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Dimitrios Savvas, Dimitrios Papastavrou, Georgia Ntatsi, Andreas Ropokis, C. Olympios, Hagen Hartmann, and Dietmar Schwarz

rootstocks that do not adversely affect plant nutrition, fruit yield, and produce quality. As reported by Edelstein and Ben-Hur (2007) , the concentrations of heavy metals and microelements, including manganese (Mn), zinc (Zn), copper (Cu), and boron (B

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W.J. Hill, J.R. Heckman, B.B. Clarke, and J.A. Murphy

Take-all patch, caused by Gaeumannomyces graminis (Sacc.) Arx. & D. Olivier var. avenae (E.M. Turner) Dennis (Gga), is a disease of creeping bentgrass (Agrostis stolonifera Huds.), which most often is associated with golf courses. Synthesis of ligneous and phenolic compounds by plants requires adequate Mn+2 and Cu+2 nutrition and may be a factor in disease resistance. An experiment was conducted on a creeping bentgrass fairway naturally infested with Gga to determine if foliar applications of Mn+2 (1.02 and 2.04 kg·ha–1 per application) and Cu+2 (0.68 kg·ha–1 per application) would reduce take-all severity. Prior to initiating treatments, soil pH was 6.4 and Mehlich-3 extractable Mn+2 and Cu+2 were 5 mg·kg–1 and 1.7 mg·kg–1, respectively. Manganese and copper sulfate treatments were initiated in July 1995 and foliarly applied every 4 weeks through 1997 with the exception of December, January, and February. Disease incidence was decreased from 20% on untreated turf to 5% with the high rate of MnSO4. For both years, turf treated with the high rate of Mn+2 had less disease than turf receiving the low rate of Mn+2. The application of CuSO4, however, did not influence disease development.

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Joshua Sherman, Richard J. Heerema, Dawn VanLeeuwen, and Rolston St. Hilaire

the southwest today typically make multiple Zn fertilizer applications each growing season as part of their regular mineral nutrition programs ( Heerema, 2013 ; Walworth and Pond, 2006 ). Manganese, on the other hand, has received relatively little

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Samuel Kwakye, Davie M. Kadyampakeni, Edzard van Santen, Tripti Vashisth, and Alan Wright

al., 2019 ). Currently, there are no detailed guidelines for optimal leaf manganese (Mn) concentration in HLB-affected citrus trees in Florida. These guidelines will enable researchers and citrus growers to better understand the role Mn plays in the

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Michael R. Evans and Mary M. Gachukia

sampling time. All potential interactions were significant ( Table 1 ). For all sampling times, substrates containing 20% perlite or 20% PBH had similar manganese concentrations ( Fig. 4, A–C ). However, as PBH increased, the Mn concentration increased

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Suphasuk Pradubsuk and Joan R. Davenport

time of dormant (DM), budbreak (BB), three- to four-leaf stage (34), bloom (BL), veraison (VR), harvest (HV), and postharvest (PH). Data points represent means with se at each sampling date (n = 4). Manganese concentrations in permanent structures

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Desmond G. Mortley

The effects of 0.25, 1.0, 2.5, 10, and 100 mg Mn/liter on sweetpotato [Ipomoea batatas (L.) Lam] were evaluated in a greenhouse during 2 years using the nutrient film technique. Foliage and storage root dry weights declined linearly as Mn concentration increased in either whole plants or fibrous roots. Foliage and storage root dry weights were equally sensitive to Mn concentration in whole plants but 5 to 15 times more sensitive to increased Mn concentration in the fibrous roots. Foliar N, P, K, Ca, and Mg concentrations were adequate and did not appear to limit plant growth. Manganese concentrations in solution had very little effect on Fe, Zn, or B concentration. Manganese concentration was higher in the foliage than in fibrous roots. Plant roots showed browning at the higher (10 or 100 mg Mn/liter) concentrations in solution, which indicated the presence of oxidized Mn. Characteristic toxicity symptoms were observed in plants receiving 2.5 (moderate), 10, or 100 mg Mn/liter in solution.

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Creighton Gupton and James Spiers

To determine whether manganese tolerance in rabbiteye blueberry (Vaccinium ashei Reade) is heritable, a 10-parent diallel cross was produced. A 250 ppm Mn solution (200 ml/plant) was applied to a sand culture, of the progeny daily. Visual ratings (1 - dead plant - 13 - no Mn toxicity symptom) were made after 6 weeks. Shoot weight and Mn content of leaves were determined. Narrow-sense heritability estimates (h2) were 0.45±0.28 for Mn content, 0.49±0.27 for visual ratings, and 0.37± 0.21 for shoot weight. The genetic correlation between neither shoot weight nor visual rating and Mn content (0.11 and -0.15, respectively) was very high; however, the correlation between shoot weight and visual ratings (1.00) was extremely high. This suggests that visual ratings provide an estimate of Mn effects on plans equal to objective measurements of shoot weight. Though h2 estimates for Mn content and visual ratings were similar, the lack of genetic correlation between the traits indicates that tolerance to Mn toxicity is independent of Mn content. The high h2 for visual ratings suggests mass selection as the method of choice for improving Mn tolerance in a rabbiteye blueberry population.

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Menahem Edelstein, Roni Cohen, Meital Elkabetz, Shimon Pivonia, Ami Maduel, Tom Sadeh-Yarok, and M. Ben-Hur

leaves of tomato ( Le Bot et al., 1990 ). Accordingly, in our experiment, the enriched fertilizer caused a significant increase of ≈100% in leaf Mn concentration for all plants in both years ( Fig. 1 ). Fig. 1. Concentration of manganese (Mn) in leaves of

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Osman M. Elamin and Gerald E. Wilcox


Muskmelons (Cucumis melo L.) ‘Harvest Queen’ were grown in sand culture to evaluate the response to Mn toxicity as affected by solution concentration of Mn and Mg. Manganese toxicity symptoms were developed as water-soaked spots, necrotic spots, and necrotic lesions, which were most severe on the lower mature leaves. Leaves developed toxicity symptoms when they contained ≥900 μ-g·g-1 Mn. Increased levels of Mg in the nutrient solution alleviated symptoms of Mn toxicity, decreased Mn concentration in shoot and root tissues, and increased growth of muskmelon plants. The reduction in Mn toxicity was brought about by reduced root absorption of Mn at high Mg supply.