نشریه علوم آب و خاک (علوم و فنون کشاورزی و منابع طبیعی)
سال پنجم شماره 2 (پیاپی 16، تابستان 1380)

Flood is one of the catastrophic events that has attracted the hydrologists’ attention. In this research one of the important flood indices, i.e. maximum-daily mean-discharge, was determined for several western Iran watersheds, namely, in the catchments of Gamasiab, Qarasou, Saimare, Kashkan, Sezar and Abshineh. Daily data were prepared from stream-gauging stations and a 30-year concurrent period was selected. Flood frequency analysis was performed using HYFA and TR computer programs and optimum distributions were chosen by goodness of fit tests. Extreme flow values having different return periods of 2, 5, 10, 25, 50, 100, 500 and 1000 years were calculated. Modeling was done with regional analysis using multiple regression technique between maximum-daily mean-discharge and physiographic characteristics of the basins. The most important parameter for the selection of the model was the adjusted coefficient of determination while significant level, standard error and observed discharger vs. computed discharge plot acted as controlling parameters. Finally, different models with different parameters were selected from power, exponential, linear and logarithmic forms. The results showed the power model to be the best among the four types. The main channel length, drainage density and time of concentration were the most effective parameters on flow. After analyzing the errors, it appeared that increasing the return period would cause an increase in the model error. At 1000-year return period, the error reached 32.2%.

The main objective of the present study is to analyze the effects of agricultural crop insurance on farmers’ technical efficiency and risk attitude. Required data came from questionnaires that were completed by the Institute for Planning and Agricultural Economics of the Ministry of Agriculture. Farmers’ technical efficiency and attitude toward risk were estimated using stochastic frontier production function and equally likely certainty equivalent method for both insured and non-insured groups. Results revealed that effects of agricultural insurance on farmers’ technical efficiency were significantly positive in the three study regions. Results of estimating risk aversion coefficients of study farmers showed a positive effect of insurance on risk aversion coefficients. However, this effect was significant only in two of the climatic regions under study.

In order to produce Tristeza virus-free plants from Satsuma mandarin (Citrus unshiu) cultivars (Ishikawa, Sugiyama and Myogawa), unfertilized ovules of plants suspected of CTV (Citrus Tristeza virus), from Mazandaran Mahdasht orchard were cultured on 4 media. Embryogenesis of nucellus tissue of ovules from Ishikawa and Sugiyama cultivars on MS medium were 31% and 25% and on MT medium from Ishikawa was 40.5%. Unfertilized ovules of Myogawa did not germinate on all media. Nucellar embryos of Ishikawa and Sugiyama developed on MT+GA3+ME were 83% and 95%, respectively. Embryo differentiation, leaf and plantlet formation were observed on MT+GA3+ADE+ME medium. In the stage of two leaves, the plantlets’ growth under 1500 lux illumination was twice its growth under 800 lux illumination. Budding of in vitro plantlets from both cultivars on susceptible to Tristeza and virus-free seedlings of Key Lime did not show any infection by Tristeza.

Tillage system effect, Conventional (CT) vs. No-Till (NT), on soil physical properties and Br transport was studied at two locations in North Carolina. The soil types were a Typic Paleudults at Coastal Plain (site 1) and a Typic Kanhapludults at Piedmont (site 2). Bulk density (BD), total porosity (TP), macroporosity (MP), and saturated hydraulic conductivity (Ks) .were measured in plant row (R), and trafficked (T) and untrafficked (N) interrows. A rainfall simulator was used to apply two early season rainfalls to 1 m2 plots where KBr suspension was surface applied for Br leaching study. The first simulated rainfall event (30 min) consisted of a low (1.27 cm h-1) or a high (5.08 cm h-1) rate applied, 24 h after Br application. One week later, the high rainfall rate was repeated on all plots. Soil samples were taken two days after applying first and second simulated rainfall (a week between them) and the end of season from different depths for measuring Br concentrations. Soil physical properties were affected by both tillage system and position. Bulk density was higher in NT versus CT and in T position versus Rand N positions. Total porosity was lower in NT versus CT but MP was significantly higher in NT. Saturated hydraulic conductivity was about 90% lower at T position versus N and R positions. Coefficient of variation was quite large, making it difficult to obtain statistical differences between tillage systems. The surface l0-cm of soil contained the highest Br concentration for depth treatments with treatment differences occurring primarily in 0 to 25 cm depth. In first and second sampling dates, more Br leached under NT versus CT system. However, there was no significant difference between the two tillage systems in Br leaching at the end of the growing Season. In site 1, Br leached more due to the coarse texture and high Ks of the soil.

The main sources of cadmium in soil-plant continuum in amounts that might present a hazard are liquid and solid wastes of sewage sludge, farm manures and fertilizers. In the southwest of Iran (Khuzestan Province) over 50,000 ha of land is under sugarcane (Saccarum officinarum) cultivation and more than 80,000 ha will be under sugarcane by the end of the year 2000. In these sugarcane fields, about 400 kg ha-1 diamonium phosphate (DAP) and 400 kg ha-1 urea are applied annually. There is no data available to show the fertilizers impact on soil, water and plant contaminations in Iran with respect to cadmium. The objective of this research was to compare the extractable cadmium of virgin soils with that of soils under sugarcane. Four sugarcane growing stations viz. Haft-tapeh, Karoon, Shoeibieh and Ghazali with cultivation histories of 36, 20, 2 and 1 year, respectively, were selected. In each site, along a transect soil samples from 0-30 cm of both furrows and ridges of cultivated soils and of virgin soils were collected. Electrical conductivity (EC), pH, clay and organic carbon contents, CI and Cd of 101 soil samples were measured according to standard methods. Results showed that increasing either EC or CI increased Cd concentration with its maximum in virgin soils and its minimum in furrows. Results also indicated a slight decrease in the Cd content of cultivated soils.

In order to analyze the genetics of tobacco cultivars’ resistance to blue mould (Peronospora tabacina A.) and to estimate the combining ability of the four resistant and susceptible tobacco cultivars (Bel 61-10, Bergerac C, Samsoun and Trumpf) received from CORESTA, these cultivars were crossed in 1997 in a half-diallel crossing system and in 1998 their parents and their progenies were sowed. Also to estimate gene effects controlling resistance and susceptibility of cultivars and to obtain F2, BC1 and BC2 generations, F1 generation was selfed and backcrossed with their parents. In 1999, the six generations (P1, P2, F1, F2, BC1 and BC2) from six families were evaluated in a complete block design with 3 replications and the resistance of genotypes against Peronospora tabacina were evaluated by the standard method of CORESTA and the parents with their F1 and F2 progenies were analyzed as a 4×4 half-diallel crossing system. The ANOVA showed significant differences among genotypes concerning resistance to Peronospora tabacina and the generation means analysis indicated fit of families Bel 61-10 x Bergerac C and Bel 61-10 x Trumpf with additive-dominance model. The rest of the families showed non-allelic digenic interactions (epistasis) and were fit to 6-parameter model of Mather and Jinks. Because of moderate to high narrow sense heritability of resistance to Peronospora tabacina (from 34 to 85% for different families), the selection of resistant lines may be successful. The results showed significant GCA of parents for the resistance to Peronospora tabacina. So, the role of additive effects of genes concerning resistance to Peronospora tabacina was recognized and the estimated heritability (in the narrow sense) was from 72% to 75% for this trait.

In order to evaluate the relationship between SDS-sedimentation value and breadmaking quality of wheat (Triticum aestivum L.), glutenin subunits of different genotypes (foreign and Iranian cultivars) were analyzed by reverse-phase high performance liquid chromatography (RP-HPLC). SDS-sedimentation value was used as an indirect criterion for breadmaking quality. Correlation coefficients revealed a closer relationship between low molecular weight (LMW) glutenin subunits and variation in SDS-sedimentation value. Principal component analysis confirmed the presence of association between some of the glutenin subunits and SDS-sedimentation value. Based on the stepwise regression analysis, two LMW and four high molecular weight (HMW) peaks (subunits) were selected which accounted for 70.2 and 18.7% of variability in SDS sedimentation values, respectively. On the basis of the results of the stepwise regression analysis, a discriminant function was developed. The great efficiency of discriminant function in correct classification of completely different genotypes (Iranian landraces and cultivars) showed that the observed relationship between glutenin subunits and SDS-sedimentation value has a genetic basis and the effects of LMW and HMW glutenin subunits on SDS-sedimentation value are additive. Therefore, it seems that this method based on more protein components (rather than only on HMW glutenin subunits) can be used to predict breadmaking quality of wheat against many genetic backgrounds.

Sensitivity of developmental stages of three sunflower cultivars to day length and temperature changes under field conditions were evaluated, and their development rates during various growth stages were modeled in a field experiment conducted in 1996 at the Agricultural Research Station, Isfahan University of Technology. Five dates of planting (April 27, May 12 and 27, and June 12 and 29) and three open pollinated sunflower cultivars (Record, Vnimik 8931 and Armavirec) were evaluated using a randomized complete block design with split-plot layout in three replications. Date of planting was considered to be the main plot and cultivars were randomized in sub-plots. Number of days from planting (P) to head visible (HV) and P to first anther (FA) were significantly reduced with delay in planting as the result of increase in temperature during these periods. Number of days from P to physiological maturity (PM) was also significantly reduced with delay in P. This response, however, could not be explained by changes in temperature variables or day length. Number of days from HV to FA, in harmony with the partial stability of maximum and minimum temperatures during this period, was not affected by date of planting. Duration from FA to PM of the last planting date was significantly shorter than the other planting dates. This response was related to the persistence of the effect of high and stable maximum temperatures prevailing during HV to FA period of the last planting date. Armavirec was significantly earlier than Record and Vnimic 8931 for number of days from P to HV and from P to FA Cultivars showed significantly large differences for the FA to PM and P to PM durations. Armavirec was the earliest and Record was the latest cultivar. Based on the results obtained, it may be concluded that the cultivars under study were non-sensitive to photoperiod. Development rate (DR) of Armavirec responded linearly and DR of Record and Vnimic 8931 responded non-linearly to increases in temperature variables during P to HV and P to FA Development of Vnimic 8931 was faster than Record at high temperatures. DR of the cultivars decreased linearly during P to PM as day length increased. The relationship between DR and photoperiod could be used as a practical model for estimating P to PM duration of these sunflower cultivars.

In order to evaluate the morphological and agronomic characteristics of 19 land races of onions and one foreign cultivar (Yellow Sweet Spanish), an experiment was conducted in 1998 at the Research Farm of the College of Agriculture, Isfahan University of Technology. Analysis of variance showed significant differences among genotypes for all of the morphological and agronomic traits. Dry weight and number of days to emergence had the highest and lowest coefficients of genetic variability, respectively. Plant fresh weight, yield of 30 plants and total yield also had high coefficients of variability. Broad sense heritability estimates were high for all of the traits, indicating low environmental affects them. Based on cluster analysis and plot of the first two canonical variables, the genotypes were classified in four groups with different agronomic traits. Canonical discriminant analysis based on nine agronomic traits introduced three canonical variables which justified 99.9 percent of the total variation among characters. Principal component analysis revealed four components while factor analysis showed three factors which explained 87.3 and 95.5 percent of the total variation among characters, respectively. The first and second factors were related to adaptation and assimilate translocation, respectively. Bulb diameter, bulb height and bulb weight in positive directions and sensitivity to Fusarium in negative direction had greater loads in the third factor.

Two experiments were conducted to investigate the effect of dietary energy levels on the performance of Arian broiler chicks. Trial 1 was performed in summer and trial 2 in fall. Both experiments were accomplished in 5×2 factorial designs, involving 5 levels of dietary metabolizable energy and two sexes. Each of the 10 resulting treatments was replicated 4 and 3 times in trials 1 and 2, respectively. The metabolizable energy contents in diets number 1 to 5 were 2800, 2900, 3000, 3100 and 3200 Kcal/kg for starter (0-4 weeks) period and 2900, 3000, 3100, 3200 and 3300 Kcal/kg for grower (4-7 weeks) period, respectively. The ratios of energy to each nutrient were the same for all diets in each stage of the experiments. In both experiments, body weight gain and feed conversion ratio improved significantly (P<0.01) when diets with higher levels of energy were consumed. Feed intake was affected (P<0.01) by the dietary energy content only in summer (trial 1) resulting from the reduced intake of chicks fed with the lowest energy level. Abdominal fat percentage was decreased (P<0.01) in chicks fed with the lowest energy diet in summer. In both experiments, the cost of the feed per unit of live body weight was reduced (P<0.01) in accordance with the reduction in diet density. As expected, body weight gain, feed conversion ratio, abdominal fat and cost of the feed per unit of live body weight for male chicks were significantly better than the same values for females (P<0.01).

This experiment was carried out to study the effects of supplemental Cu (0, 100 and 200 mg/kg) and vitamin C (0, 400 and 800 mg/kg) on cholesterol and other blood components in broiler chicks. A total of 360-day-old chicks in a completely randomized block design in a factorial arrangement were used. At 56 days of age one male and one female from each pen were selected, slaughtered and blood samples were collected at slaughtering time for further analysis. After separation of serum, cholesterol, fat components, Cu and vitamin C contents of serum were measured using the relevant methods. Copper, vitamin C, cholesterol, LDL and HDL of serum were significantly (P<0.05) affected by vitamin C and Cu supplementation. Hematocrit and mortality were not significantly affected.

This experiment was carried out to study the effect of different levels (3.06, 3.23, 3.4, 3.57 and 3.74%) of calcium and vitamin D3 (2000, 2200 and 2400 IU/kg diet) on eggshell quality of laying hens. In a completely randomized design and in a 5×3 (15 treatments) factorial arrangement, two hundred and forty (240) white leghorn laying hens, strain Hy-Line W36 and 26 weeks old, were divided into 60 replicates, four hens per replicate. The experimental period lasted 90 days until the hens were 38 weeks of age. The results indicated that shell strength, shell thickness and shell percentage increased significantly (P<0.05) at 3.06% Ca level. Calcium levels had no effect on ash shell percentage. Vitamin D3 did not have a significant (P<0.05) effect on ash shell percentage and calcium shell, but shell strength, shell thickness and shell percentage significantly (P<0.05) increased at 2400 IU/kg diet vitamin D3. Only plasma calcium raised significantly (P<0.05) due to the added vitamin D3. Interaction between vitamin D3 and calcium on shell strength, shell thickness, shell percentage and plasma calcium were significant (P<0.05). Correlation between egg shell quality parameters and blood parameters with calcium and vitamin D3 was significant (P<0.05).

In this study 130 honeybee colonies in 4 locations (Damavand, Tehran, Qum and Karaj-Savojbolagh) were sampled to determine the phenotypic correlations among 9 morphological and 3 production traits. The morphological traits were length (FL) and width (FB) of fore wing, cubital index (CI), length of hind leg (HL), length of probosics (LP), slender index (SI), length (WL) and width (WT) of wax mirror, distance between wax mirror (WD), index of wax mirror (IW) and corbicular area (CA). The production traits were honey yield (WH), pollen gathering (WP) and wax: production (WW). Data were subjected to analysis of variance, phenotypic correlations, stepwise regression and path coefficient analysis. Results of phenotypic correlations demonstrated that correlations between FL with FB (0.65), WL (0.361), WT (0.261), HL (0.555) and LP (0.257), WH with WP (0.300), WW with WH (0.560) and CA with WH (0.234) were significant (P≤0.01). FB with WH (r=0.204) was also significant but there was no significant correlation between CA and WP. Results of stepwise regression and path coefficient analysis showed that whereas morphological traits were settled as independent variables, much of the corresponding changes in production traits remain uninterpreted. In spite of the significant correlations among several morphological and production traits, body measurements alone are not suitable criteria to select colonies for high productions of honey, pollen and wax.

Field studies of S. cretica Led. damage and potential crop losses on two important cultivars of sugarcane, NCo 310 and CP 57-614, were carried out in southern Khuzestan in 1998-1999. CP 57-614 showed greater mean percentage of bored nodes and internodes (20.7%) than NCo 310 (11-2%). Apart from the direct losses in cane weight (cane yield) due to boring from the larvae, cane juice quality is also adversely affected, resulting in lower recovery of sucrose in the factory. Sugar per ton of stalks also was greater in NCo 310 (132 kg) than in CP 57-614 (110 kg). Estimated sugar losses were 0.11 tons ha-1 for every 1% bored and rotten stalks. Other indirect losses are also discussed.

Wheat as a main food source is partly lost in different ways such as planting, harvesting, storage and even in consumption processes. This calls for attention to reducing these losses through application of the results from agricultural research, use of new farming practices, improvements in management system and repair and renewal of farm machinery. The present study considers the design, development and evaluation of a new pneumatic air reel system as a replacement for the conventional mechanical reel. To evaluate the new system, laboratory and field tests were conducted. In the laboratory tests, the air velocity was measured along the fan outlet width at a 10 centimeter interval from the outlet to 40 centimeters away from it, and corresponding curves of air velocity distribution along the fan outlet width were drawn. On the basis of the results, 13 fans were calculated to be required on the cutting platform of a 14-foot (4.3 meter) combine. The results from the field tests of mechanical and air reels show that grain losses of air reel during harvesting are less than those of the mechanical reel because the air reel has no mechanical contact with the crop and applies less shock on plant stem than the mechanical reel. According to the results, grain losses increased linearly with increasing fan speed. In addition to the change of fan speed (2247, 2503, 2860, 3218 and 3932 RPM), three air discharge directions of 10, 20 and 30 degrees from horizontal line were examined. According to the data analysis in Randomized Complete Block Design (RCBD) through Tukey’s procedure (15 treatments and 6 samples in each treatment), there were significant differences between grain loss at these directions and mechanical reel at a level of 5%. A wind direction of 20 degrees and fan speeds of 2503 to 2860 RPM are recommended.

Any mechanical force exerted on a potato tuber during the harvesting may result in mechanical damage. A few weeks prior to harvesting, haulm destruction could improve the rheological properties of the tuber and reduce its susceptibility to mechanical damage. The effects of elevator and oscillatory sieve diggers and haulm destruction on potato loss and mechanical damage were studied on a farmer field in Fereidan region of Isfahan. Two haulm management treatments (destruction and non-destruction) along with five potato diggers (elevator digger with a long main web and with agitator, elevator digger with primary and secondary webs and with agitator, elevator digger with a main web and with/without agitator, and reciprocating riddle digger) were laid out in a strip block design within a randomized complete block design with four replications. The main crop variety, namely Marfona, was planted in the field. The results showed that the percentages of undigged and soil-covered tubers were significantly different among the potato diggers tested. These losses were due to the dices located to the sides of shares or gage wheels and wrong adjustments on the diggers. Comparing the performance of reciprocating riddle with elevator diggers, its sieving capacity was low and the severity of the mechanical damage and the numbers of tubers covered with soil were high. Haulm destruction was effective in reducing the peeler type damage (the less than 3 mm deep damage to flesh). Although the elevator digger with a main web (elevator chain) and without agitator had the least mechanical damage index, the differences among the elevator diggers tested were not significant (5%).

A suitable instrument capable of inserting mulch into soil is needed to improve soil water holding capacity. The goal of this research is to design and manufacture an instrument with a blade and mechanism that can insert rice mulch into the soil. All the parameters in sub-soiling operation were taken into account, and the technique presented can be recommended as a special method of injecting rice husk. The instrument designed was easy to use on a tractor. Sub-soiling operation and husk injection were carried out satisfactorily using various amounts of husk and at different soil depths. This method was added to the conservation chart presented by Morgan as an integrated technique.

Muteh wildlife refuge, with an area of about 220,000 ha, is situated at 95 km north of Isfahan. In this refuge, 511 species of vascular plants belonging to 284 genera and 59 families live along with 117 species of vertebrate animals belonging to 84 genera and 37 families. Rare plants of the area were classified into two categories of “endangered” and “vulnerable” according to IUCN, 1996 categories. The endangered species include Astragalus chaetopodus Bunge. Astragalus eriostomus Bornm. Astragalus indistinctus Podl. and Maassoumi Cousinia phyllocephala Bornm. and Gauba Cousinia rhaphiocephala Rech. f. Cousinia straussii Hausskn. and C. Winkl. Ferula kashanica Rech. f. Onobrychis psoraleifolia Boiss. var. Psoraleifolia and var. pleiophylla Bornm. The vulnerable species include Bunium caroides (Boiss.) Hausskn. ex Bornm. Dielsiocharis kotschyi (Boiss.) O. E. Schultz Dionysia caespitosa (Duby) Boiss. Dorema ammoniacum D. Don. Dorema aucheri Boiss. Dracocephalum kotschyi Boiss. Echinophora platyloba DC. Hymenocrater bituminosus Fisch. and C. A. Mey. Pimpinella deverroides (Boiss.) Boiss. Prangos cheilanthifolia Boiss. and Thymus daenensis Celak subsp. daenensis. The rare animal species of the region were classified into four categories: “critically endangered”, “endangered”, “vulnerable”, and “conservation-dependent species”. The critically endangered species are Felis silvestris Schreber F. caracal Schreber Jaculus blanfordi Murray (mammals) Gypaetus barbatus Falco pelegrinoides F. cherrug and F. peregrinus (birds). The endangered species include Vulpes cana Blanford Ochotona rufescens Gray (mammals) Falco naumanni F. columbarius Chlamydotis undulata (birds) and Varanus griseus (reptilian). The vulnerable species are Gazella subgutturosa Guldensteadt Canis lupus Linnaeus Meles meles Linnaeus Hyaena hyaena Linnaeus (mammals) and Aquila chrysaetos (bird). And, finally, the conservation-dependent species include Ovis orientalis Linnaeus Capra aegagrus Elxleben Panthera pardus Linnaeus (mammals) and Ammoperdix griseogularis (bird). The results from this survey were compared with the findings from the survey of some other protected areas in Iran.