Vegetation and Crops

The effects of air pollution on plants range from subtle to catastrophic, as shown in Fig. 8-1. Historically, these effects have been classified as 

Other forms of visible injury are related to various physiological alterations. Air pollution injury can cause early senescence or leaf drop. Stems and leaf structure may be elongated or misshapen. Ornamentals and fruit trees can also show visible injury to the blooms of the fruit, which can result in decreased yield. 

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

Physiological or biochemical changes have been observed in plants exposed to air pollutants, including alterations in net photosynthesis, stomate response, and metabolic activity. Such exposure studies have been conducted under controlled laboratory conditions. An understanding of the processes involved will help to identify the cause of reduction in yield. 

Laboratory studies have also investigated the interaction of air pollutants and the reproductive cycle of certain plants. Subtle changes in reproduction in a few susceptible species can render them unable to survive and prosper in a given ecosystem. 

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Extraction efficiency. The efficiency of extractions of imidacloprid from vegetables and crops decreases in the order acetonitrile > acetone > ethyl acetate. Acetonitrile is not a suitable extraction solvent because of the large number of co-eluting peaks on the chromatograms on HPLC at 210 or 270 nm. ... 

Spinach absorbed higher amounts of U than other vegetables and crops did, in spite of the fact that the U availability in the soil was low. The uptake of U by spinach from soil can be accompanied by the uptake of other elements that are also insoluble in soils. In order to compare U and other trace elements taken up by spinach tissues, concentrations of Mg, Al, Ca, Fe, Cu and Zn in acid digests of spinach samples were analysed by inductively coupled plasma optical emission spectrometry (VistaPro, Varian). 

As gardeners, we are most likely to notice the pest insects in our yards and gardens. However, entomologists estimate that more than 90 percent of all insects are beneficial. Wild and domestic bees and also some flies and moths pollinate crops this is essential for the development of many fruits, vegetables, and crops grown for seed. Honeybees are also farmed to provide honey, and silkworms are farmed to yield silk from their cocoons for fine clothing. 

FIGURE 4 Comparison of observed and modeled ecosystem discrimination estimates for natural vegetation and crop systems. Observed A, values were calculated using Eq. 3 (see Appendix) modeled values were estimated using BIOME3.5. 

Carbamate pesticides are used extensively to control pests and fungus in lawns, gardens, and agriculture to protect fruits, vegetables, and crops. These compounds are esters of carbamic acid and their general structure, as well as, the structures of selected compounds of this class are shown below. 

Vegetation and crop samples are treated for subsequent purification by removing the bulk of the matrix—typically 99%—in oven drying and ashing. After dissolving the ash with mineral acid, a minor residue of insoluble silica can be volatilized by boiling with HNO3-HF solution. 

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