Tugba Oztekin

Edible halophytes are attracting attention due to their potential for agriculture in saline and marginal areas. The salt tolerance mechanism was analyzed in Crithmum maritimum L., based on ionic, osmotic, and redox homeostasis strategies under salt stress. The methodology involved growing C. maritimum seeds in pots under controlled greenhouse conditions and exposing them to different NaCl concentrations (0, 100, 200, and 300 mM) for five months. High salinity levels decreased plant length and biomass, but the shoot-to-root length and biomass ratio increased significantly. Photosynthetic pigments (chlorophyll and carotenoids) were quantified using spectrophotometric analysis, while macro- and micro-nutrient contents were determined via the Kjeldahl method, flame photometry, and atomic absorption spectrophotometry. Osmolyte accumulation, including proline and glycine betaine, was analyzed using specific biochemical assays, and antioxidant enzyme activities (SOD, CAT, and POX) were measured to assess redox homeostasis. Photosynthetic pigments in C. maritimum leaves slightly increased at 100 mM NaCl, but significantly declined at 200 and 300 mM NaCl. A high Na content in the shoots indicated no restriction in mineral uptake in the roots. Nitrogen and phosphorus slightly decreased under high salinity. The cation content in the shoots varied: potassium decreased, while calcium and magnesium increased with salinity, although the Mg⁺²/Na⁺ and K⁺/Na⁺ ratios showed similar declining patterns. The micro-nutrients iron and manganese increased in the shoots, while copper remained unchanged. The content of osmolytes proline and glycine betaine significantly increased under the 200 and 300 mM NaCl treatments. Antioxidant enzyme activities (SOD, CAT, and POX) decreased at 100 and 200 mM NaCl, but were strongly induced at 300 mM NaCl. The total antiradical activity of the leaves increased with higher salinity levels. Our results indicated that the facultative halophyte characteristics of C. maritimum emerged after exposure to 200 mM NaCl. Increased calcium content may be a key factor in salinity tolerance. We concluded that C. maritimum employs strong osmotic adjustment and redox homeostasis mechanisms, making it a promising candidate for cultivation in saline environments.

Integrating light-emitting diode (LED) lighting systems in greenhouse and plant hydroponic culture represents a significant stride towards sustainable agriculture. This study explores the pivotal role of LED technology, particularly for purple, blue, and red light in nurturing to enhance plant growth and development. Plant photoreceptors absorb different wavelengths of light and activate a signaling cascade from upstream to downstream that will activate several complex physiological processes and morphogenesis. Red light (R, 620–700 nm) is recognized by phytochrome which controls photomorphogenesis via promoting vegetative and generative growth and development including germination, flowering and fruiting. On the other hand, blue light (B, 445–500 nm) is recognized by cryptochromes which stimulate photosynthesis, chlorophyll - carotenoids biosynthesis, and stomatal opening. In terms of nutritional quality, applying B light to plants can increase the accumulation of anthocyanins, carotenoids, and ascorbic acid contents. R lights determine better growth compared to B lights. Furthermore, adding B light to R light as a combination at low intensity can prevent excessive etiolation and reactivate chlorophyll synthesis. In addition, it has been reported that the combination of R and B light increases the development of photosynthetic apparatus, accumulation of biomass, forming more compact plant structure and inhibits flowering. The efficiency of absorption and assimilation of macro and micronutrients in hydroponic systems is also stimulated by the combination of R and B light. Combining R and B in balanced percentages can form purple light fixtures. Purple light is commonly used in the early stages of growth to induce seed germination, cell division and shoot regeneration. A combination of R and B light for LED lighting in the greenhouse and hydroponic culture systems may provide improved control of the crop growing environment and reduce pollutant emissions, producing a homogeneous and high-quality crop, time efficient and low-cost production with predictable results. Through this farming strategy, LED-equipped facilities maximize spatial efficiency and become a solution for obtaining efficient yields and high nutritional value, thus providing a strong case for integrating them into future modern agricultural practices.