Responses of rare and common segetal species to wheat competition and fertiliser type and dose

Abstract

Fertiliser application is considered crucial for determining the crop-weed competition relationship by stimulating plant growth and modulating the competition for below-ground (soil nutrients) and above-ground resources (e.g. light and space). Segetal species, those preferentially inhabiting cereal fields, have suffered a strong decline, owing to agricultural intensification. Under continued pressure, particularly the rarest species may disappear. In this study, we aimed to assess the competitive ability of common and rare segetal species when growing with wheat and how this competitive relationship is modulated by the type (organic and mineral) and dose (low or high) of fertilisation in a pot experiment. The segetal species grew better at higher doses of fertilisers when growing alone. However, when growing with wheat, they were outcompeted by the cereal plants. Overall, flowering was not affected by the competition with wheat under the different fertiliser regimes. Only the onset of flowering of some segetal weeds tended to be delayed by crop competition. Some rare species were more affected by the competition with wheat, indicating that they may be disadvantaged in a community context. However, not all rare segetal species tested responded in the same way, which highlights that competitiveness alone is a poor predictor of the rarity of segetal species.

Reintroduction of rare arable plants by seed transfer. What are the optimal sowing rates?

“…In nutrient‐rich arable fields, we expect a higher competitiveness of rye and lower crop yield losses caused by the rare arable plants (Rotchés‐Ribalta et al. ).…”

Seedling emergence response of rare arable plants to soil tillage varies by species

“…Although herbicides may be an important driver of RAP decline, they are not necessarily a direct cause of rarity for all species [ 10 ]. Moreover, for other factors such as crop competition and/or fertilizers not all rare segetal species respond in similar ways, which highlights that these factors alone are poor predictors of the rarity of RAP species [ 11 ], and others should also be considered.…”

Management options for the conservation of rare arable plants in Europe

“…However, in some instances, individuals of rare species characterized by relatively greater competitiveness may be able to compensate for reduced establishment by increased growth (Svensson and Wigren 1982;Kleijn and Van den Voort 1997). In contrast, in the absence of crops, introduced rare species generally benefit from additional fertilizer (Svensson and Wigren 1982;Kohler et al 2011;Rotchés-Ribalta et al 2016). However, some particularly uncompetitive rare species may fail to benefit from fertilizer even then, possibly due to being outcompeted by spontaneous non-crop species.…”