Journal of Agricultural Sciences and Natural Resources
Year:2001 | Volume:8 | Issue:1|Papers Count:18

A study was conducted on 2 species of Gobiidae N. fluviatilis and N. melanostomus in the Madarsoo Stream, an upper reach of Gorganrud river in the province of Golestan situated in the southeast Capian basin, from February 1995 to February 1997. 316 fish speciemens were captured by electrofishing of which N. fluviatilis and N.melanostomus 95% and 5% of the catch respectively. In the catch of N.fluviatilis, there were 22.2% male and 77.8% femalet. The Ivlev index was used to determine food selection in different months of sampling. The selected food in .February 1995 and July 1997 were Chironomidae and Ephemeroptera with 0.2 and 0.21 respectively. Shannon index of species diversity were highest in Habitat and stomach contents in spring with 0.84 and 0.56 respectively. Horn index of nich overlap showed that Apr. 1997 with 0.68 and Feb. 1997 with 0.19 had the maximum and minimum niche overlap respectively.  

The study was conducted to determine breeding birds in three international wetlands of Turkman steppe (Aji-gol, Ala-gol and Alma-gol) from late winter 1998 to late spring 1999. Different sites such as those containing marginal and sub-merged plants. Vertical banks of, the wetlands, and muddy islands were investigated. Usual measurement such as length, width, height, number of eggs and chicks were conducted in the observed nests. The results show that at least 36 birds breed in the three wetlands. Based on the previous reports and the resident opinion, there can be 11 other breeding birds that need to be further investigated.  

Gypsy moth, Lymanatria dispar L.(Lep., Lymantriidae), which is a polyphagous and dangerous pest, is spread in different areas of Arasbaran forests and feed on many species of trees and shrubs specially oak trees. The pest overwinters with egg stage in Arasbaran. First instar larvae emerge gratually from egg masses depend on c1imat and latitude of different areas from early spring of next year. The young larvae after lasting 4 instar (for males) or 5 instar (for females) transform to pupa in folds of leaves or trunk of host plants. From late july the moths come out of the cocoons and mate. Then the female moth lays her eggs after 3 to 4 days of emerging. The fall and winter passed in the egg stage. There is only 1 generation per year. Following three parasitoid wasps and one parasitoid nematode are obtained in the natural enemies study of the pest. 1) A parasitoid nematode (Mermithidae) destroyed the last instars of larvae, it probably is belong to Hexamermis genus. 2) Monodontomerus aereus Walker (Torymidae) 3) Glyptapanteles porthetriae Mues.(Braconidae) 4) Glyptapanteles indiensis Marsh (Braconidae) Three last mentioned species that they parasitize on pupa(No.2)and larvae (No.3 and 4), are reported for the first time from Iran. Also all of natural enemies are new records on the pest.  

Exotic conifers have been planted in this country to test their adaptability to climatic conditions since many years ago. One of these exotic conifers is Cedrus deodara which has been introduced in Iran long time ago. There is a small population of this species in Passand Research station, behsahr, which has been established in 1970. This population was the subject of study in this research. In this investigation in the years of 1993 and 1999, all of the trees were measured in terms of such as vegetative parameters (stem diameter at breast height, the middle height and height of trees with accuracy of centimeter). Stem middle height diameter was used to determine total stand volume. More over average diameter growth, average height growth, average annual volume increment were determined which were 1/3cm, 0/68m and l0/9 m3/ha respectively in the year of 1993 and were 1/2cm, 0/57m, 11/4m3/ha respectively in the year of 1999. Studying of this stand has been done with comparison of quality and quantity measurements, climatic conditions and soils physical and chemical properties during investigation years. Finally, we commend the aforestation of this species in some areas of Mazandaran Province. The use of this species must be restricted, mixed with hardwoods and medium period harvesting (40-45 years) on soils with more evolution respect to Passand Research Station. In the mean time climatic and ecologic conditions of this areas should be as like as the studying plants area.  

In order to investigate vegetative propagation of Persian walnat (Juglans regia L.) a matter of importance for a successful establishment of seed orchard for this species, several experiment were conducted on air (Chinese) layering methods. The results for air layering showed that application of 500 PPM mixture of the two plant regulator (Indolbuteric acid mixed with naphtalinacetic acid= IBA + NAA) on calluse formation at the layered space were highly significant, in comparison to the other treatments(At 0/05 statistical level). Meanwhile, five months after applying the two hormones, caused the root formation at the layering location, the average root length was 18.03cm. (x=10.03) which is significantly different with other treatments at 0.05 level.    

In this research, amount of production in different heights and aspects were measured. Study areas were Gharabugh and Belghis with 2750 ha and 875 ha correspondingly as protected areas in Anguran, Zanjan. Un-protected areas were chosen beside mentioned areas. This plan was made as completely random design. Plant production was measured in key areas and inside 1 m2 plots in each height category inside main aspects (north, south, east and west). Significant difference between height categories was observed in 1% probability after analysis of variance of production. Maximum production was for 2650 m to 2850 m height and minimum production for 1450 m to 1650 m height in both of protected and un-protected areas. Maximum production for first class plants in protected areas was in 1450 m to 1650 m height. Minimum production was observed in 1850 m to 2050 m height category too. Maximum production of first class plants in un-protected areas was for 2850 m to 3050 m height category and minimum production was for 1450 m to 1650 m height category. It was not observed significant different between protected and un-protected regions in terms of production. First class plants showed significant difference in protected areas in different aspects.    

The preparation of land use maps through traditional methods is very expensive, takes a lot of time and it is not usually efficient, but the use of satellite data may compensate the traditional methods. The main objective of this study is to evaluate the capability of TM spectral bands for mapping land cover and land use in the Mook area located in the south of Shiraz. In this study 7 Landsat TM images recorded on October 13th, 1990 were used. Before using the landsat satellite data, the quality of the images were investigated, in view point of geometric and radiometric errors. The field work were designed and the representative training areas were selected, randomly then the TM bands 3,4,5 and 7 as the most informative bands were chosen for image classification. In order to classify the images, the 26 spectral classes were trained and maximum likelihood classification method was performed. Finally the spectral classes were re-grouped into 10 information classes. The GIS was applied for correcting the wrong pixels of some classes, such as urban and river classes. The accuracy of classified image was assessed by additional samples after classification. The high accuracy of maximum likelihood algorithm shows that, the Landsat TM data have high capability in mapping land use and land cover types in arid and semi-arid areas.    

Application of vegetation indices derived from Landsat Thematic Mapper imagery to estimate standing crop percentage of rangeland vegetation of Jahan-Nama was assessed. Stratified random sampling was designed and 370 sample plots on 37 sample units were allocated in the Field using Global Positioning System (GPS). Landsat Thematic Mapper image, dated on 1998, was geometrically corrected with RMS error of less than 0.98 pixel size. Corresponding mean spectral values of 9- pixel elements belonging to sample units for all seven thematic bonds were extracted. Corresponding field measurements have been regressed against TM data, as an independent variable, and 69 vegetation index values created by different combination of TM bands as dependent variables. Their statistical model have been developed. Results show that if standing crop data, without their arrangement in classes, are entered in the regression analysis, Landsat data are unable to detect their changes. The results also show that Landsat date are capable of detecting high standing crop classes when Filed data are categorized. Regression analyses show promising results in estimating standing crop of rangeland vegetation.  

This study was performed on the basis of field experiment to evaluate the effects of different speeds on wearing 4 steel blades of mold board plow in an uniform soil depth and to measure the amount of fuel consumption during operation. In this experiment, we used a jandeer tractor with 90 HP and the effect of three independent variables each having three speed levels of 3,4 and 5 km/hr with 0.15 difference on two dependent variables of steel blades moldboard plow and fuel consumption were tested and determined. The results obtained were analyzed statistically using Dancan's multiple-test range for mean treatment comparisons. The results indicated that the amount of wearing blades N0.1 and N0.2 were significantly more than blades No.3 and No4. However, there were interaction between blades wearing and type of blades. In German made blades, wearing was in No.1 and No.2 where as in Iranian type Blades wearing was almost equal in all blades. The interaction between tractor speed and blade wearing was significant. The amount of wearing was increased in blade No.1 by increasing the tractor speed but in other blades it was almost independent of tractor speed Meanwhile the effect of tractor speed on fuel consumption were significant. The possible cause of differences have been investigated and discussed.  

An experiment was conducted to evaluate the quantitative and qualitative forage characteristics of sorghum in Agricultural Research Station of Gorgan in 1997. The experiment was carried out in pots under controlled conditions. Treatments comprised of three levels of N fertilizer (0,3 and 6 gr N/pot simulating control, 100 and 200 kg N/ha respectively) and drought stress which was applied on four growth stages of sorghun (7-8 leaf stage, flag leaf appearance, heading stage and control). Treatments were arranged factorially and were compared in a Randomized Compe1ete Block Design with three replications. For each drought stress treatment, irrigation was stopped at the beginning of the expected growth stage and re-started when the signs of temporary wilting were seen in plants (pressure of soil moisture equal to - 17 bars). After drought stress, plants were irrigated normally. Application of N fertilizer enhanced dry matter production, water use efficiency, percent crude protein, protein production, ash production and crude fiber yield. However, no significant effects were observed on days to harvest as well as the percent fiber and ash by N fertilizer application. Temporary drought stress applied at different growth stages manipulated dry matter production, days to harvest, water use efficiency, crude protein production, ash production and crude fiber. No significant effects were observed on percent ash, percent crude fiber and prussic acid content by drought stress. Drought stress at 7-8 leaf stage and flag leaf appearance increase vegetative growing period and postponded the generative growth. However, drought stress at heading stage accelerated generative growth and decreased plant weight. No significant interaction effect was observed for the measured characteristics in this experiment.    

Effect of drought stress, seeding density and cultivar was studied on the growth, development and yield of dryland wheat in Mashhad and Shirvan. Treatments (in Mashhad) were consisted of draught stress in grain filling period (with and without stress), density (85,103,175 kg\ha) and cultivar (Sarday and Sabalan) in a spilt factorial design with three replications. In Shirvan (rainfed), treatments were seeding density (70,100,130,160,190 kg\ha) and cultivar (sardary and sabalan) in a factorial design with three replications. Results showed that, in Mashhad, drought stress decreased anthesis to maturity period, spike number thousand kernel weight, seed and biological yield, and harvest index and increased leaf area index, total and dead dry matter at anthesis. Effects of seeding density on spike number, seed and biological yield and thousand kernel weights followed a diminishing trend after a maxmium. In Mashhad and for all of the traits (in except of tiller number), Sabalan  was supperior over Sarday. In Shirvan, increasing seeding density resulted in decreasing of tiller number, kernel number per spike, harvest index and increasing of leaf area index, total and dead dry matter at anthesis, spike number and seed yield. Superiority of Sabalan was ,also obvious in rainfed condition of Shirvan.  

In order to study the interrelationships between the grain yield and its components and determine the most effective components on grain yield of opaque - 2 maize, 16 opaque-2 lines and their testcrosses were evaluated in Seed and Plant Institute, Karaj , Iran in 1994. The experimental design was nested split plot with three replications. Each replication consisted of two main-plots (inbreds and testcrosses). Within main plots, 16 opaque - 2 inbred lines and 16 corresponding testcrosses were arranged, respectively. Twenty traits were measured as: number of days to tasselling and silking, plant and ear height, stem diameter, length, width and area of the leaf above the first ear, relative growth rate, total number of leaves, number of leaves above the first ear, number of kernel rows, number of kernels per row, ear length and diameter, cob diameter, percentage of cob, kernel depth, 300 kernel weight and grain yield. Before path analysis stepwise regression of 20 traits on grain yield was done using inbred lines and also their testcrosses. Path analysis and stepwise-regression showed that the grain yield of opaque-2 lines is affected by the direct and indirect effects of number of days to silking, ear length and diameter, number of kerels per row and percentage of cob. Regarding the residual of 0.37 and coefficient of determination of 0.86, it could be stated that the large proportion of variation in grain yield of opaque-2lines is related to the traits mentioned above. The grain yield of testcrosses was explained by the direct and indirect effects ear length, ear diameter and number of kerenels per row. Considering the residual of 0.44 and coefficient of determination of 0.76, the large proportion of the variation in grain yield of testcrosses were determined with these characteristics. In conclusion ear length, ear diameter and number of kernels per row could be regarded as the major components of grain yield in opaque-2 maize.  

In order to investigation of the effect of pH and its application time on growth and biological nitrogen fixation (BNF) in subterranean clover, a factorial experiment was carried out using a completely randomized design with 3 replications in hydroponis culture. The treatments were three pH rates (5.5, 7.0 and 8.5) and their application times (before and after in inoculation). Seedlings, after 50 days growth, were measured for number and fresh weight of nodules, leaf area, root shoot and total dry weight, and nitrogen content of and shoot (using miro- kjeldal method). Results showed that pH application before inoculation had more negative effect on measured characteristics that its application after inoculation. Nodule fresh weight was 12.6 % lower when pH treatment was applied before inoculation. The lower leaf area, root and ahoot dry weight and root nitrogen content were observed in pH=8.5 applied before inoculation. At pH=7.0 all measured traits were maximum and the minimum amounts were measured in pH=8.5. the best growth and BNF were observed at pH=7.0  

An experiment was conducted based on RCBD with four replication and eight teammates during Fall of 1995 to compare the efficacy of trifluralin , ethalfluralin Cyanazine , alachlore and propizamid herbicides us well as hand weeding inxcontrolling of oil seed rape weeds in Eraghi-Mahalleh agricultural research station.xResults indicated a significant difference on wild mustard density between herbicide treatments and control as well as two or four times hand weeding. Wild out significantly controlled by herbicides. However, cyanazine and alachlore herbicides were less effective on it. Treatments didn't affect on oil seed rape density. Crop yield in herbicide treatments significantly increased compare to control.  

In order to evaluate the existing relationship between the locations of production and storage of assimilates in cotton, an experiment was conducted in Varamine. A factorial test based on a randomized complete blocks design with three replications was used. The factors under investigation consisted of source to sink manipulation and genotype. Four manipulation levels were partial fruit pruned (sink decrease), control, sympodial leaf pruned and monopodial leaf pruned (source decrease). Okra leaf (low LAI), Varamine (medium LAI) and Tashkand - 1 (expanded LAI) were cultivars which used in the experiment. According to the results, sympodial and monopodial leaves had the same importance in cotton bolls development. The measured traits showed different response to the different source to sink ratios. In this respect, boll weight and average of fibers length were known source limited, but seed weight (only in first position of monopodial bolls), seed number, lint percentage, thickness and strength found out sink limited and these greatly depended on cotton genotype. Suitable planting arrangement and cotton canopies bred may be useful for increased light penetration and decreased source limited.