Document Type : Original Article
Authors
1
Department of Horticultural Sciences, Faculty of Agriculture, Shahed University, Tehran, Iran
2
Department of Horticultural Sciences, Sari Agricultural sciences and Natural Resources University (sanru), Sari, Iran
Abstract
Introduction: Although beneficial effects of silicon for plants were well documented (Liang et al., 2015), leaf uptake efficiency of this element in most of plants including tomato remains to be explored. So, this experiment aimed to evaluate penetration of silicon into the tomato leaf mesophyll.
Materials and methods: This pot experiment was conducted hydroponically in a completely randomized design with 7 treatments, 3 replications and 2 samples in research greenhouse of Sari Agricultural Sciences and Natural Resources University, Sari, Iran. Treatments comprised potassium silicate (K2SiO3), sodium silicate (Na2SiO3), and orthosilicic acid (H4O4Si), each of them in two concentrations of 1 and 2 mM, along with a control. All treatments were applied weekly as foliar spray. Evaluated parameters included yield, photosynthetic pigments (Carter and Knapp, 2001), leaf silicon concentration (Elliott and Snyder, 1991), and silicon distribution among mesophyll profiles. The later parameter was determined in three different points of the transverse section of the leaf (near adaxial, middle of mesophyll, near abaxial) using Energy Dispersive X- ray Spectroscopy (EDX).
Results: All of the silicon treatments resulted in an increase in leaf silicon concentration compared to the control. However, the application of potassium silicate at 2 mM led to the highest silicon concentration, which was not significantly different from potassium silicate at 1mM. Evaluation of the middle of mesophyll elemental profile showed that only two treatments, orthosilicic acid at 1 mM and sodium silicate at 2 mM, resulted in a higher silicon ratio than the control in the whole mesophyll and near abaxial point. The other treatments showed no significant differences from the control. The Silicon ratio at the near adaxial point was significantly higher under potassium silicate treatment compared to the control. The highest yield was recorded under orthosilicic acid at 2 mM, which was not significantly different from sodium silicate at 1 mM concentration.
Conclusion: Overall, the results of this research confirmed that silicon can infiltrate tomato leaves, indicating that silicon fertilizers can be safely applied via foliar spray. Furthermore, an important finding from this experiment was that there is no correlation between leaf silicon concentration and tomato yield in normal conditions.
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