biostudies-literatureLatimer JOCotton Research and Development Corporatione0334700https://www.ebi.ac.uk/biostudies/studies/S-EPMC12700366biostudies-literatureUnknown20(12)Low molecular weight (LMW) soil organic nitrogen (N) can be a significant source of N in commercial cotton (Gossypium hirsutum L.) systems, potentially comprising a meaningful portion of N uptake in Australian irrigated cotton. Cotton obtains the majority of its N from the soil N pool rather than directly from fertiliser-N. Organic N is the major component of the soil N pool. The purpose of this study was to test the ability of G. hirstutum to take up different organic and inorganic N forms using isotopically labelled compounds. This was done in a sand matrix to reduce potential for microbial competition and enable a clearer view of the physiological capacity of the plant to access different N forms. The experiment showed that cotton took up inorganic N (NO3- and NH4+) and organic N (alanine and urea) concurrently, with a slight preference towards inorganic N overall. The uptake mechanism for organic carbon (C) associated with the organic N was also examined, showing that alanine-C was taken up linearly, with a consistent internal 13C:15N ratio suggesting that some alanine was absorbed intact without extracellular deamination. Overall, the experiment demonstrated that G. hirsutum can rapidly and concurrently access different soil N pools, with a slight preference for inorganic N. The uptake mechanisms for organic N and C are complex, differing between compound types, and warrant further investigation. This study expands the list of plants known to utilise organic N to include commercial cotton, with implications for the management of N fertiliser in cotton growing systems.PloS oneNitrogen uptake preference of cotton (Gossypium hirsutum L.).PMC12700366CSP1904Latimer JOMacdonald BCTFarrell MfalseNitrogen uptake preference of cotton (Gossypium hirsutum L.).Low molecular weight (LMW) soil organic nitrogen (N) can be a significant source of N in commercial cotton (Gossypium hirsutum L.) systems, potentially comprising a meaningful portion of N uptake in Australian irrigated cotton. Cotton obtains the majority of its N from the soil N pool rather than directly from fertiliser-N. Organic N is the major component of the soil N pool. The purpose of this study was to test the ability of G. hirstutum to take up different organic and inorganic N forms using isotopically labelled compounds. This was done in a sand matrix to reduce potential for microbial competition and enable a clearer view of the physiological capacity of the plant to access different N forms. The experiment showed that cotton took up inorganic N (NO3- and NH4+) and organic N (alanine and urea) concurrently, with a slight preference towards inorganic N overall. The uptake mechanism for organic carbon (C) associated with the organic N was also examined, showing that alanine-C was taken up linearly, with a consistent internal 13C:15N ratio suggesting that some alanine was absorbed intact without extracellular deamination. Overall, the experiment demonstrated that G. hirsutum can rapidly and concurrently access different soil N pools, with a slight preference for inorganic N. The uptake mechanisms for organic N and C are complex, differing between compound types, and warrant further investigation. This study expands the list of plants known to utilise organic N to include commercial cotton, with implications for the management of N fertiliser in cotton growing systems.2025-01-01T00:00:00Z20252026-06-06T02:01:19.64Z2026-05-24T03:12:09.575ZS-EPMC127003664138550810.1371/journal.pone.0334700