The Combination of Selenium and LED Light Quality Affects Growth and Nutritional Properties of Broccoli Sprouts

Rational Combination of Selenium Application Rate and Planting Density to Improve Selenium Uptake, Agronomic Traits, and Yield of Dryland Maize

Exogenous selenium application could effectively improve the selenium absorption of crops affected by different climatic conditions due to changes in the planting environment and planting conditions. We planted maize at planting densities of 67,500 plants ha-1 (D1) and 75,000 plants ha-1 (D2). Five selenium fertilizer gradients of 0 mg m-2 (Se0), 7.5 mg m-2 (Se1), 15.0 mg m-2 (Se2), 22.5 mg m-2 (Se3), and 30.0 mg m-2 (Se4) were applied to investigate the response of the plants to selenium fertilizer application in terms of the gradient selenium absorption and substance accumulation. With the increase in the amount of selenium fertilizer applied, more of the selenium fertilizer will be absorbed and transported from the leaves to the grains, and the selenium content of the grains will gradually increase and exceed the selenium content of leaves. Under the D2 density in 2022, the selenium content of the grains under Se1, Se2, Se3, and Se4 treatments increased by 65.67%, 72.71%, and 250.53%, respectively, compared with that of Se0. A total of 260.55% of the plants showed a gradient of grain > leaf > cob > stalk from the Se2 treatment, and the overall selenium content of the plants increased first and then decreased. Under the D1 density, compared with the Se0, the dry matter mass of the Se1, Se2, Se3, and Se4 treatments significantly improved by 5.84%, 1.49%, and 14.26% in 2021, and significantly improved by 4.84%, 3.50%, and 2.85% in 2022. The 1000-grain weight under Se2, Se3, and Se4 treatments improved by 8.57%, 9.06%, and 15.56% compared to that under the Se0 treatment, and the yield per ha under the Se2, Se3, and Se4 treatments was 18.58%, 9.09%, and 21.42% higher than that under Se0 treatment, respectively. In addition, a reasonable combination of selenium application rate and density could improve the chlorophyll content and stem growth of dryland maize. This lays a foundation for the efficient application of selenium fertilizer and provides an important reference.

The Role of Light Quality in Regulating Early Seedling Development

It is well-established that plants are sessile and photoautotrophic organisms that rely on light throughout their entire life cycle. Light quality (spectral composition) is especially important as it provides energy for photosynthesis and influences signaling pathways that regulate plant development in the complex process of photomorphogenesis. During previous years, significant progress has been made in light quality's physiological and biochemical effects on crops. However, understanding how light quality modulates plant growth and development remains a complex challenge. In this review, we provide an overview of the role of light quality in regulating the early development of plants, encompassing processes such as seed germination, seedling de-etiolation, and seedling establishment. These insights can be harnessed to improve production planning and crop quality by producing high-quality seedlings in plant factories and improving the theoretical framework for modern agriculture.

Effects of light quality on growth, nutritional characteristics, and antioxidant properties of winter wheat seedlings (Triticum aestivum L.)

Wheat seedlings are becoming popular for its high nutritional value. Effects of White (W), White + Red (WR), and White + Blue (WB) light-emitting diodes (LEDs) treatments on growth, nutritional characteristics and antioxidant properties of wheat seedlings were studied in a plant factory. The results showed that height, leaf area, shoot fresh, and shoot dry weight per wheat seedling were the highest under WR at 13 and 22 days after planting. Soluble sugar content in leaves and stems were 22.3 and 65% respectively higher under WB than those under W. Soluble protein content in leaves and stems were 36.8 and 15.2% respectively lower under WR than those under W. Contents of total flavonoids, glutathione (GSH) and ascorbic acid (ASA) in leaves were the highest under WB, whereas malondialdehyde (MDA) content in leaves was the lowest under WB. The activities of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX)] in leaves and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability were also the highest under WB. In conclusion, WR promoted the growth of wheat seedlings, and WB promoted antioxidant level and nutritional accumulation. This study provides guidance for wheat seedlings to carry out preferential production (biomass or quality).

Effects of exogenous sucrose and selenium on plant growth, quality, and sugar metabolism of pea sprouts

BACKGROUND

Pea sprouts are considered a healthy food. Sucrose is a key nutritional factor affecting taste and flavor. Meanwhile, selenium (Se) is an essential micronutrient that plays multiple roles in wide variety of physiological processes and improves crop quality and nutritional value. Nonetheless, the effects of the combination of sucrose and Se treatment on growth, quality, and sugar metabolism of pea sprouts have not been explored.

RESULTS

The results revealed that sucrose at 10 mg L-1 obviously increased fresh weight, vitamin C, soluble protein, soluble sugar, fructose, glucose, and sucrose contents. Se treatments also improved nutritional quality, but higher Se (2.5 mg L-1 ) significantly inhibited the growth of seedlings. Interestingly, the combined application of sucrose (10 mg L-1 ) and Se (1.25 mg L-1 ) could effectively promote vitamin C, sucrose, and fructose contents, especially the Se content, compared with Se application alone. Additionally, there were significant differences in the regulation of sugar metabolism between Se alone and combined application of sucrose and Se. Acid invertase and neutral invertase play a pivotal role in the accumulation of soluble sugar under Se treatments alone, and acid invertase might be the key enzyme to limit sugar accumulation under combined application of sucrose and Se.

CONCLUSION

The moderate combined application of sucrose (10 mg L-1 ) and Se (1.25 mg L-1 ) more effectively regulated sugar metabolism and improved nutritional quality than Se application alone did. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of Plant Hormones, Metal Ions, Salinity, Sugar, and Chemicals Pollution on Glucosinolate Biosynthesis in Cruciferous Plant

Cruciferous vegetable crops are grown widely around the world, which supply a multitude of health-related micronutrients, phytochemicals, and antioxidant compounds. Glucosinolates (GSLs) are specialized metabolites found widely in cruciferous vegetables, which are not only related to flavor formation but also have anti-cancer, disease-resistance, and insect-resistance properties. The content and components of GSLs in the Cruciferae are not only related to genotypes and environmental factors but also are influenced by hormones, plant growth regulators, and mineral elements. This review discusses the effects of different exogenous substances on the GSL content and composition, and analyzes the molecular mechanism by which these substances regulate the biosynthesis of GSLs. Based on the current research status, future research directions are also proposed.

Light Intensity and Photoperiod Affect Growth and Nutritional Quality of Brassica Microgreens

We explored the effects of different light intensities and photoperiods on the growth, nutritional quality and antioxidant properties of two Brassicaceae microgreens (cabbage Brassica oleracea L. and Chinese kale Brassica alboglabra Bailey). There were two experiments: (1) four photosynthetic photon flux densities (PPFD) of 30, 50, 70 or 90 μmoL·m^-2·s^-1 with red:blue:green = 1:1:1 light-emitting diodes (LEDs); (2) five photoperiods of 12, 14, 16, 18 or 20 h·d^-1. With the increase of light intensity, the hypocotyl length of cabbage and Chinese kale microgreens shortened. PPFD of 90 μmol·m^-2·s^-1 was beneficial to improve the nutritional quality of cabbage microgreens, which had higher contents of chlorophyll, carotenoids, soluble sugar, soluble protein and vitamin C, as well as increased antioxidant capacity. The optimal PPFD for Chinese kale microgreens was 70 μmol·m^-2·s^-1. Increasing light intensity could increase the antioxidant capacity of cabbage and Chinese kale microgreens, while not significantly affecting glucosinolate (GS) content. The dry and fresh weight of cabbage and Chinese kale microgreens were maximized with a 14-h·d^-1 photoperiod. The chlorophyll, carotenoid and soluble protein content in cabbage and Chinese kale microgreens were highest for a 16-h·d^-1 photoperiod. The lowest total GS content was found in cabbage microgreens under a 12-h·d^-1 photoperiod and in Chinese kale microgreens under 16-h·d^-1 photoperiod. In conclusion, the photoperiod of 14~16 h·d^-1, and 90 μmol·m^-2·s^-1 and 70 μmol·m^-2·s^-1 PPFD for cabbage and Chinese kale microgreens, respectively, were optimal for cultivation.

Combination of Selenium and UVA Radiation Affects Growth and Phytochemicals of Broccoli Microgreens

Addition of selenium or application of ultraviolet A (UVA) radiation for crop production could be an effective way of producing phytochemical-rich food. This study was conducted to investigate the effects of selenium and UVA radiation, as well as their combination on growth and phytochemical contents in broccoli microgreens. There were three treatments: Se (100 μmol/L Na₂SeO₃), UVA (40 μmol/m²/s) and Se + UVA (with application of Se and UVA). The control (CK) was Se spraying-free and UVA radiation-free. Although treatment with Se or/and UVA inhibited plant growth of broccoli microgreens, results showed that phytochemical contents increased. Broccoli microgreens under the Se treatment had higher contents of total soluble sugars, total phenolic compounds, total flavonoids, ascorbic acid, Fe, and organic Se and had lower Zn content. The UVA treatment increased the contents of total chlorophylls, total soluble proteins, total phenolic compounds, and FRAP. However, the Se + UVA treatment displayed the most remarkable effect on the contents of total anthocyanins, glucoraphanin, total aliphatic glucosinolates, and total glucosinolates; here, significant interactions between Se and UVA were observed. This study provides valuable insights into the combinational selenium and UVA for improving the phytochemicals of microgreens grown in an artificial lighting plant factory.

Roles of selenium in mineral plant nutrition: ROS scavenging responses against abiotic stresses

Agronomic biofortification of crops with selenium (Se) is an important strategy to minimize hidden hunger and increase nutrient intake in poor populations. Selenium is an element that has several physiological and biochemical characteristics, such as the mitigation of different types of abiotic stress. Selenoproteins act as powerful antioxidants in plant metabolism through the glutathione peroxidase (GSH) pathway, and provide an increased activity for enzymatic (SOD, CAT, and APX) and non-enzymatic (ascorbic acid, flavonoids, and tocopherols) compounds that act in reactive oxygen species (ROS) scavenging system and cell detoxification. Selenium helps to inhibit the damage caused by climate changes such as drought, salinity, heavy metals, and extreme temperature. Also, Se regulates antenna complex of photosynthesis, protecting chlorophylls by raising photosynthetic pigments. However, Se concentrations in soils vary widely in the earth's crust. Soil Se availability regulates the uptake, transport, accumulation, and speciation in plants. Foliar Se application at the concentration 50 g ha^-1 applied as sodium selenate increases the antioxidant, photosynthetic metabolism, and yield of several crops. Foliar Se application is a strategy to minimize soil adsorption and root accumulation. However, the limit between the beneficial and toxic effects of Se requires research to establish an optimal dose for each plant species under different edaphoclimatic conditions. In this review, we present the compilation of several studies on agronomic biofortification of plants with Se to ensure food production and food security to mitigate hidden hunger and improve the health of the population.