Evaluation of weed flora changes in Portugal in a 10 year basis

Abstract

The aim of this study was to assess the composition of weed communities starting from a rainfed farming system (1997), to the early period of transformation in agricultural systems with the adoption of irrigation (2007). The assessments were made within a 10-year interval and the floristic surveys were conducted in the same georeferenced plots. In 1997, the surveys were mostly performed in winter cereals (wheat, oat, barley), while in 2007, considering the same georeferenced plots, there were winter cereals and also irrigated olive groves, parcels of fallow, pasture and pine forest. Weed flora was determined by means of relative frequency, abundance and weed infestation degree. The effect of time was also evaluated by applying the methodology of variance analysis on the values of Shannon-Wiener Index. Canonical Correspondence Analysis was used to complement this information only for 2007 to know how the flora was distributed by the different cultures. Our results revealed that in both cases weed flora was of high diversity (229 and 264 species in 1997 and 2007, respectively), with the most representative families being always the same, namely Asteraceae, Poaceae and Fabaceae. The number of weeds that could be of concern for the farmers revealed to be relatively low. Our study confirmed that despite of the intensification of the agricultural production system, biodiversity increased over time. In both years, Lolium rigidum was present at high densities.

Changes in the weed flora of cotton fields in the Eastern Mediterranean region of Turkiye

“…Bükün (2005) found that irrigation reshaped the weed flora of cotton fields in the Harran Plain in Turkey and that the frequency of some species changed, whereas new species joined irrigated cotton fields, such as Physalis species. Similar results have been shared by Arslan (2018) in Turkey and Ramôa et al (2017) in Portugal. However, the growers are intended to regrow the same crop again and again using irrigation facilities.…”

“…There were 29 annual species and 8 perennial species (Table 1 to 4). Previous research indicated that Mediterranean basins became foregrounding in terms of weed richness compared to other basins to provide suitable growth conditions for the weeds because of climatic conditions and geological factors (Ramôa et al, 2017;Glemnitz et al, 2006). This richness was more apparent in the survey fields when the number of rare or less frequent species were considered.…”

“…In addition, combining crop sequences with agricultural practices not only enhances weed control but also reduces the adverse impact of tillage (Ruisi et al, 2015). Similar to other factors, irrigation may also change the weed communities of horticultural and field crops including cotton at various degree (Ramôa et al, 2017;Bükün, 2005).…”

Evaluation of Changes in Weed Flora in Response to Agricultural Practices in the Arable Lands of El-Menoufia Governorate, Nile Delta, Egypt

“…Different agricultural practices discussed above may have led to these results. Several studies have reported similar results from different areas around the world (Andreasen et al, 1996;Heap, 2010;Richner et al, 2015 andRamôa et al, 2017).…”

“…Richner et al (2015) reported that the arable flora has dramatically altered in response to changing in agricultural practices since the Second World War. Ramôa et al (2017) studied the weed flora changes in response to the modern reformations in agriculture in Portugal. Changes in agriculture practices don't only affect the weed flora of agroecosystems but extends to all biotic and abiotic components (Chamberlain et al, 2000).…”