Publicação
Seed priming of bread wheat with Iron and Zinc: effects in germination, mitosis, nucleolar activity and grain yield
| Resumo: | Iron (Fe) and Zinc (Zn) are important micronutrients in plant metabolism and development. However, in some types of soils, the availability of soluble Fe and Zn can be reduced, and the exogenous application of these micronutrients is required. The suitable dosage of each micronutrient to be applied for biofortification purposes in bread wheat and other plant species requires previous studies at different levels. This study intends to evaluate the effects of seed priming with different dosages (1 mg.L-1 to 8 mg.L-1) of Fe and/or Zn in germination, mitosis, nucleolar activity and yield-related characters of the Portuguese bread wheat cv. ‘Jordão’. Concentrations of Fe and/or Zn higher than 4 mg.L-1 significantly decreased the germination rate and increased the mean time to germination relative to control (0 mg.L-1 Fe + 0 mg.L-1 Zn). Fe and/or Zn concentrations higher than 2 mg.L -1 significantly decreased the mitotic index (MI) (p < 0.001) and increased the percentage of dividing cells with irregularities relative to control. Additionally, in seed priming with 2 mg.L-1 Fe + 2 mg.L-1 Zn, the average values of tillering and other yield-related components were higher than in control. Seed priming treatments performed with 8 mg.L-1 Fe and/or 8 mg.L-1 Zn were considered toxic to bread wheat, causing negative effects in germination, mitosis and yieldrelated characters. At the nucleolar level, the control showed a maximum of four nucleoli per nucleus whereas the remaining treatments showed five or six nucleoli per interphase cell. Anomalies such as irregular nucleolar shapes, dispersion of silver stained particles in the nucleus and nucleolar disruption were found. The highest frequency of irregularities was found in treatment 8 mg.L-1 Fe + 8 mg.L-1 Zn. The average nucleolar area diminished significantly (p ˂ 0.001) with the increase of nucleoli number in all treatments being lower in the treatments 4 mg.L-1 Fe + 4 mg.L-1 Zn and 8 mg.L-1 Fe + 8 mg.L-1 Zn. Hence, the nucleolar area was statistically affected by the effects treatment (p < 0.001), nucleoli number (p < 0.001) and by the interaction treatment x nucleoli number (p < 0.001). Seed priming is a costeffective method for agronomic biofortification of bread wheat, and the present work revealed that dosages of 2 mg.L-1 Fe + 2 mg.L-1 Zn were non-cytotoxic, ensured a high rate of germination (80%) and normal dividing cells (90%), and enhanced the evaluated yield-related characters. On the other hand, the treatments 4 mg.L -1 Fe + 4 mg.L-1 Zn and 8 mg.L-1 Fe + 8 mg.L-1 Zn were the most prejudicial for the germination, mitosis, nucleolar activity and yieldrelated components of bread wheat. As far as we know, the effects of seed priming with different dosages of Fe and/or Zn in germination, mitosis, nucleolar activity and yield-related characters have never been studied in the bread wheat cultivar ‘Jordão’. Thus, the present work may contribute in the future for its improvement at the nutritional and production levels. |
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| Autores principais: | Reis, Sara Alexandra Domingos |
| Assunto: | Actividade nucleolar germinação micronutrientes mitose priming de sementes de trigo características relacionadas com a produção |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Trás-os-Montes e Alto Douro |
| Idioma: | português |
| Origem: | Repositório da UTAD |
| Resumo: | Iron (Fe) and Zinc (Zn) are important micronutrients in plant metabolism and development. However, in some types of soils, the availability of soluble Fe and Zn can be reduced, and the exogenous application of these micronutrients is required. The suitable dosage of each micronutrient to be applied for biofortification purposes in bread wheat and other plant species requires previous studies at different levels. This study intends to evaluate the effects of seed priming with different dosages (1 mg.L-1 to 8 mg.L-1) of Fe and/or Zn in germination, mitosis, nucleolar activity and yield-related characters of the Portuguese bread wheat cv. ‘Jordão’. Concentrations of Fe and/or Zn higher than 4 mg.L-1 significantly decreased the germination rate and increased the mean time to germination relative to control (0 mg.L-1 Fe + 0 mg.L-1 Zn). Fe and/or Zn concentrations higher than 2 mg.L -1 significantly decreased the mitotic index (MI) (p < 0.001) and increased the percentage of dividing cells with irregularities relative to control. Additionally, in seed priming with 2 mg.L-1 Fe + 2 mg.L-1 Zn, the average values of tillering and other yield-related components were higher than in control. Seed priming treatments performed with 8 mg.L-1 Fe and/or 8 mg.L-1 Zn were considered toxic to bread wheat, causing negative effects in germination, mitosis and yieldrelated characters. At the nucleolar level, the control showed a maximum of four nucleoli per nucleus whereas the remaining treatments showed five or six nucleoli per interphase cell. Anomalies such as irregular nucleolar shapes, dispersion of silver stained particles in the nucleus and nucleolar disruption were found. The highest frequency of irregularities was found in treatment 8 mg.L-1 Fe + 8 mg.L-1 Zn. The average nucleolar area diminished significantly (p ˂ 0.001) with the increase of nucleoli number in all treatments being lower in the treatments 4 mg.L-1 Fe + 4 mg.L-1 Zn and 8 mg.L-1 Fe + 8 mg.L-1 Zn. Hence, the nucleolar area was statistically affected by the effects treatment (p < 0.001), nucleoli number (p < 0.001) and by the interaction treatment x nucleoli number (p < 0.001). Seed priming is a costeffective method for agronomic biofortification of bread wheat, and the present work revealed that dosages of 2 mg.L-1 Fe + 2 mg.L-1 Zn were non-cytotoxic, ensured a high rate of germination (80%) and normal dividing cells (90%), and enhanced the evaluated yield-related characters. On the other hand, the treatments 4 mg.L -1 Fe + 4 mg.L-1 Zn and 8 mg.L-1 Fe + 8 mg.L-1 Zn were the most prejudicial for the germination, mitosis, nucleolar activity and yieldrelated components of bread wheat. As far as we know, the effects of seed priming with different dosages of Fe and/or Zn in germination, mitosis, nucleolar activity and yield-related characters have never been studied in the bread wheat cultivar ‘Jordão’. Thus, the present work may contribute in the future for its improvement at the nutritional and production levels. |
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