Inter-specific competition between finger millet and Guinea grass for growth and nutrient uptake under nutrient-limited conditions

ABSTRACT Crop–weed interactions in nutrient-deficient environments can induce strong intra- and inter-specific competition for such nutrients. The study investigated nutrient uptake by finger millet (FM; Eleusine coracana (L.) Gaertn.) in the presence of the upland weed, Guinea grass (GG; Panicum maximum Jacq), under nutrient-limited conditions. A pot experiment was conducted with different neighbor-densities of the two species, including monocultures and mixed cultures. The effects of inter-specific/intra-specific competition on nutrient uptake and growth of the two plant species were measured. Varied plant combinations impacted on plant dry weight, uptake, and use efficiency of nitrogen, phosphorus, and potassium by FM. Root and shoot dry weights of FM were markedly reduced in the presence of GG compared to that when neighbors were from the same species. The largest reduction of tissue nutrient concentration of FM was recorded in FM:GG plant combination of 1:2. The results indicated that the growth and nutrient uptake of FM was suppressed when it co-existed with GG due to strong inter-specific competition under nutrient-limited conditions. GG maintained similar biomass irrespective of the fertilizer treatment and plant combinations, demonstrating its ability to outcompete neighboring species when resources are limited in the growing environment. The present study also provides scientific evidence that GG is well adapted to nutrient-poor environments, which is attained through enhancing the use efficiency of limited nutrients in biomass formation. This might have helped GG to gain the competitive advantage over other plants in the same habitat and dominate in most agro-ecological systems as an invasive weed species.