m. r. safari motlagh

Kiwi (Actinidia deliciosa) is rich in minerals, vitamins and antioxidants. Kiwi fruit is sensitive to ethylene and has high perishability. There are some physical and chemical methods to delay aging and maintain postharvest quality of fruits. Light irradiation is a physical and pollution-free method that has been reported to be effective in controlling fruit decay and increasing its shelf life. Sodium nitroprusside (SNP) acts as an important signal in some physiological activities of the plant. SNP improved the quality and durability after fruit harvest in some fruits.Amino acids are effective in delaying the aging process and increasing the postharvest life of horticultural crops. Arginine plays an important and vital role in plant growth and development processes. The positive effect of arginine in increasing the shelf life of some fruits has been reported. The aim of this study was to increase the shelf life and quantitative and qualitative characteristics of ‘Hayward’ kiwi fruit after harvesting with the use of blue light, SNP and arginine.

Healthy and uniform fruits were selected and exposed to blue light (6, 12 and 24 h) at a wavelength range of 470 nm by LED lamps, SNP (0.5, 1 and 2 mM) and arginine (0.5, 1 and 2 mM). The experiment was performed in a completely random design with 10 treatments in 3 replications with 30 plots and 10 fruits per plot. After immersing the fruits at different levels of arginine, SNP and distilled water (control treatment), the surface of the fruits was dried and then sterilized. The fruits were monitored daily and their quantitative and qualitative properties were recorded during the experiment. Parameters of shelf life, tissue firmness, flavor index, loss of fresh weight, proline, ionic leakage, malondialdehyde (MDA), and dry matter, as well the activity of ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes were measured. Analysis of data obtained from sampling during the experimental period and laboratory were performed using SPSS statistical software and comparisons of means was done based on LSD statistical test.

The results showed that SNP at a concentration of 2 mM caused the highest shelf life (117.20 days) and the highest proline content (80.14 mg/kg) in kiwi fruits. The reason for this increased shelf life may be that SNP delays ethylene production process by activating the genetic and biochemical mechanisms, thus increase the postharvest life of ethylene-sensitive products. The highest firmness (4.56 kg/cm2) and the lowest fresh weight loss (1.26%) was obtained in fruits treated with 12 h of blue light. Some of the most important causes of this finding are that blue light delays the peak time of ethylene production, and as a fungal agent, reduces fruits decay after harvesting. The data showed that 12-h irradiation of blue light and 2 mM SNP caused a significant increase in the amount of antioxidant enzymes (SOD, POD and APX) of kiwifruit. Other traits such as flavor index, dry matter content, ion leakage and malondialdehyde were also measured. Blue light treatment can effectively reduce the decay of many fruits during postharvest storage. The study on kiwifruit showed that the qualitative treatments of different lights on various cultivars at different times had a significant effect on some physiological, morphological and gene expression traits. LED irradiation was found to be a suitable method for improving the quality of nutrients and the quality of flavor after harvest of some fruits. SNP was a good treatment to maintain fruit quality and improve disease resistance in kiwi cultivar ‘Bruno’ during storage. Fruits treatment with arginine is a promising technology to reduce cold and brown damages by stimulating the activity of antioxidant enzymes. Plant resistance to environmental stresses due to the use of arginine is in order to the effect of this substance on polyamine accumulation through increasing arginine decarboxylase and ornithine decarboxylase enzymes and increasing proline accumulation by enhancing ornithine amino-transferase enzyme activity as well as increasing nitric oxide through increasing the activity of nitric oxide synthase enzyme. Quality of kiwi fruit decreases during storage due to rapid softening and contamination with some fungi. In this study, effective treatments were used to reduce these complications. Overall, the results of this study showed that 2 mM SNP caused the highest shelf life. The highest firmness and the lowest fresh weight loss were observed in fruits treated with 12 h blue light. 12-h irradiation of blue light and 2 mM SNP caused a significant increase in the antioxidant enzymes of kiwifruit.

 Pears have a high nutritional and economic value worldwide. One of the major problem in growing pear cultivars is their late fertility on seed bases. To solve this problem, using asexual propagation methods can lead to the production of root trees. Cuttings are commonly used for proliferation either softwood, semi-hardwood or hardwood. Clonal propagation is considered proper in rapid propagation of shrubs and trees species. Adventitious root formation in stem cuttings is a crucial physiological process for vegetative propagation of many plant species. Rooting ability of tree species through stem cuttings is affected by several factors particularly plant growth regulators. Rooting of pear stem cuttings is time consuming. Auxin is effective in stimulating root formation on cuttings. The most widely used auxins in rooting of stem cuttings are indole-3-butyric acid (IBA) and naphtaleneacetic acid (NAA). Of these two auxins, IBA is the most widely used root promoting chemical, because it is nontoxic over a wide range of concentrations. Applied concentration is an important factor. Typically, a concentration of 2000 to 4000 ppm will result in good rooting for most shrubs and trees.

 In this experiment, pear (Pyrus communis) was used as mother plants. Stem cuttings were used as plant materials in this experiment. The effect of different levels of indolebutyric acid (IBA) and naphthalene acetic acid (NAA) was studied on the rooting of pears in a factorial experiment based on a randomized complete block design with 16 treatments and 4 replications. The experimental treatments included IBA and NAA at the rates of 0, 1000, 2000 or 4000 mg L-1. Rooting percentage, rooting time, root number, root length, root volume, plant height, leaf number and fresh and dry weights of cuttings were measured after about 130 days.

 The results showed that the highest rooting (3.56 per seedling) was observed in cuttings treated with 4000 mg L-1 IBA. Also, the highest root number was obtained from the treatment of 1000 mg L-1 NAA and 2000 mg L-1 IBA with an average number of 0.16 roots per plant. According to the means comparison for the simple effect of IBA on the rooting time, the highest rooting time was related to the application of 4000 mg L-1 IBA.  The results revealed that plants treated with 4000 mg L-1 NAA and 2000 mg L-1 IBA grew the longest roots. Also, ANOVA showed that among the applied factors, only the simple effect of IBA was significant on root volume. Means comparison for the simple effect of IBA on root volume showed that the highest was related to the application of 2000 mg L-1 IBA. According to the means comparison for the interactive effect of IBA × NAA on cutting fresh weight, the highest fresh weight was, on average, 8.36 g in plants treated with 4000 mg L-1 NAA and 2000 mg L-1 IBA. As well, means comparison the effect of IBA × NAA on cutting dry weight showed that the highest dry weight was 15.9 g related to the application of 4000 mg L-1 NAA × 2000 mg L-1 IBA. It was also observed that 2000 mg L-1 NAA × 1000 mg L-1 IBA was related to the longest cutting with an average length of 2.82 cm. Finally, plants treated with 4000 mg L-1 NAA and 2000 mg L-1 IBA produced the highest number of leaves (15.9 g, on average). One of the effective factors in the success of vegetative propagation of plants with stem cuttings, especially woody plants with hard-rooting stems, is the production of more roots in a short time. Plant growth regulators, including auxins, play an important role in this regard. The effect of auxins on the percentage and number of roots produced on stem cuttings has been shown by many researchers on various plants, including plants with hard-rooting cuttings particularly in trees. The most widely used auxins in this regard are IBA and NAA, respectively. The individual or combined effect of auxins for successful rooting depends on a number of factors, including plant type, cuttings type, cuttings size, cuttings age, and the time of year the cuttings were removed. In the present study, the combined effect of IBA and NAA had the greatest effect on most of the measured traits.

White stem rot caused by Sclerotium rolfsii is a soilborne disease which is extensively common across the groundnut farms of Guilan province, especially during the harvest period. Using the beneficial microbial agents is an alternative method for applying the chemical fungicides.

To find the appropriate fungal antagonistic isolates for the biological control of peanut white stem rot, the effect of three isolates of Trichoderma spp., three isolates of Penicillium spp., two isolates of Aspergillus spp. and one isolate of Cladosporium cladosporioides were studied on S. rolfsii in vitro using dual culture, slide culture, volatile metabolites and non-volatile metabolites. Peanut plants were inoculated with these fungal isolates as well as S. rolfsii in greenhouse experiments, and parameters including disease severity, height, fresh weight, and dry weight of the plant were measured.

The results showed that in the dual culture method, T. harzianum and T. virens were most capable of suppressing the mycelial growth of S. rolfsii with a suppression capability of 93.58% and 92.94%, respectively. In the slide culture method, all isolates turned out to be effective in suppressing the mycelia growth of S. rolfsii, except for T. virens and T. viride. In the volatile metabolite assay, P. glabrum and A. flavus with 81.25% and 75%, respectively and in the non-volatile metabolite method, T. harzianum and T. viride with 93.75% and 97.5% respectively showed the greatest ability to inhibit S. rolfsii mycelial growth. Moreover, the effects of these fungi on the control of S. rolfsii pathogen were explored in greenhouse trials. The results revealed that P. glabrum was 39.4% effective and T. viride was 38.8% effective in reducing the extent and intensity of the disease. Under the presence of the pathogen, the treatment of these antagonistic fungi in greenhouse conditions enhanced plant height, shoot and root fresh and dry weight. In the in vitro and greenhouse approaches, an analysis of variance and a comparison of means of the attributes using the least significant difference (LSD) indicated significant differences (P ≤0.01 and P≤ 0.05) among the examined fungi.

The results of the in vitro and greenhouse trials showed that T. viride, T. harzianum, P. glabrum, A. flavus, and C. cladosporioides, which are present in the natural flora of groundnuts, have the potential capability of the biological control of S. rolfsii as the pathogen of groundnut stem white rot.

Ricebakanae disease caused by Fusarium fujikuroiis one of the most important diseases of rice in Iran and in the world. Studies show that the disease has spread to a wide range of paddy fields worldwide, with losses in Japan up to 20%, in India up to 15%, and Thailand's northern and central areas have been reported to be 7.3% -14.7%. Symptoms include rice foot blackness and yellowish and then wilting of infected plants. The pathogen is more likely to attack the foot rot which is a sign of the abnormal growth of contaminated plants in the farm. Infected seedlings are slender and taller than healthy plants, and highly infected plants may die before or after transplantation. The tillering is reduced, consequently the leaves die in a short time. The fungus causes the disease threats the human and animal health through the production of phytotoxins. Identification of Fusarium species is currently confusing, on the other hand, several Fusarium species have always been isolated together with rice contaminated with the disease. Therefore, it is not clear which species of this fungus are the main reason of the disease. This fungus is soil-borne and has a long life in heavy soils. It has also a global expansion and is active in most parts of the world. Rice foot rot disease in all major rice producing countries in the world is considered as a seed disease and the transmission of the disease agent from one season to another season is mainly due to contaminated seed, but soil-borne fungus can be as well. Currently, treating the seeds with fungicides is the best method to control this disease, however using chemical pesticides can lead to environmental pollution. In this situation, it is important to achieve a healthy alternate method. For this purpose, biological control is one of the ways in which today a large investment is being made around the world.

Samples of rice exhibiting the symptoms of bakanae were randomly collected from different parts of Gilan province, Iran. Pieces of organs with rot symptoms were cut and they were surface-disinfected after washing with 0.5% sodium hypochlorite solution. At the next step, they were washed with distilled water and dried on filter papers. Then, they were cultured in Petri dishes containing potato dextrose agar (PDA) culture medium and were placed in an incubator at 28°C for 3-5 days. Afterward, they were placed on a water-agar medium for purification and morphological identification. In this research, from a total of 80 samples collected from rice farms in Gilan province, 18 bacterial strains were isolated and the antagonistic ability of 8 strains of bacteria in the laboratory and greenhouse was investigated. For this purpose, in laboratory, dual culture method, volatile compounds, siderophore and antibiotic production were used. These bacterial strains were inoculated into rice under greenhouse conditions, and then the severity of the disease was determined in the tested treatments. After calculating the severity of the disease, the height of the rice bushes was measured by the ruler. To measure the fresh weight, the rice bush with the roots was removed from the soil and measured by a scale. Each bush was then separately placed for 48 hours in an oven at 80-90°C. After leaving the oven, each of the bushes was re-weighed. This weight was recorded as dry weight.

A total of 18 isolated bacterial strains, 8 bacterial strains including Bacillus subtilis, Bacillus circulans, Pseudomonas putida, Pseudomonas syringae, Pseudomonas aeruginosa, Pseudomonas fluorescens (N47), Pseudomonas fluorescens (149) and Pseudomonas fluorescens (CHA0) were identified and used for biological control studies in laboratory and greenhouses. P. putida with 39.99 % in the dual culture, B. subtilis with 31.01% in the volatile metabolites, in the method of siderophore production, P. fluorescens (N47) and B. subtilis with 52.10 % and 45.85 % respectively, and in the antibiotic production, P. putida with 59.21% had the greatest effect on inhibiting the mycelial growth of the disease causative agent. Based on the results of the analysis of variance under greenhouse conditions, there was a significant difference between treatments for severity of disease, fresh weight, dry weight and plant height at 1% probability level. Among the studied bacteria, the least severity of the disease belonged to the treatment with P. putida and B. subtilis, respectively. Regarding height, the highest height was related to treatment with P. putida and B. subtilis and in terms of fresh weight and dry weight, the highest weight was related to P. putida.

According to the results of biocontrol studies in laboratory and greenhouse conditions, P. putida and B. subtilis strains were the most effective bacteria for controlling rice foot-rot disease.Therefore, isolating and identifying these bacterial strains as much as possible can be promising for the greater effectiveness of biocontrol methods in the management of rice crown-rot disease control.

The brown spot disease is one of the seed-borne diseases of rice, found in the all stages of its growth from nursery to farm. It causes qualitative and quantitative damage on rice. Therefore, some studies carried out on the different aspects of this disease and the reaction of some cultivars of rice against the pathogenic fungous agent of the diseases. To do so, 120 isolates, isolated from plant samples were collected from the 91 paddy fields in Guilan. To isolate the pathogenic fungous agent of the disease, the collected samples were cultured on PDA and filter paper. According to the results, the present isolation related to Bipolaris with the 3 species : Bipolaris oryzae (Ito & Kurib.) Drechsler ex Dastur Bipolaris victoriae Nelson Bipolaris sp. The total isolataes were consisted of 15% Bipolaris oryzae, 75% Bipolaris -victoriae and 10% Bipolaris sp. The study of pathogenicity of isolation in these three species was applied to Khazar rice in desicator. The symptoms created by these three species were different from necrotic spots to leaf death. The results indicated that not only the symptoms but also the virulence in these three species were different. The virulence in B. oryzae was more than B. sp and this was more than B. victoriae. To study the reaction of some cultivars of rices to the pathogenic fungous agent, 8 cultivars of rice: “ Bejar, Khazar, Sepeedroud, Domsephid, Hassan saraee, Binam, Neda, Nemat” respectively were used in the two stages of the plant growth, to leaf in the seedling stage and heading. The results indicated that in seedling stage there was no significant difference between these cultivars with respect to the amount of infection. And in heading stage, according to “Dunken” test (5%) they divided into the 3 groups: “Neda, Sepeedrud, Khazar and Binam” with the lowest amount of infection were in the first group, “Bejar, Domsephid and Hassan saraee” classified in the second group and “Nemat” was in the third one. But there was no significant difference between them according to the variance analysis table.