نوع مقاله : مقاله پژوهشی
نویسندگان
1 بخش تحقیقات علوم زراعی و باغی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان مرکزی، سازمان تحقیقات، آموزش و ترویج کشاورزی، اراک، ایران.
2 گروه علوم کشاورزی، دانشکده کشاورزی، دانشگاه پیام نور، تهران، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The aim of this research was to prepare a map of the spatial distribution of aril paleness, soil texture, climate, rain gauge centers and salinity of irrigation water and soil of 19 pomegranate orchards in Saveh region to investigate the relationship between these factors with the occurrence and severity of paleness. The results showed that in all orchards, paleness occurred with different severity during two years of study and the severity of the complication was higher in the second year. Also, 68% of the orchards had unsuitable irrigation water and salty soil. According to the meteorological data in the whole region, the average air temperature in the second year was higher than the first year. The results of overlapping the maps with gardens layers showed that 60% of the studied orchards are located in the area with sandy-loam soils; all the gardens are situated in the area with dry climate, and the precipitation center. Generally, the occurrence of aril paleness is not affected by the geographical location of the orchards; but the factors of temperature, salinity of irrigation water and soil and soil texture play a role in the occurrence/severity of this complication in Saveh region. Temperature was directly identified as the main factor in the occurrence and severity of this complication. The salinity of irrigation water and soil together with temperature or each alone has a significant role in the incidence and severity of paleness. Regarding the soil texture, it seems that the role of this factor in the severity of the complication can be considered during the salinity of the soil or irrigation water.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
In recent years, due to the occurrence of aril paleness in pomegranate orchards of Iran, the export of the produce has decreased significantly. Therefore, this study was performed in two phase, the first phase aimed to prepare a map of the spatial distribution of aril paleness, soil texture, climate and rain gauge centers in Saveh region using differential Global Positioning System (GPS) and Geographic Information System (GIS) approaches and the second phase aimed to investigate the relationship between the temperature (environmental factor), rainfall (environmental factor), soil texture (non-environmental factor), based on the overlap of the distribution maps prepared in the initial phase, and the electrical conductivity coefficient of soil and irrigation water (non-environmental factors) with the occurrence and severity of pomegranate aril paleness in Saveh region.
Materials and Methods
Nineteen pomegranate orchards of 'Malase Saveh' cultivar were selected and their geographic coordinates were recorded with a GPS device. The fruits were harvested at the commercial mature stage and sorted based on the severity of the complication using a 5-point scale, then the percentage of aril paleness was calculated for each orchard. Electrical conductivity coefficient of soil and irrigation water of each orchard was also determined and data were analyzed in a completely randomized design with ten replications during two years. Meanwhile, soil texture layer, climate layer, rain gauge points, and orchards layer were prepared in GIS environment using a digital model. Then overlaying of layers was done in order to investigate the relationship between environmental factors and soil texture with the distribution and severity of pomegranate aril paleness.
Results and Discussion
The results showed that in all the selected orchards, paleness occurred with different severity during two consecutive years; So that the severity of the paleness was higher in the second year than the first year in all orchards. On the other hand, the results showed that 68% of the selected orchards had unsuitable irrigation water and salty soil, based on the measured electrical conductivity coefficient. Three groups of soil texture, including sandy-loam, loam-clay-sand and clay-loam were identified based on the soil test. Also, based on meteorological data, the average and maximum air temperature in the second year was higher than the first year throughout the region in the period of May to mid-October. The results of overlapping the orchard layer with the soil texture layer, temperature and rainfall showed that about 60% of the investigated orchards were in the range of soils with sandy-loam texture (coarse texture), all the gardens were in the dry climate and also all the orchards were located in the area of the Markazi province's rain center.
Conclusion
In total, the results of the spatial distribution study showed that the geographical location of the orchards probably did not affect the occurrence of aril paleness; but factors such as temperature, irrigation water salinity, soil salinity and soil texture play a role in the occurrence/severity (or both) of pomegranate aril paleness in Saveh region. Temperature was directly identified as the main factor in the occurrence and severity of this physiological complication in Saveh region. Also, the quality of irrigation water and soil from the point of view of electrical conductivity coefficient together with temperature or each alone has a significant role in the incidence and severity of paleness in this region. Regarding the soil texture, it seems that the role of this factor in the severity of the complication can be considered during the salinity of the soil or irrigation water.
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