جستجوی مقالات مرتبط با کلیدواژه « geographic information system » در نشریات گروه « گیاهپزشکی »

Oilseeds are the second largest food sources in the world after cereals. Soybean (Glycine max L.) is the largest source of protein and oil in the world and is cultivated in some regions in Iran. Golestan province is one of the important agricultural regions in Iran with about 62.01% of the soybean cultivation area. Most of these areas are located in Gorgan County. There are a number of approaches that they use to management of weeds in agroecosystems. Management and protection of crops from weed damage depend on our knowledge about weed richness and their distribution status. For this purpose, generation of weed distribution maps provide very important information for weed management. Also, determination of weed flora help to managers and farmers to identify weeds and select the best method for weed control, especially invasive weeds in soybean fields. Therefore, the aim of study was to determination of flora and distribution of weeds in the current soybean fields in Gorgan County.

This research was carried out in 48 soybean fields of Gorgan County, during 2015-2016. In the field section, the W method used to collect weed samples in order to calculate the number, frequency, species density, etc. The spatial information of the fields was recorded by GPS and sampling was done by 0.25*0.25 square meters quadrate. Total weed samples moved to weed research laboratory of Gorgan University of Agricultural Sciences and Natural Resources (GUASNR) and identified in terms of scientific and family names based on taxonomical classification way. Then, all data entered to Microsoft Excel spread sheets var. 2010, and were averaged and arranged. In order to determine the weed flora status of these fields, some indices such as frequency, relative species frequency, species uniformity, relative species uniformity, density and relative species density were calculated. To better display of distribution maps, weeds were divided based on frequency index into three categories; 50-100%, 50-30% and less than 30% and weeds with a frequency of 50-100% were considered as important weeds of soybean fields in Gorgan. Finally, the data were processed in ArcGIS software var. 10.3, and then weed distribution maps of soybean fields were generated.

In this study, 21 types of weeds were identified from 14 plant families, which 14.28% were belonged to perennials group and the rest amounts were annual weeds. Also, 76.19% were belonged to dicotyledons and about 23.81% were monocots. The highest density was related to ground cherry (Physalis divaricate L.) with 16.68% compared to other weed species in the measured plots. Crab grass (Digitaria sangunalis L. Scop.) with a density of 0.94 and sorghum (Sorghum halepense L. Pers) with a density of 0.78 had the highest density than other weeds. The weeds of the studied fields included 23.80% of narrow-leaved weeds and 76.19% of broadleaf weeds. In terms of photosynthetic cycle, 28.57% of weeds classified to C4 cycle and 71.42% to C3 cycle. Also, the most important plant family was Poaceae with 19.04% of the observed weeds in soybean fields, compared to other plant families. The most dominate species of this family are sorghum, cockspur grass (Echinochloa crus-galli L. P. Beauv) and crab grass. The weeds with a frequency of 50-100% were included ground cherry, sorghum and wild melon (Cucumis melo var. agrestis L.) with a frequency of 91.66, 54.16 and 52.08%, respectively. Results of weed distribution maps showed that weeds with frequency of 50 to 100% were observed in the most of surveyed field and they were distributed across the county, from east to west.

In the study, the weed distribution maps showed the existence of broadleaf weeds such as ground cherry, sorghum and wild melon in the most of the studied fields. Also, we identified the large number of weed families in this study. Considering this high number of identified weed and the presence of some invasive weeds in the surveyed fields, these results can useful for weed management programs of soybean fields and other crops in Gorgan County. Therefore, it is necessary that farmers and agricultural managers of the Gorgan County care to distribution of invasive weeds. Finally, it concluded that a combination of local and longer-term weed management can possible to deliver reduced weed infestation levels. Also, integrated weed management is an essential practice for reducing the impact of pesticides in the agroecosystems.

Wild mustard (Sinapis arvensis L.) is a very common weed within cereal and rapeseed fields in Iran and many other countries. This weed is usually controlled by tribenuron-methyl in wheat fields of Iran. However, due to consecutive application of tribenuron-methyl for the last 27 years in wheat fields, control failures were reported by farmers. Resistance to ALS inhibiting herbicides is the most common form of herbicide resistance in the world. So far, 165 resistant biotypes to this family have been reported. Therefore, present study was carried out to survey suspected of resistance wild mustard accessions to tribenuron-methyl in wheat fields of Ramhormoz and preparing distribution map of resistant fields.

An experiment was conducted in Agricultural Sciences and Natural Resources University of Khuzestan during 2017-2018. 22 no. of the suspected resistance wild mustard accessions to tribenuron-methyl were gathered from wheat fields of the Ramhormoz. One susceptible accession was also gathered from a field with no history of spraying. Pot experiments were carried out in two stages including the initial screening with the recommended dose of tribenuron-methyl (15 g ai ha-1) and dose-response assay that accessions were investigated for the effect of tribenuron-methyl on dry weight and survival plant no. under outdoor conditions. The plants per pots were sprayed, based on tribenuron-methyl dose (0, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, and 32-fold of recommended dose). The shoot dry weight data were converted to a percentage based on control plants data within each accession. A log-logistic curve with three and four-parameters was used to describe dose–response relationships. Dry-weight data were fitted to a nonlinear log-logistic regression model using the package drc in the statistical program R (R Development Core Team, 2008). The distribution map of the resistant populations was plotted using ArcGIS 10.3 software.

Screening results showed that nine accessions (B, C, H, P, S, T, W, X, U) were strongly resistant (R) and 10 accessions (A, E, F, G, K, L, M, O, Q, R) were probably resistant (PR or RR), and three accessions (D, N and Y) were susceptible (S) or suspected resistance (SR) to tribenuron-methyl based on Adkins and Mo‘s 's ranking system. While, Screening results based on Mo‘s 's ranking system showed that nine accessions (B, C, H, P, S, T, W, X, U) were completely resistant (RRR) and 10 accessions (A, E, F, G, K, L, M, O, Q, R) were probably resistant (RR), and two accessions (D and N) were suspected resistance (SR) and one population (Y) was susceptible to tribenuron-methyl. With increasing doses of the herbicide tribenuron-methyl, the dry weight of susceptible and susceptible accessions decreased during the sigmoid process. Resistance factor of accessions (W, U, X, S, B, C, T, K, R, G, Q, O, E, A, P, M, F, H, and L) based on dry weight (% of control) and survival (% of control) ranged from 1.10- 8.17 and 2.08-7.60, respectively. A different resistance factor was observed between the accessions; thus, the W accession with the highest resistance factor of 8.17 and 7.60 and the L accession with the lowest resistance factor of 1.10 and 2.80 based on dry weight and survival (% of control) were resistant to the herbicide tribenuron-methyl. While 6.80 g ai ha-1 caused a 50% reduction in the dry weight of the susceptible Z accession, this reduction was calculated to be 60.55 g ai ha-1 for the most resistant accession (W), which differed significantly based on the calculated confidence limits. A map of the distribution of contaminated fields of resistant wild mustard accessions using GIS showed that most resistant accessions were observed in eastern and southeastern regions of Ramhormoz.

The results of this experiment confirmed the presence of resistance in wild mustard accessions to tribenuron-methyl. Repeated use of tribenuron-methyl in wheat fields of Ramhormoz is one of the most important reasons for resistance in these fields. Distribution map makes it possible to predict farms infected with resistant accessions and help prevent the recommendation and use of ALS inhibiting herbicides in these farms, so that in order to break the resistance in resistant accessions and it will be effective reduce the use of herbicides. Therefore, the use of distribution maps can be used to implement integrated weed management programs and to prevent the development of resistance accessions in other areas.

In a natural ecosystem, there is a close relationship between natural enemies and environmental factors. Use of Geographic Information System (GIS) in analysis of spatial patterns of pest populations has increased during recent years. The purpose of this study was using Analytic Hierarchy Process (AHP) to determine the relationship in predatory ladybird, Exochomus nigripennis (Erichson) for biological control of the sucking pests. In order to determine the suitable areas for activity of E. nigripennis, the variables of temperature, humidity, rainfall, elevation and nutrition were selected as the most important criteria. The basis of AHP is the pair comparison of options and the possibility of examining different scenarios. ArcMap 10.1 and ArcCatalog 10.1 softwares were used to form spatial data and related analytics. The results indicated that nearly 4.34% of the province's regions, including some parts of Taft, Abarkuh and Mehriz were very good for activity and nearly 17.07% of the province's areas, such as the major part of Ardakan, Bahabad and Meybod were determined as very unsuitable for activity. Furthermore, comparison of the studied factors showed temperature with the final weight of 0.0529 is the most important factor influencing the activity of E. nigripennis and nutrition, humidity, elevation and rainfall are important in the next categories, respectively.

The GIS is a computer system for storing, processing and displaying land reference data that is used to assist in decision making in specific crop management. In this study, the technology of GIS has been used as a quick and easy solution in monitoring Dubas bug (Ommatissus lybicus de Bergevin). The aim of this research was to prepare a digital map of distribution and density of pest, to determine the outbreak points and the direction of contamination spreading and determining the areas of orchards infested by the pest in Bam and Browat. For this purpose, orchards of the Bam and Browat area were networked using Google Earth, then from each cell, an orchard, and in total in 41 orchards, the density of pest was measured using pest and honeydew counts. Then, the data were entered into the GIS so that the distribution maps and pest density were developed and evaluated. The results showed that in most orchards where pest density was measured, the damage was moderate to high. In more than 69% of the orchards, the density of Dubas bug (O. lybicus) was moderate, high and very high. For this reason, it can be said that more than 69% of the orchards in the area need immediate attention. These orchards should also be reconsidered for redesigning and improving practices such as reducing tree density, pruning and fighting pests. The severity of pest infestation in the northeastern and southeastern boundaries and generally in the east and south of the region is much higher than the northwest of the area. Therefore, the control practices should be focused on regions ranging from 58 degrees and 22 minutes east longitude and 29 degrees 7 minutes northern latitude to 58 degrees and 29 minutes east longitude and 29 degrees 2 minutes northern latitude. The elevation map showed that in a distance of 21.5 km there was altitude differences between regions, the altitude increased from 975 m in south of Brovat to 1190 m in north of Bam. From south of Browat area to the north of Bam, the severity of pest density has decreased. From the results, this level of information can be ascertained that as the altitude increased, the severity of the pest decreased. The total area of the date palm orchards of Bam and Brovat was estimated 3647 hectares calculated with the help of satellite image of Sentinel 2 and controlled by the classified classification. The area of gardens where the average pest density was moderate to very high was 2533 hectares.