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Robert R. Shortell, Stephen E. Hart, and Stacy A. Bonos

causes a transitory chlorosis that starts in tolerant grasses such as creeping bentgrass ( Agrostis stolonifera L.) and perennial ryegrass ( Lolium perenne L.) 1 WAIT and lasts for ≈3weeks ( Anonymous, 2004 ). This transitory chlorosis is represented in

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Gerardo H. Nunez, James W. Olmstead, and Rebecca L. Darnell

adjusted to 5.5 for each weekly change, but solutions were prepared without MES to document pH changes in the rhizosphere starting on day 14 as well. After 56 d of treatment (70 d in total), subjective interveinal chlorosis ratings of the plants were made

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Hill Kenneth, D. P. Coyne, and M. L. Schuster

Abstract

‘Great Northern (GN) Nebraska #1, sel. 27’ and PI 150414 dry bean lines were highly tolerant to races 1 and 2 of halo blight bacterium (Pseudomonas phaseolicola) when inoculated with 5 × 106 and 2 × 108 cells per ml. The tolerant reactions to both races was completely dominant in the F1 ‘Gallatin 50’ (susceptible) crossed with both tolerant parents when inoculated with the low cell concn. However, tolerant and susceptible plants occurred in F1’s when inoculated with the high cell concn. In the F2 generation derived from the above crosses, the tolerant inoculated leaf, pod, and plant non-systemic chlorosis reactions to race 1, were each controlled by a different major dominant gene designated by the symbols LHB-1, PD HB-1, SC HB-1, respectively. Coupling linkage was detected between the genes controlling the leaf and systemic chlorosis reactions. This is the first report of 3 different genes, each separately controlling the expression of the halo blight reaction in different plant parts, namely, susceptible water-soaked reaction in inoculated pods and leaves, and systemic chlorosis reaction of leaves.

The leaf tolerant reaction to race 1 in ‘GN Nebraska #1, sel. 27’ and PI 150414 was controlled by the same allele. The same dominant allele in PI 150414 controlled the tolerant reactions to races 1 and 2.

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Heinz K. Wutscher, E. O. Olson, A. V. Shull, and Ascension Peynado

Abstract

Four-year-old nucellar ‘CES No. 3 Redblush’ grapefruit trees on 16 rootstocks, including 8 hybrids, growing on a calcareous soil of pH 8.4 differed in tree size and leaf color. Trees on sour orange, ‘Kunenbo’ mandarin and ‘Cleopatra’ mandarin rootstock were considerably larger and their foliage was greener than those of trees on other rootstocks. Trees on ‘Changsha’ mandarin, C61-250 (‘Shekwasha’ mandarin × ‘Koethen’ sweet orange) also were chlorosis-resistant but they were smaller than the trees on the other tolerant rootstocks. Rootstock effects on 10 mineral element levels in the leaves are discussed.

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Ewell Rogers

Abstract

Sodium ferric ethylenediamine di-(o-hydroxyphenylacetate) containing 6% metallic Fe (FeEDDHA) and hydrogen ferric ethylene bis (a-amino-2-hydroxy-5-methylphenylacetate) containing 6% metallic Fe (157HFe) increased Fe and decreased Mn concentration in leaves of ‘Redhaven’ peach (Prunus persica (L.) Batsch). Both chelates reduced Fe chlorosis, depressed leaf N concentration, and increased fruit size. FeEDDHA at 227 g per tree increased fruit yield. The two chelates reduced the leaf Mn:Fe ratio. There was no discernible treatment effect on P, K, or Zn concentration in the peach leaves or on trunk and shoot growth.

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H.Z. Zaiter, D.P. Coyne, R.B. Clark, D.T. Lindgren, P.T. Nordquist, W.W. Stroup, and L.A. Pavlish

Iron deficiency chlorosis (FeDC) causes extensive reduction in yields of edible dry beans (Phaseolus vulgaris L.) grown on high-pH and calcareous soils. Fifteen bean cultivars/lines differing in response to FeDC were grown 2 years (1988 and 1989) on a high-pH (8.0), calcareous (2.3% calcium carbonate equivalent in surface 20 cm), and low-Fe (2.2 mg Fe/kg) Typic Haplustolls silt loam in the field (central Nebraska) to determine the effects of FeDC on seed yield of cultivars/lines sprayed with Fe. A significant interaction (P < 0.05) between cultivars/lines × Fe spray treatment was noted for visual FeDC ratings in 1988 only, and no significant interactions were noted for seed yield either year. Sprayed cultivars/lines generally produced higher yields than unsprayed ones. Overall increases were 47% in 1988 and 41% in 1989. Even though only slight FeDC was noted on some cultivars/lines receiving no Fe spray, seed yields were significantly increased when sprayed with Fe. Some cultivars/lines with moderate or moderately severe FeDC ratings did not show a significant increase in yield when sprayed with Fe, while other cultivars/lines did. Seed yield reductions for the cultivars/ lines per unit of FeDC rating (1 = green to 5 = severe chlorosis) were 915 kg·ha-1 for unsprayed and 1518 kg·ha-1 for sprayed plants in 1988 and 344 kg·ha-1 for unsprayed and 608 kg·ha-1 for sprayed plants in 1989.

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Marci Spaw, Kimberly A. Williams*, Ingrid L. Mallberg, Laurie Hodges, and Ellen T. Paparozzi

Case studies promote the development of problem-solving skills, but few have been created for horticulture and related curricula. This web-based decision case presents the challenge of determining the cause of symptoms of foliar chlorosis in a crop of cut Dicentra spectabilis while forcing it for Valentine's Day sales. It provides a tool to promote the development of diagnostic skills for production dilemmas, including nutritional disorders, disease and insect problems, and evaluation of the appropriateness of cultural practices. Cut Dicentra is a minor crop and standard production practices are not well established. Therefore, solving this case requires that students research production protocol as well as nutritional and pest problems to develop a solution. In this case study, which is supported by an image-rich web-based version at www.hightunnels.org/cutflowercasestudy.htm, a grower at Flint's Flower Farm must determine the cause of foliar chlorosis that is slowly appearing on about half of the plants of her cut Dicentra crop. The condition could be related to a number of possible problems including a nutritional disorder, insect attack, disease infection, or production practices. Some resources are provided to aid students in gathering background information. Data accumulated by the grower is presented to allow students to logically eliminate unlikely solutions and predict (a) probable cause(s). The solution, which is rather unique to this crop, is provided. This case study is intended for use in upper-level undergraduate courses of floriculture production, nutrient management, plant pathology, and entomology.

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Timothy K. Broschat

Container-grown Bougainvillea Comm. Ex Juss. `Brasiliensis' were fertilized with ammonium sulfate, sodium nitrate, or ammonium sulfate plus sodium nitrate as N sources. Plants fertilized with sodium nitrate were stunted, extremely chlorotic, and produced few flowers compared to those receiving ammonium sulfate. In a second experiment bougainvilleas were fertilized with 12 different controlled-release or soluble ammonium, urea, or nitrate fertilizers as N sources. Plants grown with only nitrate N were chlorotic, stunted, and produced fewer flowers compared to those receiving N from urea or ammonium salts. High substrate pH, associated with nitrate fertilization, was believed to be a cause of the chlorosis, but possible toxicity symptoms (small necrotic lesions and premature leafdrop) were also observed on nitrate-treated plants. Plants receiving controlled-release urea or potassium nitrate were of higher quality than those receiving similar uncoated fertilizers.

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Li-Song Chen and Lailiang Cheng*

To determine the cause of zonal chlorosis of `Honeycrisp' apple leaves, we compared CO2 assimilation, carbohydrate metabolism, xanthophyll cycle and the antioxidant system between chlorotic leaves and normal leaves. Chlorotic leaves accumulated higher levels of non-structural carbohydrates, particularly starch, sorbitol, sucrose, and fructose at both dusk and predawn, and no difference was found in total non-structural carbohydrates between predawn and dusk. CO2 assimilation and the key enzymes in the Calvin cycle, ribulose 1,5-bisphosphate carboxylase/oxygenase, NADP-glyceraldehyde-3-phosphate dehydrogenase, phosphoribulokinase, stromal fructose-1,6-bisphosphatase, and enzymes in starch and sorbitol synthesis, ADP-glucose pyrophosphorylase, cytosolic fructose-1,6-bisphosphatase, and aldose 6-phosphate reductase were significantly lower in chlorotic leaves than in normal leaves. However, sucrose phosphate synthase activity was higher in chlorotic leaves. Thermal dissipation of excitation energy was enhanced in chlorotic leaves under full sun, lowering the efficiency of excitation energy transfer to PSII reaction centers. This was accompanied by a corresponding increase in both xanthophyll cycle pool size (on a chlorophyll basis) and conversion of violaxanthin to antheraxanthin and zeaxanthin. The antioxidant system was up-regulated in chlorotic leaves in response to the increased generation of reactive oxygen species. These findings support the hypothesis that phloem loading and/or transport is partially or completely blocked in chlorotic leaves, and that excessive accumulation of non-structural carbohydrates may cause feedback suppression of CO2 assimilation via direct interference with chloroplast function and/or indirect repression of photosynthetic enzymes.

Open access

Ewell Rogers

Abstract

Sodium ferric ethylene di (o-hydroxyphenylacetate) (FeEDDHA) increased Fe and reduced Mn concentration in leaves of ‘Fay Elberta’, ‘Shippers Late Red’ and ‘Redhaven'peach trees (Prunus persica (L.) Batsch) and reduced Fe chlorosis and depressed the leaf Mn:Fe ratio. FeEDDHA increased Fe and reduced leaf Mn more than did equivalent amounts of sodium ferric ethylene bis (α-amino-2-hydroxy-5-methylphenylacetate) (NaFe) and hydrogen ferric ethylene bis (α-amino-2-hydroxy-5-methylphenylacetate) (HFe). FeEDDHA at 14 g of Fe per tree increased size and yield of ‘Redhaven'peaches. NaFe increased Fe and reduced Mn of the leaves and decreased Fe chlorosis of ‘Fay Elberta’ and ‘Shippers Late Red’ trees. HFe increased Fe and reduced Mn of the leaves and decreased Fe chlorosis of ‘Redhaven’ and ‘Fay Elberta’ trees. The treatments had no discernible effects on Zn concentration of the leaves or on shoot growth.