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The morphological and physiological parameters were measured for 15 green bean genotypes, and enzymatic activities were measured for two genotypes (tolerant and sensitive) grown under controlled greenhouse conditions during waterlogging stress and recovery periods. Plants were exposed to waterlogging stress for 7 days followed by 7 days of recovery. The leaf area and color, leaf relative water content and turgid losses, and the degree of cell membrane injury were determined. ‘Seker Fasulye’ genotype was relatively tolerant among the genotypes studied. Besides, waterlogging treatment caused the loss of sampled organs in the sensitive genotypes, ‘40 Gunluk’, ‘L3’, and ‘L4’. After these three genotypes, the ‘L1’ genotype was found to be sensitive. Therefore, enzymatic activities were measured for ‘Seker Fasulye’ and ‘L1’. Nicotinamide adenine dinucleotide phosphate oxidase [NAD(P)H oxidase, EC.1.6.3.1] activity increased during waterlogging treatment and decreased during the recovery period. To the contrary, waterlogging treatment degraded catalase (CAT, EC.1.11.1.6) and glutathione reductase (GR, EC.1.6.4.2) activities in leaves and roots. The activity of both enzymes increased during recovery treatment. In conclusion, leaf area, cell membrane injury, and stress-related enzyme activities were found to be an effective means for determining a green bean genotype’s response to waterlogging stress.

The mechanism of tolerance to high temperatures was investigated in two strawberry (Fragaria × ananassa Duch) cultivars, ‘Redlands Hope’ (‘R. Hope’, heat tolerant) and ‘Cal. Giant 3’ (‘CG3’, heat sensitive). Leaves were collected from plants that were exposed to gradual heat stress and heat-shock stress separately. The contents of nonenzymatic antioxidants such as ascorbic acid (AsA) and glutathione (GSH) and the activities of enzymatic antioxidants such as ascorbate peroxidase (APX) (EC 1.11.1.11), catalase (CAT) (EC 1.11.1.6), and glutathione reductase (GR) (EC. 1.6.4.2) were measured followed by heat treatments. Additionally, proline content was determined, and heat shock proteins (HSPs) were analyzed with an immunoblotting method to investigate protein markers involved in the heat-stress tolerance of strawberry plants. The contents of AsA and GSH did not change depending on heat stress type, temperatures, or cultivars. While APX and CAT activities increased with high temperatures, GR activity was almost unchanged. The proline content of the cultivars increased in both treatments. Anti-HSP60 immunoblots revealed that a 23 kDa polypeptide was detected during the heat acclimation of strawberry cultivars. The intensity of the heat shock protein in ‘R. Hope’ plants was more than in ‘CG3’ plants. Thus, the accumulation of 23 kDa heat shock protein was correlated with the heat tolerance of the cultivars. In conclusion, strawberry leaf tissues of ‘R. Hope’ were found to enhance the structural stability of cellular membranes under high temperature by increasing both the activity of such enzymes as CAT and APX to activate the antioxidative systems and the expression of 23 kDa HSP. © TUBİTAK. 108O063 Grants from the Scientific and Technological Research Council of Turkey (T?B?TAK-TOVAG, 108O063) supported the current research. The authors are thankful to Yaltir A.S. for their material support regarding strawberry seedlings

The bark tissues were collected from 4-year-old sweet cherry trees cvs. 0900 Ziraat and Lambert grafted on Gisela 5 and Mazzard rootstocks in cold-acclimated (CA) and nonacclimated (NA) stages. Bark tissues subjected to 4 degrees C and -5 degrees C injured to a limited extent in both stages. However, more than 50% injury occurred by temperatures equal to or colder than -15 degrees C only in NA period. Total soluble sugar (TSS), reducing sugars, and sucrose contents were higher in CA than those in NA stages in all samples. The activities of acid invertase (EC 3.2.1.26) and sucrose synthase (SS) (EC 2.4.2.13) enzymes were higher in NA stage than those in CA stage. Considering the rootstocks, reducing sugars were higher in both cultivars grafted on Gisela 5 whereas sucrose contents were higher in both cultivars grafted on Mazzard. However, the enzyme activities of both cultivars were higher on Mazzard rootstock than on Gisela 5. In conclusion, cold hardiness of sweet cherry graft combinations was suggested by increasing their TSS, reducing sugars, and sucrose contents significantly in the CA stage. Moreover, acid invertase and SS are down regulated during cold acclimation. Indeed the results suggested that Mazzard is more cold-hardy rootstock than Gisela 5.

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...

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.

Physiological parameters were used to investigate genotypic variations in 15 strawberry cultivars [‘Aromas’, ‘Camarosa’, ‘Carmine’, ‘Cal. Giant 3’ (CG3), ‘Cal. Giant 5’ (CG5), ‘Elsanta’, ‘Fern’, ‘Festival’, ‘Honeoye’, ‘Kabarla’, ‘Redlands Hope’ (R.Hope), ‘Ruby Gem’, ‘Selva’, ‘Sweet Charlie’ and ‘Whitney’] and their relationship to heat-stress tolerance (HST). Cold stored (frigo) strawberry seedlings were grown in pots for six weeks and then transferred to a growth chamber. The temperature in the growth chamber was increased stepwise from 35 to 40, 45 and 50°C to create a heat-stressed environment. Leaf relative water content (RWC), loss of turgidity and chlorophyll content were measured at each temperature. The ‘Elsanta’ and ‘R.Hope’ had the highest RWC, while the ‘Festival’ and ‘CG3’ had the lowest. However, ‘Elsanta’ and ‘R.Hope’ had the lowest loss of turgidity, while ‘Festival’ and ‘CG3’ had the highest. ‘Elsanta’ and ‘R.Hope’ showed the lowest chlorophyll content, and ‘CG3’ and ‘Whitney’ had the highest. To determine HST (LT50), leaf discs of each cultivar were exposed to 35, 40, 45, 50, 55 and 60°C. A considerable decrease in the LT50 was observed with increasing temperature in all cultivars. The LT50 of the cultivars ranged from 51.8 to 52.9°C. Based on the data collected, ‘Elsanta’, ‘R. Hope’ and ‘Camarosa’ were determined to be relatively heat-tolerant cultivars, while ‘Whitney’, ‘Fern’, ‘Festival’ and ‘CG3’ were heat-sensitive cultivars.

Plants of strawberry cvs Aromas and Diamante were removed from the field in cold acclimated (CA, January) and non-acclimated (NA, July) stages. Crown parts of the plant were used for analysis. Apoplastic total soluble sugar (TSS), reducing sugars and sucrose contents did not change in both cultivars in both sampling stages. Symplastic TSS, reducing sugars and sucrose contents were higher in CA stage than that in NA stage in all samples. Considering the cultivars, TSS, reducing sugars and sucrose contents were higher in Diamante than Aromas. The activity of acid invertase (EC 3.2.1.26) enzyme was higher in NA stage than that in CA stage in the apoplast of crown tissues. In general, acid invertase activity in the symplast of crown tissues in both cultivars was higher in CA stage compared with that in NA stage although not significantly, as a function of hardening. In addition generally, the cultivars had significantly higher sucrose synthase (SS) (EC 2.4.2.13) activity in the symplast of crown tissues when sampled at the CA than at the NA stage. In conclusion, cold-hardiness of strawberry was suggested by increasing their TSS, reducing sugars and sucrose contents significantly in the symplast of crown tissues in the CA stage. Moreover, both acid invertase and SS are regulated by cold-acclimation and deacclimation.Key words: Acid invertase, apoplast, cold-acclimation, Fragaria x ananassa, soluble sugar, strawberry, sucrose synthase, symplast.

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.

In this study, apoplastic antioxidant enzymes in the leaves of two strawberry cultivars ('Aromas' and 'Diamante') and their relationship to cold-hardiness were investigated. Fully expanded, uniformly sized leaves from 1-year-old field plants of the cultivars were collected at the hardening (late autumn, in November and winter, in January) and de-hardening (summer, in July) stages. Leaf samples were exposed to low temperatures of 5, -5, -10, -20 and -30 degrees C for 12 h to determine their cold-hardiness (LT50; lethal temperature, where 50% of the plants were killed). Cold-acclimation produced a remarkable increase in cold-hardiness. It was found that Diamante had higher cold-hardiness than 'Aromas'. Moreover, malondialdehyde and total carotenoid content increased during the hardening stage and decreased during the de-hardening stage. The activities of catalase, peroxidase and ascorbate peroxidase in the leaf apoplast and nicotinamide adenine dinucleotide phosphate oxidase activity in the leaf tissue were correlated with changes in cold-hardiness. The activities of these enzymes were higher in the hardening stage than in the de-hardening stage. The activities of apoplastic catalase, peroxidase and ascorbate peroxidase varied significantly depending on the cold-acclimation stage and the cold-hardiness level of the cultivars. This study indicates that elevated apoplastic antioxidative enzymes may be determinants of cold-hardiness in the strawberry plant. The lower malondialdehyde content and higher total carotenoid and apoplastic enzyme activities in 'Diamante' indicated an enhanced cold-hardiness capacity of this cultivar, serving to protect the plant from oxidative damage. Ciltar A. Ş. (Adana, Türkiye)