Journal of Crop Production and Processing

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Qasemi M, Shamili M, Mirzaalian Dastjerdi A. The Effect of Nano Selenium and Sodium Selenate on Growth and Photosynthesis Parameters of Spinach (Spinacia oleracea L.) Virofly Variety. Journal of Crop Production and Processing 2025; 15 (2) :1-18
URL: http://jcpp.iut.ac.ir/article-1-3332-en.html

Extended Abstract
Introduction
Selenium is an essential element for humans and animals. Seleno-proteins contribute in antioxidant regulation, so the deficit leads to dysfunction of immune system. Plants, the main source of this element for mammals, absorb selenium from the soil. Nanotechnology, as a promising area of biology, has introduced stable particles as fertilizers. Foliar application of nano-selenium in plants has been involved in alternation of photosynthetic pathway and generation of secondary metabolites. Since selenium is one of the useful elements in plants (including spinach) and due to toxic effects of this element under high concentrations, in this study, the effects of  bulk or nano forms of selenium were compared on spinach plants. The research aimed to compare foliar spraying of sodium selenate (5, 10 and 20 mg/L) with nano-selenium (5, 10 and 20 mg/L) on growth parameters, photosynthetic indices and selenium content  in spinach.

Material and Methods
The current study was carried out under greenhouse conditions in horticulture department, Hormozgan university, 2022. The experiment was designed as a completely randomized design. The spinach virofly variety was used. The treatments were included foliar spraying of drip irrigation with distilled water (control plants), sodium selenate (5, 10 and 20 mg/L) nano selenium (5, 10 and 20 mg/L). Growth parameters (including leaf number, leaf and root dry matter, plant and root length), photosynthetic indices (including intercellular CO2, stomatal conductance, photosynthetic rate, transpiration rate, chlorophyll (a,b, total) and carotenoid contents) and selenium content were evaluated. The normality of the data was checked by the Shapiro-Wilk test. Tukey's test was used for mean comparisons (P < 0.01, 0.05). The data statistical analysis was perfumed by SAS Ver.9.4. Also, the figures were drawn  using EXCEL 2016.

Results and Discussion 
Based on the results of analysis of variance, the effect of treatment (nano selenium and sodium selenate) was significant on leaf dry matter, root dry matter, shoot length, root length and leaf number (P ˂ 0.05). The effect of treatments was significant on carotenoids (P ˂ 0.01), chlorophyll a, chlorophyll b, total chlorophyll (P ˂ 0.05), leaf stomatal conductance, photosynthesis (P ˂ 0.01), intracellular CO2 concentration and transpiration (P ˂ 0.05). Based on findings, root dry matter, shoot length, leaf number, total and chlorophyll a content, carotenoid, photosynthesis rate, intercellular carbon dioxide, stomatal conductance and leaf Se content improved 25.69, 54.78, 14.99, 23.11 and 8.86, 31.01, 222.39, 40.49, 132.25 and 26.31 %, respectively via enhancing the levels of both treatments, compared to the control. Despite recording the highest amount of leaf dry matter (25.69%), leaf number (30.67), intercellular CO2 (476.46 µmol CO2/mol) and stomatal conductance (0.072 mol water/m2/s) under 20 mg/L of sodium selenate, the maximum shoot length (21.67 cm), chlorophyll a and total (respectively, 18.11 and 23.95 mg/g FW), carotenoid (6.97 mg/g FW), photosynthesis rate (8.35 µmol CO2/m2/s) and Se content (0.25 mg/L) were observed under the 20 mg/L of nano-Se. In addition, leaf dry matter also indicated a similar trend. However, the highest leaf dry matter was observed at 10 ppm nano-Se. Finally, despite considering 20 mg/L Se (bulk or nano) as the most effective level in enhancing traits, this level did not show a significant difference with 10 mg/L level. Selenium improves plant growth and development by increasing photosynthesis rate, stomatal conductance, increasing electron transport chain activity, and decreasing transpiration rate. Selenium improves cell division in root tip meristem, but high levels lead to reduced cell division. Nanoparticles move to the roots via apoplast and symplast pathways and are ultimately transported to the leaves and stems via phloem and xylem. Nano selenium promotes plant growth by improving water status and increasing leaf strength. Low concentrations of selenium increase plant growth, possibly by increasing starch content in chloroplasts.

Conclusion
The selenium content of plants can be increased by soil fertilization, foliar application, hydroponic cultivation, aeroponic cultivation, and seed priming in a selenium-containing solution. Data obtained from the effect of selenium compounds on spinach Virofly variety, revealed that high concentrations of selenium in nano form had an ascending impact on shoot and root length, and in the form of sodium selenate on root dry matter and leaf number.  The difference in the effect of different levels of treatments on the studied traits shows that each trait appears optimally under certain levels of treatments. The 10 mg/L of nano selenium treatment can be noted as the optimal level for boosting photosynthetic and growth traits of spinach. Nevertheless, the treatment type and optimal dosage require extensive experiments in different studies with diverse plant species.