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Susan S. Han

Yellowing of excised Easter lily leaves was significantly delayed by foliar application of gibberellic acids (GA3) ≥ 250 mg·1-1 or benzyladenine (BA) ≥ 50 mg·1-1. Rapid development of foliar chlorosis following cold storage was delayed significantly by applying 500 mg·1-1 of GA3 or BA before storage. Post-storage treatments were less effective. Development of chlorosis was associated with rapid loss of fresh weight and was not related to the aperture of the stomates. Respiration rate of leaves treated with growth regulators were significantly lower than that of the controls. Differences in the rate of carbohydrate depletion may explain the striking effects of growth regulators on the development of foliar chlorosis.

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Haytham Z. Zaiter, Dermot P. Coyne, and Ralph B. Clark

Abstract

Dry bean (Phaseolus vulgaris L.) cultivars/lines differed in their iron-deficiency leaf chlorosis response when grown in field trials on a calcareous soil in western Nebraska. The genetic basis of this response was determined. Crosses were made between three susceptible (PI 165078, Navy ‘Tuscola’, and Light Red Kidney ‘Redkloud’) and seven resistant parents (G.N. ‘Valley’, G.N. 1140, G.N. ‘UI 59’, G.N. ‘Emerson’, Pinto EP-1, Pinto ‘Olathe’, and Black Neb-WM1-83-10). The parents, F2, and several F3 progenies were evaluated visually in replicated field trials for leaf iron-deficiency chlorosis. Based on F2 and F3 segregation patterns, it was hypothesized that resistance was controlled by two major complementary dominant genes. The environment also influenced considerably the range in expression of the leaf chlorosis, particularly in the susceptible parents and progenies.

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D.S. Achor and L.G. Albrigo

Permanent chlorosis of leaves on plants fertilized with urea containing high levels of the contaminant biuret has been observed in several crops including citrus. Little has been reported as to the cellular changes that result from such chlorosis. Branches from `Ruby Red' grapefruit (Citrus paradisi Macfadyn) and `Hamlin' orange [C. sinensis (L.) Osbeck] were sprayed with urea solutions containing 1.05% biuret. As visible symptoms developed, leaf tissue samples were prepared for transmission electron microscopy. For comparison purposes, leaves from similar trees showing chlorosis from age-related senescence and Zn deficiency were also sampled. The progressive development of chlorosis in biuret-affected leaves was characterized by: the loss of starch, thylakoidal and granal membranes in chloroplasts along with the enlargement and increase in number of plastoglobuli or lipid bodies. The lipid bodies were liberated alone or in association with membrane vesicles to the cytoplasm and vacuoles. The number and volume of the individual chloroplasts became smaller. Concurrent loss of cytoplasmic content and the enlargement of the vacuolar space were also observed in the biuret affected leaf tissue. Similar findings were observed in the cells of senescent leaves. In cells of leaves showing nutritional deficiency, losses in cytoplasmic content and vacuolar enlargement were observed but there was neither complete loss of thylakoidal or granal membranes nor the release of lipids from the plastids. It was concluded that 1) the cytological characteristics of the biuret-affected samples were more similar to age-related senescent samples than to chlorosis from Zn deficiency and 2) that complete loss of the lipid bodies from the chromoplasts to the cytoplasm and vacuole in the biuret-affected samples and in age-related senescence in citrus leaves was responsible for the permanent nature of the chlorosis.

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Donald F. Schoeneweiss

Abstract

Leaves of chlorotic pin oaks growing in alkaline soil regained normal green color within 30 days following soil injection with solution of FeEDDHA iron chelate [ferric ethylenediamene (di(o-hydroxyphenyl acetate)]. Soil injections using solutions or suspensions of iron sulfate, sulfur, soluble fertilizer, or combinations of these materials were completely ineffective in correcting iron chlorosis. Trees treated with chelated iron remained green throughout two growing seasons following treatment, whereas all other test trees declined steadily and were dead due to severe chlorosis at the end of the second growing season.

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Dario Ramirez and Harvey J. Lang

Two studies were conducted to determine the effect of applied Fe concentration on the occurrence of phylloclade marginal chlorosis in holiday cactus. Schlumbergera sp. `White Christmas', `Twilight Tangerine', `Christmas Charm', and `Lavender Doll' were grown in either solution culture or a peat-based medium and supplied with a nutrient solution containing Fe-EDTA at either 0, 0.18, 0.36, 0.54, or 0.72 mm. Growth decreased while marginal chlorosis increased on all cultivars as Fe-EDTA treatment levels increased. Phylloclade marginal chlorosis developed more severely and consistently in plants grown in peat-based media versus solution culture. Marginal chlorosis and accumulation of Fe in the potting medium occurred very slowly, and first symptoms were not observed until after about 2 months of treatment. Symptomatic phylloclade tissue had a greater Fe concentration than corresponding asymptomatic phylloclade tissue. Cultivars varied in tissue Fe concentration and symptom severity across Fe-EDTA treatments. There were no significant correlations in other tissue micronutrient concentrations with either Fe treatment or symptom development. The pH of either the culture solution or peat-based medium leachate did not change significantly throughout either study, and there were no significant amounts of Fe+2 detected in solution. Chemical name used: ferric ethylenediaminetetraacetic acid, monosodium salt (Fe-EDTA).

Open access

H.Z. Zaiter, D.P. Coyne, and R.B. Clark

Abstract

Two resistant (Great Northern ‘Emerson’ and Neb-WM1-83-10) and two susceptible (PI 165078 and ‘Steuben Yellow Eye’) cultivars/lines of dry bean (Phaseolus vulgaris L.) to iron (Fe) deficiency chlorosis, and their reciprocal graft combinations (two methods) were grown in pots in Tripp sandy clay loam (coarse-silty, mixed, mesic Aridic Haplustoll) known to induce Fe deficiency chlorosis. Experiments were conducted in a growth chamber under low (24°/13°C) and high (29.5°/18.5°) air temperature regimes at 15/9 hr (light/dark) periods. The experimental plan was a split-plot with temperature regimes as main plot and treatments in a completely randomized design with two replications. When scions of entries susceptible to Fe deficiency were grafted onto rootstocks of resistant entries, the leaves of the grafted plants were greener than the ungrafted susceptible entries. In reciprocal combinations, the leaves of scions of the resistant entries became chlorotic. These data indicate that rootstocks of dry beans appear to control chlorosis resistance, presumably due to root uptake or translocation of Fe. The chlorosis was more severe on leaves of cleft-grafted-scions than with approach-grafted-scions and more severe under the low compared to high temperature regimes.

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Katsumi Ohyama, Yoshitaka Omura, and Toyoki Kozai

Providing continuous light (24-h photoperiod) at a relatively low photosynthetic photon flux (PPF) is one possible way to reduce both initial and operational costs for lighting and cooling during transplant production with an artificial light. However, physiological disorders (i.e., chlorosis and necrosis) are often observed in several species under continuous light with a constant temperature. The objective of this study was to find an effective air-temperature regime under the continuous light to avoid such physiological disorders, and simultaneously enhance floral development, using tomato [Lycopersicon esculentum Mill.] as a model. The seedlings with fully expanded cotyledons were grown for 15 d at a PPF of 150 μmol·m–2·s–1, a relative humidity of 70%, and a CO2 concentration of about 380 μmol·mol–1 (atmospheric standard). Leaf chlorosis was observed when the air temperature was constant regardless of average air temperature (16, 22,or 28 °C). Neither leaf chlorosis nor necrosis was observed when the air temperatures were alternated [periods of high (28 °C) and low (16 °C) air temperatures of 16/8, 12/12, and 8/16 h·d–1]. Faster floral development was observed in the seedlings grown at lower average air temperatures. These results indicated that physiological disorders of tomato seedlings grown under continuous light could be avoided, and at the same time floral development could be enhanced, by lowering the average air temperature through modification of the periods of high and low air temperatures.

Open access

D. C. Zeiger and J. E. Shelton

Abstract

‘Red Prince Delicious’ apples/‘M7’ rootstocks, growing in sand culture and receiving ½, 5 or 50 ppm Mn, developed internal bark necrosis (IBN), and an Fe-deficiency chlorosis in its severest expression, at the highest level of Mn supply. Fe was as high in leaves of chlorotic as in those of non-chlorotic plants, but the chlorosis was cleared up by increasing the Fe supply.

Ground twigs showed a brownish coloration which had a max reflectance at 700 mμ. Differences in coloration were correlated with the Mn supply, the severity of IBN symptoms and the Mn/Fe ratio in the leaves and bark, but not with the Mn/Fe ratio in the ground twigs.

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Brandon R. Smith and Lailiang Cheng

`Concord' grapevines (Vitis labruscana Bailey) can readily develop iron deficiency-induced leaf chlorosis when grown on calcareous or high pH soils. Iron (Fe) chelates are often applied to the soil to remedy chlorosis but can vary in their stability and effectiveness at high pH. We transplanted own-rooted 1-year-old `Concord' grapevines into a peat-based medium adjusted to pH 7.5 and fertigated them with 0, 0.5, 1.0, 2.0, or 4mg·L–1 Fe from Fe-EDDHA [ferric ethylenediamine di (o-hydroxyphenylacetic) acid] to determine the effectiveness of this Fe chelate for alleviating Fe deficiency-induced chlorosis at high pH. Vines were sampled midseason for iron, chlorophyll, CO2 assimilation, and photosystem II quantum efficiency (PSII) and at the end of the season for leaf area, dry weight, and cane length. We found that leaf total Fe concentration was similar across all treatments, but active Fe (extracted with 0.1 n HCl) concentration increased as the rate of Fe-EDDHA increased. Chlorophyll concentration increased curvilinearly as applied Fe increased and was highly correlated with active Fe concentration. CO2 assimilation, stomatal conductance, and PSII were very low without any supplemental Fe and increased rapidly in response to Fe application. Total leaf area, foliar dry weight, and cane length all increased as Fe application increased to 1 mg·L–1 Fe, but above this rate, a further increase in Fe did not significantly increase growth. Our results demonstrate that Fe-EDDHA is very effective in alleviating Fe deficiency-induced leaf chlorosis in `Concord' grapevines grown at high pH, which provides a foundation for continuing research related to the optimum rate and timing of application of Fe-EDDHA in `Concord' vineyards on calcareous soils. Compared with total Fe, leaf “active Fe” better indicates the actual Fe status of `Concord' vines.

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Trinidad Reyes, Terril A. Nell, and James E. Barrett

`Tara' and `Boaldi' were fertilized with 150 and 450 ppm from 20N–4.7P–16.6K soluble fertilizer and moved at flowering to postproduction conditions (21 ± 2C and 10 μmol·m–2·s–1). Shipping was simulated for 1 week at 26C. `Tara' exhibited burned leaf margins (necrosis) and chlorosis following shipping. At 150 ppm, leaves had brown, dried margins, but the damage did not progress indoors. Necrosis was worse at 450 ppm. Leaf chlorosis/necrosis of non-shipped plants at the 450 fertilizer level did not appear until the 3rd week indoors. At experiment termination, no leaf damage occurred in non-shipped `Tara' or `Boaldi' with 150 ppm. `Boaldi' did not show damage after shipping regardless of the treatment but symptoms (necrosis and wilting of leaves) evolved during the first 2 weeks indoors on plants fertilized with 450 ppm. A 50% reduction in root soluble carbohydrates was found at the highest fertilizer rate at flowering, suggesting that leaf chlorosis/necrosis is related to carbohydrate depletion in chrysanthemum.