جستجوی مقالات مرتبط با کلیدواژه « برنج » در نشریات گروه « آب و خاک »

Currently, the agricultural sector is considered to be the major consumer of underground water in this region, among different economic sectors, and due to excessive exploitation of underground water, the annual drop in the level of these waters is significant. Therefore, calculating the economic value of each unit of water and calculating the side effects of over-harvesting water resources is very important. In this study, the determination of the economic value of water, the optimal level of water input use and the effect of changing the groundwater level on the level of social well-being of rice producers in Ramhormoz city are discussed.

For this purpose, the appropriate production function was first estimated, and using it, the economic value of water and the optimal limit of water input use were determined. Then, by forming the function of profit or social welfare, the effect of change in the level of underground water on the amount of social welfare of the producers was determined.

The results of this research show that the economic value of water in the study area is 649.54 rials per cubic meter. So that the economic value of each unit of water is more than the cost of extracting each unit, and this difference leads to excessive extraction of underground water and the reduction of the level of underground water, and finally the welfare of rice producers. So that if the underground water level decreases by 0.81 meters, the social benefit of the beneficiaries will decrease by 1110257.61 riyals.

This study suggests that in addition to price policies, non-price solutions such as applying restrictions on the amount of water extraction should be used in order to preserve underground water tables

The present study aimed at investigating the productivity and energy indicators of rice, wheat, fodder corn, seed corn and citrus fruits in Tajan Plain during 2022-03. Sampling was done based on 300 designed questionnaires. The collected information included man-days, working hours of machinery, fuel consumption of machinery, application of nitrogen, phosphate, potassium fertilizers, application of various types of chemical pesticides, including herbicides (in L/ha), the amount of applied water (m3/ha), the amount of seeds (k/ha), and the crop yield (k/ha). Results showed that the highest amount of energy in the input energy sector for rice was (593256 mega Joules per hectare, (MJ/ha), output energy for fodder corn (141795 MJ/ha), net energy for fodder corn (110758.53 MJ/ha) and energy efficiency was also for fodder corn (1.1 kg/MJ). Also, it was found that in all the products, the four inputs of water consumption, nitrogen fertilizer, machinery and fuel had the highest amounts. Results of water showed that the highest productivity in the Tajan plain was related to fodder corn and citrus (6.3 and 5.3 kg/m3), and the lowest productivity was related to rice (0.5 kg/m3). Also, the productivity of wheat and grain corn was 2.6 and 1.8 kg/m3, respectively. In general, to increase the productivity of lands and products in terms of productivity and energy indicators, it is necessary to use plants with appropriate yield, highest level of productivity, and lowest level of input consumption. Among the researched products, fodder corn had more suitable conditions than other products for increasing the cultivated area, due to its great impact on ensuring food security and reducing the need for livestock and poultry consumption inputs.

The increase in water demand, especially in the production of agricultural products, has led to increased competition for fresh water. Therefore, improving agricultural water productivity and reducing water stress caused by agricultural production is an important measure to improve the sustainable use of water resources. One of the most important indicators proposed for water management is the concept of water footprint, which can be used as a useful tool to measure and predict the amount of water consumed in the agricultural sector and the required demand. In addition, water stress and water poverty indicators are among the other widely used indicators to evaluate water scarcity. Iran is an arid and semi-arid country that has faced severe water shortage and this has had adverse effects on the economy, ecosystem functions, and the welfare of the country's people. The agricultural sector is one of the most important and largest consuming sectors of water resources in Iran, so more than 92% of freshwater resources are consumed in this sector, so the knowledge of water resources allocated for the production of agricultural products is important for managers. And the country's policymakers are very important. So, one of the main solutions to reduce water shortage is to reduce water consumption in the agricultural sector. Among agricultural products, rice is one of the most important food products, which feeds more than half of the world's population. Therefore, the purpose of this study is to use the indicators of water footprint, water stress, and water poverty to evaluate the water scarcity of water in rice production in Iran.

Among the agricultural products, rice is a valuable food and the most important and widely consumed grain. The study area is the rice-producing provinces. which feeds more than half of the world's population. It accounts for about 19% of the world's dietary energy. After wheat, this product is known as one of the most important food items. The average area under rice cultivation (ha), production (ton), yield (tons/ha) as well as the necessary data and information were collected concerning the water resources available for rice production from the Ministry of Jihad Agriculture and the Water Resources Management Company of Iran. The evaluation of water footprint components, including blue, green, and gray water footprints, is based on the method provided by Hoekstra et al. (2011). The water stress index of rice is calculated as a ratio of the total water footprint in rice production to the total water resources available in the region. The amount of water poverty caused by rice production is defined by the product of the total water footprint in rice production and the value of the rice water stress index. Finally, the amount of export and import of virtual water due to rice production in Iran has been estimated.

On average, the total footprint of rice is 3037 m-3 t and the total volume resulting from its production is 4313 MCM, with the share of blue, green, and gray water footprints being 91.68, 6.93, and 1.39 %, respectively. The available water resources (AWR) for rice production in the producing provinces are 21,992 MCM, of which 6,872 and 15,210 MCM are related to blue water and green water, respectively. The results of the investigation of the water stress index (RWSI) caused by rice cultivation in Iran, which is the result of dividing the total water footprint in rice production by the available water resources, is on average equal to 0.5 (out of 1.9), which shows Iran is in moderate water stress of rice production. Changes in water stress in rice production on a provincial scale showed that the provinces of Qazvin, Zanjan, Isfahan, North Khorasan, Razavi Khorasan, and Sistan and Baluchistan have water stress with a value between 0.6 and 1.2 are high and very high water stress in rice production, while the provinces of Mazandaran, Guilan, Golestan, Fars, and Khuzestan are in the range of less than 0.3 (low water stress) Also, the water poverty caused by rice production is equal to 1073 MCM in Iran, which is the highest and lowest amount of water poverty in Guilan and Khuzestan provinces (290 and 11 MCM).

Water sustainability in rice production in Iran has been investigated using water stress, water poverty, and water footprint, as well as the amount of exports and imports. Among the components of the water footprint, the highest value is related to the blue water footprint, and the lowest is related to the green water footprint. The high blue water footprint shows that most of the surface water and groundwater is used for rice production, and the low green water footprint shows that the amount of rainfall is not enough for rice cultivation in Iran. According to the results, the amount of gray water footprint in rice production is more than the green water footprint, this issue shows that the low yield of rice in the studied provinces as well as the high consumption of fertilizers and chemical pesticides cause the increase of gray water footprint in rice has been produced. Assessing water scarcity using the water footprint approach can be useful for identifying the risks of high rice production due to the potential of water scarcity. The dependence and high consumption of blue water compared to green water have increased the water shortage related to the production of rice. Therefore, it is necessary to change the pattern of water resource allocation based on the status of water resources and water scarcity indicators.

Puddling process is a part of land preparation in rice cultivation. In other words, puddling is an important method of soil management, which is done to disturb the structure of the surface layer of the soil and prepare the field for rice transplanting. Usually, in this process, the soil is flooded and tillage is done on it. The soil texture and the soil moisture conditions before flooding are factors that affect the process of the puddling. Therefore, this study was conducted to determine the effect of initial soil moisture and soil texture on some properties of paddy soils puddling process in Guilan province.

The experiment was conducted as a factorial based on a randomized complete block design in three replications. Three textures (silt, silty clay, and clay) of paddy soils were prepared under four initial soil moisture treatments (85, 90, 95, and 100% degrees of saturation). After preparing the soil samples, they were puddled using a laboratory panel. During and after the puddling process, the amount of net water consumed, the depth of water collected on the soil 2 and 6 days after puddling, the soil swelling at the end of the operation, the depth of soil settlement after 2, 4 and 6 days and the final depth of the soil were measured. Statistical analysis of the effect of the experimental treatments on the measured properties and their mean comparison was done with LSD test using SPSS 23 software. Calculations and graphs were done using EXCEL software.

The results showed that the independent effects of initial soil moisture and soil texture on all of the measured properties except the depth of soil after 6 days were statistically significant at 1%. With increasing initial soil moisture, the amount of net water consumption and the final depth of soil decreased and other measured parameters increased. On the other hand, the effect of soil texture on net water consumption, water collected on the soil 2 and 6 days after puddling, soil amass at the end of the operation, depth of soil after 2 and 4 days, and the final depth of the soil were statistically significant at 1%. The interaction effect of initial soil moisture and soil texture on soil amass at the end of the operation and final soil depth was statistically significant at 1%, and for the depth of water accumulated on the soil 2 days after puddling and the depth of soil after 2 days was statistically significant at 5%. By increasing the initial soil moisture content from 85 to 100% of saturation degree, the amount of water used for the puddling process decreased by 61%.

According to the results, the features of the puddling process are affected by the initial moisture and soil texture. Therefore, the results of this research can be used in the agricultural management of paddy fields in Guilan province. With increasing soil clay content, the measured parameters include the amount of net water consumed, the depth of water collected on the soil 2 and 6 days after puddling, the soil swelling at the end of the operation, the depth of soil settlement after 2, 4 and 6 days and the final depth of the soil were increased. The range of net water consumed in the puddling process for experimental treatments varied between 31 and 114 mm, and the lowest was obtained in silty soil texture with 20% clay and initial moisture treatment of 100% degree of saturation. Estimating water consumption in the puddling process and its correlation with initial soil moisture and clay percentage can inform the management of the agricultural calendar and water allocation program in the Sefidroud irrigation network for paddy fields. This information can help optimize water usage, especially in light of rainfall events at the start of the irrigation season, with the goal of reducing overall water consumption.

Due to the upcoming climate threats, challenge of water shortage and its impact on the food security of the growing population in Iran, the optimal use of soil and water resources is very important. With the development of remote sensing technologies, free access to a variety of field data has become widely available, which can be used to reduce the uncertainty of simulation models. The aim of this study was to simulate actual evapotranspiration (ETa) and rice crop coefficients (Kc) during its growth stages using the SWAP model updated with satellite data and evaluate the accuracy of the results with/without updating. This research was conducted at the National Rice Research Institute of Iran in Rasht in the year of 2017. Based on the obtained results, total ETa measured by lysimeter and simulated by SWAP model with and without updating were 395.4, 373.2 and 363.6 mm, respectively. The average crop coefficients during the growth stages of vegetative, reproductive and ripening were estimated as 1.13, 1.49, 1.21, respectively. The crop coefficients for the proposed stages estimated by SWAP model without using satellite data were 1.02, 1.39, 1.04, respectively. After updating with satellite data, the crop coefficients were modified as 1.05, 1.43 and 1.07, respectively. Finally, the statistical analysis indicated that the SWAP model has a reasonable performance in estimation of ETa (RMSE=0.89; EF=0.98; R2=0.74) and rice crop coefficients (RMSE=0.53; EF=0.96; R2=0.63). The results indicate that the SWAP model combined with satellite data improved the accuracy of ETa estimation (RMSE=0.75; EF=0.99; R2=0.86) and rice crop coefficient (RMSE=0.40; EF=0.99; R2=0.74) at field scale.

Selenium is one of the essential micronutrients for human health. Since the amount of selenium in the plant is related to its amount in the soil and also the physical and chemical properties of the soil affect the amount of selenium uptake by the plant, therefore it is important to study the relationship between selenium uptake by the plant and physical and chemical properties of soil. In this study, first, different methods of selenium extraction were investigated to determine selenium concentration in the soil and rice grain in Silakhor plain of Lorestan province in 2021. Then, the correlation between soil properties and soil selenium content was investigated. The results showed that the extractable selenium with phosphate had a significant correlation with selenium uptake by plant (available selenium) and 0.1 M monopotassium phosphate solution (KH2PO4) could be used as the best extractor of selenium in the plant. There was also a significant correlation between soil selenium and some soil properties such as organic carbon content (-0.547*), calcium carbonate content (0.648**), clay percentage (-0.519*) and sulfate concentration (-0.275. The regression coefficient between soil and selenium properties of soil and plant was 0.72 and 0.68, respectively. Selenium concentration of rice grain in the region was between 1.016 to 1.985 mg / kg. Also, the concentration of selenium in the soils was between 0.17 to 0.52 mg / kg, which indicates that there is no deficiency of selenium in rice -cultivated soils in the Silakhor plain of Lorestan province.

Arsenic as aheavy metal, is one of the most important pollutant in the environment that has a detrimental effect on the morphological, physiological and biochemical properties of rice. Zinc application is one of the way to reduce negative effects of arsenic. For this purpose, an outdoor experiment was performed in the form of three-factor factorial experiment based on complete randomized design with three replications at the Rice Research Institute of Iran (Rasht) during growing season in 2019. The proposed factors were zinc at three levels (0, 10 and 20 mgkg-1) as zinc sulfate, arsenic at three levels (0, 1 and 2 mg kg-1) as Arsenic oxide, and three  rice cultivars (Hashemi, Gilaneh, Ghodsi). The results indicated that all factors had significant effect on the amount of zinc uptake in the soil, straw and grain, amount of arsenic in the soil, straw and grain, plant height, total and fertile tiller number, panicle length, 1000-seed weight, biomass and grain yield.   The uppermost increase in plant height, total tiller number, fertile tillers, panicle length, 1000-seed weight and grain yield were recorded 1.5, 68.4, 85.05, 31.5, 6.6 and 58.5 percent, respectively due to soil application of 20 mg zinc per kg-1. In terms of zinc uptake by straw and grain, Hashemi cultivar> Ghodsi cultivar> Gilaneh cultivar  showed the highest zinc content, respectively, which Hashemi and Ghodsi cultivars are more efficient in terms of zinc uptake and are more tolerant to arsenic. The highest amount of arsenic in straw and grain was observed in Gilaneh> Ghodsi> Hashemi cultivars, respectively. Therefore, due to the interaction of zinc with arsenic, the use of zinc and cultivars with high zinc uptake capacity might be a good way to reduce arsenic toxicity in rice plants.

Compared to the other micronutrient fertilizers, chelated amino acid can significantly improve rice growth, increase grain yield, and macro and micronutrient contents of rice aerial tissues due to better uptake, higher efficiency and nitrogen content. In this study, the effect of glycine amino acid chelated zinc and iron on yield, grain biofortification, and macro and micronutrient contents of rice aerial tissues was compared to zinc sulfate. The experimental treatments were conducted in a randomized complete block design with three replications on the most common Iranian local rice cultivar (Hashemi). The experimental treatments were the foliar application of 0.5, 1, and 1.5 kg ha-1 of Zn and Fe glycine amino acid chelates and ZnSO4 under recommended and 50% of the recommended NPK application. The highest increase in the grain yield was recorded at 0.5 kgha-1 Fe-glycine amino acid chelate by about 29.2%. The maximum increase percentage of Fe, Zn, N, P, and K content of rice grain was observed through foliar application of glycine amino acid chelated zinc and iron by about 32, 22,23,17 and 7%, respectively. This trend also was recorded for white rice and rice straw, but milling processes through removing of rice husk significantly reduced head rice iron, zinc, nitrogen, phosphorus and potassium content by about 10 to 15.5, 0.5, 6.5, 3.8 to 8, and 8 to 12 times compared to rice grain.

Today, the use of chemical fertilizers to increase agricultural production has created many environmental problems. In addition, environmental stresses are one of the most important factors reducing crop yield and production. Given the importance of rice plants in ensuring food security nationally and globally and increasing the price of chemical fertilizers, it is necessary to find eco-friendly routes for sustainable agriculture. The use of biofertilizers is the most worthy way to reduce the use of chemical fertilizers and improve plant resistance in rice fields. Azotobacter has been used as a biofertilizer for over a century and has been well studied on a laboratory and field scale. Azotobacter have also been reported as nitrogen-fixing bacteria in the rhizosphere and roots (endophytically) of rice. In this study, the effect of Azotobacter biofertilizer as a plant growth-promoting rhizobacteria, on rice and the mechanisms of this effect were investigated. The results showed that this bacterium produces phytohormones and stimulants of plant growth and fix atmospheric nitrogen in the rhizosphere and as an endophyte in rice. In addition to nitrogen fixation, this bacterium increases plant growth indices, nutrient uptake, and grain yield of rice by dissolving insoluble phosphates, producing indole acetic acid, hydrogen cyanide, siderophore. Also, the use of Azotobacter inoculant in acute salinity conditions increased the concentration of proline, malondialdehyde, ACC-deaminase enzyme, and some hormones in the plant, which increased the resistance of rice to this stress. Considering the positive effect of using Azotobacter inoculant as a biofertilizer on rice plants and the effect of this bacterium on reducing the consumption of nitrogen fertilizers, preparation of biofertilizers containing native bacteria of Azotobacter and their application in rice fields is recommended.

In Golestan province, despite the lack of water resources, traditional rice cultivation, a crop with high water consumption, is increasing due to economic justification. This issue has become one of the main problems of the province's agricultural sector in recent years. In order to prepare the planting bed (puddled transplanting) in the traditional method of rice production, a significant amount of irrigation water is used before planting the seedlings in the main land. Moreover, the plant is in the water during the growing season, which causes high water losses by surface water evaporation and deep penetration. Rice direct seeding cultivation is a method that has been considered in the world for various reasons, including higher water productivity. Currently, reports indicate that more than 50% of groundwater resources are extracted and allocated annually for rice cultivation in the region investigated. In general, field information and observations indicate that the level of paddy cultivation is increasing in the province. In the past few decades, agricultural policymakers have sought to restrict and ban rice cultivation in the country, except in Gilan and Mazandaran provinces. The rationale behind this decision is high water consumption, declining groundwater aquifers and long-term instability of water resources. The developed strategy did not work effectively, as it did not consider the benefits of the farmers in the short run. The increasing trend in the area under paddy fields from 1995 to 1500 hectares per year shows the unsuccessfulness of this up-to-down strategy.

A field experiment was conducted to investigate the effect of rice cultivation and irrigation methods on yield, water consumption and water productivity over two rice cropping seasons (2019–2020) in northern Iran (Gorgan Agricultural Research Station). Irrigation method as the main factor in four levels (permanent flooding, intermittent as wet and dry, sprinkler, tape) and cultivation method in three levels (direct seed in dry bed, non-puddled transplanting and traditional transplanting) in the form of a strip design. The plot was based on a randomized complete block design with three replications. The applied water, yield and some yield components and water productivity were measured and calculated during the growing seasons.

The results showed that in all irrigation methods, yield was significantly reduced by changing the traditional seeding transplanting to dry seed. The amount of water applied in sprinkler and drip irrigation methods from traditional seedlings was significantly reduced as compared to direct seed seeding. Dry seed cultivation, however, consumed more water than traditional transplanting in the flood irrigation treatments (wet and dry and permanent). The highest yield (8206 kg/ha) was obtained for traditional seedling cultivation by flood irrigation, and no significant difference was observed between the yields for the other irrigation methods. In general, changing the irrigation systems had a greater effect on water consumption than changing the rice cultivation method. In addition, changing the cultivation method had a greater effect on changing the type of irrigation systems. In traditional transplanting cultivation, the yield decreased by about 14, 9 and 11%, respectively, by changing the irrigation systems from permanent flood irrigation to sprinkler, wet and dry, and drip irrigation. The highest water use was observed for flood irrigation method in direct seeding (12490 m3/ha) and direct transplanting (11967 m3/ha).

Currently, farmers cultivate rice by transplanting in padded land irrigated by flooding techniques in Golestan province, which results in high water consumption (about 13,000 m3/ha). By changing the irrigation method from flood irrigation to drip for traditional transplanting cultivation, water consumption decreased by about 39% and as a result water productivity increased by about 22%, albeit a 11% reduction in yield occurred. With the conversion of traditional transplanting seedling by flood irrigation to non-puddled transplanting by drip irrigation, the yield decreased by about 24% and the amount of water by about 45%, and water productivity in this case reached 0.9 kg/m3. This can be considered as the best alternative for conserving both water resources and production. If only reducing water consumption is the main priority (regardless of yield reduction), the best treatments are drip irrigation with direct seeding, non-puddled transplanting and then traditional seedling, respectively. If there is a sprinkler irrigation system in the field, this option is given priority in the direct seeding and non-puddled transplanting. If changing the irrigation system is not considered, the use of intermittent irrigation (as a wet and dry) with non-puddled transplanting, traditional methods and direct seeding are preferred, respectively.

Nutrient management, as recommended by fertilizers, is essential for achieving an economically sustainable rice crop. Nutrient management programs for each farm condition should have the least adverse environmental effects while optimizing farmer's production and profits. This study was conducted to determine the most appropriate rice plant nutrition management in paddy fields in terms of yield and economic benefit from 1397 for two years. In this study, ten farms were selected in Kuchesfahan section, that were different in terms of soil characteristics and nutritional management. Then, in each field, six plots were prepared and fertilizer treatments including N0 (without nitrogen), P0 (without phosphorus), K0 (without potassium) and N1P1K1 (general fertilizer recommendation of Rice Research Institute), N2P2K2 (fertilizer recommendation of rice research institute based on soil testing) and N3P3K3 (fertilizer recommendation based on soil test plus full fertilizer and growth stimulant fertilizer) were applied in them and compared with the customary fertilizer management of the farmer. In this study, characteristics related to soil fertility and crop yield were measured and soil nitrogen, phosphorus and potassium supply were calculated. The results showed that indigenous supply of nitrogen and phosphorus in the soil was low in the range of 20 to 37 and 3 to 9 kg.ha-1, respectively. Combined analysis of data variance showed that the effect of fertilizer treatments on paddy yield was significant at 5% probability level and the highest average yield related to N3P3K3 treatment was 3968 kg.ha-1. But this recommendation did not differ significantly from the treatment (N2P2K2) with an average yield of 3914 kg.ha-1. These two recommendations significantly increased the average rice yield by 259 and 313 kg ha-1, respectively, compared to the usual crop management yield. The economic benefits of N2P2K2 nutrition management practices were not significantly different from N3P3K3, however they were significantly different from the management of farmer custom. These findings showed that for economically sustainable production of rice, it is necessary to pay attention to the interest-cost balance along with the type, amount and time of fertilizer inputs.

Siderophores are low molecular weight organic chelators which mostly expressed under iron deficiency to chelate Fe (III) metal ions in order to regulate iron based activities. Cyanobacteria, which are Gram-negative photoautotrophic prokaryotic organisms, hydroxamate type of siderophore predominates. The objective of this investigation was to determine the potentials of some indigenous cyanobacteria for siderophore production in Tabarestan Biotechnology Institute in 2014. For this purpose, 30 strains of cyanobacteria were isolated from Guilan paddy field. Potentials of these strains for siderophore production were evaluated by chrome azorel-S assay (CAS-agar) through color change. Pot experiment was performed to evaluate the application of selected top strains of cyanobacteria on growth and yield of rice plant (cv. Tarom Hashemi). Cyanobacter inoculation treatment was selected with the top seven strains and control treatment without inoculation with three replications was performed in a randomized complete block design in the greenhouse. The results of this study showed that the highest rate of siderophore production in CAS- agar Chroococcus sp. GGuCy-34 and Anabaena sp. GGuCy-49, 4.19 and 4.08 respectively and in spectrophotometer method strains of Anabaena sp. GGuCy-21 and Nostoc sp. GGuCy-47, 6.69 and 5.75 (µmol/L.day) respectively. Anabaena sp. GGuCy-42 highest grain yield (8.27 g pot-1) Chroococcus sp. GGuCy-34 showed the highest iron uptake (2.31 mg pot-1) and Cylendrospermum sp. GGuCy-25 the highest N (81.3 mg pot-1) and P (11.7 mg pot-1) uptake in pot experiment in rice plant. The results of the evaluation of siderophore production of cyanobacteria in CAS- agar with the results of the pot experiment were more consistent. Increased iron uptake can be attributed to the effect of siderophore strains on plant iron availability. Due to the fact that cyanobacteria capable of producing siderophore can also be used as stimulants of plant growth.

To evaluate the effects of different levels of sewage sludge and sewage sludge-derived hydrochar a greenhouse experiment was performed in a factorial combination based on a completely randomized design with three replications and three factors of organic matter at three levels (control, 10g sewage sludge, and 10 g sewage sludge-derived hydrochar per kilogram), nitrogen at two levels (0, and 250 mg per kg soil as urea), and copper at three levels (0, 10, and 250 mg Cu per kilogram as copper sulfate). The results showed that by applications of sewage sludge and its hydrochar, the dry matters of shoot and root, tillers number, spikes number, leaves number, leaf length, leaf width, plant height, and stem diameter were significantly increased as compared to the control and the amount of this increase in the presence of sewage sludge was greater than that of hydrochar. Also, the using of 250 mg N per kilogram increased the mentioned characteristics relative to the control. The soil contamination Cu significantly reduced the tillers number, spikes number, leaves number, and root dry matter as compared to the control. The use of sewage sludge hydrochar and N fertilizer reduced the Cu toxicity and increased rice tolerance to Cu toxicity by reducing the Cu concentration in rice shoot. To achieve rice optimum growth in both Cu contaminated and non-contaminated conditions, the use of 10 g sewage sludge or sewage sludge-derived hydrochar and 250 mg N per kilogram soil can be recommended at similar conditions.

Photosynthetic parameters are the most sensitive process in the physiological metabolism of plants that are affected by irrigation regime and silicon fertilization. Thus, silicon is one of the effective elements in increasing the net rate of leaf photosynthesis, water use efficiency, stomatal conductance and intercellular carbon dioxide. Therefore, the aim of this study was to determine the effects of different levels of silicon sources and irrigation regimes on rice.

A pot experiment was conducted to investigate the effect of different levels of silicon sources and irrigation regimes on rice photosynthetic parameters at Sari Agricultural Sciences and Natural Resources University in 2018. The experiment was laid out in a split-factorial design with three replications. In this design, soil texture was considered as the main-plot factor, and irrigation regime and different levels of silicon sources as factorial-subplot factors. Factors included two Si doses of 60 and 120 mg Si Kg–1 as potassium silicate (Ps), sodium silicate (Ss), calcium silicate (Cs) and biochar (Bi) sources under two irrigation regimes (continuous flooding (W1) and periodic wetting-drying (W2)) in two soil series with different textures (Sandy-loam (S1) and Silty-clay (S2)). After plant growth, dry matter weight of straw and photosynthetic parameters such as relative leaf moisture content, transpiration intensity, stomata conductance, chlorophyll index and photosynthesis were measured in flag leaf at the flowering stage of rice.

The results showed that the highest leaf relative moisture content (63.80%), transpiration intensity (12.03 mmolm-2s-1), stomata conductance (384.79 mmolm-2s-1), chlorophyll content (55.00), photosynthesis rate (24.33 µmolm-2s-1) and dry matter weight of straw (33.3 gr/pot) were observed in plants treated with potassium silicate at a concentration of 120 mg Si Kg–1 of silty-clay soil under continuous flooding irrigation regime. The lowest dry matter weight of straw and photosynthetic parameters were observed in sandy-loam soil under periodic wetting-drying irrigation regime without using silicon fertilizer. Also, in sandy-loam soil, the leaf relative moisture content (58.95%), transpiration intensity (11.20 mmolm-2s-1), stomata conductance (340.32 mmolm-2s-1), chlorophyll content (51.80), photosynthesis rate (19.55 µmolm-2s-1) and dry matter weight of straw (18.6 gr/pot) was the highest in biochar treatment at a concentration of 120 mg Si Kg–1 under continuous flooding conditions. Also, a decrease in dry matter weight of straw and photosynthetic parameters was observed at the higher Si rates (120 mg Si Kg–1 compared to 60 mg Si Kg–1) in treatments of potassium silicate and sodium silicate in sandy-loam soil under periodic wetting-drying irrigation regime. This may be due to the inhibitory effect of high concentrations of silicon on photosynthetic function.

Although most of the photosynthetic parameters of plants and dry matter weight of starw in periodic wetting and drying irrigation regime were somewhat reduced compared to continuous flooding irrigation regime, application of different sources of silicon to both soil textures under both irrigation regimes improved relative leaf moisture content, transpiration rate, stomata conductance, chlorophyll content, photosynthesis rate and dry matter weight of straw were compared to treatments without silicon fertilizer application. This reflects the protective effect of silicon against low irrigation conditions. Therefore, in the scope of this experiment, it seems that the use of silicon to improve the photosynthetic parameters of rice plant and dry matter weight of straw under low-irrigation regime was satisfactory. But, the amount of use of this element is very important to maintain the balance of soil and plant properties.

To counteract the widespread negative effects of zinc deficiency on rice yield and the health of the majority of people who depend on this crop for nutrition, it will be necessary and effective to find cultivars resistant to zinc deficiency. For this purpose, field experiments during the crop years of 1396 and 1397 in farm located in the village of Pas-visheh, Rasht city, Gilan province,  A two factors split plot experiment was conducted in a completely randomized design with three replications. Experimental factors include soil application of zinc sulfate fertilizer as the main plot in two levels (0 and 20 kg  ha-1 zinc sulfate) and cultivar as a sub-plot in 27 levels (including local and improved cultivars and promising lines). The results showed that the Zn application  and its interaction with  cultivar waere significant for all measured  traits except the length and width of the flag leaf. The lowest and highest values ​​of zinc uptake in plant organs in the treatment of non-application of zinc sulfate belonged to line RI18430-2 (Hashemi × Saleh) and Kadous cultivar, respectively. Comparison of the mean of treatments showed that the lowest and highest zinc uptake in plant organs in the treatment of zinc sulfate application belonged to two lines RI18432-2 (Mohammadi × Saleh) and RI18431-1 (Abji Boji × Saleh), respectively and three cultivars or lines that have the highest zinc uptake in plant organs in the application of 20 kg / ha of zinc sulfate are RI18432-2 (Mohammadi × Saleh) and RI18430-22 (Hashemi × Saleh) and Ahlemi-Tarom cultivar, respectively. The results of the GGbiPlot analysis  showed that in both levels of zinc (control and application of 20 kg per hectare of zinc sulfate) Gohar, Kadous and Caspian cultivars have been ranked 1 to 3 in terms of Zn efficiency. Saleh, Dilmani, Gilaneh and RI18430-1 (Hashemi × Saleh) cultivars were also ranked as high Zn efficient cultivars and line in both levels. Therefore, for future research works, these cultivars are suitable for cultivattion on Zn deficiency paddy soils or selection of  higher Zn uptake cultivar(s) for rice grain quality purpose.

Considering the effective role of soil fertility in advanced agriculture, preparing soil fertility map for better planning and achievement of specific management on based soil spatial variability seems necessary. The purpose of this study was to prepare a soil fertility map for rice, based on the effective parameters on soil fertility including organic carbon, total nitrogen, available phosphorus and potassium, clay and cation exchange capacity by integrated AHP with two types of Kandel and S-shaped fuzzy membership functions. For this purpose, soil samples were collected in 50 observation points and their physical and chemical properties were measured. Interpolation of these points for the studied parameters was done by kriging method. Then the fuzzy map of each parameter was prepared by defining the S-shaped and Kandel membership functions and weighted using AHP method. Finally, by integrating them in GIS environment, soil fertility map was prepared for rice. Fertility maps obtained from S-shaped and Kandel membership functions showed that 95.73% and 53.68% of the studied area have high and very high fertility, respectively. Comparison of fertility maps through re-sampling points to control the accuracy of the maps showed that the fertility map resulting from S-shaped fuzzy membership function (64%) is more efficient and realistic than Kandel membership function (40%). Therefore, the integration of AHP with the S-shaped fuzzy membership function can quantify and classify the soil fertility of the studied area and be useful for managing fertilizer use and monitoring soil nutrition changes.

Population growth, climate change and improper management, have caused a water shortage crisis in the world and especially in Iran. So it is necessary to change attitudes in irrigation management from the emphasis on production per unit area to maximize production per unit of water consumption. The aim of this study was to investigate and evaluate the effect of localized irrigation tape (TIP) on water productivity (CPD) and water economic productivity (NBPD) in paddy fields. The experiment was carried out as a split plot design with three replications in 2019-2020 crop year. In this experiment, the main factor was irrigation method including flood irrigation (FI) and three levels of deficit irrigation; 25, 50 and 100 cm tape space (TP25, TP50, TP100) and the sub-factor was two rice cultivars; Amir and Fajr. Results showed that the highest values ​​of CPD of water consumption and water delivery and NBPD were corresponded to TP25 irrigation treatment for both cultivars. The highest CPD of water consumption was 0.66 and 0.94 kg/m3 in Amir and Fajr cultivars, respectively, and the highest CPD of irrigation water was 0.74 and 1.07 kg/m3 in Amir and Fajr cultivars, respectively. Also, the highest NBPD in Amir and Fajr cultivars were 32107 and 40852 Rials per cubic meter, respectively. The TP25 irrigation treatment increased NBPD in Amir and Fajr cultivars 36 and 63%, respectively. Also, in average about 4500 cubic meters per hectare of water will be saved annually. Therefore, this irrigation treatment increases water productivity of water consumption and water delivery and also economic benefits in both cultivars.

Rice is a staple food source and the most important grain in developing countries, which is most commonly consumed by more than 90 percent of the world populations. Moreover, this plant is produced and consumed in Asia. However this major crop faces severe limitations such as water scarcity and other environmental stresses. Limited water resources along with climate change effects, have increased attention to methods which improve water use efficiency in crops such as rice cultivation. On the other hand, traditional irrigation methods for rice production often waste considerable fraction of irrigation water. Therefore, it is necessary to modify irrigation and other farming methods. Furthermore, using biochar and nitrogen fixing bacteria as organic biofertilizers can be effective methods to improve water use efficiency and yield attributes of rice plant. Therefore, the present research was conducted to investigate the effect of biochar and Azosprillum lipoferum rhizobacteria on yield and water use efficiency on Tarom Hashemi rice cultivar of under flooded and alternating irrigation regimes. 

This study was conducted at the research fields of the Sari Agricultural Sciences and Natural Resources University in 2017 and 2018. The experimental site is located at 36º 39ʹ42ʺ N latitude and 53º03´54ʺ E longitude with -11 m above sea level. Soil samples were taken from depths of 0-30 cm before land preparation. The experiment was done in factorial split-split plot arrangement with complete randomized blocks based design with three replications. Treatments included two irrigation management methods (flooding and irrigation regimes) in combination with nine fertilizers levels (100% of recommended nitrogen or N100, N100+ 10 ton biochar or biochar 10, N100+ biochar 20, N75, N75+ biochar 10, N100+ biochar 20, N50, n50+ biochar 10 and N100+ biochar 20) as main plots and seedling inoculation with Azospirillum lipoferum bacteria (without inoculation was also included as control) as sub plots.Plot ridges were covered by plastic sheets and inserted into the soil at 50 cm to prevent water flowing from one plot to the others. The plots were then leveled and 3-4 leaf seedlings stage. A specific number of seedlings were gently washed and placed for 30 minutes in a pan containing 10 L of water mixed with 1 L of bacterial inoculum. Carboxymethyl cellulose, 15 g, was added to increase adhesion of bacteria into the plant roots. Nitrogen, phosphorus and potassium fertilizers were applied according to the results of soil analysis. Weeds and pests were controlled mechanically or by hand and no herbicides or pesticides were used.

Results showed that biochar and nitrogen fertilizers, irrigation methods, and seedling inoculation with bacteria had significant effects on water use efficiency indices. Comparison of means of interaction effects showed that the highest paddy yield (5950.43 and 5330.78 kg/ha, respectively) were observed by flooding irrigation method in combination with N50 + biochar 20 treatment and inoculated by Azospirillum lipoferum bacteria and alternating irrigation management method which was along with N50 + biochar 20 without inoculation. Alternating irrigation plots experienced water shortage in some growth stages and therefore slightly lower paddy yield is acceptable. Application of biochar 20 and flooding or alternating methods which treated by N75 and N50, respectively showed 49.1% increase in economic efficiency index.

In general, application of 20 ton biachar along with 75% nitrogen fertilizers led to 42.8% increase in economic advantages in alternating irrigation method as compared to the flooding systems. These observation indicates beneficial effect of fertilizer in economic advantage enhancement in rice cultivation.

Rice is the second most important edible grain after wheat in Iran. The most important factor for sustainable production in rice production lands, is water. Almost 75 percent of the world's rice is produced from paddy fields and rice is the largest consumer of water among all crops. Its growth is significantly affected by climate change and water scarcity. This research was carried out to compare the direct cultivation and transplanting of rice under different irrigation methods from the point of view of water productivity. The current work was designed as split plot based on randomized complete block design with 6 treatments and three replications in 18 plots with 6 m wide and 12 m length (72 m 2) in area of approximately 1500 m2 at the Agricultural Research Station of Golestan province in spring and the summer of 2018. Treatments including three levels of basin irrigation, sprinkler and drip (tape) irrigation were considered as main factors and two methods of direct cultivation and transplanting were considered as sub-factors. The results of analysis of variance showed that the effect of irrigation and sowing method on the yield of rice were significant at 0.01 level probability. The highest amount of biological yield in transplanting was obtained by basin irrigation (8177 kg/ha) and in direct seeding in basin irrigation and taper irrigation (7375 and 6836 kg/ha, respectively). The highest 1000-grain weight in transplanting method was obtained in basin irrigation and direct seeding method in traditional irrigation and tape irrigation. The highest number of filled grains in the panicle was observed in the basin irrigation treatment in transplanting, with significant difference compared to the amount observed in direct seeding. Traditional irrigation between planting methods had not significant effect on the number of hollow grains; while in sprinkler and tape irrigation (with an average of 51 and 56 for sprinkler and tape irrigation, respectively), the number of hollow grains had a higher rate in direct seeding (with an average of 41 and 45 for sprinkler and tape irrigation). The results showed that basin irrigation with 8177 kg/ha grain yield in transplanting method and basin and tape irrigations with 7375 and 6836 kg/ha in direct seeding method had the highest grain yield. Sprinkler irrigation had the lowest paddy yields in transplanting (4188 kg/ha) and direct seeding (5712 kg/ha). Tape irrigation with 7390 and 6840 m3 of consumed water, resulted in lower water consumption compared to traditional irrigation (10700 and 1693 m3), respectively. The highest amount of water use efficiency was obtained in direct and tape irrigation (0.99 kg/m3) and in traditional and tape irrigation (0.76 and 0.66 kg/m3, respectively). Adjusting water consumption both through lower water consumption and reduced water wastage can lead higher water productivity of rice production systems creating sustainable rice production systems. In transplanting method, tape irrigation and traditional irrigation had higher water use efficiency than sprinkler irrigation, although a significant water use reduction in tape irrigation rather than basin irrigation should be analyzed economically at real water prices. Overall, in this study, the tape irrigation method, by reducing water consumption, was able to increase water productivity and maintain the yield of rice in direct cultivation. Sprinkler irrigation had the lowest yield of rice in transplanting and direct cultivation. Problems such as lack of uniformity of spraying and waste water through the wind as well as poor quality of sprinklers are the main reasons for the decrease of the efficiency of sprinkler irrigation.

Phosphorus (P), is the second important nutrient for rice that its deficiency and low application efficiency causes severe nutrient disorder in the world paddy fields. Therefore, the effect of phosphorus fertilizer splitting on morphological characters, yield, and yield components of two rice cultivars (Hashemi and Guilaneh) in two soil type was investigated by a factorial experiment in a randomized complete block design with three replications. The experimental factors included time division of phosphorus fertilizer at five levels, two soil types, and two rice varieties (local Hashemi and modified Guilaneh). Results showed that the grain yield of Hashemi cultivar in two-division treatment (50% at the base and 50% at 60th day after transplantion) incresed 14.9% and the grain yield of Guilaneh cultivar in two-division treatment (50% at the base and 50% at 20th day after transplantion) incresed 8.42% as compared to the base application treatment. The maximum increase in filled grain percentages were found to be 9.1% for Hashemi cultivar and two-division treatment (50% at the base and 50% at 20th day after transplanting) and 18.3% for Guilaneh cultivar and two-division treatment (50% at the base and 50% at 60th day after transplanting) in silty clay soil.  Hence, the two-split application of P might be a solution to enhance the rice grain yield at paddy field conditions.