rate and their lack of defenses, aphids are used as a food source by many other insects. They are the “cattle” of the insect world for predators, such as lady bird beetle adults and larvae (Fig. 8), lacewing adults and larvae, and syrphid fly (Fig. 9). They are also attacked by parasitic wasps (Fig. 10). When aphid populations grow quickly it may take a while for the predators and diseases to catch up. These natural control agents eventually will reduce aphid numbers to tolerable levels.
While oxygen is necessary for the process of respiration, glucose plays a crucial role in the diet; and that explains why the photosynthesis is important for all the lifeforms on the planet - including humans.
Several ecologists have attempted to calculate NPP on a globalscale by classifying the earth's land surface into biomes orother functional units and then using a few detailed measurementsof above and below-ground productivity within each biome (Ajtayet al. 1979, Lieth end Whittaker 1975, Whittaker and Likens1973). We use the calculations of Ajtay et al. (1979), whichyield a biomass of 1244 Pg and an annual NPP of 132.1 Pg (Table1), as the basis for our discussion because they classify landuse in detail. Their overall values for terrestrial productivityare nearly identical to those of Olson et al, (1983), but theformer's estimate for forest biomass may be high. Successiverevisions of forest biomass information have yielded decreasingestimates (Brown and Lugo 1984, Olson et al. 1983). Additionally,all the summaries may underestimate the magnitude of belowgroundNPP. For NPP in marine and freshwater ecosystems, we use DeVooys's (1979) estimate of 92.4 Pg (Table 1). The estimate formarine systems may be low because the production of extremelysmall phytoplankton may have been systematically excluded by thewidely used carbon- 14 method (Li et al. 1983).
The excess energy not used up in the chemical reactions isstored as chemical energy in the organic products formed.The rate of photosynthesis is dependent on the followingenvironmental factors: light intensity, temperature, and theavailability of carbon dioxide, water, and certain minerals.
The protein matterincludes some of the enzymes and coenzymes used in the photosyntheticprocess; the lipid portion contains two types of chlorophyll, alongwith other pigments that assist in absorbing light energy.
The action spectrum of photosynthesis is a graph showing the rate of photosynthesis for each wavelength of light. The rate of photosynthesis will not be the same for every wavelength of light. The rate of photosynthesis is the least with green-yellow light (525 nm-625 nm). Red-orange light (625nm-700nm) shows a good rate of photosynthesis however the best rate of photosynthesis is seen with violet-blue light (400nm-525nm).
The reactants of cellular
respiration are the products
of photosynthesis and the
reactants of photosynthesis
are the products of cellular
Most of the energyreleased both by the burning of fossil fuels and by the metabolism ofliving cells is given off as heat and must be replaced by thecontinued input of radiant energy from the Sun.The principal organic products of plant photosynthesis arecarbohydrates.