Leaves damage

Principle Chlorophyll fluorescence is a sensitive and early indicator of damage to photosynthesis and to the physiology of the plant resulting from the effect of allelochemicals, which directly or indirectly affects the function of photosystem II (Bolhar-Nordenkemf et ah, 1989, Krause and Weiss 1991). This approach is convenient for a photosynthesis analysis in situ and in vivo and quick detection of otherwise invisible leaf damage. The photosynthetic plant efficiency was measured using the method of induced chlorophyll fluorescence kinetics of photosystem II [Fo, non-variable fluorescence Fm, maximum fluorescence Fv=Fm-Fo, variable fluorescence t /2, half the time required to reach maximum fluorescence from Fo to Fm and photosynthetic efficiency Fv/Fm]. 

Tip-over of plants Discolors fruit Disfigures fruit Discolors green fruit Discolors green fruit Leaf damage Leaf damage Leaf damage Infects ripe fruit Vector of bunchy-top... 

Many eaterpillars (here of a sawfly), adult beetles and their grubs, and of eourse slugs and snails, graze on leaves and sometimes stems. Other larvae mine or tunnel leaves. Leaf damage reduees the area where photosynthesis operates, sapping the plant s strength and redueing fruit set. 

Brennan, E. G., I. A. Leone, and R. H. Daines. Atmospheric aldehydes related to petunia leaf damage. Science 143 818-820, 1964. 

Chlorophyll levels and net photosynthetic rates were significantly lower than those grown in 0.41-0.81 mg B/L solutions (3) Leaf damage evident lower chlorophyll levels and lower net photosynthetic rate than 0.4 and 0.8 mg B/L groups (3)... 

By June 11 all of the field load Insects had died or left the trees. Leaf damage to the test trees when measured on June 3 was relatively light. Leaves exhibiting noticeable damage averaged 27.6 i 2.1% (S.E.) for the control trees and 49.0 i 4.7% for test trees (p < 0.01, one-tailed paired t test). Estimated leaf area loss averaged 2.5 + 0.2% for controls and 11.3 i 2.1% for test trees (p < 0.005, one-tailed paired t test). Damage to control trees was due to unidentified insects other than tent caterpillars. 

Table 2.2. The effect of leaf damage on extrafloral nectar production... 

Landolt, P. J. (1993). Effects of host plant leaf damage on cabbage-looper moth attraction and oviposition. Entomologia Experimentalis etApplicata 67 79-85. 

In plants, the meristematic tissues in general are particularly rich in potassium, as are other metabolically active regions, such as buds, young leaves, and ioot tips. Potassium deficiency may produce both gross and microscopic changes in the structure of plants. Effects of deficiency reported include leaf damage, high or low water content of leaves, decreased photosynthesis, disturbed carbohydrate metabolism, low protein content and other abnormalities. 

In foliage, the concentrations of serine proteinase inhibitors are lower than that in seeds however, the induction of serine proteinase inhibitors has been reported in many plants including tobacco and tomato, and the inhibitors have been proven to function as a plant defense system.79-81 Leaf damage by the tobacco hornworm Manduca sexta was much bigger in tomato plant line deficient in proteinase inhibitor induction than in those that can induce proteinase inhibitor on herbivory.82... 

The timing and location of the emission of HIPVs from com plants have been studied by chemical analysis.135-137 Immediately after leaf damage, the com plant releases several typical octadecanoid-derived GLVs from the damaged leaf Additionally, elicitors in the herbivore s oral secretions induce a systemic release of volatiles that are mainly composed of terpenoids but also include some phenolics, such as indole and methyl salicylate. 

Look for evidence of leaf damage by other herbivorous insects count leaf holes, notches at leaf edges. 

The correlation between nicotine accumulation and its defensive role in M sylvestris has been convincingly demonstrated. Increased alkaloid production may also be demonstrated by true herbivory. Tobacco plants subjected to leaf damage showed a fourfold increase in the alkaloid content of their undamaged leaves. This resulted from increased alkaloid synthesis and, as a result, a tenfold increase in alkaloids in the xylem. Experimental evidence has indicated that alkaloid induction maybe triggered by a phloem-translocated signal (Hartmann, 1991 and references therein). 

Symptoms Leaf damage starts as small yellow spots that gradually turn brown they are often surrounded by a ring of yellow or brownish black tissue. Whole leaves may turn yellow and drop, exposing fruit to sun, which may result in sunscald. This disease usually starts on lower leaves and progresses upward. 

Symptoms Symptoms of cold injury can be very similar to the symptoms of sunscald blotchy, water-soaked areas on leaves. Shoot tips often die back. For other information on leaf damage, see Winter Injury" on page 380. 

Nicotine, C10H14N2, is a highly toxic, pale yellow alkaloid produced in tobacco plants in response to leaf damage. Nicotine is synthesized in the roots of tobacco plants in response to hormones released by damaged tissue, and it is then carried to the leaves, where it is stored in concentrations of between 2 percent and 8 percent by weight. Nicotine is used commercially as an insecticide (it is one of the few poisons to which insects have not become resistant). Tobacco smoke contains nicotine, believed to be the active (and addictive) ingredient. 

Specific symptoms of sodium excess are not known. High levels of sodium reduced calcium uptake in some cases (Leh 1973). Citrus and stone fruit species are particularly susceptible to salt damage. The leaf damage sometimes starts with chlorotic blotches, which are followed by necrotic lesions at the leaf tips and margins or between the veins. The leaves of lucerne growing on saline soils turn reddish, and the leafstalks collapse, possibly indicating calcium deficiency (Bergmann 1992). 

In hybrid poplar and trembling aspen, leaf damage by wounding or herbivory induces polyphenol oxidase activity (PPO EC 1.10.3.2). This enzyme can... 

Discrimination and generalization of leaf damage by blue jays (Cyanocitta cristata), Anim. Learn. Behav., 12 202. 

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