In the present study, the effects of three ethylene inhibitors, silver nitrate (AgNO 3 ), silver sulfate (Ag 2 SO 4 ), and cobalt chloride (CoCl 2 ), on the morphogenic and biochemical responses in CAB-6P and Gisela 6 cherry rootstocks were investigated. In both rootstocks, AgNO 3 and Ag 2 SO 4 promoted shoot regeneration while CoCl 2 had such an effect only in Gisela 6. The rooting percentage of CAB-6P and Gisela 6 explants was diminished with AgNO 3 , Ag 2 SO 4 , and CoCl 2 . AgNO 3 increased root number (40 µM) and root length (50 µM) in the CAB-6P rootstock while it had an inhibitory effect in Gisela 6. Ag 2 SO 4 and CoCl 2 enhanced root length of Gisela 6 explants whereas Ag 2 SO 4 decreased root number and root length of CAB-6P explants. CoCl 2 at 10 µM in both rootstocks augmented root number whereas 20 µM CoCl 2 increased root length of CAB-6P microshoots. AgNO 3 , Ag 2 SO 4 , and CoCl 2 decreased leaf chlorophyll and carbohydrate content in CAB-6P rootstock. On the other hand, in Gisela 6, 10 µM AgNO 3 gave elevated chlorophyll levels and 20 µM AgNO 3 or 10-50 µM CoCl 2 raised leaf carbohydrate content. The three ethylene inhibitors led to elevated leaf proline levels in the CAB-6P rootstock, whereas in Gisela 6 the increase or decrease in leaf proline content was dependent on both type and concentration of ethylene inhibitor. An efficient micropropagation protocol was established for the CAB-6P and Gisela 6 cherry rootstocks using ethylene inhibitors.

The present study investigates the effects of indole-3-butyric acid (IBA) alone and in combination with myo-inositol on in vitro rooting and biochemical responses in the cherry rootstocks CAB-6P (Prunus cerasus L.) and Gisela 6 (Prunus cerasus × Prunus canescens). For the CAB-6P rootstock, the best results for root number (6.31), fresh mass (FM), dry mass (DM), and rooting percentage (100 %) were obtained on Murashige and Skoog (MS) medium with 2 mg dm -3 IBA and maximum root length (30.57 mm) was obtained at 1 mg dm -3 IBA. Myo-inositol suppressed the positive effects of IBA on root length. In the Gisela 6 explants, the inclusion of 2 mg dm -3 IBA together with 0.5 mg dm -3 of myo-inositol in the culture medium significantly enhanced root number (9.91) and root FM and DM. The root length was maximum in the combination of the lowest IBA and myo-inositol concentrations (0.5 mg dm -3 ). The rooting percentage was the greatest (100 %) with the application of 1 mg dm -3 IBA alone. In both explants, the application of IBA alone or in combination with myo-inositol resulted in a lower leaf proline content in comparison with the control (without growth regulators). The maximum leaf chlorophyll content was at 1 mg dm -3 IBA in the CAB-6P whereas at 2 mg dm -3 IBA and 1 mg dm -3 myo-inositol in Gisela 6. Addition of myo-inositol mostly increased sugar content in comparison with control or IBA alone in both rootstocks.

Two-year-old own-rooted sour orange (Citrus aurantium L.) plants grown in a greenhouse were irrigated for 15 weeks with Hoagland nutrient solutions containing either NaCl (0, 20, 40, 60, 80 or 100 mmol L -1 ) or a combination of salts NaCl + CaCl 2 ·2H 2 O (10 + 10 mmol L -1 , 20 + 20 mmol L -1 , 30 + 30 mmol L -1 , 40 + 40 mmol L -1 and 50 + 50 mmol L -1 ). The effect of the combined treatments on vegetative growth (fresh matter) was similar to the effect of NaCl. Salinity did not affect the leaf water potential, but did significantly increase the water content of the leaves and the shoot : root ratio (fresh matter). Furthermore, the N concentration of the leaves and the Mg concentration of the new stems were reduced, whereas the K concentrations of the leaves increased. Salinity led to a general increase in Na and Cl concentrations in all plant parts. Chloride concentrations were significantly greater than the corresponding Na values in all tissues. Little or no effect of salinity was recorded with regard to the P, Fe, Mn and Zn concentrations. The addition of Ca to the nutrient solution in the form of CaCl 2 ·2H 2 O decreased the Na and Cl concentrations in the leaves. Thus, the application of CaCl 2 ·2H 2 O might mitigate the accumulation of these toxic ions caused by NaCl.Effects of salinity on sour orange plants 911

The effects of sodium nitroprusside (SNP) on micropropagation of CAB-6P and Gisela 6 cherry rootstocks were investigated. Shoot multiplication of CAB-6P was reduced by adding 4.4 µM 6-benzylaminopurine (BA) and SNP. Gisela 6 microcuttings treated with BA + 30 µM SNP gave the highest average shoot number (4.15) and multiplication percentage (100%). In CAB-6P, α-naphthaleneacetic acid (NAA) + 30 µM SNP led to the maximum root number (13.79) and fresh weight (0.336 g); average root length (82 mm) and rooting percentage (95.45%) were greatest after adding 40 and 10 µM SNP + NAA, respectively. In Gisela 6, NAA + 40 µM SNP resulted in the highest root number (9.75) and fresh weight (0.238 g), while NAA + 30 µM SNP enabled maximum root length (30.77 mm). Rooting percentage was greatest (84.62%) when Gisela 6 microcuttings were treated only with NAA. Application of SNP alone in CAB-6P reduced leaf chlorophyll, carbohydrate, and prοline levels. In contrast, 30-50 µM SNP increased leaf chlorophyll levels of Gisela 6. SNP augmented leaf carbohydrate and proline content, but it diminished root carbohydrate content. In BA + SNP or NAA + SNP treatments, changes in biochemical constituents were dependent on SNP concentrations and genotypes.

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