Nano urea effects on Pleurotus ostreatus nutritional value depending on the dose and timing of application

The work investigated the effect of Lithovit-Urea50 on the composition of Pleurotus ostreatus (Jacq. Ex Fr.) P. Kumm. (1871) cultivated on spent oyster substrate mixed with wheat straw (1:1, w/w mixture). The product was applied in different doses (C 1 : 3 g kg −1 and C 2 : 5 g kg −1 ) at three distinct timings (t 1 : at spawning, t 2 : after first harvest, t 3 : at spawning and after first harvest). Protein and fiber contents increased respectively by 0.64 and 0.2% in C 1 t 1 and by 0.46 and 0.8% in C 2 t 2 compared to control (C 0 t 0 ). Total carbohydrates increased by 0.48–3.76%. Sucrose and glucose contents decreased in the majority of treatments, while fructose increased in C 2 t 1 (by 0.045%). Essential amino acids were the highest in C 1 t 1 , wherein respective improvement of 0.31, 0.10, 0.05, 0.21, 0.18, and 0.09% compared to C 0 t 0 . Similarly, C 1 t 1 was superior in non-essential amino acids. Potassium, sodium, calcium, iron, and copper contents decreased in all treatments, with minor exceptions, zinc decreased in C 1 t 1 and C 2 t 1 , while nickel and lead increased in all treatments. Conclusively, despite important ameliorations in the mushroom nutritional value, mostly in C 1 t 1 , the product should be further tested in lower doses (