Rickinreallife's picture
A recent article in Seed Today "Arcadia Biosciences Announces Successful Field Trials of New Nitrogen Use Efficient Rice" [http://www.seedtoday.com/articles/Arcadia_Biosciences_Announces_Successful_Field_Trials_of_New_Nitrogen_Use_Efficient_Rice-135090.html] reported the results of two-year trials of genetically engineered rice varieties that appear to have achieved impressive results including that at half the nitrogen fertilizer application, the varieties outyeilded the controls by 22% the first year and 30% the second year. How exactly are plants modified to increase nitrogen use efficiency, what alternatives to genetic engineering exist to endow plants with greater nitrogen use efficiency, what are the potential applications of nitrogen use efficiency traits?

A:Expert Answer

One of our research priorities is developing corn hybrids that use nitrogen more efficiently. 

A corn plant utilizes nitrogen in multiple ways, including how the plant takes in nitrogen, stores it, and remobilizes it. While I can’t comment on the work by Arcadia, DuPont researchers are taking multiple approaches to developing plants that use nitrogen more efficiently. We are applying transgenic, molecular and conventional breeding methods to enhance nitrogen utilization in corn hybrids. 


One option to make a plant more nitrogen use efficient is changing root architecture to improve nitrogen uptake (which also may improve tolerance to drought, as a group of maize researchers in Africa have demonstrated). Another strategy is helping a plant more rapidly convert nitrogen into useful amino acids and proteins, or directing more nitrogen into harvestable plant parts like the grain (this is called changing the “harvest index”). Simply helping a plant stay green longer also helps by prolonging photosynthesis and put more nitrogen to use; we’ve done that, too.  


The applications for improved nitrogen use efficiency are exciting. Nitrogen is one of the most significant input costs for farmers raising corn, typically accouting for at least 20 percent of variable costs depending on crop rotation. If we can develop corn plants that deliver higher yields while maintaining the current level of nitrogen applications, that will give farmers the opportunity to reduce input cost per bushel of corn produced.  It also reduces the environmental impact of nitrogen fertilizer production, application and use.


Think of farmers in Asia and Sub-Saharan Africa, working in highly weathered soils with limited access to expensive nitrogen fertilizer. A crop that utilizes nitrogen better and is more productive in these difficult environments would probably be very popular with local farmers (and the consumers who rely upon them!).  In areas where nitrogen fertilizer is readily available, using that nitrogen more efficiently would save farmers money, increase yields, put more nitrogen into the crop, and leave less in the soil where it has the potential to reach surface and ground water. Developing more options for farmers, like nitrogen use efficiency, which improve productivity and environmental sustainability is what we’re about.

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Rickinreallife's picture

Dr. Gaffney:

Thank you for your answer. To me, enabling a plant to increase production with the same fertilizer input or alternatively, to maintain yields at reduced nitrogen input is a great application of crop improvement technology, whether involving genetic engineering or otherwise. I personally believe it would be a significant game changer if there we are able to achieve such a breakthrough, and I believe it is an application of genetic advancement that may be made possible through bioengineering techniques that could have widespread public support. It is one application that could be beneficial in organic systems to help overcome the nitrogen cap, and even for conventional farming would make a lot of soil stewardship practices more practical.

I don't know how much greater yield can be attained through greater N use efficiency as I would anticipate that there may be a maximum theoretical yield for any given crop, (there is a finite amount of sunshine for example) but I think it is important to pursue.