دکتر میثم محمدی

In order to investigate the pre-harvest and priming application effects of gibberellic acid, salicylic acid and nitrogen on seed germination indices of Echinacea purpurea, this experiment was designed on factorial experiment in base completely randomized design with three replications at 2018 in field conditions and laboratory in the department of horticultural science of Ilam University. Experimental factors included gibberellic acid at two concentrations (100 and 200 mg/L), salicylic acid at two concentrations (100 and 200 mg/L) and nitrogen (from urea sorce) at two concentrations (3 and 6 g/L) that were investigated separately and in combination with each other. Treatments were applied with control samples as pre-planting (before maturity and seed harvesting) and seed priming (after seed harvesting). The results showed that the highest germination percentage, vigor index and shoot length were obtained in pre-harvest interaction with gibberellic acid 200 mg/L and nitrogen 6 g/L. The highest germination rate was observed in gibberellic acid 200 mg/L and the highest seed dry weight was obtained in gibberellic acid 100 mg/L. The highest root length was observed in pre-harvest treatment with 200 mg/L of gibberellic acid and 200 mg/L of salicylic acid. Also, pre-harvest nitrogen treatment had significantly higher germination percentage, germination rate, vigor index, shoot length and dry weight than their priming. Therefore, in present study, preharvest treatments of gibberellic acid in combination with nitrogen or salicylic acid were introduced for improving the seed germination of Echinacea purpurea.

In order to maintain the postharvest quality and vase life of the "Stanza" cultivar of gerbera cut flowers, an experiment was designed as split-plot for time based on a completely randomized design, with four replications, at 2018 in horticulture department of Ilam university. The treatments consisted of preharvest application of Spermine 2 mM and γ-Aminobutyric acid 2mM (GABA), as sub-plot, at two stages (2T) of spraying (the stage of emergence of flower branch and 10 days later) and three stages (3T) of spraying (the stage of emergence of flower branch, 7 and 10 days later) that investigated, as the main plot, at 0, 3, 6 and 9 days postharvest at 22±1 °C and relative humidity of 65 to 70%. The results showed that, respectively, spermine 3T, spermine 2T, GABA 3T and GABA 2T treatments increased vase life and maintaind postharvest quality of Gerbera cut flowers compared to the control. The results of the 9th day showed that the highest fresh weight, absorption of vase solution (VSU), soluble solids, protein, phenol and total flavonoid, activity of the catalase (CAT), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and Phenylalanine ammonia lyase (PAL), as well as the lowest ion leakage (EL), malondialdehyde MDA and polyphenol oxidase (PPO) activity respectively were observed in Spermine and GABA treatments, and in some of the studied traits, there was no significant difference between two and three stages of spraying. Therefore, the use of spermine 3T as the best treatment in present study is recommended as an application method to increase the vase life of "Stanza" cultivar of gerbera cut flowers.

Capsicum annuum L. fruits have amount of natural antioxidants and essential nutrients such as: vitamin C, carotenoids, phenolic compounds, and elements like potassium. Appearance of the crops, such as the shape, color, size, freshness of the fruit, lack of physiological disorders and microbial diseases, have a very important role in the marketability of green bell peppers. Therefore, this crop always requires a method to reduce losses and maintain marketability in postharvest. One of the methods for reducing postharvest losses of horticultural crops is using of edible and non-edible coatings that, increased shelf life of crops by changing of exchange of gas and water surrounding of horticultural crops.

In order to reduce the losses and preserve the quality of green bell peppers (“California Wonder” cultivar), this study was designed by using a factorial experiment in basic of completely randomized design in Ilam University at 2018. Experimental treatments were consisted immersion of fruits in Aloe vera gel 25% and 50%, Arabic gum 5% and 10%, Aoe vera 25%+Arabic gum5%, Aloe vera 25% + Arabic gum10%, Aloe Vera 50%+Arabic gum 5%, Aloe vera 50% + Arabic Gum 10% and control, which their effects on the characteristics of green bell pepper was investigated during 14 and 28 days of storage at 10 ̊C and RH 90%.

The results showed that with increasing the storage period, the quality and marketability of pepper fruits decreased, but the experimental treatments maintained the quality and marketability of green bell pepper in storage. In this study, Arabic gum10%, Aloe vera 25% + Arabic gum 10% and Aloe vera 50% + Arabic gum 10% treatments in most of the studied characteristics were more effective in maintaining the quality of green bell peppers in storage. These treatments showed less weight loss and ion leakage compared to other treatments and maintained marketability, total soluble solids, titratable acidity, total phenol, total antioxidant capacity, total chlorophyll and activity of catalase and peroxidase enzymes during 28 days of storage. It is likely that a thicker layer and fewer exchanges of atmosphere surrounding the fruit would be due to the greater efficiency of 10% Arabic gum in these treatments than other treatments. Therefore, according to this results the use of Arabic gum 10% or in combination with Aloe vera gel 25 and 50% are recommended as a method for reducing losses and maintaining the quality and marketability of green bell peppers during the storing and marketing.

To investigate the effects of foliar application of gibberellic acid (GA3) and salicylic acid (SA) on the morphophysiological, biochemical, and yield characteristics of Echinacea purpurea (L.) Moench, an experiment began as a factorial in a randomized complete blocks design with three replications at the research farm of Agriculture Faculty, Ilam University, Iran, by sowing the plants in 2018 and continued by evaluating the plant characteristics for the two consecutive years (2018 & 2019). The experimental treatments included the foliar spray of plants during vegetative growth period with GA3 (0, 100, and 200 ppm) and SA (0, 100, and 200 ppm) as well as their combinations. The results showed that the highest plant height, number of flowers, and fresh and dry weight of the plants (in both years) were obtained in the GA3-200 ppm treatment and the highest amount of total chlorophyll and carotenoids (in both years) in the GA3-100 ppm one. The highest capitol diameter and fresh and dry weight of flowers in the first year and the highest anthocyanins content in the second year were observed in the GA3-200 ppm treatment. Also, the highest capitol diameter in the second year and the highest anthocyanins content in the first year were obtained in the SA-100 ppm treatment. In addition, the highest fresh and dry weight of flowers in the second year was recorded in the SA-200 ppm treatment. The highest essential oil amount of flowers, shoots (without flowers), and total essential oil (in both years) were obtained in the GA3-100 ppm+SA-100 ppm combination treatment. Considering that increasing the plant dry matter yield as well as essential oil content were the most important objectives of this study, the GA3-200 ppm treatment for the plant dry weight increase and the GA3-100 ppm+SA-100 ppm combination treatment for the essential oil content increase could be suggested as the best treatments.

Gerbera, one of the important cut flowers, is sensitive to early wilting and neck bending which reduce its postharvest vase life. Towards improving the quality and the vase life of “Stanza” and “Pink Elegance” cut flowers, this study was conducted using putrescine by using a factorial experiment in basic of completely randomized design with 4 replications. The treatments were included postharvest spraying with 4 mM of putrescine, pulse treatment with 8 mM putrescine, permanent solution (vase life solution) with 2 mM putrescine and control. The results showed that Stanza cultivar had a higher vase life index and better quality than Pink Elegance cultivar in postharvest. All putrescine treatments increased vase life in both cultivars; however, the highest vase life was related to permanent treatments, pulse treatment, spraying treatment respectively. In most cases, all treatments maintain the postharvest quality of Gerbera cut flowers for four and eight days. in both cultivars permanent treatment has more relative fresh weight, VSU, marketability, TSS, CAT, PAL, and less of EC and MDA. In contrast, control has the lowest quality although in some cases, such as TSS, EC, CAT and PAL, there was no significant difference with postharvest spraying treatment. The best result was obtained once permanent treatment of putrescine and pulse treatment were used.

Gerbera is one of the important cut flowers in the floriculture industry, but it is sensitive to early wilting and neck bending which reduce its postharvest vase life. In cut flowers, water deficits are created when transpiration is more than water absorption. Therefore, petal wilting and neck bending increase in these flowers. These conditions are mainly due to occlusion of the vascular bundle, which can occur in different ways, such as the activity of pathogenic bacteria and other microorganisms in vascular bundle. In recent years, due to the adverse effects of chemical antimicrobial compounds on human health and the environment, many studies have been conducted to find replacement materials to maintain the quality and vase life of cut flowers in postharvest. Therefore, in this study, the effect of different concentrations of harmel aqueous-alcoholic extract (Peganum harmala L.) on bacterial population and vas life of ‘Stanza’ and ‘Pink Elegance’ cultivars of Gerbera cut flower were studied.

The effect of concentrations 0, 0.25, 0.5, 0.75 and 1% of the aqueous-alcoholic extract of Harmel plant was studied in a factorial experiment based on completely randomized design with four replications. At harvest time, 3, 6 and 9 days after harvest (at 20 °C and 70% relative humidity), the effect of treatments on the bacterial population of the vase solution and end stem, vase life and some characteristics of ‘Stanza’and ‘Pink Elegance’ Gerbera cut flowers were studied.

The results showed that the inhibitory effect of harmal extracts on gram-positive bacteria was higher than gram-negative bacteria. Also,‘Stanza’cultivar had better quality and longer vase life than ‘Pink Elegance’ cultivar. By increasing the vase life of flowers, the quality of these flowers decreased. In the first place, however, concentrations of 0.25% and then 0.5% of the harmal extract performed better than other treatments in various aspects: first, they reduced the bacterial solution, stem end, and electrolyte leakagein stem and petals; second, they preserved quality (discolored of vase solution, discolored of petals and stem), relative fresh weight, stem diameter, totalsolublesolids, catalase activity and phenylalanine ammonia lyase activity; and finally, they increased vase life of gerbera flowers in both cultivars. Concentrations of 0.75% and 1% increased allelopathic substances in cut flower. While these treatments decreased the bacterial population in vase solution and stem end, they did not have a significant effect on the quality and vase life of gerbera cut flowers.

The results of this study showed that the different concentrations of harmal extract significantly reduced the growth of microbial agents, including the bacterial population, but by increasing the concentration of the harmal extract, the allelopathic effects of this plant extract on gerbera cut flowers were harmful and did not affect their vase life and quality. Therefore, the concentration of 0.25% then 0.5% reduced the bacterial populations in vase solution and stem end of cut flowers and preserved the quality and vase life of ‘Stanza’ and ‘Pink Elegance’ cultivars. Therefore, the use of low concentrations of the harmel aqueous-alcoholic extract is recommended to reduce the microbial population of the vase solution and maintain the quality and vase life of the gerbera cut flowers.

In order to investigate the possibility of chilling resistance induction and reduce the chilling injury of cucumber seedlings, a factorial experimental based on completely randomized design with three replications was conducted in a greenhouse at Ilam University, Ilam Iran in 2018. The experimental factors were included concentrations of 0, 5, 10 and 15 mM gamma-aminobutric acid (GABA) and two methods of application including seed priming and foliar application at four true leaf stages. Treated plants were incubated at 3 °C for six nights and then investigated for different characteristics. Results showed that all GABA treatments reduced chilling injury in cucumber seedlings. Moreover, although there were no significant differences among the different GABA concentrations for most of the studied characteristics, seed priming was better than foliar application. The lowest chilling index, lipoxygenase activity and highest shoot fresh weight were observed in seed priming application of GABA but with no significant differences among GABA concentrations. The highest shoot dry weight (6.77 and 6.68 g.plant-1), chlorophyll index (20.57 and 21.07 mg.g-1 FW: leaf fresh weight), total protein (1.29 and 1.25 g.kg-1), proline (21.92 and 22.42 μmol.g-1 FW), catalase activity (115.67 and 126.9 U.g-1 FW) peroxidase (0.61 and 0.63 U.g-1 FW) and the lowest ion leakage (30.22 and 29.22 %), malondialdehyde (0.65 and 0.60 μmol.g-1 FW) and hydrogen peroxide (1.27 and 1.19 μmol.g-1 FW), were observed in seed priming application of 10 and 15 mM GABA concentrations, respectively. Therefore, seed priming application of 10 mM GABA is recommended for reducing the chilling injury in cucumber seedlings.

In order to reduce losses and preserve the fruit quality of green bell pepper cultivar “California Wonder”, this study was designed by using a factorial experiment on the basic of a completely randomized design at Ilam University. Treatments were consisted of pre-harvest spraying of calcium chloride 0.5% (CaCl2), packaging with cellophane, pre-harvest spraying of CaCl2 0.5% with packing of cellophane (CaCl2+ cellophane) and control (without spraying and cellophane packaging). Fruits were stored at 10°C and relative humidity 90-95 percent for 20 days and characteristics were evaluated at harvest, and after 10 and 20 days storage. Results showed that increasing the storage period decreased marketability and the quality of the fruits, but all treatments preserved the quality and marketability of the fruits over the storage period. Among the treatments, weight losses and variation in total soluble solids (TSS), titratable acidity (TA), taste index (TSS/TA ratio), chlorophyll and carotenoid content were lower under calcium + cellophane treatment than what recorded for other treatments and control. Also, calcium + cellophane combination had higher marketability, texture firmness, vitamin C, total phenol and antioxidant capacity. Although, for some characteristics, the treatment’s effect was not significantly different with pre-harvest spraying of CaCl2 0.5%. Altogether, all treatments preserved the quality of fruits in post-harvest, but the combination of calcium + cellophane was better than other treatments. Therefore, using a combination of calcium + cellophane is recommended as a method for reducing losses and maintaining the quality and marketability of green bell peppers during the storing and marketing.