Journal of Agricultural Sciences and Natural Resources
Year:2001 | Volume:7 | Issue:4|Papers Count:16

Karstic lands are one of the important resources in Iran and in the world. Therefore, investigation of these catchments are necessary for better using. In this article, the main objective is to compare hydrological characteristics of two types of catchments, calcareous rock and noncalcareous rock formed. Vehrgan catchments is a karstic watershed that mostly covered by limestone, and is located in Zagross mountain ranges on the Chahar-mahal-bakhtiary, Esfahan and Lorestan states boundaries, compared with a nonkarstic catchments, namely Golpayegan catchments that having a 160 kilometers distance from west of Esfahan and north of Vehregan in view of maximum discharges, runoff coefficient, specific discharge and relation between maximum instantaneous discharge and maximum daily mean discharge with the similar climate, catchments area, slope and annual rainfall. This study indicates that runoff coefficient is 1.28 for Vehregan's karstic catchments and is 0.32 for Golpayegan that is a non-karstic catchments. Specific discharge for vehregan catchments on a concurrent period is 0.0174 and for Golpayegan is 0.051 discharges for vehrgan catchments on a concurrent period is 0.0174 and for Golpayegan is 0.051 m3/sec/km2. Relation between maximum instantaneous discharge and maximum daily mean discharge in the water year 49-69 for vehregan karstic catchments is between 1.001 and 1.76 with an average of 1.45. This relation for Golpaygan catchments for that period is between 1.01 and 2.01 with an average of 1.38. The main result of this study is that application of rational and empirical formulas for karstic catchments is unreliable.

Soiloss computer model has been improved from universal soil loss equation (USLE). This model is being used in Australia. In this research the soil loss model has been tested in 3.2, 3.3, 3.4, 4.1, 4.2 and 4.5 land units of north Karun watershed. The results have been compared with PSIAC model. The first objective of study is to determine the capability and the efficiency of model in evaluating the erosion of soil. Using land units map, the soil samples were taken from each land unit and analyzed for some physical and chemical characteristics. The soil loss model wasb run with the analyzed and measured data. Measured soil erosion of 3.2, 3.3, 3.4. 4.1, 4.2 and 4.5 units were 7.7, 4.4, 7.7, 1.4, 1.7 and 1.3 ton/ha respectively. Comparing erosions measured with PSIAC (obtain from previous studies). Shows the harmony and similarity between them. These show the capability and efficiency of the soil loss model.

To determine the effects of environmental and edaphic factors on the vegetation at protected area of Jahan-nama, within 37 sampling units (100×l00m), random plots of I-m2 were selected. Canopy coverage, production, utilization of range species, and physical and edaphic factors were measured. Based on entire data of 37 sampling units, by the use of stepwise regression, soil moisture was the only variable, which entered to the model of the canopy coverage as a dependent variable. The relation between production and elevation was quadratic, so that by increasing the elevation, production decreased first and then gradually increased. With utilization as a dependent variable, elevation and interaction of siol moisture and elevation were entered to the linear model. Based on categorized data of elevation, quadratic relationship established between production and different classes of elevation. Utilization decreased linearly as the elevation increased. There were also an inverse linear relationship between utilization and classes of slope that can be related to the immobility of herds that prefer steep slopes. Canopy coverage for dominant species of Stachys sp. and Poa bulbosa declined as the elevation increased. At higher elevations, the canopy coverage Juniperus communis was increased that is a cushion plant, occupies vast areas.

This experiment was carried out to investigate micronutrients status to determine the nutritional problems of apples. The cultivator was Golden Delicious. Twenty four apples were selected and soil and leaf samples were collected from the apple field. Using soil and leaf samples, Fe, Zn, Mn and Cu analysis was conducted. The results of soil and leaf analysis were compared with sufficiency values and the nutritional of apple was evaluated in regard to micronutrients. The result showed, according to this evaluation no problems was found considering the nutritional levels of Cu, but significant Fe, Zn, and Mn were determined in the majority of apples. The Fe, Zn and Mn contents of leaf samples were deficient in 67%, 61% and 42% of the apple trees, respectively.

Pollen ultra structure components and characters including; polar axe, equatorial axe, ratio of polar axe to equatorial axe, ridge diameter, pit surface area percentage and length of furrow were evaluated to test usefulness of each character for identification of pear species and cultivars. We used Scanning Electron Microscope (SEM) and image analysis software program. Statistical analysis of the data were conducted in a RCDB design. Results showed that polar axe, ratio of polar axe to equatorial axe and pit surface area were identified as useful means of identification. Result showed that there was no significant difference for equatorial axe among different pear cultivars and species. Thus, pollen equatorial axe was not a suitable character for identification of pears. On the other hand, polar axe, ratio of polar axe to equatorial axe, length of furrow and pit surface area percentage were all useful characters for identification of pear. All the pears for these characters were divided into 3 groups of maximum, moderate and minimum. Pollen with a polar axe 43 to 45 micrometers in maximum, 39 to 43 in moderate and 36 to 39 in minimum were grouped. For the ratio of polar axe to equatorial axe a ratio of over 2 was located in maximum, 1.85 to 2 moderate and lower than 1.85 were grouped in minimum. For the germinal furrow, pollen with a length of germinal furrow of 37 to 43 micrometers in maximum, 36 to 37 in moderate and lower than 36 were grouped in minimum.

Jujube tree (Zizyphus Jujuba Mill syn: Zizyphus vulgaris Lam) is one of the valuable medicinal plants in the Iranian traditional medicine. It is used as laxative and blood purifying. It grows in arid and semi - arid zones of Iran (Such as Birjand). Jujube tree is tolerated to saline water, saline soil, pests and diseases. The main aim of this research was to study the effect of age of offsets and their suitable time of transplanting on the propagation of Jujube tree. The statistical design was factorial on the basis of randomized complete block design with four replicates in every treatment. In this investigation have been used of one - year -old, two - year - old and three - year - old offsets and transplanted on October and March. On the basis of the results the most suitable offset age was two - year - old and suitable time for transplanting was October (before winter freezing).

During1997 more than 40 soil samples were collected from the rhizosphere of cotton fields in Gorgan and Gonbad areas (Golestan province). Nematodes were extracted from soil by sieving and centrifugal sugar- flotation method. The specimens were killed and fixed by hot solution of FGA 4:1:1 formaldehyde, glycerin and acetic acid), processed to anhydrous glycerin by the modified Seinhorst method (De Grisse, 1969 ) and studied by light microscopy. Nine Tylenchid species belonging to eight genera such as Boleodorus thylactus Thorne, 1941; Helicotylenchus pseudorobostus (Steiner, 1914) Golden, 1956;Merlinius brevidens AlIen 1955; Neopsilenchus magnidens (Thorne, 1949)Thorn and Malek, 1986; Pratylenchus neglectus Rensch, 1924; Pratylenchus thornei Sher and Allen, 1953; Pratylenchoides ritteri Sher, 1970; Psilenchus hilarulus De Man, 1921 and Tylenchorhynchus latus Allen, 1955 were identified. All species are reported for the first time from cotton fields in Iran. The population density and the distribution of Pneglectus and. Pthomei were more than the other species.

Forage sorghum in two forms of germplasm and hybrid varieties is used for planting in the world. In order to evaluate native sorghum in comparison with Speed feed, an experiment was conducted in Araghi Mahalleh experimental research station in 1377. A split plot statistical design with four replication of harvesting time was used to this experiment. Main plots of this experiment were included of Speed feed hybrid as control and KFS1,KFS2, KFS5, MFS2 and LFS56 germplasms. Subplot was harvest included first and second harvesting time. Results showed that there were significant difference for the level of %1 were observed in fresh forage, dry matter, leaves to stem ratio, number of nodules, thickness of stems and height of plants, and there was also a significant difference for the -level of %5 in number of leaves. LFSrS6' MFS2' KFSs, LFSS6 and MFS2 showed better results in height of plant, number of nodules, thickness of stem, number of leaves and number of tillers respectively. MFS2 was better results than other native varieties and it can be compared with Speed feed hybrid due to highly of yield and proper leave to stem ratio.

In order to study the relationship among various morphological and physiological traits, yield components and grain yield in grain sorghum (Sorghum bicolor), a field experiment was conducted in 1373 at Isfahan. Path coefficient analysis of correlation coefficients revealed a complex pattern of relationship among traits. This pattern was partly hidden in superficial study of correlation coefficients. Path coefficient analysis showed that in determination of vegetative dry- matter (VDM), this order of contribution was true: Leaf area index > Plant height > Days to anthesis > Leaf number. VDM had a negative influence on number of kernels per unit area: kernel number was the most important yield component. Late-maturing, via increasing of VDM and decreasing grain filling rate per unit area, reduced grain yield. Then, in view of relationships among traits and significance of the traits to yield formation, a sorghum ideotype proposed for Isfahan.

In order to study effects of sowing depth and seed size on growth and yield of corn hybrid SC704, an experiment was conducted in 1996-1997 at Ramin Agricultural Research and Education School of Shahid Chamran University. The design of the experiment was a split plot in which main plots were consisted of 2 sowing time (August 9 and 21), subplots were collected of 3 sowing depth (2, 4.5 and 7 cm) and sub subplots were 4 seed size (5.9-6.1 mm as small, 6.9-7.1 mm as medium, 7.9-8.1 mm as large size and mix) in randomized complete block with 4 replications. Analysis of variance showed that sowing depth and seed size affect seed emergence, which inf1uence growth and yield. Low sowing depth (2 cm) with uniform seeds compare to mix seeds induce uniform emergence and same time germination without competition in emergence time, therefore yield of corn increased. With medium sowing depth (4.5 cm) large and mix seeds grain yield increased significantly. More sowing depth (8 cm) in compare to low and medium depth, small seed and latter medium seed size had higher yield than large and mix seeds. Among yield components, number of kernels per row (41.93) in surface planting (2cm) with large seeds size was more than other size of seeds. In medium sowing depth (4.5 cm) mix seeds had highest number of kernels per row (41.41). In 7cm sowing depth number of kernels per row was 42.45. The results of this study suggest that increase in sowing depth caused a delay in germination, emergence of seedlings and relative growth of plants. Thus yield would be reduce.

In order to evaluating the effect of flooding on growth and biological nitrogen fixation (BNF) in subterranean clover, an experiment was carried out using a randomized complete blocks with 4 replications and 2 treatments. Treatments were normal conditions of Gorgan and artificial flooding condition. Dactylis gelomerata was used as a reference plant to estimate BNF in subterranean clover. Result showed that flooding conditions reduced dry matter production, BNF, nodules fresh weight and leaf area by 14.6, 31.7, 28.7 and 14.4% in comparison to control. But, nitrogen yield was not significantly affected by flooding.

In germination stage, decreasing wheat seedling growth as affected by drought stress is a common phenomenon. Seedling growth can be defined as a product of three components: (1) Initial seed dry weight, (2) Fraction of seed reserves mobilized, and (3) Conversion efficiency of mobilized reserves to seedling tissue. The objective of this study was the determination of sensitive seedling growth component in response to drought stress. To do this, two factorial experiments with two wheat cultivars (Tajan and Baconara) and various osmotic pressures induced by PEG (0 to1.8 MPa) were carried out. In experiment II, seeds were moistened for 24 h before transferring to osmotic solutions. In both experiments seedling growth (dry weight), seed reserve mobilization ratio and conversion efficiency of mobilized reserves were measured. Results showed that in both experiments seedling growth and seed reserve mobilization ratio are linearly (more or less) decreased with increasing osmotic pressure. However, PEG induced drought stress had no effect on conversion efficiency. Pre-moistened treatment had no effect on response of seedling growth, seed reserve mobilization ratio or conversion efficiency to induced drought stress. But across osmotic pressures higher seedling growth (5.5 mg seedling-1) and seed reserve depletion ratio (0.35 mg mg-1) and lower conversion efficiency (0.1 mg mg-1) were observed. It was concluded that decrease in seedling growth of wheat under drought stress is a result of decrease in mobilization of seed reserves (i.e. metabolic processes relating to production and activation of Gibberlin and hydrolytic enzymes).

Rice (Oryza Sativa L.) is one of the leading food crops of the world and the staple food of over half of the world's population. Because of it's very common consumption in Iranian dish dietary, more attention is necessary to be paid to rice and its properties. Starch is the major constituent of milled rice and its properties affect the cooking and processing quality of milled rice. Different rice varieties that have specific properties are used in specific rice products. The elected samples selected for this study were eight cultivars of nonwaxy rice (milled rice of long, medium and short grains). Water uptake, protein, amylose and alkline spreading value of milled rice were determined. Starch was isolated from milled rice by sodium hydroxide and then quantity of ash, protein, amylogram peack temperature, viscosity, BEPT, gelatinization time were determined. Data of the experiments were analyzed in complete randomized design. According to significant differneces between rice sample properties, application of each rice cultivar in various industries were defined. Models were designed based on relationships and correlations among gelatinizations properties.

In preliminary statistics, mean is one of the centralized criterion and got many different types which each of them, plus their contribution shows many views of datas population statistics to any researcher and also called power means. With the importance of these means, theirs relationship on the other hand, unequal theirs always is noticeable. This article shows a new approach on how we are going to use this inequality with the help of Ln weighted function. Also with some useful examples the importance and the impact of such a these mean and their application on agricultural problems and natural resources are going to discuss.