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    Agronomic and physio-biochemical responses of lettuce to exogenous sodium nitroprusside (SNP) applied under different irrigation regimes
    (Elsevier, 2023) Yavuz, Duran; Seymen, Musa; Kal, Unal; Atakul, Zeliha; Tanriverdi, Omer Burak; Turkmen, Onder; Yavuz, Nurcan
    Drought adversely affects crop production in areas with water shortages. In such areas, various methods need to be implemented to alleviate the effect of water stress on plants. Nitric oxide (NO) is an important plant growth regulator that affects various physiological processes. In this study, we determined ways to increase water-stress tolerance of lettuce by applying exogenous sodium nitroprusside (SNP, a donor of NO). In total, 12 treatments were administered, including three SNP doses (0, 50, and 100 mu M) and four levels of irrigation (I100, I80, I60, and I40). An increase in the doses of NO partially increased the water consumption of lettuce under full and deficit irrigation conditions. The highest water consumption (125.1 mm) and the highest yield (39.1 t/ha) were recorded for lettuce plants that were administered the I100 treatment with 100 mu M SNP. SNP significantly increased the lettuce yield and irrigation water productivity (IWP) under deficit irrigation and full irrigation. SNP promoted chlorophyll synthesis by increasing photosynthesis. The application of 100 mu M SNP increased catalase (CAT) activity approximately three times compared to CAT activity in the control group, and it also significantly increased peroxidase (POD) activity. Additionally, high doses of SNP reduced membrane damage in lettuce leaves. These results indicated that under water stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, activates antioxidant enzymes, such as CAT and POD, protects lettuce against oxidative damage, and increases irrigation water productivity, thus increasing the yield.
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    Application of nitrogen for mitigating the adverse effects of flooding stress in lettuce
    (Taylor & Francis Inc, 2023) Kal, Unal; Dal, Yesim; Kayak, Necibe; Yavuz, Duran; Turkmen, Onder; Seymen, Musa
    Global warming and the subsequent climate change increase the severity and frequency of floods day by day. Therefore, there is a need to develop new strategies to prevent the negative effects of flooding stress and to determine the changes that may occur in the plant under extreme water stress. Thus, in this study, changes in agronomic, physiological, and biochemical properties of lettuce plants exposed to flooding stress under greenhouse conditions were analyzed. In this study, two different irrigation regimes, including full irrigation (I-100) and flooding stress (I-150) and three different nitrogen doses, including no-nitrogen (N-0), 100 kg ha(-1) (N-10), and 200 kg ha(-1) (N-20), were applied. The results revealed that while flooding stress caused significant decreases in above-ground fresh and dry weights, membrane damage (MD), contents of carotenoid (CT), proline (PL), and protein (PT), as well as catalase activity (CAT), leaf relative water content (RWC) and peroxidase (POX) content showed significant increases. Increasing nitrogen doses caused the increase in the pigment contents (Cl a, Cl b, and CT) and PL, superoxide dismutase (SOD) of the lettuce. In addition, RWC content and the uptake of Fe and Mn elements increased under flooded conditions. It has been revealed that the application of at least 100 kg of nitrogen fertilizers per hectare to prevent the negative effects of flooding stress in the regions where lettuce cultivation was carried out supported the plant growth both under full irrigation and flooded conditions.
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    Collection of local Kyrgyzstan Melon genotypes and determination of morphological relationships between some Anatolian Melons
    (Tubitak Scientific & Technological Research Council Turkey, 2022) Can, Hasan; Turkmen, Onder
    Collection, characterization, and protection of genetic resources are among the high-priority issues of increasing importance throughout the world, especially for the breeding and release of novel cultivars. To understand and describe the characteristics of germplasm, the morphological status of genetic resources must accurately represent their agricultural applications. In this study, the genotypes of melon in Kyrgyzstan were collected by visiting several regions and contacting farmers. The genetic diversity of 35 Kyrgyz and 13 Turkish melon accessions was characterized based on the corresponding phenotypes. The morphological characterizations were largely based on the IPGR and, to some extent, UPOV standards. The genotypes from the collections of both countries were separated into three main clusters using the ward method. It was demonstrated that among the 40 morphological parameters, the fruit-related characteristics contributed most significantly to the separation of genotypes in the PCA analysis, and the results of the PCA analysis also validated the cluster analysis. According to the squared eigenvalues, the accessions Kg-G and C-09 were observed to be the closest related genotypes, whereas the accessions Kav-3 and YYU-13 were the most distantly related. Accessions YYu-22, C-02, and C-03 were observed to have the heaviest fruits, Manas-6 and Os-02 were observed to have the highest fruit flesh thickness, and C-08 was determined to have the highest SSC contents among all the accessions. It was observed that the characteristics of melon fruits from both countries differed significantly.
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    Determination of Resistance Levels to Fusarium oxysporum f. sp. melonis and ZYMV and Homogeneity in Some Melon Genotypes
    (Centivens Inst Innovative Research-Ciir, 2021) Cetin, Aye Nur; Uncu, Ali Tevfik; Sen, Fatima; Erdeger, Seyma Nur; Turkmen, Onder
    ZYMV and Fusarium oxysporum f. sp. melonis are one of the main disease factors limiting melon cultivation. ZYMV (Zucchini Yellow Mosaic Virus) is one of the most important diseases caused by potyvirus and causing the most important yield losses in melons. Another important disease agent, Fusarium oxysporum f. sp. Melonis, is a soil- borne disease with four races FOM 0, 1, 2, 1-2. The most common races are 1 and 2 in Turkey. This study, 87 melon accessories ZYMV and Fom 1 and Fom 2 races resistance levels and homogeneity testing levels of genotypes were determined. Result of the study, when the resistance among the genotypes for two races was examined, Fom 1 and Fom 2 strains, 23 genotypes were found to have homozygous resistance alleles against to both races, while for Fom 1 there were 46 allele resistance lines in total, and 30 genotypes had homozygous resistance alleles, 16 of them had heterozygous resistance alleles. This situation for Fom 2, it was found that there were 75 allele resistant alleles, 69 genotypes had homozygous allele and 16 genotypes had heterozygous allele. All genotypes are sensitive against to ZYMV. Homogeneity levels,29 of the genotypes were observed to be between 85-95%.
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    Molecular and Physiological Responses to Exogenously Applied Melatonin in Spinach Under Deficit Irrigation Conditions
    (Springer, 2024) Seymen, Musa; Yavuz, Duran; Can, Hasan; Kiymaci, Gulbanu; Turkmen, Onder; Paksoy, Mustafa; Yavuz, Nurcan
    Melatonin, an important phytochemical, encourages plants to redirect growth in response to environmental stresses. The study aims to investigate the changes in the morphological, physiological, biochemical, and molecular properties of spinach subjected to the exogenous application of melatonin (MEL) at different doses under different water stress. The following four irrigation levels were applied: I100 (complete irrigation), I80 (20% water deficit), I60 (40% water deficit), and I40 (60% water deficit). MEL was applied through a spray on the leaves in three doses-0, 50, and 100 mu M. In the present study, the application of MEL50 exhibited no significant decrease in water use efficiency (WUE) at the I80 irrigation level compared to the I100 irrigation level, while a significant decrease in the WUE was observed beyond this point. The application of MEL contributed to influencing the morphological parameters while also positively affecting the photosynthesis activity and, contribution to the antioxidant defense system. It was observed that the genes involved in the carbon metabolism of photosynthesis), the antioxidant mechanism, and the continuity of photosynthesis, all of which affect the expression of melatonin, facilitated water stress reduction in spinach. Therefore, it was inferred that the application of MEL50I80 could serve as an important irrigation strategy in semi-arid regions with limited water resources.