Nitrogen Use Efficiency Modification

Smart farming techniques continue to make inroads into improving fertiliser application timings to crops and improving plant N bioavailability. Nitrogen use efficiency (NUE) by plants is partly dependent on root architecture, but also a diverse group of cellular N-transporting systems which move nitrogen in its different forms from roots to stems and leaves where it is remobilised. N-partitioning between stems and leaves together with photosynthetic activity and leas senescence status define NUE. New gene editing technology is targeting different plant N-transporter genes to try and upregulate them for improved NUE and help fertiliser application. Achieved in rice, NUE modified cereal crops are still in the R&D phase.

Another disruptive technology is the introduction via a simple seed coating of a symbiotic non-nodulating bacterium from sugar cane into crop plants such as wheat. The bacterium known as Glauconacetobacter diazotrophicus symbiotically colonises wheat and can fix atmospheric N even when nitrate and ammonium fertilisers are applied. It is also able to excrete around half of its fixed N as ammonium which is then available to the plant.

Up or downregulating N-transporter genes are targets for CRISPR gene editing and are being investigated by several researchers for developing plants which are able to better use nitrogen.

Azotic technologies have developed a patented seed coating to introduce the N-fixing bacterium Glauconacetobacter diazotrophicus into wheat plants where it develops a symbiotic interaction between and inside plant cells.  Although limited wheat field trials have been undertaken in the UK, Germany, France and USA – they all showed significantly better NUE than with fertiliser alone.

Ideally suited to sustainable precision farming approaches, wheat cultivars with improved NUE can be used to reduce fertiliser applications, whilst maintaining yield.