Distribution and diversity of weed species in Sugar beet (Beta vulgaris L) Fields of Kermanshah Province

In order to study the diversity of weed flora in sugar beet (Beta vulgaris) fields of Kermanshah province, 92 fields in five cities of this province investigated during the spring and summer of 2014. The first stage of sampling was in May and the second stage was in September. After sampling and identification of weeds, the diversity and evenness indices were calculated for each field. Acording to results in different cities of this province, five species of weeds have the highest value of dominance index. The most important weed in this experiment were warm season species such as Chenopodium album, Amaranthus spp, Setaria viridis, Xanthium strumarium and Convolvlus arvensis. The calculated value of domoinance index for above mentioned weeds were 197.7, 187.3, 170.3, 150.6 and 105.3, respectively and calculated dominance index for the rest of observed weeds was less than 100. Considering Shannon-Wiener diversity indices at the first stage of sampling the studied cities classified in two groups whereas in second stage the cities placed in three groups. In the first stage of sampling the highest value of Simpson diversity indice (0.78) calculated for Sahneh and the lowest value (0.67) observed in Eslamabad-e-Gharb, but in the second stage the highest value (0.93) of this indices belonged to Eslamabad-e-Gharb and the lowest value (0.83) calculated for Harsin. The obtained results after t-test showed that in both of stages there was the significant difference for species diversity of weeds among the studied cities.