Browsing by Author "Keskin, N."

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Comparison of Contents of Sugars, Organic Acids and Free Amino Acids in Raisins Obtained From Gök Üzüm (Vitis Vinifera L.)
(Hohere Bundeslehranstalt und Bundesamt fur Wein- und Obstbau Klosterneuburg, 2023) Karakus, S.; Ates, F.; Keskin, N.; Turan, M.; Kaya, O.
Raisins are known as an important source of many bioactive compounds such as organic acids, free amino acids, and sugars. In this study, oak ash and potassium carbonate solutions applied before drying were compared for their effects on the Gök Üzüm raisin, more specifically, its contents of organic acids, free amino acids, and sugar profile. The total acidity quantified in the samples of raisin, ranged from 20.30 to 117.08 ng/µL DW for the potassium dipping solution, while values ranged from 17.98 to 164.72 ng/µL DW for the oak ash dipping solution. In samples from either dip solution, serine was predominant, followed by alanine, asparagine, glutamine, aspartate, sarcosine, glutamate, and leucine, whereas gly-cine, arginine, proline, histidine, and valine were found to be the lowest amino acids. In the samples examined, fructose was the most abundant sugar, whereas the lowest sugars in raisins were xylose for oak ash application and galactose for potassium carbonate application. There was wide variation in the sugar profiles for both variants, with values ranging from 3043.48 to 0.71 g/100 g DW. Drying Gök Üzüm grapes after the treatment of oak ash dipping solution promotes a higher content of organic acids, amino acids and sugars as compared to drying after potassium carbonate solution treatments. These results could be used for the development of an attractive pre-drying solution in further studies for the production of both, raisins and perhaps other dried fruits. © 2023, Hohere Bundeslehranstalt und Bundesamt fur Wein- und Obstbau Klosterneuburg. All rights reserved.
Comparison of Two Different Methods in Determination of Grapevine Leaf Area
(Centenary University, 2018) Doğan, A.; Uyak, C.; Gazioğlu Şensoy, R.İ.; Keskin, N.
Leaves are the basic organs that control many vital mechanisms such as photosynthesis, transpiration and respiration in plants; the species or variety is determined based on them in scientific studies; and the response of the plant to various stress conditions is measured on them. The determination of the surface area of leaves also sheds light on many studies. The present study aimed to compare two different methods for determining leaf area. With the first method used, the leaf area was determined from the pixel-area calculation using pixel values using the image processing program Photoshop CS6. The other method has been tried to determine the leaf area by using the weight-area relation. It was determined that the area found between the two methods varied between-12.93 cm 2 to 9.2 cm 2 on the leaves of 28 different grapevine varieties. By comparing these two methods, leaf area coefficient was determined for each variety. The regression coefficient was found as R 2 = 0.908 (p <0.01) between the area scanned on the computer and then determined by the Adobe Photoshop 6.0 program and the area by the weighted relational method. This statistically significant relationship between the two methods shows that the determination of leaf areas by using the weight-area relationship can be used in the condition where it is not possible to determine it by computer. © 2018, Centenary University. All rights reserved.
Determination of Chlorophyll Amounts and Stoma Densities of Grape Cultivars Grown in Hizan (Bitlis) Conditions
(Centenary University, 2020) Doğan, A.; Uyak, C.; Akçay, A.; Keskin, N.; Şensoy, R.İ.G.; Çelik, F.; Özrenk, K.
In order to reveal effects of cultivar, methods used (nail polish and transparented leaf method), picking positions of the leaves (shade / sun) and sampling from different parts of the leaf surface (tip, middle, bottom) on stoma density and sizes and determine total chlorophyll, chlorophyll a, chlorophyll b, carotenoid amounts and SPAD values of the cultivars, this research was carried out on 28 local grape cultivars grown in Hizan province in 2017. In the study, it was determined that the effect of the cultivar, method used and picking position of the leaf on the stoma density was important, but the effect of sampling from different parts of the leaf surface on the stoma density was insignificant. Similarly, it was determined that the effect of the cultivar, method used and on the stoma sizes was important, but the effect of picking position of the leaf and sampling from different parts of the leaf surface on the stoma sizes was insignificant. It was concluded that the transparented leaf method should be preferred in making better stomatal observation in the hairy and rough grapevine leaves. In the study, it was determined that the effect of the cultivar on total chlorophyll, chlorophyll a, chlorophyll b and carotenoid amounts and SPAD values was important and there were important differences between cultivars in terms of these values. It was observed that the SPAD values of the leaves in the sun were higher than the leaves in the shade. © 2020, Centenary University. All rights reserved.
Effects of Crown Gall (Rhizobium Vitis) Disease on Physical and Biochemical Characteristics of ‘narince’ (Vitis Vinifera L.) Grape Berries
(International Society for Horticultural Science, 2020) Yagci, A.; Keskin, N.; Sucu, S.; Kunter, B.; Cangi, R.; Altinci, N.
Crown gall (Rhizobium vitis) is an economically important disease affecting growth of grapevine (Vitis vinifera L.). But the effects of the disease are generally focus on the lack of vine vigour rather than chemistry of berry content. In this study, impacts of crown gall disease on fruit yield and berry quality were investigated in the white wine grape cultivar ‘Narince’ planted in a commercial vineyard. ‘Narince’ vines showing symptoms and non-symptoms were compared. An equal number of 15 vines were evaluated in each group. Juice from grapes were collected at five stages of berry ripening after the onset of veraison. Number and total weight of clusters and berries were collected at the time of commercial harvest. Data on berry quality attributes (total soluble solids measured as °Brix, pH, titratable acidity, and some phytochemical characters) were investigated in grape samples of symptomatic and non-symptomatic vines. Descriptive analysis was realised by variance analysis and the test of Duncan. © 2020 International Society for Horticultural Science. All rights reserved.
Effects of Cultural Practices on Total Phenolics and Vitamin C Content of Organic Table Grapes
(South African Soc Enology & Viticulture-sasev, 2015) Isci, B.; Gokbayrak, Z.; Keskin, N.
The total phenolic and vitamin C contents of organic table grapes were determined by spectrophotometry and HPLC, respectively, after several quality-increasing treatments were applied at veraison for two growing seasons. Cane girdling and cluster-berry thinning resulted in different responses in the cultivars. 'Red Globe' generally was found to produce the lowest quantity of total phenolics in the berries, while 'Trakya Ilkeren' was the cultivar that accumulated the highest phenolics. Vitamin C accumulation in the berries was also affected by the treatments. The effect of the treatments was inconclusive in 'Buca Razakisi'. The application of both girdling and thinning caused more accumulation of vitamin C in the 'Alphonse L.' and Trakya Ilkeren' berries.
Evidence of Efficient in Vitro Micropropagation From Bulb Scales of Starch Grape Hyacinth (Muscari Neglectum Guss. Ex. Ten.)
(Serbian Genetics Society, 2024) Fi̇Da, A.; Keskin, N.; Kahriz, P.P.; Kahriz, M.P.; Khawar, K.M.
Muscari neglectum is a widespread plant species that grows in various areas of the Mediterranean region in the wild. The species has a high potential for use as cut flowers, outdoor or indoor ornamental or garden plants. It is also used as a food, and forage plant on limited scales in rural areas. There is a lack of commercial production protocols for M. neglectum. The development of a fast and efficient protocol for commercial production, may contribute to the economy of Türkiye and improve local people’s quality of life. Therefore, this study aimed to develop safe in vitro vegetative propagation techniques using 2, 3, 4, and 5 bulb scale explants on MS medium using 1 mg BAP L-1 + 0.00, 0.40, 0.60, 0.80, 1.00, 1.20 mg NAA L-1. Any number of bulb scale explants obtained from freshly harvested bulbs were not suitable for micropropagation and developed necrosis. However, any number of bulb scales obtained from 6 weeks of waiting for bulbs did not show the problem. A regeneration percentage of 13.33 to 100% was noted on 2-scale explants. Additionally, 100% callus formation was observed on these scales using MS medium containing 1 mg BAP L-1 + 0.8, 1.0, and 1.20 mg NAA L-1 (3 combinations). In addition, 1.93 bulblets with a diameter of 0.97 cm (the largest) were observed on MS medium containing 1 mg BAP L-1 + 0.4 mg NAA L-1. Although, 3, 4, and 5 bulb scale explants induced bulblets in variable numbers, the rate of bulblet induction was not at par with bulblet induction on 2 scale explants. The largest bulblets developed on 2-scale explants were rooted on ½ × MS medium containing 0.5 mg NAA L-1. The results obtained for micropropagation of M. neglectum species are of great importance for the commercial production of the species. © (2024), (Serbian Genetics Society). All rights reserved.
Exploration of Effects of Bleeding Water of Grapevine on in Vitro Germination of Single-Point Endemic Lophanthus Turcicus Seeds
(Scibulcom Ltd, 2017) Turkoglu, N.; Ozudogru, A.; Firat, M.; Keskin, N.; Tuncer, B.
Turkey is highly rich in endemic plant species. Natural spreads of these species are subjected to the risk of extinction through pressures exerted by various factors, especially by anthropogenic factors. Current traditional propagation and conservation methods are rarely sufficient to protect them, thus exploitation of the biotechnological approaches is required, as well. Lophanthus turcicus Dirmenci, Yildiz and Hedge, is a single-point endemic species of Turkey, found in a very narrow area of Van region. Present study explored the efficiency of in vitro germination for this valuable delicate species, and highlighted the promising effects of the artificial medium composed of agarised bleeding water (BW) of grapevine in vivo conditions. In addition to BW medium, also Murashige and Skoog (MS), Gamborg B5, Shenk and Hildebrandt (SH) and White (WH) media were tested for their efficiency. In vitro germination trials were performed both under 16 h photoperiod and in darkness. 90% of germination was achieved when decontaminated seeds were cultured on BW medium, providing a germination rate of 3.5 days and emergence rate of 8.12 days in 16 h photoperiod.
General View of the Research Studies on World Viticulture in the Last Decade
(Centenary University, 2021) Gökbayrak, Z.; İşçi, B.; Keskin, N.
It is seen that research subjects are shaped especially under the effect of climate change and that practices that will minimize possible negative effects are examined. Precision viticulture (modeling with data and image processing) processes for technical and biochemical analysis without damaging the product are gaining momentum. With the effect of changing weather events, variations in diseases and pests are observed and compatible management methods are investigated. The use of non-vine plants under the threat of water scarcity and ensuring that the water can be used by the vine as needed when necessary is a prominent research subject under the threat of global warming. It may be possible to use new markers to develop new drought-resistant varieties. It is noteworthy that relatively few scientific studies have been published on propagation, physiological syndromes, and storage in these journals. In the light of the collected information, projections are expressed with a broad perspective on research topics that can be pursued in the field of viticulture. © 2021, Centenary University. All rights reserved.
Production of Trans-Resveratrol in 'cabernet Sauvignon' (Vitis Vinifera L.) Callus Culture in Response To Ultraviolet-C Irradiation
(Jki-institut Rebenzuchtung, 2008) Keskin, N.; Kunter, B.
In this study, the effects of ultraviolet (UV) irradiation time, incubation time and callus age were investigated for the induction of trans-resveratrol production in callus cultures of Vitis vinifera L. 'Cabernet Sauvignon'. Callus tissues were exposed to 254 nm UV light at 10 cm distance from the source for 10 and 15 min by opening covers of the petri dishes in sterile cabin. High Pressure Liquid Chromatography (HPLC) was used for the determination of trans-resveratrol production and concentrations were recorded at 0, 24, 48 and 72 hours after beginning of incubation. Separation by HPLC was achieved using a C18 column and a gradient elution with acetonitrile and water (from 10 to 85% acetonitrile). The peak of trans-resveratrol was detected at 330 nm and identified from the retention time (12.5 min) trans-resveratrol standard. Determination coefficient for linearity (R-2), Limit of Detections (LOD), Limit of Quantification (LOQ) and relative standard deviation (RSD) values of the method were found as 0.9994, 0.12, 0.35 and 1.9, respectively. The highest trans-resveratrol concentration (62.66 mu g.g(-1) callus fresh weight) was determined in 48 hours of 12 days-old callus cultures irradiated for 10 minutes. Both 10 min and 15 min UV irradiation periods were found to be effective for the induction of trans-resveratrol production and thus callus cultures could be convenient for trans-resveratrol production.
Production of Trans-Resveratrol in Callus Tissue of Okuzgozu (Vitis Vinifera L.) in Response To Ultraviolet-C Irradiation
(Pakistan Agricultural Scientists Forum, 2010) Keskin, N.; Kunter, B.
In this study, the effects of ultraviolet (UV) irradiation time, incubation time and callus age were investigated for trans-resveratrol induction in callus cultures of Vitis vinifera L. cv. Okuzgozu. Callus tissues were exposed to 254 nm UV light at 10 cm distance from the source for 10 and 15 minutes by opening covers of the petri dishes in a sterile cabinet. High Pressure Liquid Chromatography was used for determining trans-resveratrol production and concentrations were recorded at 0, 24, 48 and 72 hours after beginning of incubation. The highest trans-resveratrol concentration (62.23 mu g/g callus fresh weight) was determined at 48 hours of 12-day-old callus cultures irradiated for 15 min. 15 min UV irradiation period was found to be effective for induction of trans-resveratrol production and thus callus cultures could be convenient for trans-resveratrol production.
Stilbenes Profile in Various Tissues of Grapevine (Vitis Vinifera L. Cv. 'ercis
(Scibulcom Ltd, 2017) Keskin, N.; Kunter, B.
This study aims to determine amount of stilbenes production in berry (skin, flesh, seed), and one-year-old cane of grapevine (Vitis vinifera L. cv. 'Ercis') as well as induced leaves and berries. The samples were obtained from potted grapevines grown in controlled conditions. Piceid, transresveratrol, e-viniferin, piceatannol, and pterostilbene were considered as stilbene compounds. In order to determine maximum stilbene production, berries and leaves were exposed to UV irradiation for 10 and 15 min. After this practice, the samples were taken at 24th, 48th, and 72nd h. HPLC (High Pressure Liquid Chromatography) technique was used to determine the amount of stilbene in the grapevine tissues. As conclusion, it was suggested that UV irradiation is one of the most effective application to induce stilbene synthesis in the tissues. In addition, it was also emphasised that the maximum stilbene production was recorded at the 48th hour of UV irradiation. And trans-resveratrol was found the most synthesisable stilbene compound in one-year-old cane. However, it was unable to determine stilbene compounds in the non-irradiated leaves and berries.