Iranian Journal of Field Crops Research
Year:2009 | Volume:7 | Issue:1|Papers Count:37

In order to determine the best planting density for rainfed safflower, this experiment was conducted at the dryland agricultural research station of Shirvan in 2004 and 2005. A factorial experiment based on RCBD with four replications was used. Factors included three distances between row (25, 37.5 and 50 Cm), three distance between plants in row (5, 10 and 15 cm) and two genotypes (PI-537598 and 287). The effect of plant distance on row on flowering period length and capitols per plant was significant. With increasing plant distance on row, capitols per plant were increased. Row distance effect was significant on flowering period length, days to maturity, plant height, capitols/plant, seeds/capitol and 1000-kernel weight. Genotype PI-537598 had more seed yield than line 287. Effect was significant on stand, days to flowering, plant height, capitols/plant and TKW. The highest grain yield (606.6 kg/ha) belong to 25 cm row distance and 5 cm distance between plants in row and genotype PI-537598. The effect of any factors weren’t significant on oil percentage. The highest oil percentage (30.74) belongs to 5 cm distance between plants in row and 37.5 cm row distance. Our results showed that the maximum grain and oil yield was obtained from density between 53-80 plants per square meter under entezary planting system of safflower in moderate cold dryland conditions.

To evaluate the effect of different corn/redroot pigweed densities and reduced herbicide doses of 2, 4- D+ MCPA on corn growth and yield and control of redroot pigweed, a field experiment were conducted at the Agricultural Research Station, Ferdowsi University of Mashhad, in 2007. A strip block design on the basis of randomized complete block design with three replications was applied. The experiment consisted of three factors: weed density (3, 6, 9 and 12 plant/m2) as vertical factor, herbicide dose (0, 50 and 100 % of recommended doses) as horizontal factor and crop density (7, 9 and 11 plant/m2) which splitted on vertical factor. Results showed that herbicide application reduced weed dry weight and leaf area index (LAI). In contrast, corn dry weight and LAI increased as herbicide application doses increased. Corn grain yield and yield components increased significantly by increasing corn density. The herbicide efficiency increased, when herbicide was applied to corn of upper crop density and corn yield losses decreased. The increase in herbicide efficiency was significant in reduced dose treatment, but in recommended dose a little increase was observed. Corn grain and biological yield, grain numbers per row, 100 seed weight and harvest index decreased significantly by increasing pigweed density, but rows number per cob was not affected. The results of this research indicated that herbicide dose could be decreased by using high corn density, without significant decrease in grain yield.

Modification of soil temperature and canopy microclimate of potato is an appropriate factor, where soil temperature during the growing season is high. Using a shade crop such as corn has been proved to be a proper tool to overcome this problem. An attempt was made to evaluate the potato/corn intercropping under climatic conditions of Mashhad. An experiment was conducted with different combination of corn and potato: MC (corn monoculture), MP (potato monoculture), S (strip intercropping), I 25%, I 50%, I 75% (with the potato/corn rows overlapping of 25%, 50% and 75% in the strip treatment) and R(row intercropping), in a randomized complete block design with three replications. The results showed that shading caused to an increase in specific leaf area of potato in such a way that the maximum and minimum value of this variable was related to R and MP treatments, respectively. With the gradual overlapping of the potato/corn rows in strip treatment (i.e I 25%, I 50%, I 75% and R, respectively), the corn yield increased as the result of higher rows distance than sole crop, in contrast potato yield decreased as the result of corn over shading. Consequently there was no significant difference between the experimental treatments LER. Therefore according to the results of this experiment the simultaneous planting of corn and potato with their sole crop density is not recommended, and in order to achieve better results, the corn density most be decreased, or alternatively relay intercropping systems could be used.

Vegetative vigor or “greenness" for wheat could be considered as an appropriate index to measure plant health, water deficiency stress and also plant density and quality, which can be determined by Normalized Difference Vegetation Index (NDVI). In this study MODIS images were used to calculate NDVI. The index values were compared with climatological factors to assess the relations between vegetative vigor and climatological factors. The consequent results can be used in crop modeling equations. The NDVI values for three selected wheat farms in Mashhad area were calculated using MODIS images for 2003-2004 growing season. The data of four clamatorial factors including air temperature, precipitation, relative humidity and sunshine hours were also collected from the nearest weather station to the farms. Then a multi-regression statistical analysis was performed to find the relations between wheat’s NDVI and climatological factors in the study area. Pertaining statistical methods including Mixed, and Stepwise (Forward and Backward) were used in this analysis. Scattering matrix was used to determine the data scattering of the models and NDVI values for the sake of comparison. The results showed that Backward method was more appropriate than the other two methods for predicting NDVI values of the study area. After finalizing this model the results were statistically tested using 20% of the samples for the test purpose and the remaining 80% for running the model. The results showed that there was no significant difference between Backward, Testing Backward and Training Backward models. The results from the latter method showed that the NDVI of the pixels could be estimated for 79% of the cases. It can be stated that the rest of NDVI values could be affected by other environmental factors such as soil type and conditions, topographical characteristics, agronomical practices, plant diseases and other unknown factors. Finally, maps showing the potential wheat farming in the area according to the model results were developed.

Plant growth promoting rhizobacteria enhance plant growth and yield directly and or indirectly. In this research the efficacy of four Pseudomonas fluorescents on yield and growth indices of wheat at various levels of phosphorus fertilization were in Two factorial experiments (a pot and a field experiment). The experiments were carried out in a completely  randomized design in greenhouse and randomized complete block design in field trials. The first factorwas : three phosphorus levels based on soil testing (0, 50% and 100% recommended P fertilizer according to soil test)and the second factor was five levels of inoculation as (non –inoculation control ; inoculation with P. fluorescens strain 153; P.fluorescens strain 169; P. putida strain108 and P. putida strain 4).wheat seeds were planted after inoculation with test strains. All agronomic practices and inputs application during planting and nursing were conducted according to regional traditions. Before harvesting growth indices including: plant height, spike length and number of tillers, were determined. After harvest, biologic , grain  and straw yield  and 1000 grain weight were measured.Grain and straw samples were sent to soil and water lab and concentration of N, P and K were determined. Results showed  that with increase in P level, grain yield, 1000 grain weight, plant height and biologic yield  increased significantly at both  greenhouse and field experiments .the effect of inoculation on yield and yield components of wheat was significant at all levels of P  fertilization.The greatest amount of grain yield, 1000 grain weight and plant height obtained from Pseudomonas putida 108 together with application of 100% p recommended treatment and the least yield was obtained from control treatment(without p application and without inoculation). According to these results strains with ACC –Deaminase enzyme had greatest effects on yield and yield indices and so the ability of producing ACC-Deamiase is a good criteria  and utilization of plant growth promoting rhizobacteria could be a suitable way in icreasing yield of wheat at various levels of phosphorus.

To study the allelopathic effects of saffron leaves and corms on redroot pigweed and lambsquarter seedling growth, an experiment was conducted at greenhouse of the College of Agriculture, Ferdowsi University of Mashhad, in 2005. For each species a factorial experiment in a completely randomized design with three replications was conducted. Factors included saffron organs at 2 levels (leaves and corms) and extract concentration at 4 levels (0.5, 1.5, 4.5 per 1000 ml of distilled water and check). The leaves and corms extract of saffron reduced the plant height, leaf area, leaf weight, stem weight, and per plant dry weight of both weeds. Comparing both species of redroot pigweed and lambsquarter indicated that the allelopathic effects of saffron leaves was more in redroot pigweed and the allelopathic effects of corms was more in lambsquarter.

In order to study of sewage and water ratios and morphological traits, yield and yield components of four forage species including maize (Zea may var.SC704), sorghum (Sorghum bicolor var.Sugar graze and Speedfeed) and millet (Pennisetu of m americanum var.nutrifeed), an experiment was done in research station of Industrial and Agricultural Institute of Astane Ghodse Razavi, Mashhad, during 2001 growing season. The experiment was done as split plot design based on randomized complet block design with four replications. Treatments including as 0%, 25%,50%,75% and 100% sewage and water ratios in main plots respectivily,  and four forage species (maize, sorghum (two cultivars) and millet) in sub plots. Morphological traits such as height of plant, diameter of stem, number of tillers per plant, percentage of leaves, stems, leaf sheath, inflorescence and dry matter yield were recorded. The results showed that significant differences existed among the sewage and water ratios treatments on height of plants, diameter of stems, number of tillers per plant and dry matter yield at 1% probability level. With increasing the different sewage and water ratios to 75%, height of plants and to 100%, diameter of stem and dry matter yield were increased. There were no significant differences between different levels of sewage and water ratios on percentage of leaves, stems, leaf sheath and inflorescence. There were significant differences between different forage species at all parameters. Intraction between different levels of sewage and water ratios and four forage species was not significant. The highest dry matter yield was belong to sorghum (var. sugar graze) at 100% sewage and water ratios with 23.1 t./ha and the lowest dry matter yield was obtained in forage millet  at fresh water (check) with 11.0 t./ha.

Bread wheat (Triticum aestivum) has the highest cultured area and production in Iran, but in recent years it looks that as a result of introduction of commercial and breeder varieties diversity of wheat varieties has been reduced. In this study AFLP molecular marker was used to investigate genetic variation of 34 wheat varieties and advanced lines and also to evaluate relationship existing within them. Seven pairs of primer combinations of EcoRI/Tru1I yielded 351 scorable bands out of which 129 bands were polymorphic. Average genetic similarity based on Nei coefficient was estimated as 0.96. Dendrogram obtained from UPGMA method specified four main groups for these 34 varieties and lines, subsequently confirmed by PCA analysis. The results indicated low level of genetic variation within commercial variesties cultivated in the country. Limited range of genetic variation suggests that the genotypes are probably of same origin and more attention should be paid for extending genetic variation of wheat varieties.

To evaluate the effect of additive intercropping grain sorghum and cowpea on weed control in limited irrigation condition, an experiment was conducted in the research farm of college of agriculture, University of Tehran in spring 2006. The experimental treatments were arranged in split plots based on a complete randomized block design with four replications. The limited irrigation (moisture stress) treatment of IR1: normal weekly irrigation (control), IR2: moderate moisture stress during vegetative and generative growth, IR3: moderate moisture stress during vegetative and severe during generative growth, IR4: severe moisture stress during vegetative and moderate during generative growth were allocated to the main plots and different combination of sorghum and cowpea additive intercropping systems of S1: sole sorghum (with weeding), S2, S3 and S4 an additive series 15,30 and 45% of the sole seed rate of cowpea mixed with full sorghum seed rate and S5: sole sorghum (without weeding) were allocated to sub plots.  The results of this experiment showed that weed biomass and weed density were significantly less in sorghum-cowpea intercropping treatments compared to sole sorghum (S5). S4 treatment had the lowest number of weeds compared to other treatments. These findings suggest that additive intercropping sorghum-cowpea suppresses weeds and it is an effective way for biological weed control and acceptable yield of sorghum.

In order to study the response of Isabgol (Plantago ovata) and Psyllium (Plantago psyllium) seed germination under salinity and drought stresses, a factorial experiment based on completely randomized design with three replications was conducted. The first factor was plant species (Isabgol and Psyllium), the second factor was different salinity and drought treatments (NaCl, Na2SO4, KCl, K2SO4, NaCl + Na2SO4, KCl + K2SO4 and PEG 6000) and finally the third factor was different osmotic potentials (0,-0.4, - 0.8, -1.2, -1.6 and -2 MPa). The seed germination percentage and rate and also seedling growth were investigated during the study. The results showed that Isabgol and Psyllium seed germination was significantly different under salinity and drought stresses, as Isabgol germination percentage and rate was more than Psyllium but Psyllium seedling growth was better than Isabgol. The results also indicated that germination characteristics decreased with increasing the osmotic potentials, especially in -1.6 and -2 MPa. Salinity and drought treatments also showed different inhibitory effects on germination so that KCl/ PEG600 had the least and the most effects on reducing the investigated characteristics, respectively. In this study it was observed that sodium salts was more toxic compare to potassium salts and similarly SO4- pointed out more toxicity compare to Cl-. Therefore, osmotic potential was not the only effective agent on germination and there existed specific ionic effects.

This experiment was conducted to study the effect of plant density (pd) and planting pattern (pp) on yield and yield components of two corn hybrids. The type of design was randomized complete block with factorial arrangement and three replications per treatment in 2003 growing season at Gerizeh agricultural station, in Sanandaj. The treatments were plant density (65000, 75000 & 85000 plant per hectare) and planting pattern (normal planting pattern, i.e. planting seeds at the center of ridges; two rows planting on the sides of wide ridges i.e. every other furrows removed and zigzag planting patter, i.e. two rows planting on the sides of normal ridges as zigzag) and two corn hybrids (KSC700 and KSC704). The results of the experiment showed that increasing plant density significantly increased seed yield. Maximum seed yield 11122.5 kg/ha obtained at highest plant density; but there were no significant differences between 75000 & 85000 plants/ha. Number of ears per plant, number of seeds per ear, number of seed rows per ear, number of seeds per seed row, 1000 kernel weight and harvest index were not affected by plan density. Planting pattern had significant effect on seed yield. Zigzag planting pattern produced highest seed yield (11054.7 kg/ha) and lowest seed yield was belong to every other furrow planting pattern. Number of ears per plant, number of seeds per ear, number of rows per ear and number of seeds per ear row were not affected by planting pattern; whereas, planting pattern effect on 1000 kernel weight and harvest index was significant. Zigzag planting pattern had maximum and every other planting pattern had minimum 1000 kernel weight and harvest index, respectively. Corn hybrid effect on seed yield, ear number per plant, seed number per ear and seed number per ear row was not significant. Seed rows number per ear in KSC700 and KSC704 were 16.33 and 13.92, respectively, this difference was significant. 1000 kernel weight and harvest index of two hybrids had significant differences. 1000 kernel weight of KSC700 and KSC704 were 267.97 and 244.61g and harvest index was 52.04% and 50.01%, respectively. KSC 704 in 85000 plt/ha and zigzag planting pattern produced highest seed yield and lowest seed yield was belong to KSC700 in 65000 plant/ha and every other furrow planting patter.

In order to investigate the effects of plant diversity and nutrient resource on weed composition, density and dry matter, an experiment was conducted as split plot based on complete randomized block design with 3 replications at the Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during 2006 and 2007. Treatments included manure and chemical fertilizers as main plots and intercropping of 3 soybean varieties (Wiliams, Sahar and Gorgan3), intercropping of 3 Millet species (Common millet, Foxtail millet and Pearl millet), intercropping of Millet, Soybean, Sesame (Sesamum indicum) and intercropping of Millet, Sesame, Fenugreek (Trigonella foenum-graecum), Ajowan (Trachyspermum ammi) as sub plots. Result indicated that nutrient resource affected weed dry matter and density. Weed dry matter and density was respectively, 1.3 and 1.8 times higher in chemical fertilizer compared to manure in first year. In the second year, weed dry matter in manure and chemical fertilizers was 173.2 and 300.2 gm-2 and weed density was 98.6 and 84.9 plants per m-2. With increasing crop diversity, weed dry matter and density decreased and intercropping systems had the lowest weed dry matter. Crop species affected weed dry matter in monocultures. There was a negative correlation between diversity and weed dry matter. In the first year Shannon diversity index was highest in sesame and Ajowan monocultures (0.75 and 0.72, respectively). Different intercropping systems had the lowest Shannon index. In the second year, Shannon index was highest in soybean (Sahar variety) monoculture (0.72) and 3 Millet species intercropping (0.71). More researches on the effects of crop diversity on weed population are needed in mixtures.

Fertilizer management is one of the most important factors in successful cultivation of medicinal plants. Fertilizers can affect the quality and quantity of plant indexes. Chamomile is one of the oldest medicinal plants that have been using by human since ancient time. In order to study the effect of biofertilizers on quantity and quality yield of Chamomile, an experiment was conducted at Research Station, College of Agriculture, Ferdowsi University of Mashhad, Iran, in year 2008. A complete randomize block design with three replications was used. The treatments were: nitroxin biofertilizer, phosphate suloblizing bacteria and nitroxin biofertilizer + phosphate suloblizing bacteria. Result showed that these treatments had significant effects on main shoot, number of flower per plant, diameter of flower, fresh flower yield, dry flower yield, seed yield, essential oil and kamauzolen yield. The Highest fresh and dry flower yield was observed in nitroxin and phosphate suloblizing bacteria. The Highest essential oil and kamauzolen yield per hectare were obtained in phosphate suloblizing bacteria (8600g) and nitroxin (923g) treatments, respectively. Moreover, the lowest fresh and dry flower yield, essential oil and kamauzolen yield per hectare related to the nitroxin biofertilizer + phosphate suloblizig bacteria treatment. It seems that biofertilizers can consider as a replacement for chemical fertilizers in chamomile medicinal plant production.

This research was conducted to determine the relationships among yield and some yield components of chickepea by using correlation and path coefficient analysis. The experiment was carried out in the experimental field Kharke Sanandaj in 2006. In this study, 36 chickpea cultivars were used. The experimental design was Triple Lattice Design. Positive and significant relationships were found among seed yield and number of pods per plant, number of seeds per pod, biological yield and harvest index. Negative and non significant relationships were determined among seed yield and 100-seed weight, number of primary branches, days to flowering, days to first pod formation and days to maturity. According to path coefficient analysis, there were strong direct effects of the harvest index (0.901), biological yield (0.194) and number of pods per plant (0.048) on the seed yield.

Two field experiments were carried out in order to evaluate the effects of planting date, method and date of weed control on yield and yield components of cumin in the experimental research field, Faculty of Agriculture, during 2006 and 2007. Treatments included planting date (30 December, 20 January and 30 February), weeding date (first true leaf, start of branching and beginning of flowering stages) and weed control methods (hand weeding, fire treatment and control). The results showed that there were significant differences between different sowing date, as the highest yield was in 30 December and the lowest was in 30 February. However, delaying of sowing date decreased the straw yield, number of umbelets in umbel, number of seed and biological yield. There were also significant differences in start of branching stage, branching stage and first true leaf stage in different times of weed control as the highest yield was considered in the start of branching. It showed that there were significant differences between hand weeding, control and fire treatments. The highest yield of seed, straw and biologic was obtained in hand weeding methods.

This research was conducted with four treatments; 1: control, 2:USW compost (20 ton/ha), 3: sulfur (1 ton/ha), 4:mixture of USW compost and sulfur (sulfur10% of compost used), each treatment with four replications to study the effect of urban solid waste compost (USWC) and sulfur on soil chemical and yield of sugar beet under field condition. Data collected was analyzed in Randomized block design (RBD) and treatment means compared by using Duncan test at p=0.05. Results indicated that crop biomass yield in USWC treatment was highest. Maximum root yield was obtained in USWC, sulfur, USWC + sulfur and control respectively. Soil pH in USWC + sulfur and sulfur treatments were minimum, probably, due to the acidic nature of both materials used. EC of soil in USWC + sulfur treatment was highest compared to other treatments. Organic carbon of soil in USWC and USWC + sulfur treatments were highest. Soluble cations of potassium, calcium and magnesium in USWC + sulfur and sulfur treatments were found maximum, but soluble sodium was highest in USWC treatment. Soluble anions of sulphate and chloride were highest in USWC + sulfur and sulfur treatments. Soil total nitrogen was highest in USWC + sulfur and sulfur treatments compared to others. Soil phosphorus was highest in USWC, sulfur and USWC + sulfur, respectively. USWC + sulfur and sulfur treatments enhanced plant macro nutrient elements availability and uptake.

In order to study the effects of nitrogen and plant density on light absorption and radiation use efficiency (RUE) in two spring rapeseed cultivars, a split plot factorial experiment based on randomized complete block design with four replications was conducted in 2005 in research farm of Ferdowsi University of Mashhad-Iran. The treatments included two levels of urea application (100 and 150 kg/ha) as main plots and subplots were combination of plant density (60, 80, and 100 plant/m2) and rapeseed cultivars (Hyola 308 and Option500, early and medium maturing cultivars, respectively). Results indicated that treatments influenced significantly on light absorption rate and RUE. Increasing nitrogen application rate, from measured factors, only LAI and RUE were significantly influenced. Hyola 308 cultivar had higher RUE, biological and grain yield and oil yield compared to Option 500. The only preference of Option 500 cultivar was 1000 seed weight. Dry matter production and RUE was significantly higher in 80 plant/m2 compared to other plant densities. Increased dry matter in this density was due to higher light absorption and consequently increased RUE. Among all determined parameters, LAI was significantly influenced, and highest LAI observed with Option 500 cultivar, which occurred in 100 plant/m2 density and 150 kg/ha urea application. Among yield components, only pod number per plant was affected by plant density, as highest number of pods observed in 60 plant/m2 treatment. None of the treatments influenced seed oil percentage.

Saffron (Crocus sativus L.) is a valuable plant which is mainly grown in Iran, India and Greece. The life cycle of this plant is short and more period of plant growth is in autumn and winter which, it is not possible for other plants to growth. Therefore it does not occupy the land during the whole year, and hence possibility of Saffron intercropping with other crops may economically be feasible. To evaluate the potential of intercropping of Saffron with other crops, this experiment was conducted in the research field of Faculty Agricultural, Ferdowsi University of Mashhad in 2006-2008. This study arranged as a Randomized Complete Blocks Design (RCBD) with three replications. Treatments were different combinations of Saffron with three groups of crops including cereals: Spring and Winter Wheat (Triticum aestivum), pulses: Chickpea (Cicer arietinum) and Lentil (Lens culinaris), and medicinal plants: Ajowan (Carum copticum), Black Seeds (Nigella sativa), Flixweld (Discurinia sophia), Green Cumin (Cuminum cyminum) and Psylium (Plantago ovata) in a row replacement series arrangement. A pure stand of Saffron was also included in the treatments for comparison purposes. Relative advantage of Saffron intercropping with other crops in terms of Relative Value Total (RVT) was only shown in Saffron intercropping with Ajowan and Black Seeds in combined analyze. These values were 2.16 and 1.85 for intercrop of Saffron with Ajowan and Black Seeds, respectively. However, the highest yield of Saffron was obtained in pure stand (1.06 kg/ha) and the lowest yield was in mixture with Ajowan (0.12 kg/ha). There was no difference between intercrop treatments in terms of Saffron yield, except between saffron intercropping with Lentil and its intercropping with Ajowan. There was no difference between intercrop treatments in terms of number of corms per plant, number of buds per corm and also fresh and dry weight of corm. Yield of Saffron was reduced with increasing irrigation frequency (water needed for companion crops) (p<0.05), but there was a positive relationship between RVT and irrigation frequency (p<0.01).

In order to evaluate drought tolerance of chickpea germplasm, 150 genotypes of chickpea (Kabuli type) were tested using Augmented Designs for Preliminary Yield Trials under stress (Rainfed) and non stress (Irrigated) conditions in Research Field at Mashhad College of Agriculture during 2005-6 growing season. Quantitive drought resistance and susceptibility indices such as Stress tolerance index (STI), Mean productivity (MP), Geometric mean productivity (GMP), Harmonic mean (HM), Drought response index (DRI) and Stress susceptibility index (SSI) based on yield in stress and non stress conditions, were calculated. There were significant variations among the genotypes in their reaction to drought stress. There were positive and highly significant correlations among MP, GMP, STI and HM with yield in stress and non stress conditions. Also, there were positive and high significant correlations for SSI and DRI with yield in non stress and stress conditions, respectively. Based on drought resistance indices and DRI, MCC544, MCC696 and MCC693 genotypes were superior to others, so they can be recommend as promising genotypes for drought resistance. These results were approved using three dimension graph and multivariate biplot graph. In stress condition, there were negative and high significant correlations between yield and days to flowering, therefore days to flowering in promising genotypes were shorter than other genotypes. 

In order to study the effects of different tillage systems on density and diversity of weeds in cotton followed by rapeseed, this research was conducted in Randomized Complete Block design with three replications in Gorgan in 2005. Treatments were different tillage methods such as no-tillage (plant in cutting residue), plowing plus disk (as a conventional method), chisel plus disk (as low tillage) and two time disking (as a minimum tillage). Weeds and rapeseed seedlings that germinated in cotton were counted three times (in two leave stage, squaring and flowering stages of cotton) in each treatment. The results showed that weed density and weeds species were affected by tillage methods significantly. Perennial weeds specially Cyperus rotundus L. were more observed in no tillage treatment but annual weeds for example Physalis alkekengi L., Solanum nigrum L. and Amaranthus spp. were more dominant in common tillage. In low tillage treatments (Chisel and Disk) there was both annual and perennial weeds .Germination of rapeseed in no-tillage, plow, chisel and disk was more than common tillage. On view of yield, there was no significant difference between low tillage systems and common tillage, therefore we can use low tillage system instead of conventional tillage, however we have to find proper methods for weed control in this system.

To evaluate the effects of nitrogen and herbicide on spatial distribution and variability of broadleaf weed patches, this experiment was conducted in 2005 at the Agricultural Research Station, Ferdowsi University of Mashhad. As a result of factorial arrangement of Nitrogen fertilizer amount (25 and 120 kg ha-1), Nitrogen fertilizer time of application (Whole application at the time of corn planting and equal split application at the time of corn planting and at six-leaf stage) and weed control (applying or not applying herbicide), eight treatments were assigned to eight fields each of which 10m wide and 30m long. Weed sampling was taken at 264 points at each corners of 2.5 by 2.5m grids and reported four times during growing season, with 23days interval, beginning before top dressing fertilizer and herbicide in related plots (June, 24th). On the whole, 12-15 weed species were observed in different treatments. At first sampling, weed populations mainly consisted of annual broadleaf species, such a way that 2-3 species were grasses and the others were broadleaf weeds. In early growing season prostrate pigweed was dominant weed in all treatments followed by common lambsquarters, black nightshade and common purslane, respectively. A pronounce weed reduction was observed in herbicide treated fields mainly due to reduction of broadleaf weed populations and mean density and relative density percentage were also decreased by the end of growing season. At second sampling, the broadleaf populations were almost the same in herbicide treated fields and N2 application did not effect on herbicide efficacy. In the non-herbicide treatments, the total and broadleaf weeds density were increased primarily but decreased later in the growing season. Broadleaf weeds mapping showed high level of weed infestation in all treatments. Nevertheless, variation range of density in the field was high and the declines of high-density spots from center toward the margin of the patches were observed. The results of this study indicated that spatial distribution could be interpreted as main factor in decision making of weed managements.

Flax (Linum usitatissimum L.) is an oil seed crop which based upon the genotype, its oil is used as industrial or edible oil. Since, agronomic management practices can effect on yield and quality of flaxseed, this study was carried out to investigate the effect of planting date and seeding rate on seed yield and other agronomic traits of various genotypes of flax. In this study, nine genotypes were planted at different seeding rates of 500, 700 and 900 seed/m2 as a factorial experiment, using a randomized complete block design with three replications in two separate experiments at planting dates of 17 March and 20 June 2004. The results showed that in the second planting date, days to 50% emergence, days to maturity, plant height, capsules/plant, seeds/capsule, seed yield/plant and seed yield was significantly decreased, but number of seedlings/m2 increased. Seed yield in the first and second planting dates were 1620 and 840 kg/ha, respectively. Increasing seeding rate significantly decreased plant height, capsules/plant and seed yield/plant, but increased days to maturity in the second planting date. Seed yield was significantly increased from 1470 to 1689 kg/ha as seeding rate increased from 500 to 700 seeds /m2. However, increasing the seeding rate to 900 seeds /m2 had no significant effect on seed yield. There were also significant differences among the genotypes for all of the traits. A landrace population from Kordestan province had the highest mean of seed yield in both first and second planting dates which were 2359 and 1806 kg/ha, respectively. Generally, the results of this study showed that higher seed yield in flax can be obtained at seeding rate of 700 seeds /m2 and early planting in the spring. High genetic variation for seed yield among the genotypes indicated that genetic potential of some genotypes like landrace population from Kordestan province can be used in breeding programs. 

Field experiment was conducted in Khorramabad, Iran during 2005-2006 to evaluate the efficacy of  9 herbicides [ethalfluralin (3 l/ha), trifluralin (2 l/ha), pendimethalin (1.5-2.5 l/ha), imazethapyr (0.7-1 l/ha), pyridate (2.5 l/ha), bentazon (2 l/ha), metribuzin (0.7 kg/ha), and haloxyfop-R-methyl (1 l/ha)] applied alone or in combination for weed control in chickpea (Cicer arientinum L.). The experiment was laid out in randomized complete block design with 4 replications. Annual weed density in weedy control was 60 plants/m2. In terms of annual weed density pendimethalin applied as soil-incorporated was the most efficacious, however pyridate applied postemergence, Imazethapyr applied pre-emergence, and Pendimethalin applied post-emergence did not show significant difference with pedimethalin when applied as soil-incorporated. Imazethapyr and pyridate when applied as post-emergence provided 83% annual weed biomass reduction. Base on the visible crop injury symptoms, Imazethapyr in all applied form caused stunting of growth, and necrosis was recorded for bentazon, and metribuzin as applied post-emergence. Haloxyfop-R-methyl as applied post-emergence, and ethalfluralin, and trifluralin applied as soil-incorporated did not show any crop injury symptoms. Maximum grain yield (697.8 kg/ha) was recorded in early hand weeding treatment, that was three-fold of weedy check control. In the basis of chickpea yield, post-emergence application of pyridate, isoxaflotole, and pendimethalin, pre-emergence application of pendimethalin or imazethapyr followed by hand weeding, and pre-emergence application of imazethapyr+post-emergence application of pendimethalin did not show significant difference with hand weeding control. No herbicides showed significant negative effects on emergence, and vegetative growth of wheat (Triticum aestivum) in the next season.

In order to evaluate the effects of sowing date, crop density and weed interference on chickpea growth and yield, and also on weed population in dryland farming system of Lorestan province, a field experiment was conducted during 2005-2006 based on a randomized complete block design, with four replications. Treatments included planting dates (autumn and winter), plant population densities (25, 50 and 75 plants m-2) and weed interference (hand weeding and weedy check). Based on the results and fitted curves, leaf-dry-weight plant-1 and leaf-dry-weight m-2 in autumn chickpea were higher than winter chickpea. Maximum leaf-dry-weight plant-1 and m-2 was achieved at 25 and 75 plant m-2, respectively. Mean chickpea grain yields were 1114 kg/ha, and 561 kg/ha for autumn and winter crop respectively. Weed control (hand weeding) significantly increased leaf-dry-weight of single plant, chickpea biomass, and grain yield. Although weed density in autumn sowing date was approximately three times more than the winter crops, but chickpea grain yield per area in autumn crop was about two times higher than winter crop. The maximum annual weed biomass were observed in autumn sowing date with 25 plants m-2 in weedy check, and minimum biomass was in winter chickpea with 75 plants m-2  with weeding. The species richness in autumn chickpea was 71% higher than winter crop. Weed control caused 58.4% increase in grain yield. The highest chickpea grain yield was harvested in autumn crop with plant density of 50 plant m-2 and hand-weeding treatment.

In order to study the effect of organic and chemical fertilizers on soil physicochemical properties, production and biomass yield of tomato (Lycopersicon esculentum L.) an experiment was conducted with randomized complete block design in 3 complete blockes and six treatments at the experimental farm of the Environmental Science Research Institute of Shahid Beheshti University in 2006. Treatments were Vermicompost (VC) from municipal solid waste, municipal solid waste compost (MC), Cow manure (CM), poultry manure (PM), chemical fertilizer (CF) and no fertilizer as a control (NF). Results showed that the treatments had significant effect (p£0.01) on percentage of organic carbon, organic matter, total nitrogen, the availability of phusforus, potassium, pH and CEC, SP of soil but had not significant effect on EC of soil. Also content of soil micro element affected by treatments and amount of these parameters were increased by using of organic fertilizers. Treatments had significant effect (p£0.01) on soil physical properties such as buck density, porosity and but had not significant effect on aggregation of soil. Biomass production of tomato were increased by using of chemical and organic fertilizers compare in control treatment and the highest value of biomass and economic yield were obtained in VC and CF treatments. As a result using of organic fertilizers especially in composted form had positive effect on soil health and fertility, which consequents increase yield in long term can be expected.

In order to evaluate the effect of animal manure on Ajowan (Carum copticum) and Fenugreek (Trigonella foenum-graecum) different intercropping, an experiment was conducted as split plot on the basis of complete randomized block with three replications in 2005. For this reason four levels of animal manure (15, 20, 25, 30 tons/ha) was allocated to the main plots and different intercropping of Ajowan and Fenugreek at 5 levels in subplots (A: pure stand of Ajowan, B: pure stand of Fenugreek, C: single-row intercropping of Ajowan and Fenugreek, D: double-row intercropping of Ajowan and Fenugreek, E: triple-row intercropping of Ajowan and Fenugreek). Results showed that Different intercropping systems had no effect on plant height, primary branches, number of pods per plant, number of umbels per plant, number of umbellets per umbel, number of seeds per umbellet and 1000-seed weight, but secondary branches, seed yield and biological yield of organs in Ajowan and Fenugreek and also dry weight per plant and harvest index in Ajowan were affected by intercropping systems. At between intercropping treatments, Seed yield and biological yield in single-row intercropping compared with double and triple row intercropping was suitable. The highest number of secondry branches in Ajowan and Fenugreek was obtained in single-row intercropping and pure stand, respectively. Harvest index and dry weight per plant in Ajowan was highest in intercropping compared with pure culture. Effect of animal manure was only significant in number of seeds per pod in Fenugreek and number of umbellates per umbel and percentage and yield of essential oil in Ajowan. The highest number of seeds per pod and number of umbellates per umbel were observed with 30 and 15 ton/ha manure, respectively. Percentage and yield of essential oil at high level of manure (25 and 30 ton/ha) were higher in intercrop compared with pure stand. The highest Land Equivalent Ratio (1.47) was obtained in singel-row intercropping and the lowest (1.28) in double-row intercropping.

Wild oat seed bank dynamics was studied using a multi-stage single cohort population model. The model predicts the size of seed bank on the basis of seed outputs (germination and mortality) and inputs (produced seeds per plant and seed burial) with annual step. Seed mortality in soil is density dependent and reproductive effort of wild oat is described based on allometric relation between individual plant weight of weed and number of produced seeds per plant. The effect of wheat and wild oat densities on biomass of species in mixture is defined by using hyperbolic equations with predefined competition coefficients. Model was used for simulation of wild oat seed bank dynamics without control measures after calibration and validation against field data. The results showed that in pure stand of wild oat size of seed bank was independent to the initial seed density and reached to equilibrium after 5 years. This was due to reduction in reproductive effort of wild oat at high weed densities and increased density dependent seed mortality in soil, leading to equal input-output from seed bank. Sensitivity analysis on model parameters showed that in the presence of wheat, crop density and interspecific competition coefficient of wheat on wild oat were the most important factors in adjustment of the size of seed bank. An increase in wheat density by 20% or 20% increase in crop competition coefficient was able to drastically reduce annual rate of wild oat seed inputs to the soil. Relative wheat yield in weed infested field without control practices was 0.8 and 0.6 after 5 and 10 years, respectively when inter specific competition coefficient of wheat was increased by 20%. It was concluded that breeding wheat cultivars with higher competition ability against wild oat together with increasing wheat density are reliable management practices to prevent weed population in seed bank and yield loss.

Water deficit is a major factor influencing yield and Canola seed oil content. A two years field experiment was conducted during 2005 and 2006 growing seasons in the Agriculture Research Station of Torogh, Mashhad to evaluate response of Canola cultivars to limited water. Experimental design was a split plot with three replications in which irrigation regimes were allocated to main plots and cultivars to subplots. Irrigation treatments included 100 (R1), 80 (R2), 65 (R3) and 50 (R4) percent of water requirement based on previously determined water requirement of Canola in Mashhad. Cultivars were Zarfam, Okapi, SLM046 and Licord. The results showed that yield and yield components were significantly affected by drought stress in two years. In R3 seed yield was decreased at first year however, at R4 decreased seed yield was observed in both years. Water use efficiency in all stress treatments was higher than control. Average of WUE at all cultivars in control treatment was 2.78 g per kilogram by 3500 m3 watered requirement and 6.13 g per kilogram by 1750 m3 watered requirement in severe stress. The highest and lowest WUE observed in SLM046 in R4 and R1 treatments by 8.20 and 1.52 g per kilogram. These results showed considerable differences between Canola cultivars regarding to WUE and yield analysis. In addition the ability of oil production by canola cultivars under drought stress is not followed by seed yield. This ability to produce seed yield is so less than oil content.

Cumin is an important medicinal plant and its cultivation in arid and semi-arid parts of Iran which water is a serious constraint to agricultural production has a high economical feasibility. In order to determine the threshold salinity and temperature and their interaction effects on cumin germination a complete randomized experiment with factorial arrangement was performed in the laboratory. Salinity levels of 0, 2, 4, 6, 8, 10, 12, 14 and 16 dS/m using NaCl and CaCl2 with 5:1 molar ratio and temperature levels of 0, 2, 4, 6, 8, 10 and 12 degrees Celsius were considered. The regression analysis of the germination data showed that the germination percentage and rate were not changed until reaching threshold salinity (EC*), and decreased linearly afterwards. The EC* values for percentage and rate of germination were found to be 3.06 (±0.55) and 3.02 (±0.83) dS/m, respectively. The regression slopes for germination percentage and rate were found to be -4.49 (r2=0.98**) and -0.147 (r2=0.97**), respectively, which means at salinity levels higher than EC* the germination percentage decreased 4.49% and the rate of germination was lowered by 0.147 seed per day.  In addition, the results showed that with increasing temperature up to 4 °C the percent and rate of germination increased. In the range of 4 to 8 °C the highest percentage and rate of germination was observed, and afterwards by increasing temperature these factors were decreased. There was no significant difference in germination characteristics between 4, 6 and 8 °C, however, there was a significant difference (P<0.05) between 0, 2 and other treatments. The analysis of interaction effects of salinity and temperature on percent and rate of germination showed to be non-linear. In all salinity levels the percentage of germination increased with increasing temperature, and reached its maximum values in the range of 4 to 10 °C. Based on the results of this research the rate of germination could tolerate a higher threshold salinity value (> 5 dS/m) within these temperature ranges. The results of this research which was performed in laboratory provided the preliminary information on cumin germination characteristics as affected by salinity and germination. Further research in the soil medium seems to be necessary.

Persistence behavior of sulfosulfuron in soil was studied under wheat cropping conditions at the Research Field of Faculty of Agriculture, Ferdowsi University of Mashhad in 2006. Forty ton ha-1 animal manure was applied to the soil and a none applied manure was allocated as check. Two doses of herbicide application, common (26.6 g ha-1) and overdose (33.73 g ha-1) also were sprayed. Soil samples were collected at predetermined intervals after herbicide application and residues of sulfosulfuron were analyzed by HPLC using photodiode array detector. The method was set by using RP-C8 column (250×4.6 mm) and acetonitril: water: orthophosphoric acid (80:20:0.1 v/v/v) as mobile phase at a flow rate of 1 ml min-1 with 20 µl injection volume and 212nm as maximum absorbance wave length. In this condition sulfosulfuron was resolved at 3.6 min retention time. The dissipation of sulfosulfuron was found to have first-order kinetics in soil and its rate was faster in the amended soil than another. The half-time (t0.5) decreased from 33.8 days to 14.3 days and 25 days to 13.3 days in common and overdose of sulfosulfuron respectively. These quantities for t0.1 (90% reduction in initial herbicide concentration) were from 112.2 days to 47.6 days and 83.2 days to 44.2 days.

Most areas under cultivation in Iran are located in arid and semiarid zones where water resources are limiting. This affects the grain yield and yield components of cereals. Nitrogen, as a key element in crop nutrition, has an important role in increasing crop yield and quality.  It also enhances crop potential against environmental stresses such as drought. In order to study the effect of grain yield alleviation by nitrogen under drought stress conditions, a filed experiment was designed and conducted during 2004-2005 growing season at experimental farm of College of Agriculture Shiraz University. This research carried out in two individual parts (irrigated and rainfed) with factorial experiments and based on randomized complete block design with three replications. Treatments involved four levels of nitrogen (0, 50,100 and 150 kg/h) and five bread wheat cultivars "21" and Ghods genotype as "resistant" cultivars, Rahim with "medium resistance" and Bezostaya and Equa, as "sensitive" cultivars. The results showed that under water stress conditions, nitrogen enhanced, leaf area index and leaf area duration significantly. Increased leaf area and leaf area duration due to high levels of nitrogen, compared to control, resulted in significant increase in grain yield. Total dry matter was decreased by drought stress under rainfed conditions. In both moisture regimes, with increased nitrogen rate, dry matter production was increased and the negative effect of stress was alleviated. Ghods and 21 genotypes which appeared to have resistance to drought stress, with good yield components attained maximum grain yield and Equa had the minimum grain yield. Small difference between grain nitrogen content of genotypes was observed. Drought stress did not appear to affect nitrogen absorption under water stress conditions, although the mean grain nitrogen content was slightly lower under water stress conditions. Further research is recommended on sensitivity of Equa cultivar to drought stress and the possibility of using N fertilizer as a mean for alleviation of the adverse effects of drought stress on bread wheat yield.