جستجوی مقالات مرتبط با کلیدواژه "نماتد" در نشریات گروه "آب و خاک"

In order to evaluate and classify the quality of wastewater treatment plant effluent of Yazd, and assessing its potential for agricultural sector usage, wastewater samples were weekly collected, and microbial tests, the traits of fecal coli forms (FC), nematode egg (NE) number per each sample, the concentrations of PO4, NO2, NO3, NH3, SO4, Na, Ca, Mg, K, HCO3, CO3, B, Fe, Zn, Cu and Mn ions, and the amounts of pH, EC, SAR, were measured using standard methods. The results showed that wastewater is classified as class B, using WHO guidelines. So, it is suitable for irrigation of cereals, industrial and fodder crops, pastures and ornamental plants. The most limiting factor for applying this wastewater in agriculture is high concentration of HCO3 which will increases SAR through sequestration of calcium and magnesium ions and consequently decreasing the infiltration rate of soil in long period of time. According to the estimates, the Gypsum Requirement (GR) for alleviating harmful effects of high SARadj level in wastewater is equal to 8.62 ton ha-1. High concentration of macronutrients in the wastewater made it feasible for cultivating industrial and fodder crops such as cotton, barley and halophytes. Boron toxicity in the wastewater is not a limiting factor. The concentration of Na and Cl in wastewater was less than the toxicity threshold of these ions for cotton, sunflower, corn, sorghum, safflower, sesame, etc. The concentration of Fe, Cu, Zn and Mn in the wastewater is under toxicity levels that are recommended by FAO, so these elements do not cause any ionic toxicity for plants.

Because of deforestation and reduction of forest areas, plantation is a vital issue for now and the future. The evaluation of planted species is very important to creation of forests with better quality and quantity in the future. Soils, as an important part of the ecosystems, are affected by tree species with differences aboveground and below ground biomass, under same field condition .Biological properties are good indices to assessment of soil quality and health. In this study the effects of different forest covers including natural forest, hardwoods and softwoods plantations, on variability of fine roots biomass, ecological group's earthworm's density/biomass and nematodes abundance were considered.
Soil samples were excavated in sixteen points from 0-15 cm (top soil) depth, for each forest covers including Carpinus betulus (hornbeam) - Parrotia persica (iron wood) as a natural stand, Fraxinus excelsior (ash), Acer velutinum (maple) hardwoods and Pinus brutia (pine), Cupressus sempervirens (cypress) softwoods plantations, located in Wood and Paper Company of Mazandaran. Soil moisture, pH, organic carbon, total nitrogen and biological indices (fine roots biomass, earthworm's density/biomass and nematodes abundance) were measured and recorded at the laboratory.
ANOVA results for soil physico-chemical properties showed significant statistical differences related to forest covers. So that the highest values of soil moisture, organic carbon and C/N ratio were found under pine plantation. Also the higher values of soil pH and total nitrogen were detected in Carpinus betulus - Parrotia persica natural stand. Greater amounts of fine root biomass (89.68 g m-2), earthworm's density (1.81 n m-2)/biomass (24.17 mg m-2) and nematodes abundance (603.37 n m-2) were found in Carpinus betulus - Parrotia persica natural stand. Also maximum epigeic density (1.43 n m-2)/biomass (19.25 mg m-2), were found under Carpinus betulus - Parrotia persica natural stand and ash plantation. Higher anecic earthworm's density (0.37 n m-2)/biomass (4.92 mg m-2) recorded in Carpinus betulus - Parrotia persica natural stand. The endogeic species were not observed under different forest covers. Greater amounts of nematodes abundance (603.37 n m-2) were recorded in Carpinus betulus - Parrotia persica natural stand. The finding of correlation between biological indices and other studied properties indicating that biological characters are influenced by soil water content and chemistry under different forest covers.
The findings of this study are showing the considerable effect of natural forest covers on soil biological properties and quality. In addition, in degraded areas of northern Iran, planting of Fraxinus excelsior species can be considered due to improvement and conservation of soil biological indices, quality and health.

In order to identify the plant-parasitic nematodes of important cereals (wheat, barley, and corn) in Isfahan Province, 120 soil and root samples were collected from the rhizosphere of these crops in various locations in the region during 1999 and 2000. Nematodes were extracted from soil by sieving and centrifugal sugar-flotation method. The specimens were killed and fixed in FGA (formaldehyde, glycerin and acetic acid 4:1:1) hot solution. The extracted nematodes were mounted in glycerin, permanent slides prepared, and studied by light microscope. The results revealed the presence of three species belonging to two genera of family criconematidae as follows: Criconemella antipolitana , C. xenoplax, Hemicycliophora poranga. H. poranga was extracted from rhizosphere of corn and reported for the first time from Iran. The most frequently occurring and dominant species was C. antipolitana that was isolated from soil around the roots of wheat and barley in several areas. C. xenoplax was extracted from a wheat field with the history of peach cultivation. These species are new records for Isfahan Province.