Effect of Continuing Monoculture of Potato (Solanum tuberosum L.) on Weed Density and Diversity in Agroecosystems of Jiroft, Iran

The study of weed flora changes under different crop management system is an important key to achieve successful weed management in every agroecosystem. This study was conducted in order to evaluate the effect of potato monoculture continuing on weed density and diversity in the conventional agroecosystems of Jiroft region-at 2015-16 in University of Jiroft, Iran. Agroecosystems, which was assessed in this study, were potato monoculture systems included continues monoculture period less than 3 years (S1), 3-6 years (S2), 6-9 years (S3) and more than 9 years (S4) and long-term fallow (F). Sampling was performed using systematic-randomized method in three stages (before sowing, 60 days after planting and 30 days after harvest) with 1×1 m2plot. Base on results 28 weed species were observed which 17 species of them were common in all five agroecosystems. ANOVA's result showed there were significant effect of continuing in potato monoculture on density weeds as Cyperus rotendus L., Cyperus esculentus L., Trifolium repens L., Chenopodium album L., Cynodon doctylon L., Amamrantus retrofloxios L. and Digitaria sanguilanis L. Increase of potato monoculture period from 3years in agroecosystem of S1 up to 9years in S4 agroecosystem caused to significant increasing in weed density so maximum weed density was observed in S4. Evaluating of diversity indices showed continuing in potato monoculture period had significant effect on diversity indices includes of Simpson, Shannon, Margalef, Menhinik and Evenness, so highest value of these indices (Simpson:0.97, Shannon: 3.65, Margalef: 5.24, Menhinik: 2.99) and lowest value (Simpson:0.87, Shannon: 2.22, Margalef: 3.88, Menhinik: 2.00) were observed respectively in agroecosystems of S4 and F. In summary continuing in period of potato monoculture caused to significant increase in weed flora density and diversity indices.