عنوان مقاله [English]
Introduction: Weeds movement and their dispersal power are amongst the major factors affecting the agricultural plants success. Diversity reflects the complexity of a system and can maintain its sustainability. Higher diversity results in higher inherent complexity of agro-ecosystems and strengthens their processes. It is necessary to realize the spatial distribution and temporal properties of the biodiversity components in agro-ecosystems, for the conservation and optimal utilization. Since weeds as a complementary component of agro-ecosystems are inseparable, studying species and their functional and structural diversity plays an important role in weed management and balance of ecological systems. Pistachio is one of the most economically important and strategic agricultural products in Iran. Weeds are one of the serious problems in pistachio orchards creating problems through competition, and costs imposed on farmers. Studying distribution and density of weed species can play an effective role in weed management. Therefore, this study was to assess the weeds flora and their distribution in pistachio orchards at Kerman city.
Materials and Methods: In order to investigate the flora and weeds distribution in pistachio (Pistacia vera) orchards of Kerman city, 19 orchards in 4 regions were selected. Weeds population sampling was conducted in a W pattern using 0.5×0.5 m² quadrates in 2014. The weeds at each quadrate were identified based on genus and species and the number of weed species was counted. Indices including frequency, uniformity of distribution, mean density, and abundance index as well as relative frequency, relative uniformity of distribution, relative mean density, and relative abundance were also calculated. Finally, weed species were classified based on cluster analysis using the Ward method and Euclidean distance square.
Results and Discussion: The weeds of pistachio orchards were belonged to 18 families and 57 species that dicotyledons with 45 species (78.95 percentage) had higher diversity than monocotyledons with 11 species (19.30 percentage). Family of Asteraceae with 12 weed species was the most abundant weed at Kerman’s pistachio orchards followed by Poaceae with 10 weed species, Chenopodiaceae with eight weed species and Fabaceae with seven weed species. According to the photosynthetic pathway, diversity of C3 weed species with 38 species (66.67 percentage) was more than twice of C4 weed species with 16 species (28.7 percentage). Based on life-cycle, diversity of annuals with 32 species (56.14 percentage) was more than perennials with 32 species (42.10 percentage). Five species of mouse barley (Hordeum murinum L.), field bindweed (Convolvulus arvensis L.), knapweed (Acroptilon repense L.), bermuda grass (Cynodon dactylon L.), and saltbush (Atriplex sp. L.) had the greatest frequency. The most important species of weeds with maximum abundance index were mouse barley, knapweed, saltbush, field bindweed, and bermuda grass. Based on cluster analysis, species were divided into four groups and based on importance were performed from the bottom to the top of the dendrogram.
Conclusions: Although the number of halophytic weeds in the pistachio orchards of Kerman was remarkable, the frequency and relative density of these weeds were not considerable. Identifying weed species, as well as their structural and functional diversity in pistachio orchards seems to improve the horticultural production management.