Caspian Journal of Environmental Sciences
Volume:6 Issue: 1, Winter 2008

Seed dormancy is a genetically inherited trait whose intensity is modified by the environment during seed development and maturation. In order to study the effect of harvest time on the seed quality and optimum time of sowing to obtain good quality seeds, freshly threshed seeds of ten diverse rice genotypes harvested from six environments were evaluated for seed dormancy and seedling vigour index as a measure of seed quality. There were significant differences in germination in different genotypes in all the six environments as well as days after harvest. The germination percentage was initially low and gradually increased with increasing in days after harvest (0. 15, 30 and 45th day after harvest). Out of these six genotypes viz., IET 8116, KMP 101, IR 30864, KRH-1, IR-64 and MTU 1001 were found dormant, immediately after harvest. The studies indicated that sowing in the first (June 2nd fortnight) and second environment (July 1st fortnight) were resulted in production of non-dormant seeds. Whereas all the six environments were favorable to take up seed production of new promising rice genotype KMP 101.

Road transport is a ubiquitous source of lead contamination in the soil near highways with direct and indirect impacts on human health. Accumulation of traffic-induced lead in the soils depends on gasoline lead content, traffic volume, as well as meteorological conditions. To evaluate the effect of traffic on soil lead concentration, 113 samples from the topsoil (0-15 cm) were collected in a regularly spaced grid (70 x 70 m) in the vicinity of a busy highway (Tehran-Karaj) ;the west of Tehran. Total lead (Pb) concentration in soil samples was extracted by 4 M HNO3. Three different kriging techniques (ordinary, universal and indicator kriging) were applied to investigate the spatial distribution of Pb. According to the measured values, the average concentration of Pb (48 mg kg -1) was very close to the upper limit of the Swiss guide value of 50 mg kg-1 with the maximum value (75 mg kg-1) exceeding this limit. The result also showed an accumulation of 5 to 25 mg kg-1 Pb in the soil based on the distance from the highway. The average concentration of Pb decreased exponentially with distance from the highway up to 200 m becoming relatively constant thereafter. The trend of spatial continuity of Pb concentration was in agreement with major wind direction. Comparing different kriging techniques indicated that UK was superior due to smaller error of estimation. The probability map of Pd concentration exceeding the Swiss guide value clearly shows the traffic to be the main cause of soil Pb contamination.

In order to determine the best form factor formula for Loblolly Pine (Pinus taeda L.) plantations in Talesh (Western Guilan province-Iran), a number of 110 trees were selected based on their distribution in diameter classes, from 12 to 34 cm (in a two- cm diameter interval). First, several quantitative factors including diameter at breast height, diameter at 0.65 m of height, and diameter at stump were measured using a diameter tape, just before the trees being felled. After cutting the trees, the heights and diameter from breast height up to the height where diameter is 5 cm was measured using a diameter tape in a two meter interval. Finally, diameter at 0.1, 0.3, 0.5, 0.7, and 0.9 meter of the total height was measured respectively. As a consequent, each tree''s volume was precisely calculated as the real volume. Next, the real form factor was calculated and its average was statistically compared to the averages of Natural , Artificial , and Hohenadl?s form factors using pair sample T-test. Results showed that there is no significant difference between the averages of real and Hohenadl?s form factors (at = 0.01 level). Furthermore, the averages of real and artificial form factors were not significantly different. Hence, both artificial and Hohenadl?s form factors are capable to replace the real form factor of Loblolly Pine over the study area.

An isolated Fusarium anthophilum (A. Braun) Wollenweber (isolate 16C) has been considered as a candidate for microbial control of barnyard grass [Echinochloa crus-galli (L.) P. Beauv]. The effects of nutrition on conidiation, germination rate and germ-tube elongation of conidia of the fungus were evaluated. Conidia yield, conidial germination and conidial germ-tube elongation of the fungus grown in a liquid medium with a C: N ratio of 5:1 was significantly more than that in the same medium with C: N ratio of 15:1 or 40:1. Glycerol at 1, 2 or 5% (v/v) in the medium with a C: N ratio of 5:1, significantly enhanced conidiation of the fungus. The highest conidia production was obtained in the medium contained 5% glycerol. Glycerol did not enhance germination and germ-tube elongation. Harvested conidia in 0.2, 0.5, 1 or 2% Tween 40 resulted in higher germination and germ-tube elongation than those harvested in distilled water, when they were placed on top water agar for 8 h at 20 oC. The effect of Tween 40, particularly at 0.5% (v/v) was more pronounced after 9 and 35 days desiccation period at 20 oC and 15% RH.

In recent years, artificial neural networks (ANNs) have become one of the most promising tools in order to model complex hydrological processes such as the rainfall-runoff process. In many studies, ANNs have demonstrated superior results compared to alternative methods. ANNs are able to map underlying relationship between input and output data without prior understanding of the process under investigation. However, they have been known as black-box models due to their problem in providing insight into the relationship learned. In this study, firstly we develop a rainfall-runoff model using an ANN approach, and secondly we describe different approaches including Neural Interpretation Diagram, Garson?s algorithm, and randomization approach to understand the relationship learned by the ANN model. The results indicate that ANNs are promising tools not only in accurate modelling of complex processes but also in providing insight from the learned relationship, which would assist the modeller in understanding of the process under investigation as well as in evaluation of the model.

Dynamic game theory is applied to analyze the timber market in northern Iran as a duopsony. The Nash equilibrium and the dynamic properties of the system based on marginal adjustments are determined. When timber is sold, the different mills use mixed strategies to give sealed bids. It is found that the decision probability combination of the different mills follow a special form of attractor and that centers should be expected to appear in unconstrained games. Since the probabilities of different strategies are always found in the interval [0,1], the boundaries of the feasible set are sometimes binding constraints. Then, the attractor becomes a constrained probability orbit. In the studied game, the probability that the Nash equilibrium will be reached is almost zero. The dynamic properties of timber prices derived via the duopsony game model are also found in the real empirical price series from the north of Iran.

Native population of raspberry fruits (Rubus spp) were treated with Methyl Jasmonate (MJ) fumigation and were assayed for the antioxidant capacity, total anthocyanins and postharvest quality after 7 days storage at 4?C. The result of experiment revealed that berries treated with methyl jasmonate (MJ) showed higher antioxidant capacity and total anthocyanins compared to the controled ones (non-treated). Decay incidence was reduced in fumigated fruits during storage at 4?C, which resulted to long postharvest life (as indicated by fugal decay) compared to the controled ones. Total soluble solid, titratable acidity and pH were influenced by storage periods. Therefore, MJ treatments could not suppress the declining, which happened during storage time. In conclusion, although raspberry fruits treated with MJ maintained higher levels of antioxidant capacity, total anthocyanins compared to untreated fruits during storage, but because of high perishable, MJ treated fruits could not maintain significant changes in internal quality.

The genus Cyrtopodion is the most widely distributed of the four gekkonid genera of the angular-toed geckos that inhabit Pakistan and the contiguous Palearctic Region (Szczerbak & Golubev 1996), from the Indus Valley to the eastern borders of the Caspian Sea. Longitudinal rows of trihedral tubercles characteristically line the dorsum of these angular-toed geckos. They primarily inhabit arid badland strips with sparse vegetation, and secondarily extend into rocks and man-made structures. The generic affinities of recently described; sub-Himalayan gecko Cyrtopodion brachykolon Krysko et.al., 2007 from northern Pakistan, are commented upon.