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Background and Objectives: Considering the high demand for tea in Iran and the insufficient local production, the use of chemical fertilizers to enhance production per unit area is increasing. The long-term use of chemical fertilizers, especially nitrogen fertilizers, in tea gardens has led to soil acidification which in turn impacted the soil quality and health. Therefore, searching for an alternative method that is as efficient as chemical fertilizers and compensates for the disadvantages caused by the excessive use of chemical fertilizers is essential in tea gardens nutrition. Materials and Methods: In this research, native nitrogen-fixing (Azospirillum) and phosphorus solubilizing rhizobacteria were isolated from the rhizosphere of tea plants and then used as biofertilizers for cultivation of Chinese hybrid tea seedlings at tea research center in 1400 under pot experiment. This experiment was conducted in a randomized complete block design with factorial arrangement and three replications. The factors include pH of soil at two levels (4.65 and 5.21), and fertilizer treatments at five levels including blank (B), control; where chemical fertilizer was applied based on soil analysis (C), nitrogen fixing bacteria was applied as biofertilizer (BN), phosphorus solubilizing bacteria was applied as biofertilizer (BP), and nitrogen fixing and phosphorus solubilizing bacteria were applied as biofertilizer (BNP). After three months of tea planting, the effect of applied biofertilizers on soil biochemical characteristics and yield of tea plant were investigated. Results: The soil pH values in all treatments that received biofertilizers were higher than that of the blank and control treatments. The highest and the lowest soil nitrogen (N) content were observed in BNP and B treatments, respectively. The highest content of soil phosphorus (P) was observed in BNP treatments, which P content in this treatment with BN was not significantly different. The soil available potassium content in treatments that receiving bio and chemical fertilizers did not show a statistically significant difference. The highest and the lowest values of fresh weight, dry weight and yield were observed in BNP and B treatments, respectively. The highest content of N and P in plant were observed in BNP (4.8%) and BP (0.24%) treatments, respectively. The potassium content of plant in treatments that received biofertilizers was lower than B, while the potassium content in all biofertilizer treatments were higher than that of the control. Conclusion: In this study biofertilizer treatments, Azospirillum and phosphorus solubilizing bacteria, increased the nitrogen and phosphorus contents in tea plant and soil, respectively. Since these bacteria improved plant growth and soil properties, it seems that native rhizobacteria isolated from tea rhizosphere have the potential to be used as biofertilizers in tea gardens in line with sustainable agriculture. Although, long term investigation during the several growth periods and different seasons of the year is needed for further evaluations. [ABSTRACT FROM AUTHOR]

Organic and inorganic amendments are routinely applied to ameliorate soil conditions in semi-arid regions. This study aimed to examine the unsaturated transport of nalidixic acid-resistance Escherichia coli (E. coli NAR) in soil amended by cow manure (CM) and natural zeolite (NZ). Two levels of NZ (5 and 15% w/w) were added to a loam soil containing 5% w/w CM and incubated for 60 days. Then, the soil mixtures were poured into cylinders (3.6 × 15 cm) and a pulse (0.1 pore volume) of bacteria suspension (106 Cell mL−1) was added on top of the soil columns and leaching experiments were conducted at a steady-state, unsaturated flow condition and filtration coefficient (λf), relative adsorption index (SR), maximum depth of bacteria transport (Zmax), average (Cav) and cumulative cell density (Ccum) were calculated. CM and NZ application significantly increased the peak density, Zmax, Cav, and Ccum of E. coli NAR. The Cav, and Ccum of E. coli NAR in both 5 and 15% NZ containing mixtures were about 1 and 2-fold higher compared to the control. CM and NZ addition to soil decreased the filtration coefficient (λf) and relative adsorption index (SR) compared to the control. According to our results, we should conclude that the presence of NZ and CM, separately or together, can significantly increase the risk of groundwater contamination and it should be used with prudence. [ABSTRACT FROM AUTHOR]

This study was to investigate the possibility of nutrient removal from landfill leachate using Chlorella sp. and its potential as agricultural fertilizer. Chlorella sp. was inoculated to a leachate suspension (1:1 ratio). Phosphate, ammonium and nitrate concentrations in the suspension and the dry cell weight of algae were measured at 0, 2, 4, 6 and 8 days of incubation. Then, the harvested microalgae biomass was mixed with a nutrient-poor soil at three levels: 0 (A0), 2 (A2) and 4 (A4) g 100 g−1. The mixtures were incubated for 2 months, and soil biochemical properties, including soil organic carbon (OC), available phosphorus (Pava), mineral nitrogen (Nmin), microbial basal respiration (MBR) and microbial biomass carbon (MBC), were determined in soil at 7, 14, 28, 35, 42, 49 and 56 days of incubation. The dry cell weight of the microalgae increased over time and removed ammonium, phosphate and nitrate from the leachate by 98.7, 92.7 and 56.9%, respectively. The added microalgae biomass to soil caused positive and significant changes in soil OC, Pava, Nmin, MBR and MBC. Therefore, it seems that Chlorella sp. cultivated in landfill leachate can be used as an agricultural fertilizer in soil. [ABSTRACT FROM AUTHOR]

Powdery mildew is one of the most important diseases of cucurbits in the world and Iran. The disease is found in cucumbers, melons, cantaloupes, squash, and watermelons in both farm and greenhouse conditions and causes great damage. Cultivating resistant cultivars or chemical control with fungicides can be used to control this disease. In this study, 28 different genotypes of hullless seed pumpkin were studied and compared for powdery mildew resistance in potted conditions in a greenhouse. To achieve this, the genotypes in the greenhouse were sprayed with powdery mildew spores, and when signs of powdery mildew appeared through infection on the plants, the severity of the disease was determined by image processing using a program written in MATLAB software. The mean comparison showed that the lowest level of infection was related to lines 11 and 23 and hybrids of 7x16, 2x16, and 2x23. The highest negative general combining ability was related to line 11 and the highest negative specific combining ability was related to hybrids 7x14, 2x16, 2x23, and 11x14. The highest negative heterosis compared to the high parent was related to 11x14, 2x23, and 2x16 hybrids. Due to the significant values obtained for specific combining ability and significant heterosis in hybrids, the role of dominance variance in controlling this trait is prominent, and hybrid production is recommended to improve resistance to powdery mildew. [ABSTRACT FROM AUTHOR]

Leucojum aestivum L. is a perennial and bulbous plant. Its bulbs are used in the medical industry because of having alkaloids. This study was conducted as split plot in a completely randomized design with 3 replications in 2018 at the University of Gilan in field conditions. The main factor included bulbs collected from three regions of Lahijan, Tonekabon and Langrood. The sub-factor included 10 levels of organic fertilizers, biochar (3, 6 and 12 tons per hectare), inoculation of Glomus intraradices, Glomus mosseae and Glomus intraradices + Glomus mosseae fungi, inoculation of Azospirillum, Azotobacter and Pseudomonas bacteria and the control. Data collected and analysed for morphological traits and absorbed macro and micro as elements by plants. There was significant difference between genotypes in terms of the plant height, leaf area per plant, leaf weight per plant, bulb weight, flowering stem weight, root weight and total plant weight (p<0.01). A significant difference was observed in the types of fertilizers used for all morphological traits and yield (p<0.01) and for phosphorus, potassium and iron content (p<0.05). The genotype by treatments interaction effect was significant for leaf number, leaf area per plant, leaf weight per plant, bulb weight, flowering stem weight, root weight and total weight showed a difference (p<0.01). Lahijan genotype plants had the highest plant height (57.6 cm), leaf length (52.5 cm) and plant leaf weight (27.2 g/per plant). The highest root weight (9.5 g) and total plant weight (74.1 g/per plant) was for biochar treatment of 12 ton/h. The study results indicated that Leucojum aestivum L. had good adaptation to crop conditions, and using biochar fertilizer and some biofertilizers improved various crop traits of this plant. [ABSTRACT FROM AUTHOR]