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Apple rootstocks were grown with either 0.02 ppm Fe (Fe0) or5 ppm (Fe3), to give very chlorotic or dark-green plants. Toinvestigate whether iron can be supplied through leaves insteadof roots the shoots of half the plants in each treatment weredipped periodically in solutions of iron. This prevented chlorosisin Fe0 plants and increased their growth, which did not, however,equal that of Fe3 plants supplied with iron through the roots.Growth of Fe3 plants was reduced by dipping. Iron was not translocated from leaves to roots, although theconcentration in leaves was greatly increased by dipping. Dippingreduced the amount of manganese in Fe0 roots to one-quarterof that in roots of undipped Fe0 plants. Effects of treatmentson nitrogen, potassium, calcium, magnesium, and copper levelsare also described. 相似文献
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Rooted one-year shoots were grown for one season by sprayingtheir roots with nutrient solution. Iron supplied as Fe-EDTAat four concentrations resulted in plants which were respectively(a) severely chlorotic, (b) mildly chlorotic, (c) dark greenand healthy (controls), and (d) dark green but with slight reductionin growth. Severely deficient plants showed 4070 per cent reductionsin growth as measured by fresh weight, shoot length, diameterincrease, leaf area, net assimilation and relative growth-rates.Dry weights were reduced 7080 per cent and of the totaldry-weight increment a greater proportion remained in the leaves,which had a lower dry weight and higher water content per unitarea. However, because the initial old stem formed a greaterproportion of the total dry weight, the leaf area ratio remainedabout 11 per cent lower than in the controls. Severely deficientplants had, per unit of chlorophyll, a higher dry-weight increaseand net assimilation rate than the controls. Mild deficiency caused 1020 per cent reductions in growthand net assimilation rate; the leaf area ratio was normal. Possible mechanisms of the effects of low iron supply are discussed,while the small growth reduction at the highest Fe-EDTA concentrationis attributed to chelate toxicity 相似文献
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Plants of the apple rootstock M.VII were grown for a singleseason by spraying their roots continuously with nutrient solutions:(a) complete, (b) low iron, (c) low magnesium, and (d) low ironand low magnesium. Detailed records were taken throughout theseason of fresh weight, shoot length, diameter, and leaf area,while the fresh and dry weights of component parts were determinedon harvested samples. The leaves of the iron-deficient plants were chlorotic and hada lower dry weight and higher water content per unit area thanthose of the control plants. Growth and net assimilation ratewere both reduced but the distribution of assimilates was similarto that in the controls. Total growth was also markedly reduced by the low-magnesiumtreatment, but the leaf symptoms were different and the plantswere morphologically distinct from the control plants. Verylittle chlorosis occurred, but necrosis and severe defoliation,progressing up the shoot, reduced the leaf area ratio and probablylargely accounted for the low net assimilation rate and relativegrowth rate. The diameter of the shoot was affected much morethan its length and the shoot/root ratio was greatly increased. Plants deficient in both iron and magnesium showed less defoliationthan when magnesium alone was low. More dry matter accumulatedin the old stem and less in the new shoot than would have occurredwith a simple combination of the single deficiencies. 相似文献
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