Effect of biostimulants combined with fertilization on yield and nutritional value of wheat crops

Background: Bread wheat (Triticum aestivum) is one of the most widely cultivated crops globally; it is nutritionally demanding and may be responsible for soil exhaustion, requiring adequate fertilization to maintain high yields and grain quality. Targeted supplementation of macro- and micronutrients can also be used for the agronomic biofortification of the grains. However, excessive chemical fertilizers can harm the environment and human health, and more sustainable options are therefore required. This work proposes alternative strategies to chemical fertilization, including applying organic fertilizers, biostimulants, and low-impact agronomical practices like foliar spraying, to achieve high yields and enrichment in cationic nutrients calcium, magnesium, and potassium. Experimental plan: The study investigates the impact of different fertilization strategies on wheat yield and nutrient composition using two wheat genotypes characterized by different nitrogen (N) grain content. The plants were grown in pots and underwent differential root fertilization with 50 kg ha-1 N at the tillering stage, comparing mineral and organic products. At heading, foliar treatments (25 kg ha-1 N) were applied, comparing a traditional urea supplementation with a combination of biostimulants from organic wastes and calcium, magnesium and potassium nitrates. The plants were analyzed for their health and the expression of genes for nutrient homeostasis during growth, and for yield and grain quality at harvesting. Results: The two alternative fertilization approaches positively impacted plant health and yield in both cultivars. Root fertilization accounted for most of the total variance, affecting both early and late-stage yield components; the organic fertilizer produced results comparable to those of the mineral one. Furthermore, the foliar application of base cations and biostimulants led to beneficial changes in nutrient homeostasis and grain mineral content, although the increase in calcium, magnesium and potassium was moderate and genotype-specific. Conclusions: This work identifies organic amendments, foliar spraying and biostimulants as alternative and sustainable strategies that can be as effective as chemical fertilization in improving wheat plant health, yield and grain composition. On the other hand, supplementing with cation nutrients at heading showed minimal biofortification benefits. The study emphasizes the importance of considering genotype-specific needs to optimize nutrient uptake and yield across different wheat cultivars.