Plant protection

Companies usually include in the charge for overhead the following items operating supphes, supervision, indirect payroll expenses, plant protection, plant office, general plant overhead, and control laboratory. This overhead charge is frequently taken as an equivalent percentage of the direc t labor cost. 

The total synthesis of caryophyllene and its Z-isomer involved a photochemical [2 + 2] cycloaddition reaction to generate the 4-membered ring and a fragmentation process Helv. Chim. Acta, 1951, 34, 2338) to establish the 9-membered ring. Caryophyllene and various oxygenated derivatives protect plants against insects. 

Because of their generally poor resistance to solvents, acids, alkalis and other corrosive agents, paints are not normally used to protect plant internals handling anything... 

We begin our exploration of delocalized bonds with ozone, O3. As described in Chapter 7, ozone in the upper stratosphere protects plants and animals from hazardous ultraviolet radiation. Ozone has 18 valence electrons and a Lewis stmcture that appears in Figure 10-36a. Experimental measurements show that ozone is a bent molecule with a bond angle of 118°. 

VII. DO MYCORRHIZAL FUNGI PROTECT PLANTS FROM HEAVY METALS ... 

Babkina E.I. Kontrol za zagryaznyeniyem pochv (Monitoring Soil Contamination) / / Zash-chita rasteniy (Protecting Plants). 1990. Issue 12. P. 7-8. 

Another field of research is the possibility offered by phytochemicals in protecting plants against diseases and pathogens (fungus, bacteria and nematodes). Numerous studies have suggested that plant-pathogen interactions are partially mediated via plant secondary metabolite production, despite the inconsistency revealed by some works on the ability of particular compounds to provide resistance to a specific pathogen. 

Phytochemicals or phytonutrients are bioactive substances that can be found in foods derived from plants and are not essential for life the human body is not able to produce them. Recently, some of their characteristics, mainly their antioxidant capacity, have given rise to research related to their protective properties on health and the mechanisms of action involved. Flavonoids are a diverse group of phenolic phytochemicals (Fig. 6.1) that are natural pigments. One function of flavonoids is to protect plants from oxidative stress, such as ultraviolet rays, environmental pollution, and chemical substances. Other relevant biological roles of these pigments are discussed in other chapters of this book. 

Bordeaux mixture for the first week. After 4 weeks the effectiveness of Bordeaux mixture decreased somewhat, but for practical purposes the other compounds had almost completely lost the ability to protect plants against the disease. It appears then that there are fungicides as effective as Bordeaux mixture, but none have the residual capacity of this mixture. Perenox (copper oxide), zinc coposil, and cupro-cide (cuprocisoxide), with and without stickers, have also been evaluated. Perenox alone at the concentration of 2 pounds per 100 gallons of water proved to be as effective as 1% Bordeaux mixture. The other two were ineffective. 

Caryophyllenes are a class of sesquiterpenes that protect plants against insects, and have a quite unusual structure a four membered-ring fused to a medium-sized ring of nine carbon atoms. There are two isomers which only differ in the configuration of an endocyclic double bond the so-called a-caryophyllene ( -isomer) (la) and the corresponding (Z)-isomer the P- or isocaryophyllene (lb). 

Some plants will need protection to survive the winter. Move tender plants under cover, or protect plants with fleece. Wrap up pots, too, so that neither the pot nor the plant roots freeze. 

The major phytotoxic components of the photochemical oxidant system, discussed in Chapter 11, are ozone and peroxyacetylnitrate (PAN), but there is indirect evidence that other phytotoxicants are present. Con siderable effort has gone into controlled exposures to ozone and into field studies. Leaf stomata are the principal sites for ozone and PAN entry into plant tissue. Closed stomata will protect plants from these oxidants. Both ozone and PAN may interfere with various oxidative reactions within plant cells. Membrane sulfhydryl groups and unsaturated lipid components may be primary targets of oxidants. Young leaf tissue is more sensitive to PAN newly expanding and maturing tissue is most sensitive to ozone. Light is required before plant tissue will respond to PAN that is not the case with ozone. 

There have been three main approaches to protecting plants from air pollution. Several researchers are including pollutant stress in standard breeding programs and thus are breeding for tolerance. Interim measures involve the use of chemical sprays. Such sprays are not now economically feasible but they are being tested, and some are protective. Cultural and land-use practices may also be used to control pollution effects, especially on a short-term basis. 

Koiwai, A., and T. Kisaki. Mixed function oxidase inhibitors protect plants from ozone injury. Agric. Biol. Chem. 37 2449-2450, 1973. 

Most research workers are now convinced that pollution abatement will have little impact on overall pollution concentrations until dean energy forms are developed and in widespread use. Because phytotoxic concentrations of ozone and other oxidants are inevitable for the foreseeable future, researchers are seriously considering other means of protecting plants from Injurious effects of oxidants. 

Larkin injected several peroxidases at 0.1-10 ppm into one-half of a tobacco leaf and found some protection. He suggested that peroxidase, which is often associated with plant stress conditions, may be important in physiologic resistance. It is doubtful that any one mechanism of action exists. It is important that we understand the mechanism of ozone injury and resistance in plants, so that we can determine better what chemicals may play a role in protecting plants against oxidants. 

Rich, S., R. Ames, and J. W. Zukel. 1,4-Oxathin derivatives protect plants against ozone. Plant Dis. Rep. 58 162-164, 1974. 

Rich. S.. and G. S. Taylor. Antiozonants to protect plants from ozone damage. Science 132 150-151, 1960. 

Condensed or catechin tannins (catechol tannins. Fig. 11.3) are the most common tannins in vascular plants, occurring in three quarters of gym-nosperms and over half of the angiosperms. They are unbranched, linear polymers of flavonoid compounds (flavan-3-ols), linked through acid-labile carbon-carbon bonds. Condensed tannins may protect plant cell walls against microbial attack and so may affect microbial fermentation of plant cell walls in herbivores. 

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