Reducing Nitrogen Input in Barley Crops While Maintaining Yields Using an Engineered Biostimulant Derived From Ascophyllum nodosum to Enhance Nitrogen Use Efficiency

Abstract

Intensive agricultural production utilizes large amounts of nitrogen (N) mineral fertilizers that are applied to the soil to secure high crop yields. Unfortunately, up to 65% of this N fertilizer is not taken up by crops and is lost to the environment. To compensate these issues, growers usually apply more fertilizer than crops actually need, contributing significantly to N pollution and to GHG emissions. In order to combat the need for such large N inputs, a better understanding of nitrogen use efficiency (NUE) and agronomic solutions that increase NUE within crops is required. The application of biostimulants derived from extracts of the brown seaweed Ascophyllum nodosum has long been accepted by growers as a sustainable crop production input. However, little is known on how Ascophyllum nodosum extracts (ANEs) can influence mechanisms of N uptake and assimilation in crops to allow reduced N application. In this work, a significant increase in nitrate accumulation in Arabidopsis thaliana 6 days after applying the novel proprietary biostimulant PSI-362 was observed. Follow-up studies in barley crops revealed that PSI-362 increases NUE by 29.85–60.26% under 75% N input in multi-year field trials. When PSI-362 was incorporated as a coating to the granular N fertilizer calcium ammonium nitrate and applied to barley crop, a coordinated stimulation of N uptake and assimilation markers was observed. A key indicator of biostimulant performance was increased nitrate content in barley shoot tissue 22 days after N fertilizer application (+17.9–72.2%), that was associated with gene upregulation of root nitrate transporters (NRT1.1, NRT2.1, and NRT1.5). Simultaneously, PSI-362 coated fertilizer enhanced nitrate reductase and glutamine synthase activities, while higher content of free amino acids, soluble protein and photosynthetic pigments was measured. These biological changes at stem elongation stage were later translated into enhanced NUE traits in harvested grain. Overall, our results support the agronomic use of this engineered ANE that allowed a reduction in N fertilizer usage while maintaining or increasing crop yield. The data suggests that it can be part of the solution for the successful implementation of mitigation policies for water quality and GHG emissions from N fertilizer usage.

Can Seaweed Extract Improve Yield and Quality of Brewing Barley Subjected to Different Levels of Nitrogen Fertilization?

“…In the current research, we only determined the NUE that demonstrated a significant enhancement in treated plants (about +18% over untreated plants). Similarly, Goni et al [61] reported an increase in NUE ranging between 29.86% and 60.28% on barley treated with a biostimulant derived from extracts of Ascophyllum nodosum. Considering the low NUE of cereals, which take up between 36% and 42% of applied N fertilizer [62], these positive results attributable to the biostimulants application are much more interesting.…”

Biostimulant Effects of an Aqueous Extract of Duckweed (Lemna minor L.) on Physiological and Biochemical Traits in the Olive Tree

“…The N supply is a key factor that can condition the activities mentioned above [2,60,61]. Generally, the impact of biostimulants on N content is attributed to their ability to stimulate the enzymes of the nitrogen metabolism and upregulate the root nitrate transporters, as shown in recent studies carried out in maize and soybean [62][63][64].…”

Current Insights into the Molecular Mode of Action of Seaweed-Based Biostimulants and the Sustainability of Seaweeds as Raw Material Resources

“…These pre-adaptation responses may lead to enhanced tomato growth and yield observed following timely applications of SF both under non-stressful and stressful field conditions [ 167 , 170 ]. Ameliorated nitrogen uptake and assimilation after using an A. nodosum extract was also demonstrated in barley [ 172 ]. The A. nodosum treatment in spinach upregulated genes coding for glutamine synthetase ( GS1 ), which catalyses the conversion of inorganic nitrogen (ammonium) to organic form (glutamine) and plays an essential role in nitrogen metabolism and assimilation [ 152 ].…”

“…Microarray analysis and gene expression data showed an increased expression in seaweed extract treated plants of the Cu transporter COPT2 and the NRAMP3 which has a putative a role in Fe and Zn translocation [ 174 ]. The A. nodosum extract treatment upregulated genes involved in the transport of amino acids ( LHT1 and AAP5 ), calcium ( CAX3 , CAX7 and ACA1 ), peptides ( ATOPT3 ), nucleotide sugar derivatives ( UTR2 and UTR3 ), copper ( COPT2 ), nitrate ( NRT1.5 ), nucleotides ( ATPUP10 ), sugars ( MSS1 ), and sulphate ( SULTR1 , SULTR3 , and AST56 ) in Arabidopsis [ 172 ]. The above-mentioned studies concluded that the mineral content from the seaweed extracts is negligible and insufficient for inducing these effects.…”