JWSS - Journal of Water and Soil Science

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Nitrogen (N) is usually low in the majority of agricultural and non agricultural soils in Iran, mainly due to the lack of adequate soil organic matter (OM). On the other hand, boron (B) toxicity is becoming more widespread in arid and semi arid regions of this country, where soils or irrigation waters contain relatively high B content. Results of the research indicate that addition of certain plant nutrients such as N may reduce the harmful effect of high B levels. Therefore, the present experiment was undertaken to evaluate the interactive effect of N and B on the growth and chemical composition of rice in a calcareous soil. Treatments consisted of six B rates ( 0, 2.5, 5, 10, 20 and 40 mg kg^-1 as boric acid) and four levels of N ( 0, 75, 150 and 300 mg kg^-1 as urea) arranged in a factorial manner in a completely randomized design with three replicates. Application of B decreased shoot dry matter. At low B levels, N application alleviated the toxic effect of B. Moreover, the addition of B increased B and N concentrations in the rice shoot. The N concentration increased and B accumulation decreased with increasing N rates. There was a general trend of increase in shoot N and chlorophyll concentrations with increasing chlorophyll meter reading. Chlorophyll concentration decreased with increasing B levels. N fertilization increased chlorophyll content and somewhat reduced the adverse effects of high B rates on this plant parameter. The results reported herein show that in soils with high B levels, N application may alleviate the suppressing effects of B toxicity and increase rice growth possibly due to a decrease in B absorption by the plant

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A considerable portion of threshing losses and waste of rice takes place in threshing stage. One of the effective factors in threshing losses and waste of threshing units, threshers and harvesting machines, is the drum speed. In this research, effects of three factors including drum speed (five levels), crop moisture content (two levels) and rice common varieties (four varieties) on threshing losses and waste were studied. The thresher T25 was used for the investigation. It has wire loop type tooth. Dependent factors included unthreshed grains percentage (threshing losses) and damaged grains percentage. The obtained data was analyzed by split–split plot test based on Complete Randomized Blocks Design. The mean values were compared using Duncan’s Multiple Range Test. The tests results revealed that significant effect of variety type and drum linear speed on threshing losses (P<0.01). Furthermore, the effects of variety type, moisture content and drum speed on damaged grains were also significant. The optimum drum speed was 14 m/s. The most and the least of threshing losses belong to Hashemy and Binam varieties, respectively. Among the tested varieties, Binam variety showed the highest percentage of the damaged grains. In general, decreasing the crop moisture resulted in increasing the mean damaged grain.

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Rice whitening is an important stage in rice milling process and improvement of the whitener machines has a remarkable effect on rice loss. To decrease the amounts of broken rice and losses, the rotor of the blade whitener was equipped with screw conveyor. To investigate the effects of rotor speed (in four levels: 600, 700, 800 and 900 rpm) and output rate (in three levels: 400, 500 and 600 kg/h) on quality of milled rice, a factorial design with randomized complete block experiments with three replications were conducted. In this study, Sorkheh variety (a medium rice variety), which is one of the prevailing varieties in Esfahan, was used. The results showed that the lowest breakage percentage (20.92%) occurred at rotor speed of 700 rpm with an output rate of 600 kg/h and the best degree of milling (6.33%) took place at rotor speed of 600 rpm with an output rate of 400 kg/h. The best rice quality (low broken rice and high degree of milling) was observed at rotor speed of 600 rpm with 500 kg/h output rate.

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The present study discusses a method used to produce updated information about vegetation cover in arid and semi-arid zones, using RS data and GIS technique. In this method, Landsat ETM⁺ data in 2002 was collected in an area of about 60000 ha in Nodoushan basin, Yazd, Iran. To collect the necessary ground data, 50 sites of different vegetation types were selected and the percentage of vegetation cover in each one was determined. Also, different vegetation and soil indices were derived and crossed with located sampling points using ILWIS software capabilities. To get the best fitted curve, the relationship between vegetation cover, as a dependent variable, and satellite data bands, vegetation indices and environmental factors, as independent variables were assessed. Therefore, a multiple linear regression model was established for the prediction of vegetation cover percentage in the studied area. Finally, a vegetation cover map with high a precision was produced. As a conclusion, it can be said that mapping of vegetation cover via remote sensing is possible even if its vegetation cover is sparse.

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In order to study the genetic diversity of 75 Iranian rice genotypes (45 Iranian land race, 25 improved cultivars, and 5 exotic cultivars) with respect to their salinity tolerance at seedling stage and to determine tolerance indices, based on biomass, genotypic code and Na⁺/K⁺ ratio a factorial experiment in randomized complete block design with three replications was conducted under control and salt stress(1.2, 4 and 8 dSm^-1) conditions at Rasht Rice Research Institute. Root and shoot length, root and shoot dry weight, Na⁺ and K⁺ concentrations, and genetic score were studied. Significant differences were detected among genotypes for all traits. Shoot length and K⁺ concentration had the highest and lowest heritability estimates, respectively. Genetic score under salinity stress showed that Tarom-mahalli, Gharib, Shahpasand Mazandaran and Ahlami-Tarom with more biological yield root and shoot lenghes, and low Na⁺/K⁺ ratio were tolerant. Khazar, Speedroud, IR28 and IR29 were the most sensitive cultivars. Tarommahalli, Ahlamitarom, Rashti and Chparsar had low tolerance index, mean productivity, stress sensitive index, geometric mean index, stress tolerance index and harmonic mean for genetic score, whereas Khazar and Speedroud had high values for theses indices. Cluster analysis, based on seedling traits at 4 and 8 dS.m^-1 divided the genotypes to three groups. Tolerante group had low genetic score and Na⁺/K⁺ ratio, but high root and shoot dry weight, biomass, root and shoot length.

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Organic matter (OM) and total N (N) are relatively low in majority of the calcareous soils in Iran, and continuous use of N fertilizer would impair the quality of surface and ground water and creates other environmental hazards. Therefore, the combined use of N fertilizer and organic wastes is important to partly supply plant N requirement, improve physico-chemical properties of soil and conservation of environment. The present study was initiated in order to study the effect of two organic wastes with and /or without N enrichment on the growth and chemical composition of paddy rice and some characteristics of the soil in pot experiment. The experiment was carried out in factorial manner in a completely randomized design with three replications. Treatments were two organic matter sources (municipal solid waste compost and cow manure), four OM rates (0, 1, 2, and 4%) and three N levels (0, 75, 150 mg kg-1 soil as urea). Application of compost and cow manure increased top dry weight of rice. The highest growth of rice was obtained with 4% compost and 150 mg kg-1 N. Rice growth increased up to 2 % cow manure and was suppressed with the higher rate, due to build up of soluble salt in soil. Enhancing effect of N on rice growth was only observed with 1% cow manure and at high level of cow manure rice growth was decreased probably due to rise in soil salinity or ammonium toxicity. The mean concentration of N increased by the addition of cow manure, whereas decreased with compost application. Soil N application enhanced the mean concentration of N, and iron (Fe) and magnesium (Mn). Rice plants enriched with either of the two organic wastes accumulated more phosphorus (P), potassium (K), N, Fe, Mn, chloride (Cl) and sodium (Na) than control plants. Post harvest soil sampling indicated that organic matter significantly improved all chemical characteristics. Furthermore, soil treated with cow manure had higher soluble salt (ECe), Cl, K, OM, total nitrogen, available P, Fe and Mn and lower Zn, Cu, lead (Pb), cadmium (Cd) and sodium adsorption ratio.

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To compare the allelopathic potential of some Guilan province rice cultivars with allelopathically approved IRRI rice cultivars, a factorial experiment was conducted in completely randomized block design with 3 replications on the Experimental Farm of Agricultural College of Guilan University in spring 2005. Two factors including a) seven rice cultivars (traditional cultivars of Hashemi, Ali Kazemi, and Tarom and 2 modern cultivars of Khazar, and Dorfak and two IRRI cultivars of Dollar and IR64), and b) two types of planting, (including monoculture and mixed culture of each cultivar with Barnyardgrass) were used. A monoculture of Barnyardgrass was also used as a control. Growth rate (GR) and leaf area index (LAI) of Barnyardgrass were determined after 2, 4, 6, and 8 weeks of transplantation (WT), in mixed and monoculture treatments. In addition, after 3, 6, and 9 WTs the type and number of weeds in 1 m2 of each plot was determined. Rice plant samples were taken in 2, 4, 6, and 8 WTs, and were extracted in the Lab to be tested for germination for barnyardgrass and redroot pigweed seeds in Petri dishes. The filed research results showed that GR, LAI, number of weeds and yield of barnyardgrass grown with Dollar cultivar were lower than the others, which indicates higher allelopathic properties of this cultivar. Rice cultivars water extract evaluation of Petri dish also showed that Dollar cultivar has higher allelopathic potential than the other cultivars. Increasing the concentration of the water extracts increased the suppression of treated seedlings. From starting to geramination stage of the rice cultivars, allelopathic effects of the water extracts decreased. Leaves had the highest level of allelopathic potential in comparison to other organs. In other words, the pure extract of Dollar cultivar taken form samples in 2 and 6 WTs had the highest allelopathy potential among the cultivars and samples.

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Sweet tasting glycyrrhizic acid is considered to be the most important chemical compound in licorice root. However, environmental factors affect chemical composition of licorice root including glycyrrhizic acid content. In this study, the effects of the harvesting time and location on licorice root composition were studied. Chemical composition of the licorice roots (Glycyrrhizia glabra) collected in summer and fall seasons from three locations in Fars province (Eghlid, Beiza and Doshman-Ziary) and one location from each of Kerman (Baft) and Kermanshah (Islam-Abad) provinces was determined. Glycyrrizhic acid, ash and sugar content before and after hydrolysis were measured in all samples after extraction. A combined analysis of variances was performed on data based on a randomized complete block design in six replications. The results showed that effects of harvesting season on sugar content, and the effects of location and its interaction with harvesting season on ash, sugar and glycyrrhizic acid content were significant (p<0.01). It was also found that the lowest ash content were obtained from roots harvested from Islam-Abad in summer the highest sugar content before hydrolysis belonged to roots harvested from both Baft and Islam-Abad in fall. Highest amount of sugar after hydrolysis was reported in the roots collected from Islam-Abad in Fall. Roots harvested from Beiza in Fars province in fall had the maximum glycyrrizhic acid content.

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This study was set up in the research station of Rice Research Institute of Iran (RRII) to determine the response of three hetrotic Indica × Indica rice hybrids (Bahar1, IR75221H and IR69688H) to anther culture on four induction media (N6, modified N6, chu and modified chu). To evaluate hybrids, the percentage of calluses which had been made from anthers in early uni- to mid- uninucleate stage and the number of regenerated plantlets of calluses in those media were determined. The results indicated that genotype, composition of callus induction medium and their interactions significantly affected callus percentage, total plant regeneration and production of green and albino plants. IR75221H hybrid was considerably superior for callus induction (1/64%) and Bahar1 hybrid was the most desirable for producing of green plants (3/43%) and total regeneration (12/24%). IR75221H hybrid produced higher albino plant (10/66%) and IR69688H hybrid produced lower albino plant (6/45%). The best medium culture in the case of callus induction was modified N6 (2%) and total regeneration (21/82%) produced green plant (5/6%), and albino plant (16/22%) was modified Chu among all media culture. However, genotypes showed different results in each media culture, and responses to hybrid of anther culture was low, but by changing the media culture we increased the response of culture.

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In order to estimate the loss of rice caused by white tip nematode, (Aphelenchoides besseyi), to Alikazemi cv., two series of experiments were conducted in greenhouse and microplot conditions at Rice Research Institute, Rasht (Guilan province) during 2005-2006. The microplots sizes were 0.5×2 meter. Rice seedlings were inoculated by plastic tube method with 0, 100, 300, 500, 700 and 900 nematodes per plant. The experiments were arranged in greenhouse and microplot conditions as a completely randomized design and completely randomized block design with four replications, respectively. The factors under investigation consisted of symptoms (number of plants and Leaves infected), yield and population density of nematodes. The variance analysis of data showed significant differences among treatments in all parameters. The minimum infestation level leading to symptoms and yield loss in microplot condition (500 nematodes) was greater than greenhouse (300 nematodes). Regression analysis of data revealed that the yield reduction was mainly explained by population of nematodes in greenhouse and microplot (R2= 92.56, R2 = 91.55). Also, there was a positive correlation at 5% level of probability between disease incidence and nematode population (R2= 84.42, R2 = 75.27). The resulting equations from regression can be used to estimate crop loss from population of nematodes.

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In order to study gene action in rice for traits related to quality (gelatinization temperature, gel consistency and amylose content), four varieties of rice (Sang-e-Tarrom, Gerdeh, IRRI2 and IR229) were investigated. Ten different generations including P1, P2, F1, RF1, BC1, RBC1, BC2, RBC2, F2 and RF2 were evaluated using generation mean analysis. In generation mean analysis, one of non-allelic interaction components, [i], [j]1, [j]2, [l]1, [l]2, [l] was significant indicating the genetic model of these characters were described by additive-dominance model with non-allelic gene interaction (except for gelatinization temperature trait in Sang-Tarrom × Gerdeh cross). The cross IRRI2×IR229 showed duplicate epistasis for gel consistency trait. Cytoplasmic effects and interactions between cytoplasmic and nuclear effects in two crosses were significant for amylose content and gel consistency traits. The estimation of narrow and broad-sense heritability for two crosses were 0.77 to 0.99 and 0.05 to 0.93, respectively. The predominantly additive nature of the genetic variability was further revealed by the variance components. Component D was detected significant in all the crosses. The covariance component and , however, showed indirectly that dominance contributed significantly to variability at the variance level. Therefore, according to the obtained results, selection can be effectively done in later segregation generations for gel consistency and amylose content and in early generation for traits.

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Six morphological traits of rice were evaluated in a 5 × 5 one-way diallel cross using a randomized complete block design corresponding with their F1 generations in 2007 at Iranian Rice Research Institute – Amol. Results from analysis of variance for traits of plant height, flag leaf angle, flag leaf length, flag leaf width, internode length and panicle length exhibited significant genetic differences among parental cultivars and their hybrids. Significant means of squares for GCA and SCA showed the positive actions of additive and non-additive effects on controlling these traits. Also, ratio of mean squares of GCA on SCA ( ) were significant in all traits that showing a higher importance for role of additive effects in comparison with role of non-additive effects in functions of genes controlling the studied traits. High narrow sense heritability of these traits proved majority roles for additive effects of genes in genetic control of the studied characteristics therefore, selection of these triats may be succeed. Overall, both of Neda and IR62871-175-1-10 were the best parents for general combining ability for reducting plant height, flag leaf length and internode length and increasing flag leaf width. Meanwhile, because of higher SCA, Neda × Binam and Neda × Dasht were the best hybrids for increasing spike length and decreasing height, respectively.

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In order to study the relationship between grain filling rate, duration and leaf relative water content (RWC) and yield, an experiment was conducted at Rice Research Institute of Iran, as a randomized block design in Split Plot with 3 replications, in 2006. 5 irrigation levels as main factor (Continuously flooded, days after water banishment, 5, 8 and 11 day intervals immediately after 10 days of transplanting) and sub main factor were used with 3 rice cultivars, Bahar (hybrid), Dorfak (improved) and Ali kazemi (traditional).Bahar cultivar showed the highest (6710 km/h) yield in continuous conditions. And no significant difference was observed between continuous irrigation conditions and 5 day interval irrigation. In continuous irrigation condition (except 1 day after flowering), Dorfak cultivar in all sampling had the highest grain weight in grain filling duration, but in days after water banishment Bahar had the highest grain weight(2/41). Grain filling rate in Dorfak in all treatments was higher than Bahar, and in Ali kazemi in all treatment s it was higher than the other cultivars. In all sampling dates (8, 11, 14, 17, 20, 23, 26, 29 and 30day after heading), leaf relative water content of Ali kazemi was significantly less than Bahar and Dorfak. Dorfak produced the highest leaf relative water content. Results of the grain filling rate showed that Bahar with the longest grain filling duration and highest yield (6710 km/h) is more adaptable than Dorfak and Ali kazemi for different irrigation management conditions.

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The objective of this research was to predict head rice yield (HRY) in fluidized bed dryer using artificial neural network approaches. Several parameters considered here as input variables for artificial neural network affect operation of fluidized bed dryers. These variables include: air relative humidity, air temperature, inlet air velocity, bed depth, initial moisture content, final moisture content and inlet air temperature. In aggregate, 274 drying experiments were conducted for creating training and testing patterns by a laboratory dryer. Samples were collected from dryer, and then dehulling and polishing operations were done using laboratory apparatus. HRY was measured at several different depths , average of which was considered as HRY for each experiment. Three networks and two training algorithms were used for training presented patterns. Results showed that the cascade forward back propagation algorithm with topology of 7- 13-7-1 and Levenberg-Marquardt training algorithm and activation function of Sigmoid Tangent predicted HRY with determination coefficient of 95.48% and mean absolute error 0.019 in different conditions of fluidized bed paddy drying method. Results showed that the input air temperature and final moisture content has the most significant effect on HRY.

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A comprehensive study is underway now to determine the predicting factors of rice blast and its loss assessment in Guilan province. In a preliminary study, the effect of climatic factors on spores population and forecasting the disease were considered. So, during cultivation season of 2006 and 2007, some fields were chosen five kilometers away from weather stations in three regions of Guilan, including, Rasht, Lahijan and Anzali, and the daily spore population was measured on slides. Climatic data including precipitation (mm), maximum and minimum daily temperature, maximum and minimum daily humidity and sunny hours were obtained from weather stations. Then the relation between spore population and weather data was analyzed, and the most important climatic factors affecting spore population and predicting of rice blast were determined. It was concluded that climatic factors such as precipitation (mm), maximum daily temperature, minimum daily humidity and sunny hours are the most important factors for predicting rice blast in Guilan province. Spore population was positively correlated with precipitation, increase of daily minimum humidity, decrease of daily maximum temperature and decrease of sunny hours. The blast disease occurred in the fields during next 7 to10 days.

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Land and its size are important as the most basic factors of production in agriculture .Fragmentation is one of the main problems that rice producers of Mazandaran province are confronted with. Non-efficiency in farm management, inability in effective using of agriculture technology and machinery, and low range productivity of production are all related to land fragmentation. In order to overcome the problems and consequences originating from land fragmentation, specialists recommend the logical solution of land consolidation process, which is a basic strategy for changing the farm size. The purpose of this research was to identify and determine effective factors in land consolidation adoption by rice producers in Mazandaran province by using Logit Regression model. In this study, 150 rice producers from 5 villages have been investigated since 2007. Results show that variables of education, land quality, fragment distance and extension effort (learning programs) are the most important factors in land consolidation adoption by rice producers in this province (Sig=1%) . Also, number of the household and credit support are the next factors affecting in land consolidation adoption (Sig= 5%). I t must be noted that other variable such as age, farmer’s income, children education, experience of rice producers, cultivation area, membership in cooperatives, land situation, number of pieces and technical supports were not significantly involved.

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Risk and uncertainty have an important role in determining farmers' goals and their decision making. Risk affects optimal use of inputs and production efficiency. Using production inputs especially new inputs is one of the effective factors in production risk hence, it is necessary to obtain information about inputs use risk in order to find solution to risk management. For investigating effect of inputs use on production risk of rice crop in Gilan province, a quadratic form of production function was applied. Mean production function indicates constant return to scale. Also, risk production function shows increasing acreage and use of fertilizer cause increase in production risk of rice crop. Therefore, consolidating program of rice acreages and policy of paying subsidies to fertilizer input should be managed by considering producers' conditions.

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In order to study the correlation of agronomic, morphologic and physiologic traits and their effects on grain yield of rice genotypes in two environments (favorable irrigation and water stress), 49 genotypes were evaluated using a completely randomized block design with 3 replications in two experimental conditions. All practices and conditions were the same for the two experiments with the exception of irrigation, where under stress conditions no irrigation was applied at tillering stage. Comparison of means showed significant differences between genotypes in each environment. Also, differences between yield and yield components of each genotype under two conditions were significant. The results of phenotypic correlations showed that the highest positive and significant correlation with grain yield belonged to number of panicle per plant (0.95) in irrigation conditions and to number of filled grains per panicle (0.92) in water stress conditions. Stepwise regression analysis for grain yield introduced number of panicle per plant, relative water content (RWC), flag leaf length and number of spikelet per panicle, respectively, as effective traits in grain yield in irrigation conditions, however, in stress conditions, number of filled grain per panicle, number of panicle per plant and relative water content were effective traits in yield. The results of path analysis showed that the number of panicle per plant had the highest positive and direct effect on grain yield in the two environments. Factor analysis introduced four factors in the two conditions named yield and crop production, phenologic, harvest index and plant shape and appearance quality of grains factors. Therefore, to select high yield and drought tolerant genotypes, we need to consider number of filled grain per panicle, number of panicle per plant and relative water content. In addition, traits such as panicle length, number of spikelet per panicle, flag leaf length and width that showed significant correlations with grain yield in stress conditions should also be considered important and second to the above mentioned traits.

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The objective of this study was to investigate the demand of food and nonfood commodities among urban and rural households. To this aim, an appropriate functional form and approximation index were established. Then, Deaton and Mulbaer Iterative (DMI) approach as a linear approximation of Almost Ideal Demand System was used. The study horizon was also 1362-1383(1983-2004). The findings revealed that for urban households housing, fuel, power and furniture, household operations and entertainment, education and food, beverages, tobacco are considered necessary. While clothing, footwear and medical care and transport, communication and other goods are consumed as superior commodities. For urban households, a weak complementary and substitution relation among selected commodities was recognized. In the case of rural households clothing, footwear and food, beverages, tobacco were revealed to be necessary, while housing, fuel, power and medical care and entertainment, education were found superior. For the rural households only furniture and house operation was found elastic. The compensated and uncompensated self price elasticizes were similar regarding the sign and magnitude coefficients for rural and urban households.

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Due to low availability of zinc and copper in calcareous soils and the antagonism of these nutrients with each other, the study of their effects on growth and chemical composition of rice seems to have great importance. Also, the relations among different chemical forms of Zn and Cu and plant responses are very important, which can be used in investigation of antagonisms of these nutrients as well. Therefore, by application of different levels of Zn and Cu, their effects on plant growth and nutrient concentration in the plant were studied and different forms of these nutrients in soil were determined. Results showed that zinc application increased plant growth, Zn concentration and total uptake, but decreased Cu concentration in the plant. However, copper application showed no significant effects on the plant growth, but increased Cu concentration and total uptake and decreased Zn concentration in the plant. Also, the results showed an increase in carbonatic, adsorbed and exchangeable Zn forms and exchangeable Cu form by Zn application. Carbonatic form of zinc has maximum effects on concentration and total uptake of this element in the plant. Copper application increased carbonatic and organic forms of this nutrient in soil, and there was maximum correlation between organic form of Cu and its concentration and uptake in the plant