جستجوی مقالات مرتبط با کلیدواژه « مزارع برنج » در نشریات گروه « کشاورزی »

This research was carried out with the general purpose of designing and explaining the optimal model for extension GAP standard in the rice fields of Mazandaran province. The research was qualitative. Data analysis was done with the method of qualitative content analysis of scientific and semi-structured interviews by extracting codes, concepts and categorizing categories, during a three-step process of open coding, central coding and selective coding through Maxqda software. The statistical population of the research was 18 experts and specialists of the Agricultural Jihad Organization and rice farmers' cooperatives of Mazandaran province and the academic staff of Sari Agricultural Sciences and Natural Resources University, who were selected by purposeful sampling. Analysis of semi-structured interviews was done through the technique of qualitative content analysis with an inductive approach. The interviews were studied line by line. the content analysis of the conceptualization process was done to explain the model. In the first stage of coding, 56 contents among 260 conceptual codes were identified, and after refining and merging, the codes were classified into 19 subcategories. Coding of categories was determined with coherence and logical order and accurate connection with axial coding. And it led to the paradigm model of explaining the pattern of extension and development of GAP standard in rice fields of Mazandaran province. The obtained pattern of causal conditions (exploitation system, psychological behavior and effective drivers), It shows strategies (system of group certificates, development of government GAP programs and development of private GAP standard), intervening conditions (supporting and facilitating factors, motivating and stimulating factors, limiting and inhibiting factors), background conditions (legal, institutional and political requirements and technological and innovative capabilities) and consequences (environmental, social and economic sustainable development) for the promotion and development of GAP standard in the rice fields of Mazandaran province. The obtained pattern of causal conditions (exploitation system, psychological behavior and effective drivers), It shows strategies (system of group certificates, development of government GAP programs and development of private GAP standard), intervening conditions (supporting and facilitating factors, motivating and stimulating factors, limiting and inhibiting factors), background conditions (legal, institutional and political requirements and technological and innovative capabilities) and consequences (environmental, social and economic sustainable development) for the promotion and development of GAP standard in the rice fields of Mazandaran province.

Rapid growth of population, followed by increasing food demand, necessitates knowledge of the relationship between yield and soil conditions. The soil quality index (SQI) is one of the indicators showing the soil conditions and the related properties very well.This study was performed to determine the effect of soil quality on rice yield in north of Iran (Gilan province). 64 soil samples from rice fields were prepared to measure the physical and chemical properties affecting soil quality and also the yield of rice in the mentioned fields were determined using plot. Then the total yields were divided into three classes with yields of less than 4000 kg/ha (first class), 4000-4500 kg/ha (second class) and more than 4500 kg/ha (third class). Among the studied properties, 16 properties as selected indicators of total data method (TDS) and five properties using principal component analysis as selected indicators of minimum data set method (MDS) were selected to determine the soil quality index. Fuzzy logic was used for scoring and the concept of communality index was used to weight the indicators and finally they were combined using weighted additive method. The results of quality index showed a positive and high correlation between TDS and MDS methods (R2 = 0.87). The results of correlation coefficient between yield and SQI by TDS method (R2 = 0.52) were higher than the SQI by MDS method (R2 = 0.28).  In the MDS method, simmilar to TDS method, there was an increasing trend in the SQI value of higher yield classes, but there is no significant difference between the second and third classes. The difference between soil quality and lower yields with MDS method is significant, but this difference is not significant at higher yield levels, because as the number of indicators decreases, the accuracy and sensitivity of soil quality assessment decreases.

As one of the world's major grains, rice has always been given special emphasis. Monitoring agricultural products plays a important role in providing global food supplies. In general, inorder to estimate product output, information such as area and production per unit area is important. Remote sensing technology can provide valuable and timely information on distribution, cropping, and production potential to decision makers in the agricultural sector. Detection by operator with field operation or visual detection cost too much, also associated with human errors. In addition, with regard to the possibility of changing land use, there is always the need for border control of rice paddies. So that the purpose of this study was to separate the rice fields with an automatic method in Gilan province. In recent years remote sensing has been raised as a valuable tool in the management and control of resources and agricultural products. By the same token using satellite images Landsat 8 and soil moisture index (LSWI) and leaves (LAI) and normalized differential vegetation index (NDVI) fully automated method is used to detect the rice paddies. According to this method, then, using the characteristics of the high water range in the early rice transplanting, these areas were identified using specific threshold. Then using another image in the harvest period, unwanted complications such as wetlands and permanent water and wet forests were removed. Final evaluation model with graphical borders of operator were taken from GEO Eye images. The results indicate conformity of 90% of the used method.

Water resources shortage threatens the sustainability of continuous flooding rice culture. To investigate the effect of initial flooding duration on herbicide efficacy and rice yield loss,a field experiment was conducted at Rice Research Institute of Iran, Rasht, Iran, in 2015. The experiment was arranged in a factorial arrangement based on randomized complete block design with three replications.The experimental factors were two rice cultivars (Hashemi and Gilaneh) and five initial flooding durations (flooding for 2, 4, 6, 8 and 12 weeks after transplanting and then applying intermittent irrigation). Consistent with the paddy fields irrigation method in northern Iran, 12-week flooding duration was considered as continuous flooding irrigation. Results showed that there was no significant difference in herbicide efficacy between Hashemi (87.9%) and Gilaneh (85.6%) cultivars. No significant reduction in herbicide efficacy was observed when initial flooding duration reduced from 12 to 6 weeks, but with further reduction in initial flooding duration to four and two weeks, herbicide efficacy was significantly reduced. The highest paddy yield (3989.2 kg.ha-1) was observed in permanent flooding(flooding for 12 weeks) + herbicide application treatment and the paddy yield was decreasedabout 10% by reducing theinitial flooding duration to six weeks but it was not statistically significant. With further decrease in initial flooding duration to four and two weeks, rice paddy yield reduced significantly by 16% and 31%, respectively. In conclusion, results of this experiment revealed that under water shortage conditions, it is necessary to apply initial flooding duration at least for 6 weeks after transplanting for obtaining favorable herbicide efficacy (more than 90%) without paddy yieldloss compared to permanent flooding treatment.

The purpose of this research was to investigating ecological sustainability of Rice Farms in Sirvan and Chardavol regions. Survey method was used for doing this research. Population of study were farmers(n-1260) that by using stratified proportionate random sampling technique and based on Cochran formula 136 farmers were selected. Instrument of data gathering was questionnaire that its validity was confirmed by expert's panel. Cronbach's Alpha coefficient has been used in order to determine questionnaire's reliability and it was to be equal to 0.87. SPSS software has been used for Data analysis. Results showed that some of indices such as exchange farm lands to other activities, amount of farm water, using disk, status of tillage, and anti bacterial seeds are sustainable in these two regions. There is deference between two regions about of indices such as returning straw residue from crop to soil, depth of surface soil, use of fertilizers and pesticides, and use of disk for preparing farm and animal fertilizer.

Rice blast caused by Pyricularia grisea (Cooke) Sacc. is one of the most serious diseases of rice throughout the world، which is generally controlled by fungicides. Appropriate selection of sprayers with respect to the field conditions، increases the efficiency of pesticide application and reduces the environmental pollution. In this study the efficiency of five different types of sprayers namely: two types of knapsack micronair sprayers (Model: KP 4000-N10، and SKN-3000) as well as two types of electrostatic sprayers (Model: motorized knapsack mist blower sprayer equipped with electrostatic head and Model: GPS-5 TM) were compared with hydraulic motorized sprayer carried on trolley using two doses (1 and 0/75 kg/ha of tricyclazole (Beam® WP 75%) applied on rice blast disease. The factorial experiment was carried out based upon a Randomized Complete Block Design (RCBD) of 3 replications. The results demonstrated that motorized knapsack mist blower sprayer equipped with electrostatic head، hydraulic motorized sprayer on trolley (conventional sprayer) as well as knapsack micronair sprayer (Model: KP 4000-N10) were of the highest efficiencies. The mean severities were estimated 1. 67±0. 13، 2±0. 12 and 3. 5±0. 33 respectively. The pesticide solution taken up by the 3 sprayers were recorded as 48، 450 and 65 L/ha. respectively. This shows considerable reduction in the level of fungicide applied in the motorized knapsack mist blower sprayer equipped with electrostatic head and in knapsack micronair sprayer، leading to an increase in efficiency and decrease in operating costs. Evaluation through water-sensitive cards indicated that motorized knapsack mist blower sprayer (with electrostatic head) and knapsack micronair sprayer (Model: KP 4000-N10) led to a better distribution of droplets than hydraulic motorized sprayer carried on trolley did. It is recommended that the above mentioned technique be only applied to leaf rice blast، since it can not be beneficial to the crop when it is at its panicle stage and tall.

Ants (Hymenoptera: Formicidae) are one of the important predators in different agroecosystems. Considering the importance of ants in predating and feeding at different life stages of pests, fauna and population fluctuation of these beneficial insects were studied in rice fields of Mazandaran province. Of the faunistic survey, totally 15 species of ants were collected and identified from the paddy fields in Mazandaran province. The results of population fluctuations on the stubbles of three varieties including, Fajr, Khazar and Nemat indicated that the ant's population density was higher on Fajr than the two other varieties, and there was not a significant difference between Khazar and Nemat. Samplings from 11 September to 15 November 2005 indicated that the population density increased until last October and then decreased gradually; the highest density was obtained in 30 October. The means comparison revealed the significant reciprocal effect of "sampling date × rice variety" on population density of ants "P<0.01".

Beetles (Coleoptera) are the largest order of insects, which exist in all agroecosystems and natural ecosystems. Since rice fields include both aquatic and subterranean ecosystems, diverse fauna of beetles are active in rice fields of the world. In regard to the importance of these insects in chain foods of biosphere, fauna of some coleopteran families was surveyed in north rice fields of Iran (including, Mazandaran, Guilan and Golestan provinces) through 2001-2006. In total 69 beetle species of 9 families including, Alleculidae (3 species of one genus), Bruchidae (3 species of 3 genera), Cleridae (3 species of one genus), Curculionidae (15 species of 8 genera), Histeridae (6 species of 5 genera), Nitidulidae (4 species of 4 genera), Silphidae (6 species of 5 genera), Staphylinidae (17 species of 11 genera) and Tenebrionidae (12 species of 11 genera) were collected from rice fields and surrounding grasslands of Northern Iran.

The production unit size is one of the effective factors in optimum uses of inputs. Since optimum size is affected by the characters and economical conditions in each district, the studies for determining the optimum farm size should be done specially for each crop and each district. In this study tried to determine the optimum rice farm size in Guilan province which is one of the most talented district for rice in Iran applying Translog cost functions to data collected from 280 farmers in the studied district who were selected by two stage random sampling method. The results showed increasing return to scale for all districts and for each town. Also the optimum sizes are 2.17 ha for province, 2.2 ha for Rasht, Somee sara 2.26 ha, Talesh 2.01, Astaneh 1.73 ha and Rudsar 1.47 ha. In general, the optimum sizes are larger than present average sizes. Due to results, encouragement of farmers to form cooperatives and convert of small farm to cumulative farms are recommended.

Any planning for agricultural sustainable development requires a realization of sustainable agricultural indices standings. Because of many farms in Shirvanchardavol County allocated to rice cultivation and also for the necessity of moving these farms in the direction of agricultural sustainability, the purpose of this research was chosen to analyze the ecological sustainability of Rice Farms in this county from farmer's viewpoints. A survey method was adopted to do the research. Using Stratified Proportionate Random Sampling technique, 136 farmers were selected. Instrument of data collection for the study was questionnaire. Cronbach's Alpha coefficient was used to determine the main scale of questionnaire's reliability which it was found to be equal to 0.87 and considered as favorable. Validity of the questionnaire was confirmed by an expert's panel. Data analysis was accomplished using SPSS. Results of Cluster Analysis indicated that 35.48 percent of ecological sustainability (subjective) indices were sustainable; 29 percent of indices comparativly sustainable; and 35.48 percent unsustainable, so a majority of the ecological sustainability (subjective) indices of the studied rice farms were among the sustainable