JOURNAL OF AGRICULTURAL SCIENCE AND SUSTAINABLE PRODUCTION
Year:2006 | Volume:16 | Issue:1|Papers Count:30

Agricultural sector plays a strategic role in economical sustainability of developing countries. Understanding the structural and major determinants influencing the qualitative and quantitative aspects of agricultural productivity is important. These determinants are human resources, physical resources, assets and inputs. Among these determinants, human resources has a major role and also affects other resources. It is, therefore, imperative to consider human resource development in order to clear the path towards sustainable agriculture. The purpose of this study was to develop a set of criteria for determining agricultural technical experts needed in agronomy, orchard farming, extension education, farming systems, plant protection, soil and water conservation, agricultural machinery, and livestock in Agricultural Jihad Organization. This descriptive research study utilized three rounds of Delphi technique. The population consisted of agricultural experts, managers and supervisors in Agricultural Jihad Organizations. Purposeful sampling was used with 50 subjects across different disciplines. Results showed four criteria for determining technical experts needed in agricultural Jihad organizations. These criteria were: 1) number of users or clientele population; 2) production rate; 3) geographical boundaries (e.g., number of hectares in crop production, orchard farming, and number of herds), and 4) technicians needed. Using Delphi technique in three rounds resulted in four criteria in order to estimate technical experts needed in eight different disciplines. Results of the case study in Agricultural Jihad Organization in Boushehr Province, showed that in situation analysis, the number of specialist (n=87) differed from the estimated number of specialist in three areas (472 specialist for geographical boundaries, 303 specialist for production rate and 964 specialist for clientele). Recommendations were given based on the results.

A factorial experiment was conducted to asses the effect of salinity on plant dry weight, leaf area, gas exchange variables, leaf chlorophyll and Na+ and K+ contents in sugar beet plants (Beta vulgaris L. cv Madison). The plants were planted in inert vermiculite and transferred to a growth chamber where temperature was 26±1°C during light period and 16±1°C at night. Four levels of salinity (0, 100, 200 and 300 mM NaCl and CaCl2 in 5:1 ratio) were used. Salt stress significantly decreased leaf area, total dry matter and the rate of photosynthesis. Salinity had a much greater effect on leaf area and dry matter than photosynthesis. Both low (100 mM) and high (300 mM) levels of salinity decreased total leaf area by 39.8% and 84.1%, total dry weight per plant by 36.7% and 75%. However, the rate of photosynthesis per unit area decreased by 22.8% and 57.9%, respectively at the same level of salinity. Salt stress also decreased respiration but the chlorophyll content was significantly increased with increasing salinity. Salinity increased the leaf Na+. However, K+ content of leaf decreased. At low level of salinity, the reduction in photosynthesis could be attributed to lower stomatal conductance due to lower internal CO2 concentration but at high levels of salinity non-stomatal factors such as RuBP carboxilase activity, RuBP regeneration and reaction center of photosystem might be involved in reduction of photosynthesis.

In order to assess the above and below ground interference of Wild Oat on wheat, a pot experiment as factorial based on Randomized complete design with 4 replications was carried out. The treatments were including four interference level (no interference, full interference, root interference and Shoot interference) and four wild oat densities (2, 4, 6, and 8 Plant/Pot). The mean of relative yield total (RYT) at full interference and root interference were lower that I. Whereas, at shoot interference was higher than 1. It is showed that the root interference effects on RYT loss was higher than shoot. Based on relative crowding coefficient (RCC) results, the wild oat at full and root interferences was most competitor than wheat, but at shoot competition both species had the same RCC. The wheat plant height at root and shoot interference were lower and higher that control, respectively. At root and full interferences, the falg leaf area, biomass, harvest index, length, volume and dry-wight of roots in wheat were significant decreased compared to control. The biomass, grain yield and harvest index of wheat were reduced significantly at shoot interference treatment.

An experiment was conducted to evaluate yield and yield components of three: 1- early (Zaria, Hybrid 25 and Chemianka), 2- medium (Armavirsky, Hybrid 33 and Golshid) and 3-late (progress, Record and Gabor) maturity groups of sunflower (Helianthus annus L.) as a second crop in Varamin, Iran, using randomized complete block design (RCBD) with three replications during growing season of 2001. All of the genotypes used in this experiment expect Hybrid 25, Hybrid 33 and Golshid, were non-hybrid cultivars. Seedbed preparation and planting were coincided with the harvesting time of wheat crop in the area and seeds were planted on June 5th, 2001. Due to high daily temperature during growth period the number of days from seeding to flowering, flowering to physiological maturity and thus from planting to physiological maturity decreased. Medium maturity genotypes, because of nutritional and genotypic differences, produced lowest number of florets per head. No statistical difference was obtained between maturity groups for empty achene percentages, although the differences between hybrids and non-hybrid cultivars were significant (P<5%). This can be related to tolerance of hybrids to adverse environmental conditions and better partitioning of photosynthates to grain during grain filling period. For the number of grains per head, no differences were obtained among maturity groups and genotypes. Differences among early types and between non-hybrid and hybrid cultivars were significant (P<5%) for 1000 grain weight, while, there was not significant difference among maturity groups. Among maturity groups and genotypes and also between hybrid and non- hybrid varieties no differences were observed for head diameters of but the difference of early types with other types was significant. Difference of maturity groups and also difference of non-hybrid from those of cultivars, hybrids, were not significant in terms of grain yield but the yield was reduced by delayed planting. It can be concluded that early maturity groups (especially Hybrid 25), as the second crop in Varamin, are preferred, because they can be harvested earlier and leave the land idle for later seed-bed preparation and proper soil fertility in the fall. In addition, Hybrid 25, due to higher yielding capacity is recommended to the region as the second crop.

In this research, a three-shank vibrating subsoiler suitable for category II tractors was designed, fabricated and evaluated. After preparation of implement, its field capacity and efficiency was evaluated in a clay-loam soil at a sugarcane field. The field performance test of the machine was conducted at oscillating amplitude of 50mm, frequency of 9Hz and vibration angle of 30°. The first experiment was performed at average actual forward speed of 2.5km/h, working depth of 50mm and shank spacing of 60 cm. The machine was found to have average effective field capacity of 0.3 ha/h, theoretical field capacity at 0.4 ha/h and field efficiency of %67. The second experiment was conducted to study effect of two levels of 1.5 and 2.5km/h forward speed and vibration on soil density. The results indicated that the vibration has significant effect on reducing soil density at %1 level of probability. Also forward speed had significant effect on soil density at %5 level of probability. The subsoiler at lower forward speed and in vibrating phase resulted in lower soil density that means better soil loosening.

Chickpea is the main important food legume crop in Iran. A major constraint to the chickpea production in Northwest and West of Iran is pod borer, Chloridea viriplaca (Noctuidae) damages, and seed yield eventually decrease significantly. The purpose of this study was to evaluate the response of some morphological and phenological traits and yield components of 16 chickpea lines (five Kabuli and 11 Des types). Chickpea genotypes were studied in two separate experiments, in pest free and pest attacked conditions, for two years, during 1998-2000 cropping seasons. In Kurdistan province (latitude: 35°,43'; longitude: 48°,8'and altitude: 2100m), West of Iran. In this study phenological traits (days to flowering and days to maturity) and morphological traits (number of primary and secondary branchs, number of podes per plant, number of seeds per pod, hair density, plant height and weigh of 100 seeds) recorded and phenotypic correlations between traits were calculated. Based on seed yield in both stressed and non-stressed experiments, stress tolerance index (STI) and tolerance (TOL) of each line was calculated and used to assess their tolerance to pod borer damages. Combined analysis of variance showed that there was significant difference between years for all traits. Correlation of seed yield in stressed and non-stressed conditions with STI were significant at 5% and 1%, respectively. Mean seed yield of both conditions were 530 kg/ha for Kabuli and 495 kg/ha for Desi types. Orthogonal contrasts between chickpea genotypes revealed significant differences between two typical groups of chickpea for several traits. Considering seed yield as well as other pheno-morphological characters, ILC 482 and Pirouz had highest resistance to pod borer damages.

The Harzandat plain of Azarbaijan province lies between Marand and Jolfa cities. Low precipitation and over-exploitation of ground water resources in recent years has caused an extensive groundwater level decline in this plain prohibiting further development of the aquifer. As a result, for studying the aquifer and for optimum management of groundwater resources a mathematical model as an efficient and economical tool was prepared. For this purpose, all the necessary climatological, hydrological, geophysical and geological data were collected and analyzed. Based on this data the mathematical model of the aquifer was prepared by visual software (Visual ModFlow). The model was calibrated and run from October 2002 to October 2003, using four time periods and 12 time steps. After calibration of the model for steady and unsteady state, the results were analyzed for sensitivity. Verification of the model showed that the model couldn't simulate natural aquifer condition, due to the uncertainty of input data. For this reason, to confirm aquifer parameters (K and S), some alternatives such as correction of the boundary condition and error factors were carried on. After these necessary corrections, model was calibrated and verified again. The verification showed that model could simulate the natural condition of aquifer. Thus, the model can be used as a management tool for evaluation of the aquifer.

Estimation of peak discharge in areas with limited data or ungaged catchment is one of the most important issues in design of hydraulic structures and water resources management in arid and semi arid areas. Index flood is one of the well known regional flood analysis methods and. one of the modern methods in regional flood analysis in arid and semi-arid regions is the hybrid method. The objective of this research was to compare the hybrid method with index flood method in estimation of peak discharge in Karkheh watershed. The index flood method was applied in both of the whole catchment and heterogeneous areas. Comparing these methods with RMSE, showed that the index flood method. in was more sufficient the heterogeneous areas. Then, regional models of flood estimation were determined by the hybrid method. Valibity of the hybrid and index flood methods, were examined by testing errors. Results showed that the hybrid method is more efficient only in small areas with the return period of and it is valid up to 50 years.

Embryonic developmental period, percentage of egg hatch, duration and percent mortality of nymphal stage, number of adult emergence, duration of oviposition period, number of eggs produced and laid per adult female, longevity of adults, body size of adult female and generation time of Orius niger in three consecutive generations and in three different regions of the East Azerbainjan province were investigated during 2003-2004. The embryonic developmental period, duration of nymphal stage, duration of oviposition period, longevity of adults and duration of generation time in the second and third generations of Orius niger in all three regions were less than that of the first generation. The percentage of egg hatch, number of adult emergence, number of eggs produced and laid per female in the second and third generations of Orius niger in all three regions were more than, that of the first generation. The maximum percent mortality of nymphal stage was observed in the first generation of Orius niger in Ahar and Bostanabad regions, and the maximum number of adult emergence was observed in the second and third generations of Orius niger in Shabestar region. The duration of nymphal stage, longevity of adults, duration of oviposition period and generation time of Orius niger in Ahar and Bostanabad regions were longer than that of Shabestar region. Furthermore, it was found that the female adults of Orius niger lay most of their eggs at petioles and veins of potato leaves. Also the highest oviposition was observed at the 4-15 days after female emergence.

In order to evaluate the effects of nitrogen (N) rate and time of N application on the grain protein content and nitrogen use efficiency of wheat (Triticum aestivum.L. var:Zagroos), an experiment was conducted under rainfed condition in Gorgan, Iran, in 1999-2000. The treatments consisted of the factorial combination of five nitrogen rates (N1=O, N2=30 , N3=60, N4=90 and N5=120 Kg N ha-1) and four different time of nitrogen application(T1= all prior to planting, T2= 1/3 prior to planting + 2/3 at tillering, T3= 1/3 prior to planting + 2/3 at stem elongation and T4= 1/3 prior to planting+ 1/3 at tillering +1/3 at stem elongation).The experiment was arranged as a randomized complete block design with three replications. Results showed that the grain protein content and protein yield increase hyperbolically with increasing N fertilizer. However, there was significant reduction in nitrogen harvest index, N utilization efficiency (NUtE), agronomic efficiency (AE), physiologic efficiency (PE) and apparent recovery (AR) with increasing amount of N fertilizer. The grain protein content, NUtE and PE were significantly affected by the time of N application.

Arbuscular mycorrhizal fungi are associated with many plants including sugar-cane (Saccharrum officinarum) and have a dramatic effect, on their growth and development. They are belonging to class Glomeromycetes from phylum Glomeromycota. In order to identify arbuscular mycorrhizal) fungi associated with sugar-cane in Khuzestan and Mazandaran provinces this study was carried out from 2001 to 2004. Sixty one soil samples were collected and trap cultures were established with maize plants. Propagated spores were extracted by wet sieving and decanting following by centrifugation in 55% sucrose solution. Extracted spores were transferred to 1:1 mixture of PVLG and Melzer reagent and microscopic slides were prepared. Three species including Glomus ambisporum, Glomus lamellosum and Glomus luteum were recognized as new records from Iran.

Many changes in combine harvesting machines can be noticed in recent years. All attempted to improve field capacity of combine. One of these changes is the introduction of stripper head. While using this type of the head, ground speed of combine can be increased up to 10km/hour. In this study a new method was introduced in pea harvesting in Iran. We tried to use stripper head in addition to transporting channel to harvest pea. The transport of chick pea pods from the stripper to the thresher was carried out not by the regular feed chains but by the throwing action of the stripper cylinder combined with the force of the produced wind thereof. The objectives of this research was to determine the effect of more important factors. Many parameters can affect transporting of materials in this mechanism. Type of stripper fingers, rotational speed of stripper rotor, inlet area of head and shape of channel towards threshing mechanism are also important factors. To study the effect of these variables, a mechanism was constructed which its inlet area was adjustable. By using of a variable speed electromotor the rotational speed of rotor could be varied. Four, types of stripper fingers were designed and constructed. Finally the transporting channels were made in three shapes. A factorial experimental based on completely random design with four factors, each at three levels, and four replicates was conducted for test anafysis under load. Experiments were undertaken in Tehran's Agricultural Machinery Engineering Discipline's Lab. A meshed conveyor was used for artificial feeding of pea pods to the stripper. The most suitable treatments level for better transportation of material as well as the effect on the shattered, damaged and returned pods was determined. Results indicated that all factors have significant effect on material transporting and head loss, at 1% probability level. Finally, after much theoretical and experimental work it was. indicated that the stripper finger of medium triangular form, inlet area of 32° opening in head interance, 75 rad/sec for rotational speed of rotor and a channel with the ratio of outlet/inlet equal to 0.20 was a desirable design for harvesting of pea in this study.

In this research, the unsteady flow was simulated and analysed in a laboratory canal using ICSS hydrodynamic model. Six ultrasonic sensors were installed along the canal in different locations for exact and simultaneous measuring of flow depths, to record their fluctuations in time data logger was used. A full monitoring system was utilized by connecting the set of sensors and data logger to a computer using VisiDAQ software. In the first case the varied canal inflow with gradually and rapidly hydrograph and in the second case the gradually and sudden opening of the canal side turnout gate were studied. Time variation of the water depths along the canal were recorded and then compared with the results obtained from the flow simulation by ICSS hydrodynamic model. Average error of the model estimation along the canal was 1.39% for gradually varied inflow, 1.22% for gradually opening of the side turnout gate, 5.44% for rapidly varied inflow and 4.30% for sudden opening of the Side turnout gate. The results showed that the ICSS hydrodynamic model would be able to simulate the gradually unsteady flow in, the canals with high accuracy. This model can be used for different purposes such as design of control systems in water conveyance canals due to gradually variation of flow and non-sudden operation of control structures.

Evaluation of rapeseed and mustard adaptability is important in relation with the increasing demand for edible oil in Iran and lack of suitable cultivars for cold drylands. Randomized block designs can reduce experimental errors caused by spatial variability between blocks excluding intra-block variability. Control of spatial variability is an analysis that investigates the variance structure of each trial and uses an appropriate structure for estimation of effects in the trial. In this research, adaptation of 15 genotypes of spring type rapeseed and mustard were studied during three years in the cold drylands using spatial analysis. Results showed that, the randomized complete block design with first order auto-correlated errors along rows was the best model in the second year and the randomized complete block design with first order auto-correlated errors along rows and columns was the most effective model in accounting for spatial variability in the first and third year. There was not any evidence for fixed trend in this experiment. Based on the selected models, the best linear unbiased estimates for all genotypes were calculated. Stability analysis on estimated means showed that mustard genotypes Bard-1 and Sel-2 had the highest stability in this experiment.

In order to supply edible oil needs of Iran, production of oil crops including safflower should be increased. Iran is one of the origins of safflower which is a drought and salt tolerant crop. Safflower can be a suitable alternative crop for cultivation in marginal lands. Results of several, studies have indicated that delaying in planting date, significantly increase injuries of cold stress, decrease seed and oil yield of winter safflower. This experiment was conducted at Agricultural Research and Natural Resources Center of East Azarbaijan (Khosroshahr Station) during 2001-2003, using a factorial experiment based on randomized complete block design with three replications. Factors were three planting dates (16 Shahrivar, 1 and 15 Mehr) three genotypes (Zargan 279, Varamin 295 and L.R.V.51.51). The results indicated that altering planting date from 16 Shahrivar to 15 Mehr decreases plant height, seed and oil yield. It seems that the best planting date for winter safflower in Khosroshahr and similar climates, is 15-25 Shahrivar and all of the studied genotypes can be cultivated in this location. However, L.R.V.51.51 is recommended for cooler and Varamin 295 for warmer climates of East Azarbaijan province.

The disappearance of dry matter (DM), crude protein (CP) and amino acid in steers after rumen incubation and intestinal passage of the feedstuffs used in ruminant diet was measured in six steers, using mobile nylon-bag technique. Disappearance of dry matter (DM) after rumen incubation varied between feedstuffs from 310 (meat meal and cottonseed meal) to 500 (soybean meal) gr.kg of feed DM, disappearance of DM after intestine incubation varied between feedstuffs from 240 (cottonseed meal) to 890 (fish meal) gr.kg of rumen residue dry matter and disappearance of dry matter in total tract was from 470 (cottonseed meal) to 930 (fish meal) gr.kg of feed dry matter. Disappearance of CP after rumen incubation varied between feedstuffs from 320 (meat meal and fish meal) to 650 (cottonseed meal) gr.kg of feed CP, after intestine incubation varied between feedstuffs from 660 (meat meal) to 930 (fish meal) gr.kg of rumen residue CP and in total tract was from 770 (meat meal) to 950 (fish meal) gr/kg feed CP. Disappearance of total amino acids (AA) after rumen incubation varied between feedstuffs from 200 (soybean meal) to 440 (meat meal) gr/kg of feed amino acids, disappearance of AA after intestine incubation varied between feedstuffs from 580 (meat meal) to 910 (fish meal) gr/kg of rumen residue amino acids and disappearance of AA in total tract was from 770 ( meat meal) to 960 (fish meal) gr/kg feed amino acids. It was concluded that nutrients that escape rumen degradation were disappeared in the intestine.

In the present study the existing situation of agricultural mechanization in Kaboodarahang County was investigated and appropriate guideline were given for its improvement. This study was based on guidelines given by FAO Agricultural Engineering Branch of Agricultural Support Systems Section. Evaluation of desired variables was carried out using a nested design for rural districts of Raheb, Mehrabaneholya and Gholtappeh as a sample, within three area spans. Results revealed that for all of the variables, except farm average size, no significant differences were among area spans, however, for most of the variables significant differences were observed between different rural districts. This means that there exist varieties of situations in the region. The results also showed that with regard to annual planted area of 143147.7 ha, the mechanization level was 0.79 hp/ha which with respect to regional farming system and climate during the peak period of operations and according to the required performance capacity of 40523 ha this level must be increased up to 1.33 hp/ha. Average mechanization degree of field operations for irrigated cereals was less than the average, especially for weed control operations in which technology and machines variety is limited. Finally, a negative significant correlation was obtained between crop diversity and average mechanization degree. This shows that to improve the level of technology in field operations, prices for agricultural products must be kept at a reasonable level to prevent multi cropping in small sized farms in particular.

The salinity of soils is the most limiting factor in agriculture development. In order to apply suitable method for sugar beet cultivation this experiment was conducted in the saline soils of East Azarbaijan. A split plot experiment was undertaken based on randomized complete blocks with four replications for two years. Main plots were different times of transplanting of paper pots (30, 45, 60 days after sowing sugar-beet seed into the paper pots in the greenhouse) and another was direct sowing of sugar-beet seed in the saline soils. The sub plots were two cultivars of sugar-beet seeds. Several variables such as plant density, root yield, white sugar yield, sugar yield per hectare and sodium, potassium, α- amino nitrogen, purity and sugar molasses were measured. The results showed that quantitative traits such as root yield, plant density, sugar yield and white sugar yield per hectare were affected by different transplanting times. The quality characteristics were not affected significantly by this factor. Direct sowing of sugar-beet seed showed the lowest root yield, sugar yield and a white sugar yield (9.8, 1.5 and 1.2 t/h, respectively) as compared to other methods. The maximum root yield, sugar yield and white sugar yield (32.8, 5.4 and 4.2 t/h, respectively) were obtained with transplanting of sugar-beet paper pots after 45 days.

In order to identify markers linked to cold resistance genes, an F2 population derived from a cross between cv. SLMO46 (winter type and cold resistant) and cv. Quantum (spring type and susceptible to low temperature) was evaluated. The parental polymorphism was assessed using 250 RAPD primers. Forty seven polymorphic primers were selected for genotyping of the F2 individuals. LT50 (the temperature in which 50% of plants killed) was used as a cold resistance index in F3 families derived from each F2 plant. Linkage map was constructed using polymorphic markers. The markers were assigned to nine linkage groups with total length of 1017.6 cM and an average distance of 23.13 cM between adjacent markers. The relationship between LT50 and genotypic data were analyzed using single marker analysis, interval mapping and composite interval mapping methods. Basedon the analyses, five QTL exploring 40 % of the LT50 phenotypic variance, were detected.

This study was conducted to evaluate the effects of feeding ammonia-treated aflatoxin contaminated-corn on performance, weight of internal organs and serum biochemistry of broiler chicks. In this study 320 day-old male chicks (308-Ross) were used in four treatments and four replicates with 20 chicks in a completely randomized design. These treatments were as follows: 1- Without aflatoxin (control), 2- Ammoniated corn (1% v/w), 3-Contaminated-corn with aflatoxin (2ppm), and 4- Ammoniated (1% v/w) contaminated-corn with aflatoxin (2ppm). The results of experiment showed that feed intake, body weight gain, feed conversion ratio and relative weight of liver, kidney, burs fabricius, pancreas and spleen in chickens fed contaminated- ammoniated corn were similar to the control group, whereas these variables changed in birds fed aflatoxin-containing diet. Serum cholestrol, calcium, total protein, albumin and phosphorus decreased significantly in diet contaminated with aflatoxins (AF) (p< 0.05). The toxin fed group had higher activities of the enzymes, lactate dehydrogenase (LDH) and aspartate amino transferees (AST) However alkaline phosphatase concentration decreased by AF (P<0.05). These data suggest that ammoniation of aflatoxin-contaminated corn in a pilot plant (~200Kg) reduces the adverse effects of AF and should be useful in prevention of aflatoxicosis in poultry.

The experiment was carried out in two years using randomized complete blocks design with four treatments and four replications. Treatments were irrigation intervals based on 14, 28, 41 and 55 mm evaporation from pan class A, I1, I2, I3 and I4, respectively. The soil physical specifications determined by profile digging and sampling the existing layers up to depth of 100 cm. The first irrigation was uniformly undertaken to wet soil up to depth of 80 cm and the amount of water in the next irrigations was calculated and executed by sampling the soil. The results showed that I2 treatment (irrigation after 28 mm evaporation from pan class A) is more recommendable to the other treatments in the same conditions. This treatment with 43006 kg/ha mean yield, 4560 m3/ha water consumption, and nine irrigations during growth season had highest water use efficiency (WUE). If irrigation intervals increase as irrigation number decrease to six times, crop yield will decrease 20% whereas saving 4% of irrigation, will reduce the amount of consumed water to 4361 m3/ha.

An experiment was designed to investigate the possibility of using rapeseed meal as a source of protein in dietary Arian broiler chickens. Five diets were tested in a completely randomized design. Rapeseed meal was tested to replace soybean meal with the levels of 0 (control), 25, 50, 75 and 100 percent during the starter and grower periods. Feed intake during the grower period was lower in the 100% replacement (P<0.05). Body weight gain was also lower in the 100% replacement during the starter, grower and total feeding periods and was statistically different (P<0.05) from other treatments, while there was no significant difference among control and 25% replacement. Different levels of rapeseed meal in the diets also affected the feed conversion ratio (FCR). The FCR in the 100% replacement for the starter, grower and total feeding periods were statistically different (P<0.05) from that of the control and 25% replacement but no difference was found between control and 25% replacement. Chemical analysis of the rapeseed meal showed that the amount of progoitrin, gluconapin, napoleiferin and glucobrassicanapin were 44.2, 16.8, 10.5 and 7.5 µmol/g DM, respectively. These findings indicated that the aliphatic glucosinolates content of the meal is rather high, as compared to the accepted limit of 30 µmol/g DM of aliphatic glucosinolates in the canola meal. It can be concluded that 25% of soybean meal in the diet of Arian broiler chickens can be replaced with rapeseed meal as a source of protein.

In order to evaluate the effect of early heat shock and vitamin C and E to alleviate negative effects of heat stress in broilers, 576 one day old Ross strain chicks were used. Initially, chicks were randomly distributed among two equal groups. At the fifth day of age, one group was exposed to early heat shock (EHS) for 48 h (36±1°C).After that, all birds were reared under normal condition up to 35days of age. At day 35, birds of each group were assigned to one of vitamin supplemented diets as follows: Vitamin C (250 mg ascorbic acid/kg), vitamin E (250 mg α-tocopherol acetate/kg) and combination of vitamin C and E (250 mg form each vitamin/kg). Birds received vitamin, supplement diets up to end of the experiment. During the last two weeks (weeks 6 and 7) of the experiment, birds were exposed to acute heat stress of 6h a day (30±1°C). Supplementation of diets with vitamin, especially vitamin C, during last two weeks of experiment under acute heat stress, significantly (P<0.01) improved feed consumption, daily weight gain (P<0.05) and breast muscle (P<0.05) Nevertheless, only feed intake was affected (P<0.05) by vitamin E supplementation. The results obtained from this experiment indicated that using early heat shock during fifth-sixth day of age and, in addition, fortifying diets with vitamin C, or combined with vitamin E, improves broiler performance under acute heat stress.

In order to evaluate genetic diversity within and among Iranian onion landraces, twenty onion landraces along with two hybrids were screened using random amplified polymorphic DNA (RAPD) markers. Twenty- six out of 200 tested RAPD primers produced 170 polymorphic bands. The total number of polymorphic bands within landraces and hybrids varied from 66 to 131 and genetic distances of entries based on Nei's formula ranged from 0.037 to 0.31. The averages of total and within population genetic diversity of landraces and hybrids were 0.341 and 0.234, respectively, and the degree of genetic differentiation was estimated 0.31. Using Nei's gene index, gene diversity within landraces and hybrids was estimated in the range of zero to 0.5. Analysis of molecular variance (AMOVA) based on squared Euclidean distances showed significant variance within and among onion entries, but the between entry variance (%25.7) was less than that of within-entry variance (%74.3). Cluster analysis grouped the entries into four clusters. Molecular grouping showed no correspondence with the geographical pattern. Principal coordinate analysis showed that the first three coordinates explained %52.29 of the total variations, indicating suitable genomic distribution for the markers under study.

In order to study the effect of vibration on the process of drying the corn seed, a low capacity drier with the ability to make three different vibrations on the corn seed hopper was manufactured. By using this drier, 70 different experiments were conducted on the corn seeds and the effect of horizontal, vertical and offset vibrations at different frequencies and angles of connecting rod, was studied on the process of drying the corn seed. Results of experiments showed that offset vibration at the angle 30°, as compared to the vertical axis, had the highest effect on reducing the moisture of the corn seed.