Plant deficiencies

Why do the leaves of plants deficient in nitrogen turn yellow Consider the structure of the porphyrin ring shown in Figure 15-6. 

Potassium is lequiied by both plants and animals Although the total amount of potassium in most soils is usually rather high, the level of available or soluble forms of the element is frequently too low to meet the needs of growing plants. Deficiencies of plant-available potassium are more frequent in the soils of the eastern rather than of the western United States. See also Soil. Potassium in the form of soluble potassium salts is a very common constituent of fertilizers. See also Fertilizer. 

The use of chemical extractants for the assessment or prediction of agricultural crop plant contents, plant growth or health and the estimation of the likelihood of plant or animal (consuming the fodder plant) deficiency or toxicity has been a major topic of study in agricultural laboratories for almost half a century, although... 

The total content of the major elements in soil is of little practical significance since only a tiny, soluble fraction is available for absorption by plant roots (West, 1981 Tinker, 1986). To some extent this is less true for trace elements and micronutrients where for example, analyses of total copper or zinc can be used to assess the likelihood of plant deficiencies or toxicities. Nonetheless, for an element to be bioavailable it has to be relatively soluble. 

It is generally believed that in condition where herbivory is regularly expected, constitutive defense is more adaptive, whereas in condition where herbivory is expected only once in a while, it is better for plants to produce defense substances when plants are damaged by herbivory, and when there are no herbivores, it is better to invest resource to plant growth rather than defense. This idea is supported by field experiments using plant disabled to induce defense substance by gene modification techniques, and comparing seed production between plant deficient in induction and the control type.123... 

A debranching enzyme called isoamylase is involved in synthesis of the starch granule and its polysaccharide components (34-37). Mutant plants deficient in isoamylase activity accumulate a soluble a-glucan designated phytoglycogen (3, 37, 38) and little starch. 

In addition to problems outlined in the cabbage entry, a combination of cold injury and viral disease can cause leaves with black specks. Destroy infected plants. Caterpillars will bore small holes into sprouts see Leaves with large, ragged holes on page 56 for more details and controls. Plants deficient in potassium have poorly developed sprouts Spray with seaweed extract at transplanting and repeat several times to prevent problems. Check potassium levels with a soil test, and amend as necessary. 

Some misinterpretations of the NBO performances still occur in the literature. For instance, 5-hydroxyguaiacyl (5-OH-G) units have been tentatively searched for among the NBO products recovered from transgenic tobacco plants deficient in caffeic acid 0-methyltransferase (COMT) activity [31], Studies on COMT-deficient bm3 maize line [32] have shown that the labile 5-OH-G units cannot survive NBO. This situation was anticipated in the pioneering studies of Kuc and Nelson [33], in which they suspected the occurrence of additional as yet undetected lignin units . By contrast and as explained in the next section, thioacidolysis provides an easy determination of 5-OH-G units in native or industrial lignins. 

Speculate about why plants deficient In Dicer activity show Increased sensitivity to Infection by RNA viruses. 

The micronutrients of major interest to soil chemistry because of plant deficiencies are boron, manganese, iron, cobalt, copper, zinc, and molybdenum. Other ions— chromium, nickel, cadmium, mercury, and lead—behave similarly in soils but the problems are usually plant toxicity. The availability of most of the micronutrient and toxic ions increases with increasing soil acidity. Those present as anions—-molybdenum, chromium, and boron—differ in that their availability generally decreases with increasing acidity. 

Acid conditions, like the presence of acid rain in the region, promote the solubility of copper ores or metal. Alkaline conditions tend to precipitate copper and may lead to deficiency of the metal in plants. Similarly, if the soil is excessively acid, the solubilized copper salts may leach out and also lead to metal deficiency. Evidently, soil deficiency of copper can lead to plant deficiency which may prove lethal to susceptible animals. 

Plants deficient in manganese accumulate elevated amounts of nitrate and nitrite, which disrupt protein production. On the other hand, manganese excess disrupts carbohydrate metabolism (Bergmann 1992). 

Zinc Deficiency in Plants The role of zinc in plants has been summarized by the NRC (1979). Because zinc is not readily translocated within the plant, deficiency symptoms first appear on younger leaves. Plant tissues containing < 20 mg Zn kg dry weight are often zinc-deficient (Kabata-Pendias and Pendias 1994, Vitosh etal. 1994). Due to impaired internode growth, disorders caused by zinc deficiency (Sauchelli 1969) result in a rosette condition... 

Plants deficient in sulfur are smaller than normally developed plants. If the deficiency occurs at an earlier stage, the plants are stunted and have a rigid, erect appearance. Some sulfur-deficiency symptoms observed in, for example, the Dark Yellow Fuji Mefo chrysanthemum, included branchless roots that aged earlier, shorter stems, smaller leaves and overall yellowing of new leaves. Without sulfur, plants did not produce flowers suitable for commercial sale (Huang et al. 1997). 

Although only very small amounts of Mo are required by plants, deficiencies of Mo have been reported from around the world for more than 40 higher plant species (Adriano, 1986). Those deficiencies commonly are corrected by raising the soil pH by addition of lime (Gupta and Lipsett, 1981). Soils commonly deficient in Mo include the following highly podzolized soils, because of either low total Mo or sequestering of Mo by oxyhydroxides extensively weathered soils, in which secondary minerals may fix Mo soils with pH values below 6, in which the Mo is unavailable sandy, well-drained soils, in which the total Mo content is low (Severson and Shacklette, 1988). 

Chaney, R.L., Giordano, P.M., 1977. Microelements as related to plant deficiencies and toxicities. In Elliot, L.F., Stevenson, F.J. (Eds.), Soils for the Management of Organic Wastes and Waste Waters. SSSA. Madison, WI, pp. 235-279. 

Another characteristic of mineral-deficient plants is the increase in nonprotein amino acids and other nitrogenous compounds which are usually present at very low concentrations or are not detectable. The most studied of these compounds is the diamine, putrescine. An accumulation of putrescine in the leaves of higher plants deficient in K was first observed in barley (Richards and Coleman, 1952) and it has subsequently been shown to accumulate in K-deficient plants of many species (Coleman and Richards, 1956 Smith, 1963, 1%9, 1970). Putrescine also accumulates under conditions of Mg deficiency (Smith, 1970, 1973 Basso and Smith, 1974), although the increase in barley (fourfold) was less than that (13-fold) in K-deficient plants. 

All this is understandable, if not condonable. However, it is necessary to remember that it is better to resolve plant deficiencies earlier rather than later. After many years of heated discussions with designers, it is easy to hear sentences like this one You made us suffer a great deal, but you were right . 

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