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    Ameliorative effects of humic acid and L-tryptophan on enzyme activity, mineral content, biochemical properties, and plant growth of spinach cultivated in saline conditions
    (Wiley, 2024) Turfan, Nezahat; Kibar, Beyhan; Davletova, Nazakat; Kibar, Hakan
    Salinity poses a significant abiotic stress that limits plant productivity, thereby posing a serious threat to agricultural sustainability and worldwide food security. Techniques that can overcome this problem are needed. Recent focus has been placed on employing organic substances like humic acid (HA) and amino acids, including L-tryptophan (L-TRP), to mitigate the negative effects of salt stress on cultivated plants. Accordingly, in this research, the impact of foliar applications of HA and L-TRP, both separately and combined, on the growth parameters and biochemical properties of spinach subjected to salt stress was investigated. In the present study, eight treatments (1. control, 2. salt (NaCl), 3. HA, 4. L-TRP, 5. HA + NaCl, 6. L-TRP + NaCl, 7. HA + L-TRP, and 8. HA + L-TRP + NaCl) were investigated. The study showed that salt stress markedly reduced several growth properties in spinach, including plant height, number of leaves, leaf dimensions, and both fresh and dry weight. Additionally, it significantly lowered contents of chlorophyll (a, b, and total), carotenoid, polyphenol, lutein, anthocyanin, polyphenol oxidase, glycine betaine, relative water content, and the antioxidant enzyme activities (ascorbate peroxidase, catalase, peroxidase, and superoxide dismutase). On the other hand, significant increases were observed in sodium, chlorine, potassium, sulfur, zinc, nickel, proline, malondialdehyde, and hydrogen peroxide levels of spinach with salinity. Individual and combined applications of HA and L-TRP positively influenced plant growth, relative water content, activities of antioxidant enzyme, chlorophyll, and mineral contents of spinach under both normal and saline conditions. In conclusion, the combined use of HA and L-TRP under salt stress conditions is promising in mitigating the negative impacts of salinity and can be suggested as an effective alternative approach for cultivating spinach in saline environments.
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    Determination of nutritional and bioactıve properties in some selected wild growing and cultivated mushrooms from Turkey
    (Wydawnictwo Akad Rolniczej W Lublinie, 2018) Turfan, Nezahat; Pekşen, Aysun; Kibar, Beyhan; Ünal, Sabri
    This study aimed determining the contents of soluble protein, free amino acid, phenolic, flavonoid, soluble carbohydrate, sugars (glucose, fructose and sucrose) and elements in selected wild growing and cultivated mushroom species collected from various locations of Turkey. Significant differences (P < 0.05) were found for the contents of total free amino acid, soluble protein, phenolic, flavonoid, soluble carbohydrate and sugars. The total free amino acid, soluble protein, phenolic, flavonoid and soluble carbohydrate contents of mushrooms ranged from 33.57-126.57 mg g(-1), 2.77-7.55 mg g(-1), 28.68-157.39 mg g(-1), 8.5530.66 mg g(-1) and 59.89-343.55 mg g(-1), respectively. Elemental analysis showed that mushrooms contained significant amounts of potassium (1345.07-9310.17 mg kg(-1)), phosphorus (1462.44-6159.45 mg kg(-1)), calcium (18.78-349.15 mg kg(-1)), sulphur (952.41-12486.63 mg kg(-1)), iron (80.62-606.26 mg kg(-1)), manganese (22.65-147.57 mg kg(-1)), zinc (103.26-522.81 mg kg(-1)) and selenium (0-115.40 mg kg(-1)). Nutritient composition varied with mushroom species. The means of total soluble protein, total phenolic, total flavonoid, potassium, phosphorus, sulphur, chlorine, sodium, iron, calcium, manganese, selenium, zinc and copper contents in wild growing mushrooms were found higher than cultivated mushrooms.
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    Determination of radioactivity levels in different mushroom species from Turkey
    (Centenary University, 2021) Pekşen, Aysun; Kurnaz, Aslı; Turfan, Nezahat; Kıbar, Beyhan
    Radioactivity in the environment occurs due to natural, terrestrial, extra-terrestrial factors or caused by human activity. Foodstuffs such as plants and mushrooms that grown in the soil which containing radioactive elements can absorb radioactive elements from the soil. Wild mushrooms can accumulate many types of toxicological, nutritional, and radioactive elements. Knowing the levels of radioactivity in the foodstuffs is of great importance for the protection of human health. In this study, the activity concentrations of the naturally occurring 238U, 232Th, 40K nuclides and artificially occurring 137Cs nuclide were determined and annual effective doses and excess lifetime cancer risk values were calculated in mushrooms commonly consumed by the Turkish people. Fifteen types of mushroom samples were collected from different locations of Turkey. The results showed that the activity concentrations of 238U, 232Th, 40K and 137Cs varied from 9.2±1.6 to 75.4±8.8 Bq kg-1, 10.9±1.6 to 76.3±8.9 Bq kg-1, 925.9±29.0 to 3848.0±73.2 Bq kg-1 and 6.1±1.1 to 2824.8±79.8 Bq kg-1, respectively. The mean total annual effective dose was found to be 11.5 µSv y-1. 40K radionuclide was the highest contributor to the mean total annual effective dose as 5.35 µSv y-1. The mean excess lifetime cancer risk (ELCR) caused by consumption of mushrooms in the study was determined as 4.6 × 10-5. © 2021, Centenary University. All rights reserved.
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    Exogenous citric acid, salicylic acid, and putrescine treatments preserve the postharvest quality and physicochemical properties of broccoli (Brassica oleracea L. var. italica) during cold storage
    (Wiley, 2023) Kibar, Hakan; Kibar, Beyhan; Turfan, Nezahat
    To extend the postharvest storage life of broccoli samples (Brassica oleracea L. var. italica), an exogenous application of citric acid (CA), salicylic acid (SA), and putrescine (PUT) was tested in multiple combinations (0.5 and 1 mM) at 4 +/- 0.5 degrees C and 90 +/- 5% relative humidity (RH) for 21 days (d). The weight loss (WL), respiration rate (RR), total soluble solids (TSS), pH, color (L*, a*, b*, chroma, and hue angle), proximate and mineral contents, phenolic and flavonoid contents, and other biochemical properties of the treated and untreated broccoli samples were evaluated throughout the storage duration. The lowest WL was observed when exposed to 0.5 mM of PUT. 1 mM CA and PUT treatments were affected by RR, depending on storage conditions. The lowest TSS content was observed in broccoli samples treated with 0.5 mM CA among all treatments. The chroma value of the samples was preserved by the 0.5 mM SA treatment. The most abundant element in broccoli samples was potassium in the control application, followed by a 1 mM SA treatment. In addition, the protein content was the highest in the 1 mM PUT treatment. The highest vitamin C was determined in the 1 mM CA treatment, and the most abundant vanillic acid was found in broccoli exposed to the 0.5 mM and treatment. Glucose content was determined at the lowest level in the 0.5 mM SA treatment, while higher increases occurred in other treatments. In terms of these findings, 1 mM CA, 1 mM SA, and 1 mM PUT delay WL, RR, and color degradation and prolong the storage life of broccoli samples stored at 4 +/- 0.5 degrees C. It was concluded that the biochemical content, fresh weight, and green color of broccoli samples throughout postharvest and storage can be maintained longer by exogenous application of these natural compounds. Therefore, we recommend 1 mM PUT and 1 mM CA treatments to maintain the quality of broccoli by minimizing losses in morphological properties, mineral, and biochemical compositions during postharvest storage.
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    Role of storage on quality, nutritional and biochemical properties of garlic bulbs grown depending on different fertilizer applications
    (Springer, 2023) Turfan, Nezahat; Kibar, Beyhan; Kibar, Hakan
    This study was carried out to determine the effects of fertilizer applications (control, inorganic fertilizer and barnyard manure + humic acid + inorganic fertilizer), storage temperatures (2, 10 and 20 °C) and durations (30, 60 and 90 days) on post-harvest quality, nutritional and biochemical properties of garlic bulbs during storage. As storage temperature and storage duration increased, weight loss and respiration rate also considerably increased. A significant effect of different fertilizer applications on weight loss, respiration rate and biochemical properties of garlic bulbs was not observed. Highly significant positive correlations were observed between pH and weight loss, b* and Chroma, L* and Hue angle, Ag and Sn, Ag and Cd, Mn and K, Sn and Cd, K and P. In conclusion, storage at 2 °C may be recommended as the best treatment to maintain post-harvest quality and to prolong storage life of garlics. Among fertilizer applications, inorganic fertilizer came to the forefront in terms of post-harvest quality. When the storage durations are examined, it was determined that garlic bulbs can be stored for up to 90 days without losing its quality much. The results of the present study will provide potential knowledge about post-harvest storage of garlic bulbs for further investigations. © 2023, The Author(s) under exclusive licence to Society for Plant Research.