SYNERGISTIC EFFECT OF POTASSIUM HUMATE AND UREA ON WHEAT GRAIN GERMINATION INDICATORS: GERMINATION, ROOT SURFACE AREA AND ANTIOXIDANT RESPONSE

Аннотация

Humic substances are widely used as plant biostimulants, yet their growth-promoting efficacy depends on nutrient background and growth stage. Here, we evaluated potassium humate (K-humate) alone and in combination with urea for wheat (Triticum aestivum L.) performance in a two-phase assay. In a Petri-dish germination test (DI water vs 0.1 % K-humate), germination was scored at day 3 using a radicle length threshold of 2 mm. Subsequently, seedlings were transferred to hydroponics and subjected to three treatments: G1 (K-humate during germination followed by K-humate + urea), G2 (K-humate followed by K-humate), and G3 (DI water control). At day 12, shoot and root fresh mass, root surface area (SmartRoot), TTC reduction, ascorbate peroxidase (APX) activity, and chlorophyll content were quantified. Germination percentages at day 3 were
similar between DI water (59.2 %) and 0.1 % K-humate (56.0 %). Root surface area differed significantly among treatments (one-way ANOVA, F = 8.35, p = 0.0015, n = 10), peaking in G1 (9.91 ±
± 3.51) and exceeding G3 (5.05 ± 1.42). Biomass accumulation was highest in G1, while APX activity increased ~4.8–4.9-fold relative to G2 and G3, indicating a stronger antioxidant response under the combined K-humate + nitrogen regime. Overall, the results support that K-humate benefits wheat seedlings primarily when paired with an available nitrogen source, translating into larger absorptive root surface area and higher biomass.