The introduction of the Lr#N short arm to elite spring wheat lines resulted in the release of BNI root exudates confirmed with a micro-bioassay. The inhibition potential on nitrifying microbes under laboratory conditions is promising, but it remains unclear if the BNI trait introduced to various wheat lines can significantly reduce nitrification under field conditions.

Measuring the expression of BNI in the field is challenging and there is no methodology that allows BNI quantification in soil-root systems. This study aims to test the yield potential of BNI translocation spring wheat lines and simultaneously confirm BNI expression under field conditions. Six pairs (parental/control vs. translocation line) were planted under four N fertilizer application rates (0, 75, 150 and 225 kg N ha-1) in three locations in Mexico. Stability for yield quantity and quality was observed after the first crop seasons.

Grain protein was higher for some BNI wheat lines. Expected reduced nitrate formation in the root zone and lower potential nitrification rates in post-harvest sampled soil could not be confirmed after one planting season. It is assumed that a significant expression of the BNI effect requires more than one planting season since both, accumulation of actively released BNIs and passively released BNIs during root turnover after harvest are responsible for significant reduction of nitrate formation.

Therefore, CIMMYT will test within the BNI mission ‘CropSustaiN’ a set of BNI translocation lines in Latin America, Africa and South Asia under different N fertilizer and soil pH conditions in the next years to verify the global potential of the BNI trait.