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Effects of Boron Deficiency on Geranium Grown under Different Nonphotoinhibitory Light Levels
- Apart from a role in cell wall structure, specific functions for boron (B) in plants are unclear; hence, responses and adaptations to B stress are incompletely understood. We tested hypotheses that net photosynthesis (P(n)) decreases with B deficiency before visible foliar symptoms and that higher nonphotoinhibitory light levels enhance soluble carbohydrate status and therefore mitigate B deficiency. Geranium (Pelargonium xhortorum L.H. Bailey cv. Nittany Lion Red) plants were grown hydroponically and were then exposed to normal (45 μM) or deficient (0 μM) B at two light levels [100 or 300 μmol·m-2·s-1 photosynthetically active radiation (PAR)]. Photosynthesis [net CO2 uptake, carboxylation, and photosystem II (PSII) efficiency] was monitored for 5 days, as were concentrations of B, chlorophyll, soluble sugars, total protein, and several photosynthetic and stress proteins [ribulose 1,5-bisphospate carboxylase oxygenase (rubisco), rubisco activase, oxygen-evolving complex-23 (OEC23), Cu/Zn-superoxide dismutase (SOD), Mn-SOD, and eukaryotic translation initiation factor 5A-2 (eIF5A-2)]. Biomass and sugar concentration were greater in high light, and mass was decreased by B deficiency only in leaves in high light. Boron deficiency decreased [B] in all tissues, especially in new leaves. Carboxylation efficiency and Pn decreased within 1 day of B deficiency in low light, but not until 5 days in high light. Chlorophyll concentration decreased, and Mn-SOD increased transiently, with B deficiency in both light levels, but no other effects of low B were observed. Protection of Pn by higher light was confirmed in a different cultivar (Maverick White) grown at 100, 300, and 500 μmol·m-2·s-1 PAR. Thus, in geranium, photosynthesis is affected by B deficiency before effects on leaf growth, and higher light can at least temporarily ameliorate B deficiency, perhaps partly due to enhanced carbohydrate status.
Mishra, Sasmita , Heckathorn, Scott , Frantz, Jonathan , Yu, Futong , Gray, John
boron , Pelargonium hortorum , nutrient deficiencies , plant micronutrients , photosynthesis , light intensity , chemical constituents of plants , plant growth , leaves , roots , plant tissues , chemical concentration , carbohydrates , ornamental plants , nursery crops , plant nutrition , cell walls , plant adaptation , signs and symptoms (plants) , hydroponics , photosynthetically active radiation , carbon dioxide , photosystem II , sugar content , protein content , plant proteins , enzymes
- Includes references
- Journal of the American Society for Horticultural Science 2009 Mar., v. 134, no. 2
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.