Glutacetine® Biostimulant Applied on Wheat under Contrasting Field Conditions Improves Grain Number Leading to Better Yield, Upgrades N-Related Traits and Changes Grain Ionome

Abstract

Wheat is one of the most important cereals for human nutrition, but nitrogen (N) losses during its cultivation cause economic problems and environmental risks. In order to improve N use efficiency (NUE), biostimulants are increasingly used. The present study aimed to evaluate the effects of Glutacetine^®, a biostimulant sprayed at 5 L ha^-1 in combination with fertilizers (urea or urea ammonium nitrate (UAN)), on N-related traits, grain yield components, and the grain quality of winter bread wheat grown at three field sites in Normandy (France). Glutacetine^® improved grain yield via a significant increase in the grain number per spike and per m², which also enhanced the thousand grain weight, especially with urea. The total N in grains and the NUE tended to increase in response to Glutacetine^®, irrespective of the site or the form of N fertilizer. Depending on the site, spraying Glutacetine^® can also induce changes in the grain ionome (analyzed by X-ray fluorescence), with a reduction in P content observed (site 2 under urea nutrition) or an increase in Mn content (site 3 under UAN nutrition). These results provide a roadmap for utilizing Glutacetine^® biostimulant to enhance wheat production and flour quality in a temperate climate.

Keywords: SPAD-502®; Triticum aestivum; X-ray fluorescence; grain quality; ionome; nitrogen fertilizer; nitrogen use efficiency; plant biostimulants.

Figure 1

Effect of the Glutacetine^® formulation under urea or UAN nutrition on grain yield and yield parameters in wheat (Triticum aestivum L.). (A) Grain yield (t ha⁻¹), (B) spike number per square meter, (C) grain number per spike, (D) grain number per square meter, (E) thousand grain weight (TGW) and (F) specific weight (kg hL⁻¹). Plant culture was carried out under three different field conditions in France, Normandy. N was provided at tillering, stem elongation and the flag leaf stages. Glutacetine^® was mixed with water and sprayed at a dose of 5 L ha⁻¹ on the same day as the last N application. Bars indicate means ± SE. ⁎ and † denote significant differences according to Fisher’s test or Kruskal–Wallis test, respectively (p < 0.05; n = 3).

Figure 2

Effect of Glutacetine^® formulation under urea or UAN nutrition on N-related traits at maturity in wheat (Triticum aestivum L.). (A) %N in grain dry weight (DW), (B) %N in straw DW, (C) total grain N (kg ha⁻¹) and (D) N use efficiency (NUE, kg kg⁻¹). Plant culture was carried out under three different field conditions in France, Normandy (otherwise, see Figure 1 for more details). Bars indicate means ± SE. ⁎ denotes significant differences according to Fisher’s test (⁎: p < 0.05; ⁎⁎: p < 0.01; n = 3).

Figure 3

SPAD index calibration and N-related traits associated with the flag leaf in wheat (Triticum aestivum L.). (A) Relationship between the SPAD index (chlorophyll level) and %N in the flag leaf of wheat, (B) %N in the flag leaf at heading stage, (C) %N in the flag leaf during seed development and (D) the Δ%N in the flag leaf between heading and seed development stages of wheat. Plant culture was carried out under three different field conditions in France, Normandy (otherwise, see Figure 1 for more details). Bars indicate means ± SE. †† denotes significant differences according to the non-parametric Kruskal–Wallis test (p < 0.01; n = 9 for the ∆%N in the flag leaf between heading and seed development stages).