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11.
Leaching of nutrients in soil can change the surface and groundwater quality. The present study aimed at investigating the effects of raw and ammonium (NH4+)-enriched zeolite on nitrogen leaching and wheat yields in sandy loam and clay loam soils. The treatments were one level of nitrogen; Z0: (100 kg (N) ha?1) as urea, two levels of raw zeolite; Z1:(0.5 g kg?1 + 100 kg ha?1) and Z2: (1 g kg?1 + 100 kg ha?1), and two levels of NH4+-enriched zeolite; Z3: (0.5 g kg?1 + 80 kg ha?1) and Z4: (1 g kg?1 + 60 kg ha?1). Wheat grains were sown in pots and, after each irrigation event, the leachates were collected and their nitrate (NO3?) and NH4+ contents were determined. The grain yield and the total N in plants were measured after four months of wheat growth. The results indicated that the amounts of NH4+ and NO3? leached from the sandy loam soil were more than those from the clay loam soil in all irrigation events. The maximum and minimum concentrations of nitrogen in the drainage water for both soils were observed at control and NH4+-zeolite treatments, respectively. Total N in the plants grown in the sandy loam was higher compared to plants grown in clay loam soil. Also, nitrogen uptake by plants in control and NH4+-zeolite was higher than that of raw-zeolite treatments. The decrease in the amount of N leaching in the presence of NH4+-zeolite caused more N availability for plants and increased the efficiency of nitrogen fertilizers and the plants yield.  相似文献   
12.
Soil salinity presents a serious threat to crop production. The relatively poor tolerance to this stress agent exhibited by conventional crops incentivizes the search for alternative producers of food and forage in salinity-affected environments. Halophytes belonging to the genus Salicornia L. have been suggested as being able to provide both forage and edible seed oil. Here, a set of 14 Salicornia europaea L. accessions was investigated for their ability to produce seed oil and forage in response to a range of salt concentrations (100, 300 and 600 mM NaCl) in the water used for irrigation. Seed of the accessions was collected from diverse sites close to saline rivers and the sea in Iran. Salinity was shown to have a major effect on biomass yield, and on seed oil yield and composition. The ratio of unsaturated to saturated fatty acids in the seed oil was remarkably high. Forage yield was highest when irrigated with 300 mM NaCl for most of the accessions, while a level of 600 mM NaCl suited the production of seed oil.  相似文献   
13.
The form of nitrogen (N) supply has a significant impact on rhizosphere chemistry and root growth responses of higher plants. The respective effects are also employed as management options to improve nutrient acquisition and to minimize nutrient losses in cropping systems. However, surprisingly little is known concerning the interactions with rhizosphere biota. In this study, we investigated the effects of selected bacterial and fungal inoculants with proven plant growth‐promoting and phosphate (P)‐solubilizing potential (plant growth‐promoting microorganisms, PGPM) in maize with nitrate or stabilized ammonium supply, on soils with limited P availability and sparingly soluble rock phosphate (Rock‐P) applied as P fertilizer. The combination of the bacterial inoculants Pseudomonas sp. DSMZ 13134 (Proradix) and Bacillus amyloliquefaciens FZB42 with ammonium sulphate fertilization, stabilized with the nitrification inhibitor 3,4‐dimethylpyrazole‐phosphate (DMPP), resulted in a superior shoot biomass production (79–111%) and shoot P accumulation (109–235%) as compared with nitrate supply. This effect could be partially attributed to (1) ammonium‐induced rhizosphere acidification via increased root extrusion of protons, (2) promotion of root hair elongation, and (3) increased shoot concentrations of hormonal growth regulators (indole‐3‐acetic acid, zeatin, gibberellic acid). The effects, induced by the microbial inoculants were mainly related to increased root length development (43–44%), associated with a 60% increase in auxin production potential. No inoculant effects were detected on root hair elongation or on chemical modifications of the rhizosphere involved in P solubilisation, such as rhizosphere acidification, release of carboxylates or secretory phosphohydrolases. However, the ammonium‐induced stimulation of root hair elongation increased preferential sites for root colonization by the selected inoculants, which may explain the increase in rhizosphere abundance of PGPMs, exemplarily recorded for the fungal inoculant Trichoderma harzianum OMG16 (210%). The presented data suggest a network of positive interactions between stabilized ammonium fertilization and plant growth‐promoting functions of various bacterial and fungal PGPM inoculants. This offers perspectives to increase the efficiency and the reproducibility of PGPM‐assisted fertilization strategies.  相似文献   
14.
A research was accomplished to find the response of Litopenaeus vannamei to different levels of aflatoxin in feed. Two hundred live L. vannamei were collected from a shrimp breeding station located on the south of Tiab, in Hormozgan province. Aflatoxin contaminated diets with 0.18, 96.21, 184.74, 711.35, 977.11 and 1605.61 µg/kg were prepared and shrimps in six experimental groups with three replicates in each group for 28 days were fed with these diets. The results showed that activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) in haemolymph and histological alternation index (HAI) value of hepatopancreas in treatement groups were significantly higher than control group (p < 0.05). Decreased total protein and fat in haemolymph and increased protein in muscle of treatment shrimps were observed compared with the control group (p < 0.05). The HAI value of 977.11 and 1605.61 μg/kg groups were significantly higher than the control and other groups (p < 0.05). Histological study results showed that calculated HAI (more than 100) in these groups as a result of necrosis lesion observed in hepatopancreas. Moderate to severe alteration was recognized in group fed by 711.35 µg/kg aflatoxin. Minor aflatoxin levels (0.18, 96.21 and 184.74 µg/kg) caused inappreciable tissue alteration. This study demonstrated body composition, haemolymph parameters and histology of hepatopancreas were affected in the aflatoxin‐contaminated feed when the concentration was over 955.14 µg/kg.  相似文献   
15.
Henna (Lawsonia inermis L.) is naturally cultivated from north-east Africa to India as a medicinal-industrial plant. The objective of this study was to evaluate the possible role of salicylic acid (SA) for mitigating the salinity stress. For this purpose, we evaluated the effect of three concentrations of SA (0, 40 and 80 μM) and salinity (0, ?3 and ?6 bar) on photosynthetic pigments, protein content, catalase (CAT, EC 1.11.1.6) activity, electrolyte leakage and leaf relative water content (RWC). The experiment was carried out with a factorial arrangement based on complete randomized design in triplicates at University of Kerman, Iran. The results revealed that salinity caused a significant decrease in photosynthetic pigments, protein content, RWC and quantum yield of henna. By increase in salinity levels from 0 to ?6 bar, the mean values of mentioned traits were reduced. CAT activity, electrolyte leakage, F0 and Fm were elevated significantly with increasing the salinity concentration. Application of SA under salinity stress increased the photosynthetic pigments, protein content, CAT activity, leaf RWCs and quantum yield, while it decreased electrolyte leakage, F0 and Fm. It can be concluded that SA alleviated the stress generated by NaCl possibly through the ameliorated antioxidant defense system.  相似文献   
16.

Background:

Bax and Bcl-2 are the major members of Bcl-2 family whose play a key role in tumor progression or inhibition of intrinsic apoptotic pathway triggered by mitochondrial dysfunction. Therefore, the balance between pro- and anti-apoptotic members of this family can determine the cellular fate.

Methods:

In this study, the relative level of mRNA expression of Bax and Bcl-2 genes was determined using RNA extraction, cDNA synthesis and RT-qPCR technique from 22 tumoral tissues and adjacent non-tumoral tissues from adenocarcinoma colorectal cancer.

Results:

The potential prognostic and predictive significance of Bax and Bcl-2 gene expression and Bax/Bcl-2 ratio were demonstrated in colorectal cancer. The significant correlation between qPCR data and different clinicopathologic parameters of colorectal carcinoma, including age, gender, tumor size, tumor stage, tumor location, and tumor differentiation was also examined. Interestingly, no significant correlation was seen between Bax and Bcl-2 expressions and clinicopathological parameters of colorectal cancer. However, Bax/Bcl-2 ratio was statistically correlated with age and tumor location. Patients with age above 50 showed decreased levels of Bax/Bcl-2 ratio. Moreover, the Bax/Bcl-2 ratio was significantly lower in tumors resected from colon compared to sigmoid colon, rectosigmoid and rectum tumors.

Conclusion:

This study indicates a significant correlation between age and tumor location with Bax/Bcl-2 expression ratio, suggesting predictive value as a potential molecular marker of colorectal cancer.Key Words: Colorectal cancer, Bax/Bcl-2 ratio, Bax expression, Bcl-2 expression  相似文献   
17.
Mycorrhizal fungi affect growth and nutrition of host plants positively. In this research, influence of vesicular-arbuscular mycorrhiza (VAM) ongrowth, chlorophyll content, and potassium (K) and magnesium (Mg) uptake in maize seedlings in pot culture was studied. This experiment was performed using natural soil containing a mixture of spores of Glomus spp. Mycorrhizal spores were exposed to four concentrations of K solution, i.e. 0.61 (soil K content), 0.92, and 1.23 meq/L and three concentrations of Mg, i.e. 4.8 (soil Mg content), 7.2, and 9.6 meq/L concurrently. Plants were watered every 4 days for 16 days with 50 mL distilled water. A pot with sterilized soil was used as negative control. For study of mycorrhizal colonization, very thin manually prepared longitudinal sections of plant roots (>1 mm in diameter) were stained with lactophenol-cottonblue and examined microscopically. Percentage of mycorrhizal colonization was determined using the grid-line intersect method. Samples from root and shoot of maize were collected for further analysis. Results showed mycorrhizal plants had significantly higher dry and fresh weight and chlorophyll content than plants grown in sterilized soil (p ≤ 0.05). Treatments with concentrations of 7.2 meq/L of magnesium alone and in combination with 0.92 meq/L of potassium with7.2 meq/L of Mg had better effect on morphological characters (dry and fresh weight of root and shoot). Mycorrhizal colonization increased Mg uptake but decreased K uptake.  相似文献   
18.
The solubility of Zn in Zn fertilizers plays an important role in the agronomic effectiveness of the fertilizer. On the basis of thermodynamics, zinc oxide (ZnO) nanoparticles (NPs) should dissolve faster and to a greater extent than bulk ZnO particles (equivalent spherical diameter >100 nm). These novel solubility features of ZnO NPs might be exploited to improve the efficiency of Zn fertilizers. In this study, we compared the Zn solubility and dissolution kinetics of ZnO nanoparticles and bulk ZnO particles coated onto two selected granular macronutrient fertilizers, urea and monoammonium phosphate (MAP). The main Zn species on coated MAP and urea granules were zinc ammonium phosphate and ZnO, respectively. Coated MAP granules showed greater Zn solubility and faster dissolution rates in sand columns compared to coated urea granules, which may be related to pH differences in the solution surrounding the fertilizer granules. The kinetics of Zn dissolution was not affected by the size of the ZnO particles applied for coating of either fertilizer type, possibly because solubility was controlled by formation of the same compounds irrespective of the size of the original ZnO particles used for coating.  相似文献   
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