Competitiveness-shifts from weeds to crops using arbuscular fungi
Arbuscular fungi (AF) colonize ca. 80% of terrestrial plant roots and typically improve their growth by enhancing nutrient uptake, reducing disease severity and/or imparting resistance to abiotic stress. Therefore, AF-colonized crop cultivars exhibit early vigor and superior growth compared to cultivars not colonized by AF. However, routine AF inoculation of crops is limited because of their obligate nature. Nevertheless, there are strategies that can be readily adopted by growers to exploit the indigenous AF community. Our project aimed at determining the relationship between the mycorrhizal dependency of crops and crop competitiveness against weeds. The mycorrhizal dependency of eight barley and eight wheat cultivars on an AF mixture resembling that of an indigenous AF community was evaluated in natural soil. There were significant differences between the cultivars in their response to AF. The most and least mycorrhizal cultivar (based on biomass) were evaluated for their competitiveness against wild oat at four crop:weed density levels (1:0.5; 1:1; 1:2; 1:4) in soil with and without the AF mixture. Results showed that the most AF dependent cultivar in both crops exhibited superior growth and competitiveness against wild oat up to a level of 1:1 crop:weed density. This confirms that mycorrhizal dependency is partially linked to crop competitiveness against weeds and that the choice of cultivar may be a strategy which can enhance crop competitiveness while reducing chemical herbicide use.
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