ABSTRACT. Determination of S-allele combinations of sweet cherry genotypes and cultivars has importance for both growers and breeders. We determined S-allele combinations of 40 local Turkish sweet cherry genotypes using a PCR-based method. Ten different S-alleles were detected. Although the most common S-allele was S 3 , as also found in Western genotypes and cultivars, there were some differences in the frequencies of some S-alleles between Turkish and Western sweet cherry genotypes. According to their S-allele compositions, 30 local Turkish sweet cherry genotypes were assigned to 10 previously identified incompatibility groups. For the remaining genotypes, whose S-allele combinations did not fit to any previous incompatibility groups, three more incompatibility groups, XLII, XLIII and XLIV, were proposed. Results obtained from this study will help both sweet cherry growers and breeders to better manage these local Turkish sweet cherry genotypes in their orchards.

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.

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.

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°C and −5°C injured to a limited extent in both stages. However, more than 50% injury occurred by temperatures equal to or colder than −15°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.

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This study examines the molecular effects of drought and recovery applications on four strawberry (Fragaria × ananassa Duch) cultivars known as relatively heat-tolerant [‘Redlands Hope’ (‘R. Hope’) and ‘Camarosa’] and heat-sensitive [‘Festival’ and ‘Cal. Giant-3’ (‘CG-3’)]. After frigo seedlings were grown in a greenhouse for eight weeks (until they had five-six leaves) in a pot, 10% Poliethyleneglycol 6000 (PEG) was applied in order to compose drought condition for 15 days. Following PEG application, plants were watered without PEG for 15 days to observe the recovery. Leaf relative water content (RWC), loss of turgidity, cell membrane injury, proline content and the activities of ascorbate peroxidase (APX, EC 1.1.11.1), glutathione reductase (GR, EC 1.6.4.2) and peroxidase (PRX, EC 1.11.1.7) were determined in leaf tissues taken from plants at the end of the drought and recovery applications. Although membrane injury was increased by the PEG application, it reduced almost to the control levels at the end of the recovery period. Proline contents were found higher in cvs. ‘R. Hope’ and ‘Camarosa’ than cvs. ‘Festival’ and ‘CG-3’ under drought conditions. APX and GR enzymes showed great activities in drought applied plants of heat-tolerant cultivars. Native polyacrylamide gel electrophoresis (PAGE) of basic PRX isozymes yielded three protein bands with Rf = 0.45, Rf = 0.55 and Rf = 0.60 that were sharply increased their activities by PEG and recovery applications in cvs. ‘R. Hope’ and ‘Camarosa’. In addition, leaves of all cultivars exposed to drought rolled up and had brown colour in various level as an indication of tolerance. Indeed ‘Camarosa’ and ‘R. Hope’ showed better recovery performance after rewatering than ‘Festival’ and ‘CG-3’. All data indicated that heat-tolerant cultivars showed relatively drought tolerance in this study.

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Article Info Received : 27.11.2015 Accepted : 22.03.2016 In this study, effect of mycorrhiza on growth criteria and phosphorus nutrition of lettuce (Lactuca sativa L.) under different phosphorus fertilization rates were investigated. Phosphorus were added into growing media as 0, 50, 100 and 200 mg P2O5/kg with and without mycorrhiza applications. Phosphorus applications significantly increased yield criteria of lettuce according to the control treatment statistically. Mycorrhiza application also significantly increased plant diameter, plant dry weight and phosphor uptake by plant. The highest phosphorus uptakes by plants were determined in 200 mg P2O5/kg treatments as 88.8 mg P/pot with mycorrhiza and 83.1 mg P/pot without mycorrhiza application. In the control at 0 doses of phosphorus with mycorrhiza treatment, phosphorus uptake (69.9 mg P/pot), edible weight (84.36 g), dry weight (8.64 g) and leaf number (28) of lettuce were higher than that (47.7 mg P/pot, 59.33 g, 6.75 g and 20, respectively) in the control without mycorrhiza application. It was determined that mycorrhiza had positive effect on growth criteria and phosphorus nutrition by lettuce plant, and this effect decreased at higher phosphorus application rates.