Erwinia amylovora, the causal agent of fire blight disease in rosaceous plants, contains type III secreted effector proteins including DspA/E, HrpN and HrpW, which are secreted into host plants during the pathogenicity stages. In order to investigate the role of these effector proteins in the interaction with the host plants, susceptible (Bartlett), tolerant (Harrow sweet) and resistant (Dargazi) pear cultivars were inoculated with wild-type and mutant strains of E. amylovora (hrpW-, hrpN- and dspA/E-) under in vitro conditions. Based on the results, HrpW protein may be involved in pathogenicity in Dargazi cultivar. Different levels of pathogenicity were observed by dspA/E- mutant in cultivars. The results showed the key role of HrpN in the defense mechanisms of Dargazi cultivar, and its pathogenic role in Harrow sweet and Bartlett cultivars. An increase in ferritin levels was observed in all cultivars inoculated with the wild type strain, but resistant and tolerant cultivars showed higher ferritin levels and a decrease in Fe2+ was observed only in these cultivars. The obtained data show that the HrpW protein does not affect iron homeostasis. Inoculation of Harrow sweet and Dargazi cultivars with all strains increased ferritin, which was associated with a decrease in Fe2+. Based on the results, it is not possible to associate any of the effector proteins with changes in ferritin and Fe2+. In general, the ability of resistant pear cultivars to increase ferritin levels and regulation of iron can be one of the reasons for their resistance to fire blight. According to the results, different mechanisms are employed by pear cultivars to respond to the causative agent of fire blight.

We studied the effect of polyethylene glycol (PEG)-induced osmotic stress on pear cultivars (Harrow sweet and Bartlett) under in-vitro culture conditions. Explants were cultured in QL medium containing 4% and 8% PEG6000 using a factorial experiment based on completely randomized design. The medium without PEG was considered as control. Drought injury index, which was calculated based on morphological disorders, increased at 8% PEG nearly to 2. 00 and 1. 50 units in cv.. Bartlett and Harrow sweet, respectively. Owing to osmotic stress, the increase of malondialdehyde was accompanied with the reduction of cell membrane stability index in both cultivars. Total phenolic components and antioxidant activity in leaves increased significantly in response to application of 4% and 8% PEG. However, the severity of increase was higher in cv. Harrow sweet. It was revealed that cv. Harrow sweet had higher tolerance to osmotic stress than Bartlett. Moreover, the parameters related to oxidative damages and ROS scavenging capacity were more descriminant against osmotic stress under in vitro system.

Oxidative stress of the fire blight disease in host plant consists of chloroplastic and mitochondrial oxidative stresses that leads to the necrosis of tissues. This research was conducted to quantify and compare the role of oxidative stress of these organelles using glutaraldehyde as chloroplastic inhibitor of electron transport chain (ETC) and rotenone as mitochondrial inhibitor ETC. Due to the necrotic effect of inhibitors, in the primarily tests, different concentrations of inhibitors were examined under in vitro conditions and two concentrations of inhibitors (5 and 10 mg l-1) were optimized for co-cultivation tests of host-pathogen interaction. In co-cultivation tests, necrosis appearance was recorded at 48 and 72 hours after inoculation in susceptible cv. Bartlett and tolerant cv. Harrow sweet, respectively. Although both concentrations of inhibitors postponed necrosis appearance and reduced necrosis progress rate, but in cv. Harrow sweet, higher effects of glutaraldehyde were observed in 10 mg l-1. The higher effects of chloroplastic glutaraldehyde inhibitor demonstrated more effective role of the chloroplastic ETC in oxidative stress of pathogen in comparison with the role of mitochondrial ETC. Additionally, in susceptible cv. Bartlett, mitochondrial inhibitor caused similar necrosis progress rate to the chloroplastic inhibitor which demonstrated another evidence for more effective role of chloroplast organelle in resistance to the fire blight disease in cv. Harrow sweet.

A one-way moldboard plow turns over soil in only one direction. Problems created by this type of tillage in Iran include compaction of boundary regions, decreased efficiency of irrigation and disruption of bed leveling, requiring the use of bed-leveling equipment every few years. To overcome these problems, the use of a two-way plow with two Harrows which turns over the soil to both the left and right sides is recommended by specialists. However, the weight and expense of these two-way plows along with the limited power of tractors available in Iran rules out this method for most farmers. The two-way three-Harrow square plow was designed to solve the problems of conventional two-way plows. In this study, the performance of the two-way three-Harrow square plow was compared to the conventional one-way three-Harrow moldboard plow. The tests were conducted according to the RNAM test code and the recommendations of Smith et al. at the training and research farm of the Abureyhan campus of the University of Tehran. The results showed that the bulk density of the soil after tillage by the two-way plow is significantly lower than for the one-way plow and soil evenness created by the two-way plow is more desirable than for the one-way plow. The difference between plow uniformity was not significant for the two types of plow. The mean soil clod diameters were 31.96 mm and 39.86 mm for the two-way and one-way plows, respectively. The draft and tractor wheel slippage of the two-way plow were significantly greater than for the one way plow. It was generally concluded that the performances of the square plow and one-way plow are similar, thus recommending the used of the two-way plow.

Seed priming is one of the seed improvement methods that could increase seed performance (germination and emergence) under stress conditions, such as salinity, temperature and drought stress. In order to study the effect of seed priming on seed germination index and some physiological properties of sweet corn in different levels of salinity, an experiment conducted based on completely randomized design with factorial arrangement with three replications. sweet corn grain was primed with 2% potassium chloride, 3% potassium nitrate, polyethylene glycol (8000) 10%, potassium dehydrogenate phosphate 1% and one treatment as a control at 20oC for 24 hours and then primed grain were treated with four levels of NaCl concentration (0, 50, 100,150, mM). Results showed that seed priming and salinity had significant effect on germination rate, germination percent and some antioxidants such as catalase and peroxidase. In general, results of this experiment revealed that seed priming improved the seed vigor and increased resistance to salinity stress at germination stage.

Evaluation of physical and chemical properties of fruit can help to optimal design and operation of processing, and safe and secure handling. In this study, the textural, physical and chemical characteristics of sweet cherry (cv. Syaahe Mashhad) in the period of ripening were investigated. Changes in the amount of soluble solid, stemming force, firmness, hardness, cohesiveness, resilience, gumminess, chewiness and color indices i.e. lightness (L*), a*, the total color difference (DE),a*/b* , Chroma (C), hue angle were measured. Simultaneously with increasing °Brix, magnitude of true density increased from 0.995±1.13 g/cm3 (for fruits with green color) to 1.032±0.33 g/cm3 (for red color fruits). During ripening period, the force required to stemming, firmness and hardness values decreased with a positive significant correlation (confidence level of 0.95). Changes in the stemming force, firmness and hardness were obtained by 4.89±1.92 N, 1.3± 0.54 N/mm, 3.8± 1.18 N, respectively, from first harvest date (47th day after anthesis( to last harvest date (68th day after anthesis(. Variations in cohesiveness and resilience were relatively insignificant, but gumminess and chewiness decreased. Results showed that during the final days of fruit development, L* and Hue angle parameters decreased, but total color differences )DE( and a*/b* increased.

About 60% of the mechanical energy consumed in mechanized agriculture is used for tillage operations and seedbed preparation. On the other hand, unsuitable tillage system resulted in soil degradation, affecting soil physical properties and destroying soil structure. The objective of this research was to compare the effects of three types of secondary tillage machines on soil physical properties and their field performances. An experiment was conducted in a wheat farm in Jouybar area of Mazandaran as split plots based on randomized complete block design with three replications. The main independent variable (plot) was soil moisture with three levels (23.6-25, 22.2-23.6 and 20.8-22.2 percent based on dry weight) and the subplot was three types of machine (twodisk perpendicular passing Harrow, Power Harrow and Rotary tiller). The measured parameters included: clod mean weight diameter, soil bulk density, specific fuel consumption, machine efficiency and machine capacity.The effects of treatments and their interactions on the specific fuel consumption, machine efficiency and machine capacity and also the effects of treatments on bulk density were significant (P<0.01). The bulk density decreased 15.3%, the specific fuel consumption increased 11.8%, whereas the machine efficiency and machine capacity increased and decreased with the decrease in soil moisture, respectively. The maximum value of the bulk density and machine efficiency were obtained by the use of rotary tiller and the maximum value of the specific fuel consumption and machine capacity were obtained by the use of power Harrow. A criterion was defined for selecting machine type and moisture content for optimum condition. The results suggested power Harrow working at soil moisture condition of 24.3% (based on dry weight).

Introduction Cherry fruit has a high nutritional value and because of its favorable taste, its attractive appearance is of great importance. Iran is the origin of many horticultural products, especially cherries. The quality and quantity of the Iranian cherry crop are much more suitable in comparison with other producing countries due to suitable climatic conditions and significant areas under cultivation. This fruit has a very short shelf life due to its susceptibility to transport damage. After harvest, the cherry fruit decays quickly and in some cases, due to the time of transfer and marketing, does not reach consumers with good quality. Therefore, the use of natural compounds to increase shelf life and maintain its quality seems necessary inlcuding lower moisture, and perishability. On the other hand, storage of products involves a series of biochemical changes that take place, which is accompanied by softening of the fruit, destruction of the cell wall, and reduction of the external and internal quality of the products. Therefore, the use of appropriate compounds to increase durability and maintain its quality seems necessary. Phytohormonal treatments such as melatonin increase the cold resistance of fruits during storage and reduce the development of mechanical damage in the refrigerator during fruit storage. Melatonins have an amphiphilic indole ring structure, through which they can easily move out of the cell and play a role in the structure of the cell wall or membrane. Besides, melatonin is structurally similar to auxin and has similar effects, helping to maintain cell wall structure under stress and reducing the denaturation of cell wall proteins. Melatonin is also known as a biostimulant. These biostimulants in plants affect the production of secondary metabolites, biosynthesis of various phytohormones, facilitate plant uptake of nutrients, stimulate growth, and increase product quality and quantity. Melatonin, in interaction with other signaling agents, increases fruit metabolism and induces stress resistance. Materials and Methods In the present study, cherry fruits were harvested from the commercial garden at full maturity and after washing with distilled water with zero melatonin (control), 50, 100, 200 micromolar were treated by immersion for 5 minutes and Store at 1. 5 with a relative humidity of 85% for 35 days. Parameters such as weight loss, titratable acidity, organic acids, soluble solids, antioxidants (DPPH), phenolic compounds, anthocyanin content, peroxidase, and ascorbate peroxidase activity were examined per week. Results and Discussion The results indicated that fruits treated with 200 μM melatonin showed less weight loss than other treatments and controls, and melatonin prevented fruit water loss, as well as of phenolic compounds, titratable acidity, soluble solids. The activity of peroxidase and ascorbate peroxidase enzymes have all increased. These compounds preserve the fruits during storage and increase the oxidation resistance. Melatonin coating on cherry fruit and can protect cells from stress by raising antioxidant levels. Consumption of edible coatings on horticultural products such as fruits increases durability and marketability. Edible coatings reduce fruit rot and prevent microbial growth on their surface. These coatings have a positive effect on physical properties and reduce physiological activity. Oral coatings better preserve organic acids by changing the internal atmosphere and slowing down the respiration of the fruit. Conclusion The use of exogenous compounds or growth regulators has in many cases been effective in reducing the effects of environmental stresses. These results show that the combination of melatonin has high antioxidant properties and can act as a protective compound and inhibit free radicals. Besides, it acts as a signaling molecule at the cellular level and manages antioxidant activity, thus preventing membrane damage and lipid peroxidation of the membrane. Melatonin also increases plant tolerance to environmental stresses and follows this mechanism by regulating gene expression in various horticultural crops. The use of melatonin improves the process of coping with oxidative stress by further regulating the biosynthesis of anthocyanins and the antioxidant-encoding gene. Decomposition of cell wall compounds may increase total soluble solids, melatonin reduces the process of wall destruction, and preserves the appearance of the fruit. Increasing the amount of soluble solids increases the total antioxidant, phenolic and increases the activity of antioxidant enzymes. Melatonin is also at the forefront of stress management, and other antioxidants act as support after melatonin. Melatonin can prevent further stress damage by activating the plant signaling pathway.

Fire blight, the most important disease of pear tree causes necrosis by an oxidative stress in tissues. Therefore, identification of resistant cultivars and mechanisms of resistance to the oxidative stress of disease, that are mainly related to the chloroplasts, are important in breeding programs of this tree. In order to study the role of chloroplasts in this interaction, expression of chloroplastic gene psbA that are under control of oxidation/reduction (redox), was evaluated in susceptible (Williams) and resistant (Harrow sweet) cultivars during 48 h post inoculation by Erwinia amylovora in in vitro condition. In addition, expression of this gene was studied at presence of glutaraldehyde and rotenone as the inhibitors of the electron transport chain of chloroplast and mitochondria, respectively. The results showed higher necrosis progress rate in the in vitroshootlets of susceptible cultivar. Expression of psbA gene at presence of inhibitors in both presence and absence of E. amylovora was higher in cultivars Harrow sweet. According to the results, the higher resistance level of cultivars Harrow sweet to the disease could be due to the higher rapid responses and reaction of the chloroplasts of this cultivar in comparison to the cultivar Williams.

Most sweet cherry cultivars are as found as self-incompatible and therefore for commercial fruit production, compatible pollinizers are needed. Controlled pollination and microscopic examination of pollen tube growth in the style are two classical methods for determination of compatible and incompatible pollen donor cultivars. This experiment was carried out to explore the compatibility of ‘Zarde Daneshkadea’ as a seed parent cultivar with ‘Sefid Rezaieh’, ‘Napoleon’, ‘Abardeh’, ‘Bing’ and ‘Shabestar’ as pollen parent cultivars in using hand pollination and controlled hybridization technique. Eight samples of pollinated flowers (pistil) using different treatments were maintained and fixed in FAA solution for further microscopic examination. In order to determine the effect of pollen source on the fruit qualitative and quantitative characteristics, some fruit criteria were evaluated. According to the microscopic examination of pollen germination on the stigma and pollen tube growth within the style, pollen of ‘Shabestar’, ‘Sefid Rezaieh’ and ‘Napoleon’ cultivars very well germinated on ‘Zarde Daneshkadea’ stigma with the pollen tube getting into the ovule within 96 to 120 hours after pollination. The studied cultivars showed compatibility with ‘Zarde Daneshkadea’ cultivar. In addition, microscopic examinations showed self-incompatibility for ‘Zarde Daneshkadea’ cultivar. Therefore, ‘Zarde Daneshkadea’ is a self-incompatible cultivar and according to the obtained results ‘Shabestar’, ‘Sefid Rezaieh’ and ‘Napoleon’ cultivars are suitable polinizers. Also pollen tube growth of `Abardeh’ and ‘Bing’ cultivars stopped in the first third length of style of ‘Zarde Daneshkadea’, so showed incompatibility with this cultivar. Although, some obtained results showed differences between fruit length and width and in addition significant differences were observed in some replicates on seed weight, fruit length, fruit width and percent soluble solid contents (oBrix), but further we suggest supplemental research on the effect of pollen source on fruit quality is needed and suggested.