IRANIAN JOURNAL OF HORTICULTURAL SCIENCE AND TECHNOLOGY
Year:2010 | Volume:10 | Issue:4|Papers Count:7

This research was conducted to investigate the effects of harvesting date on nut characteristics of Persian walnut (Juglans regia L.). The treatments of experiment were four different dates of harvesting including 5th, 12th, 19th and 26th August 2008. The experiment was laid out as a completely randomized design with 45 replications, with each replication containing 20 nuts harvested from different sides of a mature Persian walnut tree with more than 15 years old. Trees were selected randomly from an orchard originating from seeds. Based on the results obtained in this study there was no significant difference among different harvesting dates for length, diameter, width and shell thickness of nuts. Average nut dry weight of those nuts harvested on 5th August was significantly less than those harvested on 12th or 26th August. The percentage of harvested nuts with dehiscent husk on 26th August was significantly greater than those of other harvesting dates. 80.39% of nuts that harvested on 29th August had light kernels and significantly less than other dates of harvesting. Maximum kernel percentage and average kernel dry weight was belonged to nuts that harvested on 29th August and significantly greater than those harvested at other dates. It was concluded from this study that the best index for walnut harvesting date is when packing tissues color of kernel turned from white to brown and husk dehiscence is not a reliable index for harvesting date of Persian walnut.

Mycorrhizal fungi play an important role in the water and mineral nutrients uptake improvement from soil. In order to investigate the effect of arbuscular mycorrhizal fungi on water relation of onion cv. ‘Red Azarshahr’ under three irrigation intervals in two soil condition (sterile and unsterile) in a greenhouse pot experiment carried out in the University of Tabriz, Tabriz, Iran. Three preinoculated onion seedling in nursery with Glomus versiforme, Glomus intraradices and Glomus etunicatum and uninoculated seedling as a control were transplanted to the pots filled with 7 kg soil. Plants were irrigated to the field capacity every 7, 9 and II days. Along trial period, leaf relative water content (RWC), osmotic potential and free proline content were measured, then leaf potential adjustment were computed. The results indicated that, nonmycorrhizal onions had significantly higher RWC than mycorrhizal ones. Mycorrhizal onions showed lower osmotic potential and free proline than control plants, so mycorrhizal colonization improved osmotic adjustment. It was concluded that mycorrhizal onions could reduce water deficit stress by lowering leaf osmotic potential through improving absorption and accumulation of mineral solutes that enable plants to improve osmotic adjustment to uptake water from drying soil.

In order to determine the effects of number of oxidative stresses on regulation and expression of a-DOX1 .a-DOX3 Le 16 and clEc11DI5 genes in tomato shoot tissue this study was conducted under greenhouse (soil culture) and hydroponic culture conditions. Three tomato genotypes including wild type ‘Ailsa Craig’ CAC’), the near isogenic ABA deficient ‘Flacca’ (‘Fie’) strain and the ethylene receptor mutant ‘Never ripe’ (Nr’) were used. The tomato plants were subjected to different types of oxidative stresses. Shoot tissue of stress-treated plants were harvested and subjected to RNR extraction and northern hybridization analysis with probes of above mentioned genes. Results showed that Le 16 gene up regulated only by salt and drought stresses in ‘AC’ and ‘Nr’ genotypes but not in ‘Flc’ indicating ethylene-dependent of Le 16 gene. Over expression of this gene in ‘Nr’ cultivar was increased by increasing salinity levels and plant growth stage but ‘AC’ cultivar showed reverse response. a-DOX1 up regulated by H2O2 and wounding treatments. This is the first report of over expression of a-DOX1 in the shoot tissue of tomato plants. Up regulation of a-DOX3 was detected following jasmonic acid and paraquat treatments in leaves of ‘Fie’ but not in the others, indicating that abscisic acid is a key regulator of a-DOX3 expression. Although cLEC11 DI5 gene expressed in leaves of above three genotypes by all treatments but over expression was observed only in ‘Fie’ by jasmonic acid and paraquat. So, up regulation of cLEC11DI5 gene in leaves of treated plants was ABA- dependent. In general, this study showed that Le 16, cLEC11D15 and a-DO3 up regulated in leaves of tomato plants by a number of oxidative stresses. In contracts with previous reports a-DOX1 up regulated in leaves of ‘AC’ cultivar in response to H2O2 and wounding stresses. Probably by transferring of H2O2 from roots to shoot and producing of H2O2 by wounding.

An investigation was conducted to study the effects of growing media on quality and quantity characteristics of Lilium cut flowers cultivars and their vase life in a factorial experiment based on completely randomized design with three replications. The factors included cultivars in six levels (‘Amarone’, ‘Orlando’, ‘Pink superior’, ‘Pollyanna’, ‘Salsa’, ‘Vignola’), growing media in two levels ( 1/3 coco peat +1/3 perlite +1/3 loam and 1/3 sand +1/3 leaf mold + 1/3 loam) and three different preservative solutions (gibberellic acid, 8- hydroxyquinoline + sucrose and distilled water). The bulbs were planted in two growing media inside the greenhouse. Flowering time. number of flower buds, stem length and chlorophyll content were measured before harvest. All the flowers were picked and pulsed with different preservative solution for 24 hours. Then, cut flowers were transferred to distilled water at temperature of 22°C. Vase life, longevity of leaves, fresh weight and chlorophyll content were measured. Stem length in growing media involve coco peat + perlite was 4.39 cm more than another media. Effects of cultivars were significant on all the characteristics and ‘Salsa’ (mean of 10.25 numbers) has the highest numbers of buds. The cultivar ‘Arnarone’ treated with gibberellic acid showed 43.50% and 55.21 % increase over the control for vase life and longevity of leaves, respectively.

In order to study the effect of different amount of nitrogen and different time of application on yield and nitrate content in potato an experiment was conducted in 2006 in Raziabad farm. Treatments imposed were as follows: Five levels of nitrogen (0, 90, 180, 270 and 360 kg ha-1) as a main factor and four times of application T1: one third at planting, one third at emergence and one third before flowering, T2: one half at emergence and one half before flowering, T3: two third at emergence and one third before flowering, and T4: one third at emergence, one .third twenty five days later and one third before flowering. The experiment was a: complete randomized block with three replications. At harvest plant height, number of tubers per plant, average tuber weight, yield per plant, average tuber dry weight and the amount of nitrate accumulated in the tuber were measured. Results indicated that with increased nitrogen plant height, and the amount of dry weight increased but tuber number decreased both amount and time of application had pronounced effect on yield and average tuber weight. Highest yield obtained with T4 (180 kg N ha-1), however yield decreased when higher amount on nitrogen was used. The amount of nitrate accumulated in the tubers was affected by nitrogen and time of application. Highest amount of nitrate corresponded with 360 kg N ha-1 at T2 and T3.

In order to study the effect of drought stress on yield and some physiological indices in Petroselinum crispum a pot experiment was carried out using 2´5 factorial experiment with completely randomized design on two population of parsley (plain-leafed parsley and curly leafed parsley) with 5 moisture regime. The water treatments were normal irrigation (with 30 kPa matric tension) as a control and four deficit irrigation with 50, 80, 200 and 500 kPa matric tension, respectively. The plants were watered equally until four leaves stage then with daily weighting the pots and adding the water used by plants and evaporation. By this method the water of pots were fixed. During the experiment yield, relative water content (RWC), leaf water potential, number of stomata, leaf area and at the end of stress period amount of proline and soluble carbohydrate were measured. The result showed that stress levels had significant effect on all measured parameters. Water deficit reduced the yield, leaf water potential, RWC and leaf area, but increased proline, number of stomata and soluble sugars. Effect of population on leaf area, dry and fresh weights, relative water content and leaf water potential were significant. It was concluded the curley-leaf parsley with higher leaf water potential, lower leaf area than the plain-leafed parsley had higher tolerance to this drought stress.