Journal of Research in Weed Science

Abstract A study was conducted to determine the effect of climate gradient and previous crop on weed flora structure in pearl millet crop. Thus, floristic surveys were carried out during 2016 and 2017 crop years on station in Sahelian, Sudano-sahelian and Sudanian zones of Senegal. The results revealed that flora consisted of 81 species distributed in 59 genera and 19 families. Higher number of species were recorded in Sudanian zone (Kolda and Séfa) with respectively 61 and 45 species and the lowest number of species were found at Vélingara in Sudano-sahelian zone (28 species) and Sinthiou Malème in sahelian zone (28 species). According to previously crop, the higher number of species was registered in previous fallow (64 species) followed by previous pearl millet (57 species). In previous mucuna and peanut, flora is 14 percent lower than species recorded in previous fallow. Spectrum analysis indicated that the flora is largely dominated by therophytes, which includes 81.5% of the recorded species. It’s presence in pearl millet field was higher in Sahelian zone (93%) followed by Sudano-sahelian zone (89%) and Sudanian zone (Kolda and Séfa) with respectively 80 and 84% of recorded species. Domination of therophytes is more accurate in plot with previous fallow (86%) followed by previous millet (82%), previous peanut (81%) and previous mucuna (79%). Also, it was observed a decreasing of perennial species from Sudanian to Sahelian zone.

Abstract Weeds are among the most harmful factors limiting sorghum production under Sudanian conditions of southern Senegal. Despite, the taxonomic structure of the flora is relatively well known, few studies have focused on crop-weed competition. Field experiment was carried out to determine the critical time for weed competition in grain sorghum. Ten treatments, weedy for initial 15, 30, 45 and 60 DAS and then weed-free, and weed-free for initial 15, 30, 45 and 60 DAS and then weedy, weed-free and weedy up to harvest were assigned in a randomized block design with four replications. The beginning and the end of critical period of weed competition were determined respectively under fertilized and unfertilized conditions. The results showed that more the weeds competition is longer, more sorghum parameters of growth and yield are reduced. Sorghum yield were significantly influenced by many factors such as year, nitrogenous fertilization and weeding periods. The highest plant height, dry matter, and yield were recorded in weed free treatment followed by weed free up to 60 DAS and weedy up to 15 DAS. Plant height, dry matter and yield decreased significantly with each increase in competition period. Therefore, the lowest growth parameters and yield were noticed in weedy check treatment followed by weedy up to 60 DAS and weed free up to 15 DAS. Moreover, our findings showed that sorghum height, dry matter and grain yield increased significantly under fertilized conditions compared to unfertilized conditions, which is widely used in traditional cropping system. The maximum competition between crop and weed was between 15-45 and 15-55 DAS under unfertilized conditions (F0) and 10-55 and 15-55 DAS under fertilized conditions (F1), which can be considered as critical period of crop-weed competition. The weeding practice should be adopted during these periods for getting optimum sorghum production under Sudanian conditions of Senegal.

Abstract In Southern Groundnut Basin of Senegal, weed management is one of the biggest challenges for improving upland rice production. This study aimed to evaluate the systematic composition and the infestation of weed species in order to promote a sustainable management in a context of biodiversity decreasing. Thus, phytosociological surveys were carried out during rainy season in upland rice fields. The results revealed that flora consisted of 62 species distributed in 47 genera and 15 families. The families with the highest species richness were Poaceae (24.2%), Fabaceae (12.9%) and Malvaceae (12.9%) which account for half of recorded species. Biological spectrum analysis showed that the flora is largely dominated by therophytes, with 95% of recorded species. Infestation diagram based on weeds abundance and frequency showed eight groups of species reflecting their degree of infestation. Among them, Digitaria horizontalis, Mariscus squarrosus, and Spermacoce stachydea belonged to major weeds and potential general weeds were potentially the most injurious against upland rice because of their high recovery and frequency.

Abstract Weeds are among the most harmful factors limiting crop production in savannah zone of Africa. However, they are crucial for biodiversity and ecosystems sustainable management. A field experiment was conducted in savannah zone of Senegal to determine the effect of organic and mineral fertilization on weed flora in peanut crop. The experiment was laid out in randomize complete block design with four replicates and four treatments (Control, Cattle manure, Compost, and Mineral fertilizer). Our findings show that weed density was not significantly affected by the type of fertilization. However, dry matter of grasses and broadleaf weeds was significantly affected by the treatment respectively in forty and sixty days after treatment. The highest dry weight of grasses was observed in forty days after sowing in cattle manure treatment followed by inorganic fertilizer with respectively 23.7 and 15.2 g/m². In sixty days after sowing, the highest dry matter of broadleaf weeds was recorded in cattle manure treatment with 4.5 g/m². It was noticed that Digitaria horizontalis and Mesosphaerum suaveonlens were the dominant species in all treatment. The biodiversity indices were not significantly influenced by the type of fertilization but the highest values of Shannon-Webber and Simpson indices was recorded in cattle manure treatment. Moreover, the linear correlation between grain yield and diversity indices revealed that Shannon index is highly correlated with the peanut yield.