Plant sensitive

Sinnpflanze,/. sensitive plant, suinreich, a. ingenious witty. 

When an airborne toxic chemical is introduced into a plant conmiunity, some plants will be more affected than others depending on individual tolerances endowed by their genotype, as well as on their phenology, and various modifying microclimatic variables. The sensitive plants or species that are no longer able to compete adequately with the tolerant plants or species will be partially or completely replaced. Some scientists propose that the widespread... 

Higher salt concentrations (enhanced water conductivity) from urban and industrial waste waters result in lower dilution. Salinity limits the distribution of sensitive plant and animal taxa, and triggers the abundance of others. The presence of the shrub Tamarix canariensis has increased in the saline soils of the low flow affected Tablas de Daimiel (Spain), while the once dominant RopM/Ms alba retreated. 

A number of plants can eat insects. These plants are called insectivorous plants. Examples include the Drosera, Dionaeva, Venus-flytrap, pitcher plants, sundew, and blad-derworts. Insectivorous plants are most often found in moist and nutrient-poor habitats. The insects, which the plants trap, provide mineral nutrients. The amazing speeds of electrical impulses are illustrated by the capture of insects by insect-eating plants and during the tropism. Action potentials in the plants not processing motor activity are similar in their characteristics to the action potentials of sensitive plants of the... 

The roots of the sensitive plants of the genus Mimosa are supposed to be psychoactive. I hey are known to contain DMT. 

Tap water is undoubtedly convenient it is clean, usually available whenever you want it, and supplied at high pressure. The provision of this service, however, may come at an unnecessary cost—both financial and environmental. The chlorine in tap water may harm your soil s microbe population and damage sensitive plants. Tap water may also have a high pH (see pp.30-31), making it unsuitable for use on lime-hating plants. 

Stomatal closure was associated with a genetic factor in onion wherein the stomata of sensitive plants did not close. The effect of ozone and PAN on stomatal opening depends on many interacting factors those representing water stress appear to be the most important. Dean related stomatal density to the difference in sensitivity between two tobacco cultivars. Evans and Ting found that maximal sensitivity of bean primary leaves was not associated with changes in stomatal number or leaf resistance. Ozone exposure caused a decrease in relative water content, but no change in resistance. Bean leaf sensitivity seemed more a function of internal activities. 

TABLE 11 20 Response of Most Sensitive Plant Tissue to Ozone Exposures... 

This section deals with published data related to short-term exposures of sensitive plants to ozone and the resulting responses. In most cases, the measure of response is a subjective estimate of visible injury. However, various growth measures have been reported in some research, and correlations between injury and growth measures are often possible (Table 11-3). These acute ozone effects have received sufficient study to permit the construction of preliminary models to relate time, ozone concentration, and plant response for a number of plant species. 

FIGURE 11-6 Ozone concentration vs. duration of exposure required to produce a S% response in three diffinent plant susceptibility groupings. The curves were generated by developing 95% confidence limits around the equations for all plants in each susceptibility grouping from Table 11-25. Qirves a > sensitive plants, b intermediate ants, c > resistant plants. 

L. S. Dochinger (personal communication) was able to predict chlorotic dwarf on seedbed white pine with greater than 90% accuracy. Taylot found that susceptible and resistant tobacco could be identified in seedbeds. Both suggested that, for some sensitive plants, time could be saved by visual screening of transplant beds and the use of only the more resistant members of the population as transplants. 

Plants respond in different ways to pollutant mixtures less than additive, additive, and greater than additive effects have been reported. Mixtures of ozone with sulfur dioxide and of nitrogen dioxide with sulfur dioxide can cause oxidantlike symptoms in some sensitive plants. Mixtures can cause effects below the threshold for either gas, although there is some disagreement here in r ard to ozone. Ratios of mixtures, intermittent exposures, sequential exposures to pollutants, and predisposition by one pollutant to the effects of a second pollutant may all be important in nature, but little research has been done. 

Some effort is needed to explore the feasibility of using plants to monitor the overall biologic activity (or biomass reductions) caused by photochemical oxidants in specific air basins or regions. The response of sensitive plants should be correlated with the response of plants of economic and aesthetic importance. Additional monitoring of multiple pollutants is needed in rural areas. 

Ozone has been shown to initiate many physiological and biochemical changes in sensitive plant species. Decreases in photosynthesis and increases and decreases in respiration have occurred in response to ozonation. The bioenergetic status of mitochondria and chloroplasts is disturbed by ozone. Decreases in oxidative- and photo- phosphorylation have been reported as have increases in adenosine triphosphate and total adenylate content of plant tissue. The variable physiological responses appear to be related to the stage of symptom development at the time of analysis and to the mode of ozone exposure, viz. in vivo and in vitro. 

In concentrations approximating present air quality standards (Table III), O3 or SO2 in combination with NO2 could measurably suppress CO2 uptake rates of sensitive plants if exposed under favorable growing conditions. In the controlled environmental chamber studies, 1-hr exposures to 10 pphm O3 (which is slightly above the primary and secondary standards — i.e., 8 pphm for 1 hr) for example, depressed alfalfa CO2 absorption rates by approximately four percent. Exposures to 15 pphm hr SO2 in combination with an equal amount of NO2 reduced uptake rates by 7 percent. Alfalfa, barley or oat canopies exposed to these pollutants singly required higher concentrations (i.e., 1- to 2-hr treatments with more than 20 pphm SO2 or 40 pphm NO2) to measurably reduce canopy uptake rates. 

Better test methods should be developed to define and ultimately to model and predict the byproducts and degradation products associated with production and use of materials. Basic studies of biochemical effects and of the impact of various chemicals and other adverse effects on the biochemistry of sensitive plant and animal species should be strongly supported. 

Wallace has recently studied the effect of temperature upon the sensitive plant by measuring the angle of movement of the branches. The sensitivity of Mimosa is lost at 60, which is about the coagulation temperature of albumin. The sensitivity also becomes zero at 12.5°, a temperature at which there can be no ice crystals. The temperature of maximum activity was about 40°. Frogs can be made completely insensitive to external influences by putting them in water at 0°, and they are also subject to heat narcosis in very warm water. There is a striking parallelism between plants and animals in their responses to heat and cold coagulation. The... 

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