|
چکیده
|
Echinochloa crus-galli is a summer annual weed, whose long emergence period and fast growth makes its control difficult. This noxious weed is restricted to irrigated crops, like maize or rice, in the Mediterranean, but can also appear in rain fed cereals in temperate climates. Due to the climate change that is occurring nowadays, E. crus-galli is invading new latitudes and expanding its presence to new areas. Under this perspective, in this work the emergence of several populations was studied throughout Europe and the Middle East: Denmark, Germany, Greece, Italy, Iran, Latvia, Norway, Poland, Portugal, Spain, Sweden and Turkey. Two common populations, the first harvested in Norway in spring barley and the second in Italy in a maize field, were established in all locations, together with two-three local populations in each site. The local populations were collected from surrounding crops in each site, most of them from maize fields, but also from rice, cereals, vegetables, garden or orchards. Sowing was performed in 25 cm diameter pots in October 2015 by disturbing the upper 5 cm of the soil. 200 seeds were sown per pot, with five replications. The pots were buried in the soil. In those sites where E. crus-galli appears only in irrigated fields, pots were watered. Samplings were done every 2-3 days by destructive counts, from late March to July-September 2016, depending on the site. The emergences varied significantly between locations. The common population from Norway showed higher emergence rates in Northern latitudes (47-63% in Denmark, Norway, Sweden, Poland, …) than in Southern latitudes (8-14% in Iran, Italy, Spain). In the case of the common population from Italy results were more homogeneous, although highest percentages of emergence occurred in Southern latitudes (37-47% in Iran, Italy, Spain) and lowest in Northern latitudes (20-35% in Denmark, Norway, Sweden, Poland…). With respect to the highest emergence percentages in each site, the Norwegian population emerged more in Poland, Denmark, Norway, Sweden and Latvia; the Italian population did the same in Iran, while local populations showed more emergences in Spain and Italy. In general higher emergence percentages were observed from populations collected in maize field compared to populations collected in rice, orchard or garden populations. With regard to the emergence rates, these did not differ between the different populations in each site, although the Norwegian common population usually emerged some days earlier (2-7) than the other populations (Italian and local ones). E. crus-galli showed quite high plasticity in the emergence depending on the biotype. Climate of origin and the original habitat (crop type) significantly conditioned the quantity of the emergences, but not the emergence rate.
|