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Grafting on a moderate salt-tolerant rootstock (Vista-306) and bacteria (Serratia marcescens) inoculation were tested whether grafting and bacteria can alleviate salinity stress in eggplant...

The effects of salinity and zinc (Zn) priming on the physical and mineral composition of green bean genotypes were investigated on two green bean genotypes (‘ªeker Fasulye’ and ‘Local Genotype’) by soaking seeds in 0.05% Zn (ZnSO4.7H2O) solution and by exposing to salt stress by applying 50, 100 and 150 mM NaCl after first true leaf emergence. Plants not exposed to salt stress were treated as control. The effects of Zn priming on the salt tolerance of genotypes, fresh and dry weight of plant leaf relative water content (RWC), loss of turgidity (LOT), Na, K, Ca and Zn concentrations in the leaves, stem and root portions of plants were evaluated. The NaCl concentrations led to significant variations in the examined parameters. The highest concentration of salt (150 mM) caused fading in leaves and led to inhibition of growth and development. Salt application generally reduced the fresh and dry weights of plants of both genotypes where Zn priming showed an amendatory effect. Leaf RWC decreased with salt applications while LOT increased but Zn priming had no amendatory effect on these parameters. ‘ªeker Fasulye’ genotype was found to be relatively more salt tolerant than ‘Local Genotype’ on the basis of the investigated parameters. Zinc priming decreased the Na and Ca concentrations in plant organs; however, a decrease in K concentration was observed due to increase in NaCl.

The effects of salt (NaCl) applications of various concentrations (0, 500, 1000 and 2000 mg/L) for 6 months on ‘Camarosa’ and ‘Chandler’ strawberry varieties grown in perlite and perlite:zeolite (1:1) media were investigated. In order to determine the salt resistance of varieties, the tolerance index (T.I.) and tolerance ratio (T.R.) were calculated on the basis of total chlorophyll content, and leaf and root dry weight. Also, the ability of keep in balance for potassium:sodium (K:Na) ratio in the aerial part and roots of plants were considered. It was determined that the highest T.I. and T.R. values calculated on the basis of leaf and root dry weight in cv. Camarosa in both media. Concerning the evaluations calculated on the basis of total chlorophyll, the results indicated that ‘Chandler’ is more resistant in perlite medium, ‘Camarosa’ is more resistant in perlite:zeolite (1:1) medium. K:Na ratio decreased with increasing salinity in both varieties. However, it was determined that K:Na ratio is...

Effects of salt stress on the time course of stomatal behaviors and the activity of antioxidative enzymes such as catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APX) (EC 1.11.1.11), and glutathione reductase (GR) (EC. 1.6.4.2) were studied in three strawberry cultivars. The responses of the cultivars 'Camarosa', 'Tioga,' and 'Chandler' were compared when they were irrigated with nutrient solution containing 0, 8.5, 17.0, and 34.0 mM sodium chloride (NaCl) for 30 days. A significant reduction in stomatal conductance (g(s)) was seen particularly on the 30th day of the salt treatments only in Camarosa, which is parallel to transpiration rate (E). CAT activities decreased in all of the salt treatments only in Tioga, while it remained almost unchanged or slightly increased depending on the period in Camarosa and Chandler. APX activity sharply increased in 17.0 and 8.5-mM NaCl treatments for 30 days in Camarosa and Tioga, respectively, whereas it linearly increased based on the NaCl treatments in Chandler. On the other hand, only Camarosa demonstrated a sharp increase in GR activity induced by salinity applied for 30 days. All the data indicated that control of the stomatal behavior, the higher salt-stress tolerance (LT50) and higher constitutive activity of antioxidant enzymes made Camarosa and Tioga relatively salt-tolerant cultivars.

Effects of salt stress on the activity of peroxidase (PRX) isozyme and leaf proteins were studied in the three strawberry varieties, Camarosa, Tioga and Chandler. Plants were watered with modified 1/3 Hoagland nutrient solution containing 0 (control), 8.5, 17.0 and 34.0 mM NaCl for 30 days following 20 days acclimation. PRX activity was assayed in leaf extracts and PRX profiles of control and salt treated plants were performed by native polyacrylamide gel electrophoresis (PAGE). During the salt stress Tioga and Camarosa tolerated the cellular damage with less electrolyte leakage while Chandler exhibited a severe cellular damage with the highest (87.5% in 34.0 mM NaCl treatment) electrolyte leakage. Total soluble protein content was decreased by salinity in Tioga (from 11.35 to 5.86 mg center dot g(-1) DW) and Chandler (from 9.35 to 3.90 mg center dot g(-1) DW) while it was almost unchanged in Camarosa. Salt stress increased total and specific PRX activity as compared with the control in all the varieties. In native PAGE, one basic isoperoxidase band (Rf=0.27) was observed commonly with different band intensity in all the treatments. Therefore, it might be associated with lignification and recovery of cell membrane damage in strawberry plants under salt stress.

Blossom-end rot (BER) in pepper fruits is known as a " physiological" disease which is evoked by climatic and osmotic stresses (e.g., high temperatures and salinity) and by deficit irrigation management. The physiological and biochemical mechanisms involved in the stimulation of BER are still a matter of dispute. It has been proposed that BER occurs under cultivation conditions that accelerate fruit growth beyond calcium supply to the growing tissue. In the present study, we investigated this hypothesis by recording fruit growth and sugar metabolism under normal and BER-inducing conditions. The results showed that pepper fruits grown in a ventilated-cooled greenhouse, which ameliorated BER, had a higher initial growth rate than those grown in a non-cooled greenhouse, but had lower calcium concentrations in the fruit pericarp. Fruits that grew without ventilation-cooling had higher concentrations of apoplastic and symplastic sucrose and reducing sugars, and higher levels of symplastic starch than those that developed in a cooled greenhouse. Concomitantly, fruits that developed in a non-cooled greenhouse had lower acid invertase, sucrose synthase and fructokinase activities than those that developed in a cooled greenhouse. Accordingly, the non-necrotic part of BER-affected fruits had higher concentrations of symplastic starch, reducing sugars and sucrose than healthy fruits. These findings indicate that the occurrence of BER in pepper fruits was associated with impaired sucrose metabolism in fruit tissues, which led to reductions in growth rate and final size. Thus, the present findings negate the notion that BER occurs when fruit growth rate is stimulated, and favour the idea that direct impairment of fruit sugar metabolism and of normal fruit growth are involved.

The response of melon (Cucumis melo) plants to long-term salinity was investigated to determine the availability of the NaCl pre-treatments (seed priming + seedling conditioning) as an interesting strategy for increasing the salt tolerance. Seeds of melon cultivars "Hasanbey" and "Kirkagac" were primed with 18 dS m(-1) NaCl solution for 3 days at 20 degrees C. During emergence and seedling growth, non-primed seeds were irrigated with local irrigation water (EC: 0.3 dS m(-1)) whereas primed groups were treated with 9.0 dS m(-1) saline solution for 35 days. Seedlings derived from pre-treated (P) and non-pre-treated (NP) groups were transplanted to 8 1 pots. After transplanting, salinity treatments were started with the first irrigation. The salinity treatments consisted of five levels (control, 4.5, 9.0, 13.5 and 18.0 dS m(-1)) of irrigation solution for a period of 90 days. NaCl pre-treatments diminished the inhibiting effect of salinity on growth of melon plants. However, competence for salt adaptation varied with cultivar and the level of salinity. The physiological response of the P plants was also maintained in the long-term. Stomatal conductance and relative chlorophyll content of P plants tended to be higher than those of the NP ones. In addition, NaCl pre-treatments enhanced K and Ca concentrations of leaves and stems, and prevented toxic effects of salinity because less Na accumulated in stems. These results suggest that the use of NaCl pre-treatments could be a useful strategy to increase the salt tolerance of melon plants in the long-term and also to permit the establishment of melon crop by direct sowing in a saline medium.

We investigated the possibility that oxidative stress contributes to blossom-end rot (BER) initiation in bell pepper (Capsicum annuum L.) grown under high salinity. Pepper plants (cv. Mazurka, Rijk Zwaan, the Netherlands) were grown in a greenhouse and irrigated with nutrient solution made up with either desalinated water (control - rising from E.C. 1.9 to 2.4 dS m -1 ) or saline water (salinity - rising from E.C. 3.2 to 7.0 dS m -1 ). Irrigation was by a circulation system. BER symptoms were observed throughout the experiment but were highly enhanced in the salinity-grown plants during the spring and summer. The fruit calcium concentration was not affected by salinity, but manganese concentrations in both leaves and fruits were significantly reduced under these conditions. Under salinity there was an enhancement of apoplast reactive oxygen species (ROS) production, which was partly a result of increase in NAD(P)H oxidase activity in the pericarp of pepper fruit at the stage that it was most sensitive to BER. Apoplast ROS production and extracted NAD(P)H oxidase activity were inhibited by manganese, zinc and to a lesser extent by calcium. These cations also negated the enhancement of ROS production caused by incubation of fruit pericarp discs in NaCI solutions. Manganese, zinc and calcium also inhibited NAD(P)H oxidase activity, extracted following their infiltration into fruit pericarp discs. The results suggest that generation and scavenging of oxygen free radicals in the apoplast may contribute to the appearance of BER symptoms in pepper fruits under saline conditions. It is suggested that manganese may serve as antioxidant in pepper fruit and that manganese addition to peppers grown under salinity may alleviate BER symptoms in the fruits.

Seedlings of two strawberry cultivars ‘Camarosa’ and ‘Chandler’ were grown using perlite in a greenhouse for 20 days, and then plants were watered with nutrient solution containing 0, 8.5, 17.0, and 34.0 mM sodium chloride (NaCl) for 6 months. Sodium chloride treatments generally reduced the leaf and root dry weight. Relative water content (RWC) of leaves was maintained despite the increased salt concentrations while loss of turgidity was increased by sodium chloride (NaCl) treatments in both cultivars. As the most variable amino acids, aspartic acid, glutamic acid, arginine, proline, serine, and alanine were determined under salt stress in plants. Sodium chloride treatments generally increased sodium (Na) and chloride (Cl) contents in all plant parts. The plants were able to maintain high potassium (K) levels in the aerial parts with the 8.5 mM NaCl treatment. It can be concluded that ‘Camarosa’ has the ability to osmotic regulation. ‘Chandler’ also tolerates the salt injury at low salt concentrations.

Various concentrations of NaCl (0, 500, 1000, and 2000 mg/L) were applied to plants of the “Camarosa” and “Tioga” strawberry varieties for 10 weeks. At the end of the experiment, it was determined that the leaf dry weight increased especially at 500 and 1000 mg/L NaCl treatments when compared to control treatment. However, salt applications did not change total chlorophyll content. With the salt applications, iron (Fe) and manganese (Mn) content increased, while copper (Cu) content did not change in the aerial part of plants in both varieties. On the other hand, zinc (Zn) content increased in the “Tioga” strawberry variety. In the root part of plants, Fe, Zn, Mn and contents did not change according to salt applications in both strawberry varieties. However, 2000 mg/L NaCl of salt applications increased Cu content in the “Camarosa” strawberry variety significantly. *This study is part of the Ph.D. thesis project supported by Uludag University Research Foundation as project no. 2000/24.