Effect of soil pore size distribution on plant-available water and least limiting water range as soil physical quality indicators

Soil pore size distribution(SPSD) is one of the most important soil physical properties. This research investigated the relationships of location and shape parameters of the SPSD curves with plant-available water(PAW) and least limiting water range(LLWR) of the light-textured soils at the Torogh Agricultural Research Station in north-eastern Iran. Soil moisture release curve(SMRC), PAW and LLWR in matric heads of 100 and 330 h Pa for the field capacity and location and shape parameters of the SPSD curves of 30 soils with different texture and organic carbon contents were determined, and the variable relationships were statistically analyzed. The results showed that the median equivalent pore diameter(de), mean de, standard deviation(SD*), and skewness of the SPSD curves were significantly correlated with PAW(PAW330) and LLWR(LLWR330) measured in a matric head of 330 h Pa. Decrease in deand increase in the diversity of soil pore size(SD*) increased PAW330 and LLWR330. The SD* values of all the soil samples were lower than the optimal ranges suggested in literature. Neither PAW nor LLWR values were significantly different in the soils with the optimal modal deand those with non-optimal modal de. Optimal values of median and mean equivalent pore diameters and kurtosis of SPSD curves led to a significant improvement of PAW330 and LLWR330 as soil physical quality indicators. It was recommended to revise the optimal ranges for SD* and modal defor future studies.     

Integrated management of the charcoal disease by silviculture,chemical and biological methods in forest parks

Biscogniauxia mediterranea (De Not.) Kuntze, is a widespread fungus, causes outbreaks of Charcoal disease on cork oak and dieback thousands oak trees in recent years in Iran. Yet no efficient and effective management methods have been found to control the disease. The present study aimed to provide a suitable method for charcoal disease management through silviculture operations, systemic pesticides and biological compounds. The results showed that, simultaneous implementation of silvicultural practices (scarification+sanitation), use of systemic fungicides and Trichoderma compounds, reduce the number and depth of cankers, increase callus thickness, and ultimately improve health of the diseased trees. But disease severity and fungi activity were increased when scarification operation implements alone. The greatest effectiveness of the treatments and health condition improvement of the diseased trees was observed 12 months after applying the treatments. Then, preventive and therapeutic effectiveness of the treatments reduced over time. Sanitation and scarification practices can increase soil permeability and also destroy the larvae, pupa or adult insects and oak borer beetles that play an important role in disease outbreaks. Therefore, simultaneous implementation of sanitation and scarification practices with application of biological and systemic compounds can reduce primary source of pathogen inoculum and help trees to recover their health.     

Genetic variability of transpiration response to vapor pressure deficit among sorghum genotypes

Simulation studies have demonstrated that limited maximum transpiration rate (TR) at high air vapor pressure deficit (VPD) in water-limited environments could result in significant increases in sorghum yield. However, such a restriction on TR at high VPD has not been documented in sorghum. The objective of this study was to search within sorghum germplasm for the possibility of restricted TR at high VPD. Twenty six genotypes were selected for measurement of VPD response based on field observations including yield, leaf temperature, and the stay-green phenotype. These genotypes were grown in a greenhouse for about 24-d growth, and then placed into individual chambers in which VPD was varied and TR measured. The results of this study showed marked variation among sorghum genotypes in TR response to VPD. Seventeen genotypes were identified as exhibiting a breakpoint in their VPD response in the range from 1.6 to 2.7 kPa, above which there was little or no further increase in TR. Therefore, these genotypes with a breakpoint have the possibility of soil water conservation when VPD during the midday cycle exceeds the breakpoint VPD. This trait would be desirable in less humid environments for increasing yields in water-deficit seasons. The observed range in the value of the BP among genotypes offers the possibility of developing genotypes with BP appropriate for specific environments.     

Wood anatomical changes due to uptake of cadmium and lead from contaminated soils in Acer velutinum seedlings

We investigated wood anatomical changes due to uptake and accumulation of cadmium and lead from contaminated soils in Acer velutinum Boiss seedlings. Two-year old seedlings were exposed for 180 days to soil concentrations with varying cadmium and lead concentrations. We measured three wood anatomical traits, average vessel area(μm2), vessel number per square millimetre, and vessel lumen area percentage (%). For assessing the cadmium and lead accumulation, we measured the concentrations in the soil, leaf, stem, and root. Average vessel area and vessel lumen area percentage were similar (p>0.05) incontrol and treated seedlings. Vessel number per square millimetre showed a decreasing trend from pith to bark in control and treated seedlings, and the trend was more pronounced in treated seedlings. We conclude that vessel number per square millimetre in A. velutinum is influenced by soil contamination. A. velutinum Boiss is not a suitable species for remediation of soils contaminated by cadmium and lead but it can beused as an indicator of the soil lead contamination, because lead concentrations in seedlings increased with increasing amount of lead in the soil.     

Evaluation of infiltration models with different numbers of fitting parameters in different soil texture classes

In this study, the ability of eight different infiltration models (i.e. Green and Ampt, Philip, SCS (US-Soil Conservation Service), Kostiakov, Horton, Swartzendruber, Modified Kostiakov (MK) and Revised Modified Kostiakov (RMK) models) were evaluated by least-squares fitting to measured infiltration data. Six comparison criteria including coefficient of determination (R²), mean root mean square error (MRMSE), root mean square error (RMSE), the F-statistic (F), C_p statistic of Mallows (C_p) and Akaike information criterion (AIC) were used to determine the best performing model with the least number of fitting parameters. Results indicated that R² and MRMSE were not suitable for model selection. A more valid comparison was achieved by F, C_p, AIC and RMSE statistics. The RMK model including four parameters had the best performance with the majority of soils studied. RMK was better than the MK model in approximately 51.6, 57, 68.5 and 70.6% of soils, when using F, C_p, AIC and RMSE statistics, respectively, and for the other models, a higher per cent of soils was obtained. The RMK model was the best for loam, clay loam and silty clay loam soils, but the MK model was the best for silty loam soils.     

Expression Analysis of mir-21 and mir-221 in Cancerous Tissues from Iranian Patients with Gastric Cancer

Background:

Early detection is a key to survival for gastric cancer. Molecular markers such as miRNA (microRNA) can have great importance in the early diagnosis of gastric cancer. Expression of miR-21 and miR-221 are deregulated in many types of human cancers. This study aimed to investigate the differences in miRNA expression patterns within the Iranian population.

Methods:

Total RNA was extracted from gastric cancer tissues and adjacent non-cancerous tissues from 32 patients. Expression levels of miR-21 and miR-221 were detected by Real time RT-PCR using a specific primer, with 5s rRNA as the internal reference gene.

Results:

Our data showed that the expression levels of miR-21 and miR-221 in gastric cancer samples were significantly higher than in paired non-cancerous samples (P < 0.05). The receiver operating characteristic (ROC) analyses yielded the area under the curve (AUC) values of 80.30 for miR-21 and 93.30 for miR-221, and combined ROC analysis revealed the highest AUC value of 96.90 in discriminating GC patients from healthy controls.

Conclusion:

It seems that miR-21 and miR-221 expression pattern in Iranian patients with gastric cancer are similar to any other population. Considering the increased expression level of two miRNAs in cancerous tissue compared to normal tissue as well as the area under ROC curve, miR-21 and miR-221 can be used for early detection of gastric cancer. Key Words: MicroRNAs, Tumor markers, Stomach neoplasms