برآورد ذخيره بانك ‬بذر علف ‬هاي ‬هرز در باغات مركبات شهرستان بندر گز و تهيه نقشه پراكنش آنها با استفاده از سامانه اطلاعات جغرافيايي (GIS)

Estimation of weed seed bank storage of Bandar-Gaz Citrus orchards and prepare distribution maps using Geographic Information System (GIS)

به‌ منظور تخمين تراكم بذر علف هاي هرز در بانك بذر خاك باغات مركبات شهرستان بندر گز و تهيه نقشه پراكنش آنها، در سال 1393 تعداد 94 باغ اين شهرستان انتخاب و بانك بذر آنها در دو عمق 10-0 و 20-10 سانتيمتر مورد مطالعه قرارگرفت. نتايج نشان داد كه به طور متوسط در هر كيلوگرم خاك گرفته شده از عمق 10-0 و 20-10 سانتيمتر به ترتيب 2555/31 و 1346/65 بذر يافت شد. در اين باغات بذر 25 گونه متعلق به 17 خانواده گياهي مشاهده شد. تيره گندميان (Poaceae) با 5 گونه گياهي، و تيره هاي سيب زميني (Solanaceae)، هفت بند (Polygonaceae) و فرفيون (Euphorbiaceae) هر كدام با 2 گونه مهمترين خانواده هاي گياهي تشكيل دهنده بانك بذر بودند. مهمترين گونه هاي مشاهده شده تاج خروس، تاجريزي، عروسك پشت پرده، گندمك و خرفه بودند؛ بررسي نقشه هاي پراكنش اين گونه ها نشان داد كه گونه هاي فوق در كل باغات اين شهرستان از شرق تا غرب گسترش دارند. نتايج نشان داد كه در هر دو عمق نمونه برداري تراكم بذر پهن برگها بيش از باريك برگ ها و تراكم بذر گونه هاي يكساله ها بيش از چندساله ها بود. نتايج مويد آلودگي بالاي باغات مركبات به چند گونه محدود علف هاي هرز در شهرستان بندرگز مي باشد.

In order to estimate the density of weed seeds in soil seed bank of citrus orchards of Bandar-Gaz township and providing the distribution map of them, 95 orchards were selected and their soil seed bank were determined at two depths (0-10 cm and 10-20 cm) in 2014. Geographic coordinates of each orchard were determined using GPS. These data were used for mapping of different weed species using ArcGIS 10 software .On average, 2555.31 and 1346.65 seeds per kg of soil were found at 0-10 cm and 10-20cm depths, respectively. Seeds of 25 weed species belonging to 17 families were observed in Citrus orchards. Poaceae family with 5 species, Solanaceae, Polygonaceae and Euphorbiaceae families, each one with 2 species were important families that contributed in the seed bank of citrus orchards.Amaranthus spp., Solanum nigrum, Physalis alkekengi, Stellaria media and Portulaca oleraceawere important species observed in the soil seed bank of citrus orchards. Seed density of Amaranthus spp., Solanum nigrum, Physalis alkekengi, Stellaria media and Portulaca oleracea were 20 to16310, 0 to 670, 0 to 650, 0 to 5280 and 0 to 18470 seeds per kg of soil, respectively. Survey the maps of the distribution of these species showed that the above species have expanded in the orchards of the city from East to West. Seed densities of the broadleaf and annual species were higher than the grasses and perennial species. Frequency of the broadleaf and the annual species were priority on the grasses and perennial species. Shanon index at depths of 0-10 and 10-20 cm were 0-0.8 and 0- 0.74 respectively. Results indicated that species diversity was low in citrus orchards. Based on these results, citrus orchards in Bandar-e-Gaz township were infested only a few weed species.