IRANIAN JOURNAL OF AGRICULTURAL SCIENCES (JOURNAL OF AGRICULTURE)
Year:2008 | Volume:39 | Issue:2|Papers Count:26

A simple model was employed to describe Holstein dairy cattle industry under Iranian production system. Economic values (EVs) for production traits (milk, fat and protein yields) as well as longevity were estimated at farm level for maximized profit perspective and for five types of restriction systems (fixed number of dairy cows, fixed total input including forage and concentrate, fixed amount of milk, fat, and protein yields). The effects of either 20 percent increase or decrease in income from milk sales, feed and non-feed costs were taken as an estimate of model sensitivity. The average absolute EVs on profit perspective and herd size restriction for milk, fat, and protein yields (based on Rials/kg) as well as 10ngevity (Rials/Month) were 983.3, 8021.9, -2086.5 and 55841.5, respectively. Sensitivity analysis showed that the influence off actuations in milk price on EVs was the highest meaning that its influence on fat and protein EVs was highly considerable. EVs for milk, and fat production show the least and the most sensitivity to price changes (milk, feed and non-feed) respectively.

Intending to manufacture an apparatus to study the special parameters which influence the quality and quantity of extracted oil from olive, it was necessary to determine the power of its requirement crushing rollers. Pressure strengths of four olive varieties were analyzed using a factorial randomized block design. Research parameters were varieties in four levels of: Fishemi, Manzanilla, Kalamata and Roghani along with fruit ripening in two levels of: ripe and unripe. Results of analysis of variance indicated a significant effect of ripening on the different strengths of fruit stone. The effect of variety on stone breakage was significant at 5% level and on final breakage at I%. The effect of variety on the crushing of olive fruit was observed as non significant Mean strengths, as obtained from different treatments were compared through Duncan multi-range test and at a level of 5%. Ripe fruit strengths are, as a whole, lower than those for unripe fruits. As for ripe fruits (almost always used for oil extraction), there were no significant differences observed among varieties for the factors of final stone breakage and fruit crushing. As for stone breakage, significantly lower needed breakage strength was observed for variety Kalamata than for Manzanilla and Fishemi varieties. Therefore it can be concluded that variety Kalamata fruit, in its ripe state, is less resistant to different strengths as compared with other varieties.

RAPD markers were employed to determine genetic diversity among 39 garlic populations. In total 45 primers were used for PCR reactions on the template DNAs, among which 26 showed good amplification and polymorphism. These primers produced 185 bands, among which, 113 were polymorphic. Cluster analysis of the genotypes was performed based on either the presence (1) or absence (0) of the bands, using Jaccard's similarity coefficient and complete method. The highest similarity (84%) was detected between two genotypes both of which were from Tarom of Zanjan province and two genotypes from Dezfool and Ahvaz (both from Khuzestan province). Lowest similarity (0.26%) was observed between two genotypes from Behbahan and Rasht, and one from Arak at a distance of 0.50 similarities on the dendrogram. The genotypes were divided into 10 sub-clusters, mostly in accordance with their specific morphological traits while some on their geographical origin. Cophenetic coefficient of r=0.9 between similarity matrices and the dendrogram showed the goodness of fit for the dendrogram as well a for similarity data. According to the obtained results, the studied populations were of a high genetic diversity, showing the richness of garlic resources in Iran.

Seven Isolates of bacteria were studied for their ability to suppress canola (Brassica napus) damping-off, as caused by Rhizoctonia solani. Four bacterial species of Pseudomonas fluorecens (Isolates P1, P2, P3), Burkholderia cepacia (Isolate Bu1), Bacillus subtilis (Isolates B1, B2) and Streptomyces sp. (Isolate S1) were tested at greenhouse conditions against the pathogen. Seed and soil treatments with the seven bacterial isolates resulted in significant increased plant growth of canola and its reduced disease severity. Isolates applied to soil demonstrated a significantly higher increase in plant growth compared to seed treatments. Isolates P1, P2, P3, Bu1 caused a significant increase in plant fresh weight as well as in root growth. P3 Isolate was the most effective in increasing plant growth by an average of 13%, while P2 Isolate was also very effective in increasing growth and by an average of 11% as compared to control. P1, Bu1, B1, B2 and S1 (respectively by 10, 10, 9, 7 and up to 6 %) increased plant growth as compared to control. Furthermore, all isolates were capable of colonizing canola root in the free from causal agent conditions, for which, P3 was determined as the strongest colonizer of canola root.

To estimate the genetic trend for lactation milk yield, a total of 38457 monthly test day records obtained from first calving of Holstein cows, recorded during 1995-2005 at Astan-e Quds-e Razavi Dairy Farm were used. A random regression test day animal model was applied to analyse the records. In the model, the environmental fixed effects of milking times, sperm origin and herd-year-month of recording were included. To take account of the shape of the lactation curve at genetic and permanent levels, orthogonal Legendre polynomials of order 4 were also fitted in the model. For progeny, genetic trend was estimated based upon regressing of mean predicted breeding value on year of zygote formation, birth and calving of animals. For sires and dams, the genetic trends were estimated based on regressing of mean predicted breeding value on the above corresponding years of their daughters. The genetic trend (based on the year of zygote formation) was 10.64 Kg per year (p<0.05) in the progeny. Non-significant genetic trends were observed for progeny based upon their year of birth and calving. For dams' population, significant genetic trends were found to be 8.77, 8.88 and 9.1 Kg per year based on year of zygote formation, birth and calving of their daughters respectively. The genetic trends in sires' population were all statistically non-significant (p>0.05).

Wheat stem sawfly (Cephus cin’ctus Norton) larvae reduce kernels per head, kernel weight and therefore grain yield by feeding within the stem and cutting vascular bundles, which are indispensable to nutrient flow. The present study was undertaken to estimate heratibility of sawfly resistance, evaluate the relationship between sawfly resistance and some agronomic as well as quality traits, and also to identify microsatellite markers linked with sawfly resistance in durum wheat (Triticum turgidum L. var durum). A set of 155 double haploid lines were taken record of percent stem sawfly cutting and some agronomic as well as quality traits in field trials within two years. Parents of double haploid population were tested with 517 wheat microsatellite markers. Primers that were polymorphic on the parents were tested on the whole population. Heritability estimate by variance of components indicated that genetics was the controlling factor for the main part of stem sawfly cutting variations. Correlation coefficient of sawfly cutting with grain yield and 1000 grain weight was negative and highly significant within two years. Relationship of sawfly cutting and quality traits was not stable through the two years. Almost 10 percent of tested markers on the parents were polymorphic. Markers linkage map covered about 970 cM of durum genome. Results of t, F, c2 tests while using MQTL program showed a strong linkage between a markers group, including 3 markers, and sawfly cutting data. The linkage markers group is located on the long arm of chromosome 3B. There was no relationship observed between the markers linkage groups and other traits, then the markers can be used as marker-assisted selection to improve sawfly resistance without any negative effect on the other traits in durum wheat.

Most agricultural lands in Iran, being located in arid and semiarid areas, are characterized by considerable weather variability, as well as major abiotic stresses, in particular drought and cold. The intensification of crop production in these areas needs to take into consideration the agroclimatical diversity, and adapt cropping and land use patterns to the opportunities and constraints of each Agro-Climatical Zone (ACZ). UNESCO approach (1979) is one of the methods used in ACZ mapping. Moisture regime, winter type and summer type are the main parameters in this approach. In the present study mean long term climatic data were modeled through SRTM 90m DEM in GIS software for delineation of ACZ units. A comparison of the UNESCO ACZ units with landuse units derived from the newest Landsat imagery in the studied area and an improvement of this correspondence through the modified aridity indices is the main goal of the present study. In UNESCO approach, areas with aridity indices lower than 0.5 are classified as semi-arid, arid and ultra-arid zones, not fit for agricultural uses. However in arid and semi-arid area of northwest Iran the rained and irrigated agriculture are mainly concentrated on the areas with lower aridity indices than 0.5 (between 0.17 and 0.37). Moreover, based on UNESCO method, areas with aridity index higher than 0.5 are classified as sub-humid, humid and ultra-humid zones, capable of being used in normal agriculture, whereas the results of this study show that areas with aridity indices higher than 0.65 are mostly located on highlands with temperature and LGP (Length of Growing Period) limitations and normally covered by forests.

Strawberry production in controlled conditions is increasing dramatically. Therefore, it is necessary to employ new methods to improve its production management. To do so, this study was conducted during 2005-2006 in a split split plot in randomized block design with three replications. In this experiment, effects of such factors as plant density, electrical conductivity of nutrient solutions, frequency of irrigation and type of cultivar were studied on yield and quality of two strawberry cultivars i.e. Selva and Camarosa. Experiment was carried out in a greenhouse located in the Department of Horticulture, Faculty of Agriculture, University of Tehran, Karaj- Iran. Plants were cultivated in a medium consisted of perlite and peat moss inside plastic pots of 22cm. in diameter. Plant densities were 13.8 and 20 plants /m2 which were irrigated six of eight times/day with nutrient solutions of different EC of 1.5 and 2.5 ds/m2. Results showed that increasing plant density from 13.8 to 20 plants/m2 increased yield/m2 and vitamin C but reduced yield/plant. EC of 2.5ds/m2 reduced yield/plant, yield/m2, mean weight and diameter of fruit as well as total soluble solids. Cameras had a higher yield/m2, yield/ plant, length and weight of fruit, total soluble solid as well as vitamin C. However, it contained less acid as compared to Selva.

Due to the effective role of nitrogen fertilizer on growth, yield and quality of a crop, fanners nowadays apply too much of them to their crops. Excessive use of nitrogen fertilizers in agriculture not only causes surface and underground water pollution but it also can lead to nitrate accumulation in plants, causing various diseases such as methaemoglobinemia in infants and gastrointestinal cancer in adults. Tareh Irani is one of the important leafy vegetables in Iran. In spite of its high cultivation and use, there has been little fundamental research carried out specially on its fertilization. In the present study, the effects of different sources (urea and ammonium nitrate) and levels (50, 125, 200, 275, 350 and 425 kgHa-1) of nitrogen fertilizers were investigated on yield, nitrate accumulation and some of the quality characteristics of various clippings of Tareh Irani. The results showed that by increasing the amounts of nitrogen fertilizers, yield, number, length and width of leaf as well a nitrate accumulation in leaf increased. The highest yield was obtained in either of the 425 kgNHa-1 as urea or 200 kgNHa-1 as ammonium nitrate but nitrate accumulation was less in the later case. Ammonium nitrate leads to more nitrate accumulation. In spite of an increase in nitrate accumulation from 3rd clip to the last one, yield decreased. This can be due to the effects of unfavorable environmental factors such as lower temperatures and shorter days at the end of the growing season that can also lead to high of nitrate accumulation. Total soluble solids were not observed to be affected by different treatments.

Narcissus tazetta L. is one of the bulbous cut flowers native in the southern regions of Iran and cultivated most extensively in Shiraz. Due to its beauty, delicate fragrance, and due to being a bunched flower, it is superior to the other species for Iranian consumers. In order to study the effects of some chemical pulse solutions on the postharvest life of cut Narcissus, a factorial experiment was carried out in a completely randomized design with eight replications in 2002. Chemical treatments were: Silverthiosulphate, Silver nitrate, Hydroxyquinoline citrate (each in 3 concentrations) as well as tap water as control. Silverthiosulphate, Silver nitrate and Hydroxyquinolinecitrate increased the postharvest life. Silverthiosulphate, in addition, improved the general appearance of wilted florets in the cluster. In total, Silverthiosulphate was found out to be the most suitable treatment.

Thin layer drying behaviour of bergamot (citrus bergamia) slice was experimentally investigated in a convective type dryer and the mathematical modeling assessed by using thin layer drying models given in literature. Drying experiments were conducted at inlet drying air temperatures of the 40, 50, 60, 70 and 80 °C; for samples of 6 mm thickness, at a drying air velocity of 2 m/s and with three replications in each treatment. Twelve different thin layer mathematical drying models were compared (according to their coefficients of correlation) to estimate the drying curves. The effects of drying air temperature on the model constants and coefficients were evaluated through a multiple regression technique. The models were compared according to three statistical parameters of: root mean square error, chi-square, and modeling efficiency. According to the obtained results, Midilli et al. model could satisfactorily describe the drying curve of bergamot (citrus bergamia) slices with EF=0.9992, x2=0.000259 and RMSE=0.013396 at different temperatures.

In this research using three types of greenhouse tomato (lycopersicum esculentum Mill.) including: l-cultivar Trust as non grafted plants (T), 2-Trust grafted onto Eldorado (TE) and 3- Trust grafted onto Maxifort (TM) along with Three media: rockwool (RW), sawdust (SAW) and sawdust containers equipped with a capillary system (CA) were employed to study the effect of water stress on chlorophyll fluorescence parameters. Results of the experiment indicated that, when medium water potential reduces (becomes more negative), water stress can occur and cause some changes in chlorophyll fluorescence indices as measured through dark adapted method. Increasing water stress resulted an increase in FO and a reduction of Fm in all plants and media, consequently, a reduction of Fv and Fv/Fm ratio as well. Different media showed significant differences in rate of loosing water (change in water potential with time). Capillary systems helped sawdust media loose water at a slower rate, keeping the medium moist for a longer period. So, plants cultured in this medium showed less fluctuation of Fv/Fm index than those cultured in other media. Plant types also showed significant differences especially under severe water stress. The least Fv/Fm ratio was measured in "T" plants. Results of this experiment showed that, Fv/Fm can vary due to water stress, but its changes are small and hardly detectable, and just if used together with other indices, can possibly be a use full tool for evaluating a plant's stress status.

The objective of this study was to determine the effect of Saccharomyces cerevisiae on utilization of two different forages and the subsequent changes in rumen environment. Four fistulated bulls fed at maintenance level were employed in a lat in square design with 2x2 factorial arrangements of treatments (alfalfa hay or com silage with 0 or 5 g/d of S. cerevisiae) in four experimental periods. In situ dry matter degradation of forages was increased by addition of S. cerevisiae at 3 hs of incubation (P < 0.1). Crude protein disappearance of forages, daily pH, and total volatile fatty acids concentration were not affected by supplementation of S. cerevisiae (P > 0.1). Mean daily concentration of ruminal ammonia-N decreased by addition of S. cerevisiae (P < 0.1). Addition of S. cerevisiae increased molar percentage of propionate and decreased acetate to propionate ratio (P < 0.1) but no effect was observed for molar percentages of acetate and butyrate (P > 0.1). There were interactions between S. cerevisiae and the diets for acetate, propionate and acetate to propionate ratio. For alfalfa hay based diet, acetate to propionate ratio decreased while for com silage based diet it was increased through an addition of S. cerevisiae (P < 0.05). Total protozoa counts decreased in diets supplemented with S. cerevisiae at 3 and 12 h (P < 0.1) but no effect was found at the 0 and 6 h post feeding (P > 0.1). The results indicated that S. cerevisiae slightly affected most rumen parameters and could increase efficiency through improving initial digestibility, even though these responses were not, to a large extent, significant.

The effect of bacterium Pantoea egglomerans on a control of Penieillum digitatum causal agent of green mold of orange was investigated for a duration of 5 weeks. Results indicated that the disease can well be controlled by the bacterium at the temperatures 4°c and 20°c. The most effective result, with a reduction of 83.4% in infestation was obtained at 20°c. The efficacy of the bacterium was improved when mixed with Imazalil. No inhibition zone was observed between fungal and bacterial colonies when dual cultured under "in vitro" experimental treatment. In "in vivo" experiments, a subsiding of the malady was observed with an increase in the population of the bacterium. Therefore it can be concluded that the probable mechanism in control of the orange green mold disease (by the bacterium P. agglomerans) could be a colonization of fruit surface by the bacterium and it's competence with P. digitatum for nutrition as well as for habitation.

An Opto-Electronic sensor system was designed, developed and evaluated. The performance of this sensor was laboratory investigated for seed spacing uniformity through a measurement of time intervals between seeds as well as front-to-back location of seed drop events relative to the planter. The device consists of a rectangular photo gate block with 24 phototransistors mounted against 24 light emitting diodes, a comparison level phototransistor, digital input/output boards, a personal computer, as well as power supplies. Four different sizes of polymer balls similar to seeds in shape and size were employed to test the system, using a completely randomized design method. Treatments were 2, 3, 4 and 6mm (in diameter) polymer balls each of 4 replications. Precision index for any replication in each of the treatments was assessed. SAS software was employed to analyze the data. Analysis of Variance indicated, that, significant differences (P<0.I) existed among different treatments. Means comparison test of treatments showed significant differences (P<0.I) between 2mm (in diameter) treatment and other treatments. System precision for seeds of 3mm diameter and bigger ones was 99.5% while for seeds of 2mm diameter it was 95.5%.

An Evaluation of the effect of industrial sewage sludge on soil, in terms of soil contamination, and fertility as well as on groundwater quality is quite important. In order to study the effect of sewage sludge of Shahid Moffateh Power Plant on chemical propenies of the agricultural soils around this Power Plant, leaching experiments were conducted in soil columns, namely soil compacted piecemeal in the poly-vinyl chloride (P.V.C) columns (9 cm in diameter and 25 cm height). Effluent was collected and concentrations of sodium, calcium, magnesium, potassium, chlorine and sulphate were measured. Also, column of the soil were leached using distilled water. The experiment was performed in two replicates. The experiments were continued until the concentration of output and input cations became equal. At the end of the experiment, soil columns were cut into 2cm thick layers for which the concentration of exchangeable sodium, electrical conductivity as well as pH in the layers of soil was measured. The results showed that sodium ions in sewage sludge, replaced calcium, magnesium and potassium ions from the exchange sites resulted in the appearance of the peak concentration of these ions in effluent after 1 to 2 pore volumes. Peak concentration of chloride appeared following one pore volume after which the concentration equaled the chlorine concentration in input sewage sludge. This pattern was not true for sulphate ions, which can be accounted for by low rate of sulphate salt solubility in comparison with chlorine salts. Hence, sulphate release continued with the passage of time, peak concentration of sulphate appearing in third pore volumes. The leached potassium from the soil is partly compensated for, by input potassium.Because the concentration of input calcium, in comparison with calcium carbonate solubility, is high, calcium carbonate was not dissolved during the process of the experiment. The final mean exchangeable sodium percentage of the soil was 28.3. Thus, the percentage increase in exchangeable sodium in this soil was 4. Sewage sludge application also increased the electrical conductivity of this soil, preventing it from serious structural damage.

Water Scarcity in arid and semi-arid regions is the major concern for water and agricultural authorities. To confront this problem, high performance irrigation systems, such as drip irrigation and or subsurface drip irrigation, are recommended. In designing a subsurface drip irrigation system for row crops, geometry and dimension of wetted volume are the main factors needed for determining laterals' installation depth as well as emitters' spacings. For this purpose several models were developed to demonstrate a good prediction of wetting pattern using emitter discharge, volume of applied water and hydraulic properties of soil. In this paper dimensional analysis method, developed by Singh et al. (2006) was employed due to its simplicity and less input data requirement. Measured data of wetting pattern under subsurface drip irrigation system (Z+, Z- and W, lower, upper and horizontal displacement, respectively) in a clay loam soil with 30 cm emitter depth were compared with output data estimated through the model. A good agreement (R2 = 0.97, 0.99 and 0.97 for z+, z- and r, respectively.) was obtained between measured and estimated data.

According to IPCC1 global average temperature ha increased during the last century and it is anticipated that this trend will continue during the new century. Unfortunately, it is expected that climate change will have negative impacts on countries with spatial position the same as ours. Therefore, it is important to more seriously consider this phenomenon and its impacts. This research work is aimed at investigating the impact of climate change on the water level of Orumieh Lake, as the most important interior water body. For this, the lake level fluctuations were simulated based on historical data using ANNs2 technique with discharge, evaporation and rainfall as inputs. Then based on available data of HadCM3 AOGCM3 and SRES4 scenarios (A2 and B2), the discharge, evaporation and rainfall data were simulated from 2006 to 2099 for the study area. Application of the designed ANNs model and simulated data illustrated the possible changes in the lake water level due to climate change. Furthermore, the risk curves of the lake level for the 10 to 50 years return periods were developed and compared with those of the present situation. The results indicated that climate change will have significant decreasing impact on the lake water level. While the average lake water level was 1276.21 m.s.l.e during 1971-2000,it will fall 1.73m and 0.63 m based on A2 and B2 scenarios, respectively. Also, the risks will increase in a confrontation with extreme low water level conditions of the lake.

In order to study the effect of crop density and supplemental irrigation on yield, yield components, and some other quantitative and qualitative characteristics of pea in dry-land system, an experiment was conducted in Nahavand during 2004-2005 crop year. The experimental design was an RCBD of split plot layout with four replications. The main plots consisted of four dry farming levels (dry farming without supplemental irrigation, dry farming + supplemental irrigation at planting, dry farming+ supplemental irrigation at 50% flowering stage, and dry farming + supplemental irrigation during pods filling stage). Four plant densities (17, 22, 33 and 67 plants/m2) were allocated to the subplots. The results showed that supplemental irrigation leads to increased biological yield (303 kg/ha), grain yield (678.67 kg/ha), no. of seeds per plant (16 seeds/plant), 100-grain weight (7 gr) and Harvest Index (14). Supplemental irrigation led to a decrease in of grain protein percentage. Number of pods and seeds per plant were reduced with an increase in crop density. The highest grain yield (2096.93 kg/ha) as well as the highest biological yield (5773.56 kg/ha) were obtained from a maximum crop density (67 plants/m2).

The amelioration of aflatoxicosisin broiler chicks was examined through the dietary addition of Saccharomyces cerevisiae (SC). Saccharomyces cerevisiae incorporated into the diet at 1 g/Kg was evaluated for its ability to reduce the deleterious effects of 1 and 2 mg total aflatoxins (AFs) Kg-1 diet on growing broiler chicks from 1 to 42 days of age. Four hundred and eighty day-old male chicks (Ross-308) were assigned to a completely randomized design of six treatments (1:basal diet (without aflatoxin), 2: basal diet + SC (1g/kg), 3: basal diet + AFs (1 mg/kg) ., 4: basal diet +AFs (I mg/kg) + SC (1g/kg)., 5: basal diet +AFs (2 mg/kg)., 6: basal diet +AFs (2 mg/kg) SC (1g/kg)) with four replicates' each 20 chicks. The AF treatments (3 and 5) significantly decreased food consumption and body-weight gain and increased food conversion ratio (p<0.05). Changes in body weight gain, feed intake and feed conversion ratio were not significant through an addition of SC to the AF-containing diets (4 and 6). Serum cholestrol, total protein and albumin decreased significantly (p<0.05) in diets contaminated with aflatoxin. Compared to controls, the addition of SC to an AF-containing diet significantly reduced the deleterious effects of AF on cholestrol, albumin and total protein. The AF treatments (3 and 5) were accompanied by higher activities of the enzymes LDH and AST, but decreased ALP activity. The addition of SC to an AF-containing diet did not produce any significant changes in activities of enzymes as compared to control. These results suggest that SC reduces the adverse effects of AF and may be helpful in amelioration of the aflatoxicosis problem in poultry.

For a breeding of grape to obtain new superior raisin and table cultivars, seedless cultivars of Askary, Yaghooti, Bidane Sefid and Bidane Ghermez were selected as male parents, while seeded cultivars of Muscat of Hamburg, Ghezel Dzum, Dizmary, Rajabi Sefid, Ali Baba, Alhaghi Ghermez, and Tabarzehchosenas female parents. Out of 1400progenyobtainedfrom 26 different crosses, 381 of them, which produced fruits, were evaluated during the growing seasons of 2006 & 2007. For an evaluation of progenies, three fruit clusters were randomly harvested from each progeny. Five berries were randomly selected from each cluster and their traits registered. For stenospermic trait evaluation, 10 big berries were selected from each cluster. Progenies were divided into four groups of completely seedless, semi-seedless, semi seeded and completely seeded, as according to seed trace or seed weight. Some of the seedless progenies carried desirable traits such as large and fleshy berries, early ripening, proper attachment of berries to the cluster along with low density of berries, so that they were superior as compared to other Iranian seedless cultivars. Among all progenies, the 121, B98, 173,K67, L125, L127, S52, S55, K93, R84, R80, A119 and B96 genotypes stood in the seedless class. Also some such semi- seedless and completely seeded genotypes as B95, S26, 138, N81, L131 and N84 are of so desirable and noticeable traits as semi-seed lessens and big berry that they have to be given due consideration too.