محمدرضا دیلمقانی

Somatic embryogenesis is an alternative method for genetic improvement of commercially important cultivars and is an effective technique for plant propagation.In this research, effects of different factors were studied on embryogenic callus formation from different explants (petal, filament, receptacle, leaf and stem) in M.26 apple dwarf rootstock. MS basal medium supplemented with different concentrations of NAA and 2,4-D (0, 1, 2, 3 and 4 mg/l) was used for embryogenic callus induction. Auxin treatments showed significant effects on callus induction and percentage of induced explants in mediums containing NAA was higher than that of mediums containing 2,4-D. Petal explantson medium with 4 mg/l NAA had higher percentage of embryogenic callus. Higher percent of globular embryosinduction was observed in B3 treatment (MS+1 mg/l TDZ+1 mg/l ABA+0.5 mg/l GA7).

The main reasons for the fixation of some elements and consequently nutrient deficiencies, especially phosphorus, iron and zinc, are high levels of calcium (calcareous soils) and soil pH. Two sulfur fertilizers (sulfur alone and sulfur + organic material + Thiobacillus spp.) with two rates (2 and 4 kg sulfur/tree) were used to decrease soil pH and availability of P, Fe and Zn in apple trees during the growing season. A control treatment with no sulfur was also included in the experiment. The experiment was based on randomized complete blocks design with three replications and was carried out in the apple orchards of the West Azarbaijan province. Results showed that the sulfur treatments had significant effects on soil pH, chlorophyll content of leaves and phosphorus, iron and zinc concentrations of leaves and fruits in apple. On the average, applying sulfur decreased pH of soil and increased the chlorophyll content of leaves, and iron, zinc and phosphorus concentration of fruits in apple by17.09%, 4.8%, 30.24%, 11.61% and 18.76%, respectively, as compared to the control. Regarding the soil pH and other criteria about the nutrients availability and concentration, it seems that the application of 2 kg/tree sulfur fertilizer would be beneficial for apple orchards located in the highly alkaline soils of the area under study.

The effect of postharvest UV-C irradiation on phenolic compounds accumulation was investigated in berries of ‘Rishbaba’ table grape (Vitis vinifera cv. Rishbaba). Grape clusters were harvested at mature stage and irradiated with UV-C using fluorescent germicidal lamp (30 W, 90 cm) with a peak emission at 254 nm for 0 (control), 5 and 10 min. UV-C treatment had significant effect on individual phenolic compounds. Catechin, epicatechin, procyanidin B2, quercetin 3-galactoside, quercetin 3-rhamnoside, chlorogenic acid and total polyphenols increased with UV-C dosage, but procyanidin B1 and cyanidin 3-galactoside decreased. Positive correlation was observed between UV-C treatment and individual phenolics except procyanidin B1 and cyanidin 3-galactoside. In conclusion, UV-C irradiation increased phenolic compounds of ‘Rishbaba’ table grape and its nutritional value.

The entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. is one of the important arthropod pathogens that can play an important role in the regulation of mite populations in agricultural ecosystems. In this study, the combined effect of a native isolate of fungus B. bassiana (EUT105) and ether-extract of plant, Ginkgo biloba was evaluated against the two-spotted spider mite, Tetranychus urticae Koch. At first, effect of three concentrations 5, 10 and 20% of G. biloba was evaluated on B. bassiana conidial germination and mycelial growth. Then, potential synergism between B. bassiana and G. biloba was investigated in order to incorporate both in the control of this pest. Only the 20% concentration of plant extract had significantly inhibitive effect on germination and mycelial growth. The mortality of adult female T. urticae increased significantly when B. bassiana was applied with 5 and 10% concentrations of G. biloba extract. Hence, there is a synergistic effect between this native B. bassiana and ether-extract of G. biloba in controlling the two-spotted spider mite.