https://hdl.handle.net/20.500.12809/8888 2026-04-06T15:52:45Z https://hdl.handle.net/20.500.12809/11066 Effect of Rhizobacteria On Drought Stress Tolerance of Tomato Plants at Vegetative and Fruiting Growth Stages Altunlu, Hakan; Aydöner Çoban, Gökçe; Gül, Ayşe; Özaktan, Hatice This study including two successive experiments was conducted to evaluate the effect of native rhizobacteria (RB) strains on drought tolerance of tomato plants at the vegetative and fruiting growth stages. The first experiment was conducted in the growth room by growing plants in nutrient solution under polyethylene glycol induced drought stress, which initiated 7 days after planting and lasted 8 days by increasing the osmotic stress gradually every 48 h from Ψs = −0.25 to −1.00 MPa. Among the 12 RB tested, RB isolates 113 (Bacillus megaterium isolate NUC) and 377 (Bacillus cereus strain BBS7) were selected according to principal component analysis for testing in long term plant production. The second experiment was conducted in the greenhouse by growing plants in perlite filled pots for 128 days after transplanting. Irrigation was based on the water consumption of the plants, and the plants were irrigated to cover well-watered (100% FC) or drought (50% FC) of this amount. For both experiments, seeds were inoculated with the RB strains before sowing. RB inoculation increased plant growth, leaf pigment contents, antioxidant enzyme activities and ascorbic acid level, but reduced malondialdehyde levels in tomato plants under drought stress. The marketable yield was increased 8.7 and 10.6% in the absence of water stress, and 70.2 and 59.9% under water stress by RB 113 and RB 377, respectively. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10756 Effects of Salicylic Acid Application on Germination, Growth and Development of Rough Lemon (Citrus jambhiri Lush.) Under Salt Stress Güneri, Murat Rough lemon (Citrus jambhiri Lush.) - RL, is used as a rootstock for citrus plants in saline conditions. NaCl causes an osmotic stress on plants mainly preventing the water uptake by the roots and thus reducing the plant growth. The objective of this study was to determine the effects of salicylic acid (SA) on germination of seeds and the growth and development of seedlings of RL rootstock under salt stress. For seed germination, a study was conducted in a completely randomized design in a 4 x 4 factorial scheme (SA at 0.00, 0.25, 0.50, or 1.00 mM and NaCl at 0, 50, 100, or 200 mM) with 4 repetitions, totaling 64 plots, of 25 seeds per plot. RL seeds were incubated in SA solutions for 24 h. Then, they were treated with NaCl-containing water in Petri dishes and incubated in the growth chamber at 25 degrees C. For greenhouse experiment, a study was conducted in a randomized complete block in a 4 x 4 factorial scheme (SA at 0.0, 0.5, 1.0, or 2.0 mM and NaCl at 0, 50, 100, or 150 mM) with 3 repetitions, totaling 48 plots, of 2 plants per plot. Some morphological and physiological characteristics were determined. While germination time was extended, germination ratio and radicle extension were decreased in seeds under salt stress compared to control. Moreover, in these conditions the leaf membrane permeability and leaf falling were increased. In turn, plant height, diameter, root and shoot dry weight, leaf relative water content, and leaf chlorophyll were decreased in seedlings. Salt stress had negatively affected seed germination from 97.5% in control to 23.5% in 200 mM NaCl. However, SA treatments significantly decreased plant height to 67.8 cm in 2.0 mM compared to 80.1 cm in control in RL rootstock. 2023-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10562 Domates genotiplerinin kuraklık stresine tolerans açısından tohum çimlendirme ve vegetatif gelişme aşamalarında hızlı taranmasına uygun testlerin optimizasyonu Altunlu, Hakan; Gül, Ayşe; Çoban, Gökçe Aydöner Objective: This study was conducted to determine the suitability of drought stress induced by PEG-6000 for rapid screening of tomato genetic resources against drought stress. Material and Methods: Two cultivars; M28 F1 and Alyans F1 known as tolerant and sensitive, respectively; were tested. In seed germination test, two different PEG concentrations (4% and 6%) were compared with the control. The seedling stage test was performed in water culture. In this experiment, (1) bare rooted seedlings of which rooting medium were removed and (2) seedlings with rooting medium were used. Drought dose was Ψs= -1.0 MPa (full dose) and gradually increased (-0.25, -0.50, -0.75 and -1.0 MPa) every 48 hours from 7 days after planting. Results: In seed germination test, the decrease in vigour index under drought stress was lower in M28 variety. In water culture, stress symptoms appeared slowly if the seedlings with rooting medium were used. The decrease in plant growth characteristics, and chloropyll, carotenoid and relative water content and increase in proline content under stress were lower in M28 Conclusion: It was concluded that the seed germination test by 4% PEG-6000 and water culture in which the drought stress was created by PEG-6000 (Ψs= -1.0 MPa) can be used to screen tomato genetic matierials for drought stress tolerance.; Amaç: Bu çalışma, domates genetik kaynaklarının kuraklık stresine karşı hızlı taranması için PEG-6000'in neden olduğu kuraklık stresinin uygunluğunu belirlemek amacıyla yapılmıştır. Materyal ve Yöntem: Çalışmada, kurağa toleransı yüksek (M28) ve düşük (Alyans) olduğu bilinen iki çeşit test edilmiştir. Çimlendirme testinde iki farklı PEG konsantrasyonu (%4 ve %6) denenmiştir. Fide aşamasındaki test su kültürü tekniği ile gerçekleştirilmiştir. Denemede (1) kökleri yetiştirme ortamından temizlenmiş çıplak köklü veya (2) kökleri yetiştirme ortamından temizlenmemiş fideler kullanılmıştır. Su kültürüne alınan fidelere 7 gün sonra kuraklık stresi (Ψs= -1.0 MPa) kademeli olarak (-0.25, -0.5 -0.75 ve -1.0 MPa) her 48 saatte bir artırılarak uygulanmıştır. Araştırma Bulguları: Tohum çimlenme testinde, vigor indeksinde kuraklık stresi altında kontrole kıyasla meydana gelen azalma, M28 çeşidinde daha az olmuştur. Su kültüründe, kökleri yetiştirme ortamından temizlenmemiş fideler kullanılması durumunda stres belirtileri beklenen sürede ortaya çıkmamıştır. Kuraklık stresi altında bitki gelişimi, klorofil a ve b, karotenoid içeriği ve yaprak oransal nem içeriğinde meydana gelen azalış ile prolin içeriğinde meydana gelen artış M28 çeşidinde daha düşük olmuştur. Sonuç: Domates genetik kaynaklarının kuraklık stresine tolerans açısından taranmasında; tohum çimlendirme aşamasında %4’lük PEG-6000, vegetatif gelişme aşamasında durgun su kültüründe PEG-6000 ile Ψs= -1.0 MPa osmotik stres yaratılmasının uygun olduğu sonucuna varılmıştır 2022-01-01T00:00:00Z https://hdl.handle.net/20.500.12809/10271 The effects of melatonin application on the drought stress of different citrus rootstocks Korkmaz, Nazan; Aşkın, Mehmet Atilla; Altunlu, Hakan; Polat, Mehmet; Okatan, Volkan; Kahramanoğlu, İbrahim Drought is among the most crucial limiting factors for crop production and is considered a major threat to food security. Rootstock selection is an important approach for drought management. This research was aimed to study the responses of important rootstocks against drought stress and to examine the impacts of melatonin application on the drought stress of these rootstocks. Carrizo citrange, fying dragon, and sour orange were selected for the current study. To test the drought stress, three different irrigation regimes were applicated separately to each rootstock as 100%, 75%, and 50% of water requirement. The melatonin was then tested on each rootstock*irrigation plot with four different doses (0.5 mM, 1.0 mM, 1.5 mM, and 2 mM) and an untreated control application. Results suggested that melatonin application significantly increases the root and shoot growth of the test rootstocks. Besides that, the highest root length was noted from a Flying dragon, while the Carrizo citrange had the highest shoot height. As a response to the drought stress, the leaf membrane permeability of rootstocks increased and the relative water contents decreased. Both traits were noted to be improved by the melatonin application. In terms of the leaf relative water content and membrane permeability, the Flying dragon rootstock was observed to be more tolerant to drought as compared with the Carrizo citrange and sour orange. External melatonin application was also observed to reduce the proline content in the leaves under drought stress, which is a sign of improvement of the crop’s tolerance to drought. 2022-01-01T00:00:00Z