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Uri Yermiyahu, Alon Ben-Gal, and Pinchas Sarig

Table grape production has recently become popular in arid and semiarid regions where conditions of salinity and excess boron (B) can be prevalent. This study addresses B toxicity in grapevine to define toxicity symptoms and evaluate growth, production, and B accumulation. The effect of excess B on grapevines (Vitis vinifera L. cv. Sugraone) was evaluated in a 4-year study in Israel's Jordan Valley. Vines were grown in 60-L perlite-filled containers and irrigated with complete nutrient solutions with four B concentrations: 0.03, 0.12, 0.21, and 0.31 mm. Vines were monitored for growth, yield, and B accumulation. Boron accumulation in leaves correlated with B toxicity symptoms that materialized as chlorosis and necrosis of leaves beginning at their margins, reduced leaf size, and reduced internodal distance between adjacent leaves. Boron accumulated in grapevine leaves linearly as a function of increased B in irrigation solution with time and with age of leaves. The highest B levels were found at the end of each season and in the oldest leaves. No long-term (multiyear) effect of exposure to B was observed because similar accumulation patterns and levels were found in each year of the experiment. Hence, consistently sampled diagnostic leaves and time of sampling for B analysis is seen to be critical to provide valid comparisons between vines or over time. Boron supply influenced vine growth. At low levels of B (0.03 mm), canopy development was restricted but trunk size was not. At high levels of B (0.21 and 0.31 mm), substantial visual symptoms of B toxicity were observed, and the rate of trunk growth was reduced, but pruning biomass was not influenced. Despite severe visual toxicity damage and reduced overall growth rates, commercial fruit yield of the vines remained unaffected by high environmental B levels.

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Meredith V. Melendez, Joseph R. Heckman, Stephanie Murphy, and Frank D’Amico

soil phosphorus deficiencies ( Lange et al., 2017 ; Verdejo et al., 2016 ). When the copper level in plant tissue is ≥19 mg·kg −1 dry weight, it is considered toxic ( Davis and Beckett, 1978 ). Growers have expressed concerns about soil copper levels

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Jared Barnes, Brian Whipker, Ingram McCall, and Jonathan Frantz

Each essential element taken up by a plant serves to fulfill a specific physiological role, and reduced (nutrient deficiency) or excess (nutrient toxicity) levels of that element often result in unique symptomology that may be used for diagnostic

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Chun-Ho Pak and Chiwon W. Lee

Foliar micronutrient toxicity symptoms of Petunia hybrida `Ultra Crimson Star' were induced by elevated levels (from 0.25 to 6 mM) of boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) in the nutrient solution. Foliar toxicity symptoms of most micronutrients (except Fe) were characterized by leaf yellowing, interveinal chlorosis, and marginal necrosis. Mo toxicity was most severe. Leaf abnormality was not induced by Fe in the concentration range tested. Visible foliar toxicity symptoms developed when nutrient solution contained 5.4, 32, 28, 24, and 16 mg· liter-1, respectively, of B, Cu, Mn, Mo and Zn. Biomass yield was reduced when the fertilizer solution contained (in mg· liter-1): 22 B, 64 Cu, 335 Fe, 28 Mn, 24 Mo, and 33 Zn.

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Jonathan M. Frantz, Sushant Khandekar, and Scott Leisner

Worldwide, some soils are high in Cu leading to the natural occurrence of Cu toxicity ( Alonso et al., 2000 ; Cook et al., 1997 ). Most reported Cu toxicity is the result of anthropogenic sources including pesticide use ( Hoang et al., 2009 ) and

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Paul Cockson, Josh B. Henry, Ingram McCall, and Brian E. Whipker

ammoniacal-nitrogen, especially during winter production, as ammonium toxicity can occur ( Hamrick, 2003 ; Hollis, 1997 ). Avoiding excessive levels of phosphorus (P) is also recommended ( Hamrick, 2003 ; Hollis, 1997 ). Reported boron (B) deficiency

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Brent K. Harbaugh

Interveinal chlorosis of lower (oldest) leaves followed by development of interveinal necrotic spots, marginal necrosis, downward cupping of leaves, and leaf abscission were symptoms of a disorder commonly observed during production of potted pentas. The disorder was determined to be an Fe toxicity problem associated with accumulation of extremely high levels of foliar Fe (649 to 1124 ppm). Cultivars varied in their response to soil-applied Fe-DTPA chelate solutions: `Starburst', `Mauve' and `Ruby Red' were very susceptible, `Pink Profusion' was intermediate, and `White', `Lavender Delight', and `Pink Rose' were resistant. Potted plant production in a root medium with an initial pH of 6.7 ± 0.1 and a end pH of 6.4 ± 0.2 reduced the accumulation of foliar Fe to levels ranging from 59 to 196 ppm and prevented development of significant visual symptoms for all Cultivars.

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Yuting Meng, Boling Liu, Ping Zhang, Ping Cui, Yuguang Song, Nianwei Qiu, Guoliang Han, and Feng Zhou

., 2016 ). A total of 209 homologues of PBDEs have been discovered, including tetrabromobis, pentabromine, hexabromine, octabromide, decabromodiphenyl ether, etc. ( Fonnum and Mariussen, 2009 ). At present, studies on the toxicity of PBDEs have been

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Cibele Mantovani, Jonas Pereira de Souza Júnior, Renato de Mello Prado, and Kathia Fernandes Lopes Pivetta

is a risk of induced toxicity depending on the species. The description of the effects of SA on orchids is limited to the analysis of the production of polysaccharides by Dendrobium officinale cultivated in vitro ( Yuan et al., 2014 ). According to

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Jie Li, Scott M. Leisner, and Jonathan Frantz

, superoxide scavenging, lignification of cell walls, and ethylene sensing ( Epstein and Bloom, 2005 ; Fox and Guerinot, 1998 ; Marschner, 1995 ). In addition to its role as an essential element, Cu is a potentially toxic agent at supraoptimal levels due to