فصلنامه دانش کشاورزی
سال نوزدهم شماره 2 (پیاپی 74، تابستان 1388)

Lentil is only hand harvested in Iran and other developing countries which requires about 300 labour-hour for harvesting of one hectare. In developed countries such as Canada and Germany farmers use tall varieties and harvest them by grain harvesters with special adjustments. Harvesting of Iranian lentil by grain harvester is impossible because of its short stem and high cutter bar losses. About 225000 hectares is planted for lentil in Iran which requires a lot of human energy for harvesting and there is about 15% of total yield loss. In this study methods of lentil harvesting in Iran were investigated and different aspects including technical characteristics of present machines and agricultural conditions were considered and a suitable design was recommended for many of these conditions. After development and construction of first prototype machine، some experimental tests were conducted. After many observations including cinematic analysis، the machine was modified. Finally، in order to check its performance via percentage loss، field experiments using completely randomized design were conducted. Treatments of front roller radius، peripheral velocity of front roller، forward speed of machine were used separately for each experiment. Results showed that the effect of front roller radius and cinematic index on loss percent were significant in %1 probability level. In conclusion، the best condition for a front roller was to have a radius of 15 cm with a cinematic index of 3. 22 which showed a crop loss of about 4%.

Freezing resistance is a quantitative trait which is affected by 10 out of 21 wheat chromosomes. In order to identify the microsatellite molecular markers linked to freezing resistance QTLs in bread wheat, a set of 280 F2:3 families derived from a cross between cv. Norstar (winter type and frost resistant) and cv. Zagros (spring type and sensitive to low temperatures) was evaluated at 11 temperatures under controlled conditions. The LT50 was used as a frost resistance index. Parental polymorphism was assessed using 200 microsatellite primer pairs and 41 polymorphic markers were used to screen F2 individuals. QTL analysis revealed association of LT50 with seven microsatellite markers, Xgwm357, Xgwm148, Xgwm666, Xcfa190, Xgwm499, Xgwm292 and Xgwm174 located on chromosomes 1A, 2B, 5A, 5B and 5D. In total, these markers determined 27% of frost resistance variation in the population. QTL detected on chromosome 1A was the first report about the contribution of this chromosome in frost resistance.

The objective of this study was to determine some mechanical properties of chickpea which are basic with regard to the design of harvesting machines. At the present, chickpea is harvested manually with difficulty and low efficiency. Therefore two common methods in grain harvesting were studied meanwhile stem cutting force and pods stripping force were compared in the field and greenhouse conditions. The relationship of stem diameter and moisture content with shear stress was verified by the linear regression analysis. There was no significant difference between shear stress of chickpea stems planted in the greenhouse and field conditions and it varied from 2.8 to 9 MPa depending on the stem diameter. At 10.5 to 19% moisture content, there was no significant effect of moisture content on shear stress but the regression analysis showed that the effect of stem diameter on shear stress was significant. In terms of pod stripping force a significant difference was observed between greenhouse and field environments. The average of this force in the field and greenhouse were 8.8 and 6.2 N, respectively, at 12% moisture content (w.b.). As the field results did not correspond with those of the greenhouse for stripping, it can be concluded that greenhouse data may not be suitable for designing purposes and researchers should use the data from field condition.

As an option for spending leisure time، urban parks bear important recreational values. This study was carried out to determine the recreational value of «Elgoli» urban park، located in Tabriz، based on visitors'' enjoyment factor. To achieve this، double-bounded dichotomous questionnaires and contingent valuation method were used. Analyzing of data showed that the average expenditure by every visited family in order to enjoy the above mentioned park was 359988 Rials، annually. It came to 224. 99 million Rials per month for total number of visited families. Virtual importance of natural resources and obtained results from visitors indicate that urban parks، as a healthy source، demand the highest attention of responsible organizations in order to inspire and maintain the hilarity and jubilation senses among the society.

In order to evaluate different planters for mechanized sugarbeet planting، this study was conducted in Khorasan province (Jovein area). Field tests were conducted using strip plot design. Experimental factors consisted of: i) planting methods with Tarashkadeh vaccum planter (a1) Rau vaccum planter (a2) and Accord plate-type mechanical planter (a3) and ii) forward speeds with planting speed at 4 km/h (b1) and planting speed at 6 km/h (b2). In this study root yield، sugar porcent، planter wheel slippage، seed damage، seed germination، plant stand، seed consumption and drilled seed distribution were measured. It was shown that planter type had significant effect on yield at 5% probability level. Maximum yield was obtained using Rau planter with 4 km/h forward speed (96. 67 ton/ha). Planter type and planting speed also had significant effect on germination at 1% probability level، but their interaction was not significant. Tarashkadeh vaccum planter with 4 km/h forward speed had maximum seed germination (77. 67%). Coefficients of seed distribution were measured for all planters and Tarashkadeh vaccum planter with 4 km/h forward speed had maximum seed distribution uniformity in adjusted distances (56. 89%) and in average distances (58. 62%). Consequently pneumatic planters had better performance than mechanical planters and Tarashkadeh vaccum planter was better than other pneumatic planters.

Charcoal rot caused by Macrophomina phaseolina، is considered to be one of the important diseases of soybean. Two hundred eighty strains of bacteria were recovered from rhizosphere، phylosphere and nodules of soybean and purified on NA media. Eighty nine of these strains displayed antagonistic ability using dual-culture tests against pathogen، of which، nine strains with high antagonistic effect (>50%)، seven strains as Bacillus spp.، one strain each belonging to Pantoea agglomerans and Pseudomonas fluorescens biov. I، were selected for in vitro tests. Results of volatile metabolites assays indicated that P. agglomerans (ENA) isolate with 34. 5%، in antibiotic test، BIA، BL، BDQ and BIN (Bacillus spp.) isolates with 100% and in cell free culture test Bacillus (BL) isolate with 75. 29%، were the most efficient isolates in reducing mycelial growth of the pathogen. Siderophore test showed that ENA isolate produced the highest amount of siderophore (23. 8 mm in diam). P. fluorescens (P2FB) isolate was the only isolate produced IAA. To determine the population dynamics of antagonists during greenhouse experiments، mutants of antibiotic resistant were obtained. In antagonistic assays، mutants and wild types were not significantly different. Using specific primers (PrnAF/PrnAR) in wild types and mutants of Bacillus BIN and P. agglomerans ENA for detecting antibiotic-encoding genes of pyrrolnitrin indicated that the ENA strain carried gene for encoding pyrrolnitrin.

Fusarium head blight (FHB) caused by Fusarium graminearum is one of the important diseases of wheat. Traditional breeding for the disease resistance is difficult and expensive. DNA markers linked to FHB resistance genes can be useful in accelerating disease breeding programs. The objective of the study was to identify the SSR markers linked to FHB resistance QTLs in wheat. A population of 167 F2:3 families from the cross Wangshuibai (resistant) /Falat (susceptible) was developed. F2 individuals، F3 families and the parents were evaluated for Type II resistance (resistance to the disease spread within the spike) in greenhouse. The parents and two resistant and susceptible bulks from F2 plants (including 15 plants in every bulk) were screened with 341 SSR Markers. 125 markers showed polymorphism between the two parents and 16 markers showed polymorphism between both parents and two bulks. The 16 markers were used to genotype 30 individuals in two bulks. Eight markers showed significant polymorphism and were used for screening the population and QTL analysis. Furthurmore، seven markers linked to the polymorph markers were used for screening and identifying QTL. Using F2 phenotypic and genotypic data، three QTLs for FHB resistance were identified on chromosomes 2AL، 3BS and 3AS. By evaluating F3 families، two QTLs controlling FHB resistance were confirmed on chromosomes 3BS and 2AL. SSR markers linked to the QTLs can be useful in marker assisted selection for FHB resistance in wheat.

In order to investigate the effect of soluble chitosan on plantlets growth in vitro and minituber yield in potato micropropagation، single node plantlets of Agria cultivar were treated in vitro with soluble chitosan at different concentrations including 0، 5، 15، 50، 150 and 500 mg l-1 by adding to the tissue culture medium and growth parameters of plantlets were assessed in vitro. A number of plantlets were subsequently transferred to the greenhouse and sprayed with chitosan solutions including 0، 200، 400، 600، 800 and 1000 mg l-1 weekly، and minituber yield recorded. The results showed that the effect of chitosan was significant on fresh and dry weights of shoot and root and length of plantlets، but its effect on leaf number per plantlet was insignificant. Application of chitosan at concentration of 500 mg l-1 significantly increased the shoot fresh and dry weights، compared to the control. However، at low concentrations its effect was insignificant. The 15 mg l-1 of soluble chitosan significantly led to the increase in root fresh weight of in vitro plantlets. Whereas، higher concentrations، especially 500 mg l-1، significantly decreased root fresh weight of in vitro plantlets without considerable decrease in root dry weight. In vitro application of 500 mg l-1 chitosan significantly resulted in improved acclimatization of plantlets in the greenhouse as expressed by increasing minituber numbers and yields، compared to the control. However، foliar chitosan application at the greenhouse did not show significant effect on yield parameters. The present results indicate that soluble chitosan can be successfully incorporated into potato seed production from in vitro plantlet stage.

Milk thistle (Silybum marianum) is one of the most important medicinal plants and has found special place in pharmacy industries. Irregular harvest of this plant from natural habitats results in the destruction of its genetic resources. In order to optimize in vitro culture of milk thistle، this study was carried out in a factorial experiment based on completely randomized design with four replications، two genotypes (Budakalszi from Hungry and Moghan ecotype) and cotyledon and hypocotyle explants in MS medium supplemented with four kinetin and 2-4 D combinations. Seeds were germinated in MS medium without hormones under 26˚C and darkness conditions. After callus induction، the calli were subcultured four times into the fresh media. Analysis of variance revealed that in all of the subcultures، Budakalszi cultivar was superior to Moghan ecotype with respect to callus fresh weight and diameter. Callus fresh weight and diameter were also higher in the calli obtained from cotyledon compared with the hypocotyls explant. With the increase in hormone levels، callus weight and diameter were increased. In all of the four subcultures، maximum callus growth was observed in the medium supplemented with 2 mg/l 2-4 D and 2 mg/l kinetin. Analysis of somaclonal variation in the calli obtained from different culture conditions and subcultures using RAPD markers revealed different banding patterns among samples from explants of the two genotypes in different culture and subculture conditions.

Pepper root and crown rot was investigated during 2006-2007 in West Azerbaijan province. Pepper fields were checked in Orumieh، Mahabad، Miandoab، Oshnavieh and Piranshahr in August and September. Infected plants with their soils were sampled and transferred to the laboratory immediately. In order to isolate fungal agents، acidic PDA، PCA and CMA cultures were used and for pseudo-fungal agents، baiting method was applied in infected soils. Then، isolates were identified at species level using selective culture media. Eighty two isolates were taken from the infected plants and soils and were subjected to a taxonomic study. These isolates were related to Phytophthora capsici، Pythium aphanidermatum، Rhizoctonia solani، Fusarium oxysporum،F. solani، F. clamidosporum، F. sambucinum and Verticillium dahliae. Patogenicity test was carried out in greenhouse on 34 selected isolates for two pepper varieties (Bell and Local variety) in West Azarbaijan and percentage of the infected plants was calculated after a definite time from inoculation، depending on fungi species. Among the selected isolates، isolates from F. sambusinum and F. chlamydosporum had no pathogenicity effect on two pepper cultivars. It is noted that pathogenicity of F. solani on the local variety was very low. According to Koch rules، pathogens were isolated again from infected plants.

In order to evaluate the agronomic traits and grain yield of two corn hybrids، seeds were sown in a factorial experiment based on randomized complete block design with four replications. The factors were two corn hybrids (540 and 704) and three level of seed deterioration. The seeds of two corn hybrids were divided into three sub-samples from which a sub-sample was considered as non-deteriorated (b0) and the other two sub-samples were artificially deteriorated by the controlled deterioration test at 45˚ C for 48 and 96 hours (b1 and b2، respectively). The results showed that the agronomic traits and grain yield of plants from non-deteriorated seeds (b0) were better than the deteriorated seeds (b2). Also hybrid 540 for all measured traits was better than hybrid 704. The grain yield of b0 increased about 27. 5% as compared with b2. It was concluded that the sowing of high vigour seeds was led to better stand establishment and consequently higher grain yield.

Considering the role of wheat in food security of Iran and its yield reduction due to drought stress، three varieties of wheat، Azar2، Alvand and Zarin were selected and cultured under hydroponics condition. At the fourth to fifth leaf stage the seedlings were kept under 4، 8 and 12 bars potential using polyethylene glycol 8000 (PEG 8000). Hogland solution was used as the control. After 10 days، leaf samples from the seedlings were obtained and antioxidant enzymes activity (Superoxide dismutase (SOD)، Catalase (CAT)، Ascorbat peroxidase (APX) and Glutathion reductase (GR)) and lipid peroxidation were evaluated. Results showed that increase in the strength of osmotic stress increased lipid peroxidation. Moreover، the activity of SOD was declined in the varieties، but GR activity was enhanced with the increase of osmotic stress as expected. This enzyme was not the restriction factor of wheat defence mechanism activities against the environmental stresses. At 12 bars، the activity of APX in Alvand and Azar2 cultivars، contrary to Zarin، showed a significant increase (P<5%) as compared with the control. Nevertheless، the CAT activity was equal in all levels in Azar2، increased in Zarin and declined in Alvand. Subsidence of the enzyme activity of SOD، CAT and APX in Alvand and Zarin cultivars resulted in lower yield due to loss of balance among the elements of defense mechanisms. Thus with accumulation of reactive oxygen species، the key points of the metabolism and cell defence mechanisms were damaged. These factors resulted in the sensitivity of varieties to osmotic stress in contrary to Azar2.

In order to study the effect of drought stress on wheat، three cultivars (Azar2، Alvand and Zarin) were selected and grown in a hydroponic medium. At the stage of 4-5 leaf growth، the plants were kept under 4، 8 and 12 bars potential by using polyethylene glycol 8000 (PEG8000). Hogland solution was used as the control. Then the amount of total ascorbate and glutathione، their reduced form، lipid peroxidation and proline accumulation were measured in leaf samples. The results showed that in Azar2، total amount of ascorbate was increased but total glutathione decreased at 12 bars in comparison with the control level. In Alvand and Zarin cultivars، with increasing osmotic stress، total amount of ascorbate and glutathione decreased and remained constant، respectively. But reduced form of both antioxidants decreased with increasing osmotic stress level in all cultivars. Moreover، with increasing of osmotic stress، proline accumulation in Azar2 was higher than other cultivars. These factors increased osmotic stress tolerance of Azar2 as compared with other cultivars. The results indicated the negative relationship of ascorbate and glutathione content and proline accumulation with lipid peroxidation.

The agriculture sector of Iran has some special features. For example Iran is a great producer and exporter of dates but with little national gains of export earnings and drastic fluctuation. In order to find an answer for this strategic question، in this study various comparative advantage indices – namely RCA، RSCA، SAI، TEI and LQ were calculated for 1961-2005 period، and then their stabilities were evaluated by coefficient of variation. RCA، RSCA، Michaely، SAI and LQ indices indicated that we have relative advantage for most of years in Iran for dates. Also، there was no TEI advantage in all years. The results showed that RCA، RSCA، Michaely، TEI and LQ were the most stable indices during 2001-2005. Establishing policy strategies for maintaining stability of Iran’s date comparative advantages indices could improve the above mentioned product rank in the non-petroleum export basket.

Regarding to wheat production in considerable rainfed areas، identification and selection of suitable breeding methods and using proper and applicable selection criteria for recognizing drought resistant varieties are utmost important. Selection efficiency for a trait، is related to its heritability and type of genes action. Hence، to study the inheritance of leaf relative water content (RWC) in rainfed conditions، an experiment was conducted with 50 F2:3 lines and two parent lines in a randomized complete block design with three replications in year 2007. Results showed that RWC was controlled by additive gene effects with a high narrow and broad-sense heritability. Therefore، we can expect relatively high genetic gain from selection of this trait in rainfed conditions.

Models to predict the distribution of harvest dates in hybrid lily “Menorca” was developed using data from lilies treated with gibberellin in three stages of plant growth. Hormone was sprayed on plants in three stages as: VB (Visible bud) and 10 and 20 days later with three levels of gibberellin4+7 (20، 200 and 2000 µg/plant). In each stage، a sample of 10 plants were selected as control plants (without treatment). In general، in three developed models، with the range of gibberellin concentrations from 0 to 2005 µg/plant، it was predicted that the increasing of gibberellin concentrations to the limits of 780±167. 10 (µg GA4+7/plant) decreased the interval from visible bud to flowering as compared with the control plants and then in the higher concentration of gibberellin، number of days to flowering showed smaller decrease as compared with the control plants. However، in relation to concentrations lower than “minimum” point of fitted curve (30. 57±1. 461، 780±167. 10: days، concentration of gibberellin±SD) an increase in days to flowering was observed. The incidental models for each stage of hormone spray defined were pooled in a final model to predict the distribution of flowering in the total population of plants. An exponential function as the final model fit the incidental models of flowering date with an R2 of 0. 81 which is appropriate to predict the distribution of flowering for to whole population.

Thresher performance in combine harvester is evaluated with two parameters: threshing (percentage of threshed grain to the total input grain to thresher) and separating (percentage of separated grain in threshing space to total threshed grain). Modeling of threshing rate makes possible estimating of threshing loss. Threshing and separating are stochastic events. In this research، a stochastic mathematical model was developed for threshing rate. This model uses an exponential function as probability density function (pdf) to describe the threshing rate with varying feed rate، thresher speed and grain moisture content. Based on data from field experiments، threshing rate was determined. Its range varied from 2. 627 to 3. 821 in different conditions. Using nonlinear regression of SPSS، coefficients of model achieved with R2=0. 72.

In order to obtain advanced clones of potato crop and to utilize them as seed source or developing new cultivars، an investigation was conducted in 2004 using 120 new clones obtained from true potato seed and Agria، Marfona، Draga، Agata and Arinda as control cultivars in an augmented design based on randomized complete blocks with three replications in Ardabil area. Yield of each clone was adjusted for block effects، and then compared with each other using LSD method. The clone numbers 21 and 110 had the lowest and the highest yields، respectively. The clones 110، 19، 46، 41، 91، 44، 78، 111، 70، and 101 had high tuber yield over 31 ton/ha، and the difference between them and high yielding control cultivars was significant. With respect to dry mater yield per unit area، the clones 41، 110، 19، 44، 91، 46، 74، 42، 84 and 81 had the highest yield with dry matter content of 1. 0659، 0. 9406، 0. 9119، 0. 8980، 0. 8903، 0. 8852، 0. 8522، 0. 8352، 0. 8320 and 0. 8299 kg m-2، respectively and were selected as promising clones.

Gami Almasi is a dwarf rootstock of apple which was originated from North West of Iran. This rootstock can be used as a dwarf rootstock for most cultivars of the apple. Shoot regeneration step is a critical factor in apple’s in vitro proliferation and Agrobacterium mediated gene transformation. The regeneration potential is different among cultivars and must be optimized for individual genotypes. In this experiment، we tested different kind of factors that may affect the regeneration efficiency. Two explant type، leaf & callus، two regeneration medium with MS & N6 (modified) basal medium and also various combinations of BA and NAA level were used. Callus and leaves were taken from in vitro established shoots as explants. After eight weeks shoot regeneration rate، callus induction rate and mean of shoot number per leaf were measured. Results indicated that MS medium was better than N6 for shoot regeneration and optimum phytohormons concentrations were achieved in 7. 5mg/l BA and 2mg/l NAA. Regenerated shoots were obtained only from in vitro leaves، and callus didn''t regenerate any shoot. Cutting the surface of the shoots usually enhanced the regeneration from leaves.

In order to study the effect of ammonium nitrate and potassium sulphate on growth characteristics of onion (Allium cepa L. cv. Azar Shahr) a factorail experiment was carried out in a randomized complete blocks design with four replications. Treatments were consist of NH4NO3 (22. 5، 45، 67. 5 and 90 kg/ha) and K2SO4 (0، 78. 3 and 156. 6 kg/ha). The experimental results showed that bulb diameter، plant height، number of leaf، leaf area، bulb fresh and dry weight، leaf fresh and dry weight and leaf chlorophyll index significantly affected by application of NH4NO3 and K2SO4. From the experimental results it can be concluded that applying of 90 kg/ha NH4NO3 and 156. 6 kg/ha K2SO4 increased leaf chlorophyll index، bulb diameter، plant height، leaf area and leaf fresh and dry weight، whereas، the highest fresh weight of bulb was obtained by supplying 67. 5 kg/ha NH4NO3 and 78. 3 kg/ha K2SO4. Furthermore، increasing the NH4NO3 content reduced both bulb dry weight and number of leaf.

Separating clods from potato tubers is one of the most challenging jobs in a potato harvester. In this study، an acoustic-based intelligent system was developed for high speed discriminating between potato tubers and clods. About 500kg mixture of potato tubers and clods were put on the belt conveyer and impacted on a steel plate in four different velocities. The resulting acoustic signals were recorded، processed and potential features were extracted from the analysis of sound signals in both time and frequency domains. A multilayer perceptron (MLP) neural network with a back propagation algorithm was used for pattern recognition. Altogether، 17 potential discriminating features were selected and fed as input vector to artificial neural network (ANN) models. Optimal network was selected based on mean square error، correct detection rate and correlation coefficient. At the velocity of 1 ms-1 of the belt، detection accuracy of the presented system was about 97. 3% and 97. 6% for potato and clod، respectively. Detection accuracy decreased by increasing belt velocity. A potato harvester by using this system can perform at capacity of 20 ton hr-1 by accuracy of about 97%.

Oyster Mushroom (Pleurotuse ostreatus) is one of the industrial، pharmaceutical and commercial edible basidiomycetes. In this study، we examined colchicine treatment for the production of autopolyploid P. ostreatus. For production of mycelium، the spores were cultured on MEA culture medium. For colchicine treatment، the mycelia were then cultured in Czapek liquid culture medium containing glucose (0. 1% w v-1) and peptone (0. 5% w v-1) adding 0، 0. 05، 0. 1 and 0. 3% of colchicine solutions to the medium. The mycelia were stained with Safranin-O and their nuclei diameters were measured، using IX170 Olympus invert light microscope interfaced with a DP50 digital camera. The nuclei were increased in diameter at different degrees in different concentration of colchicine solutions. Such increment response indicates the increase of nuclei DNA content، verifying the autopolyploid formation of P. ostreatus. From the produced mycelia spawn were made and in order to evaluate some important morphological characteristics، they were used for inoculating wheat straw. After the start of fruiting stage، yield، diameter of basidiocarp and length of stem were measured. The yield was increased up to %82 compared to the control، the stem and the diameter of basidiocarp also enlarged in the colchicines-treated P. ostreatus.

The purpose of this study was to investigate the factors affecting the acceptance of rapeseed product insurance as an index of tendency to decrease yield risk among Amol county producers. Seventy rapeseed farmers classified as two groups of 35 random farmers with and without insurance. Explanatory (independent) variables for this study were age، experience of planting rapeseed، production income، education، farm size and prior knowledge about insurance purposes. Data were analyzed by Logit model and Chi–square test. The results showed that production income، age and experience of planting rapeseed had significant effect on insurance acceptance. Furtheremore، results of Chi–square test showed that among different groups of age، income، experience of planting rapeseed، education and prior knowledge of insurance purposes، significant difference were observed in terms of insurance acceptance and therefore tendency to decreas risk.