Changes in weed species composition in irrigated agriculture in Saharan Algeria

Abstract

Summary This work characterises the changes in composition of the weed flora commonly associated with certain south‐eastern Algerian crops over a 20‐year period. Vegetation sampling was carried out between 1990 and 2010 in three 1 ha date palm plantations that do not have understory crops, six 400 m² glasshouses used for market gardening and three 30 ha cereal centre‐pivot irrigation plots. In total, 162 species belonging to 40 families were recorded. As in many other agroecosystems around the world, the dominant families were Poaceae, Asteraceae, Brassicaceae and Amaranthaceae representing 45.1% of the species identified. The weed communities were characterised by a set of species from various origins: species with biregional, triregional and multiregional origins, and Saharo‐Arabian and Mediterranean species were particularly well represented. Overall, the most common weed species were as follows: Chenopodium murale, Lolium multiflorum, Melilotus indicus, Lysimachia arvensis, Sonchus oleraceus, Setaria verticillata, Polypogon monspeliensis and Erigeron canadensis, all of which are therophytes. The weed flora differed among the three sampled agroecosystems, which is to be expected, as their respective management sequences are quite different. Weed monitoring over the 20 years showed that weed composition changed over time, particularly in the palm plantations and the cereal plots. For a better understanding of the drivers of weed composition and changes over time and better weed management, studying weed provenance (crop seed purchase and organic fertilisation) as well as agricultural practices is necessary.

Improving seed germination of native species for camel rangeland restoration: effects of cold stratification and temperature

“…Three of them belong to the Amaranthaceae family, whose species have been shown to germinate fast to take advantage of temporarily favorable conditions for germination (Parsons 2012). Scorzonera laciniata and Asphodelus tenuifolius are eurymediterranean species (Eddoud et al 2018), which may germinate at lower temperatures than most Saharan species. On the other hand, Savignya parviflora subsp.…”

“…On the other hand, Savignya parviflora subsp. longistyla and Plantago ciliata are Saharo-Arabian species (Eddoud et al 2018), meaning that they may germinate in the colder months (December through February; Table 1) better than most naturally co-occurring species, although this would need to be confirmed by further research.…”

“…When well-conserved, these rangelands are characterized by a great diversity of native Saharan plants, many endemic (Quézel andSanta 1962-1963;Ozenda 2004;Chehma 2006), which are used as medicines and nutritive fodder (Abdelguerfi 2004;Chehma 2005;Senoussi and Bensemaoune 2011;Baameur et al 2015;Telli et al 2016). In this area, the risk of desertification comes from drought combined with anthropogenic activities, such as overgrazing, clearing of rangelands, and the installation of cereal center-pivot irrigation plots (Marfoua et al 2010;Eddoud et al 2018), all of which put certain plant species at risk of disappearing (Ayyad 2003;Darkoh 2003).…”