The Effect of Foliar Application of Biostimulants/Fertilizers in Potato (Solanum tuberosum L.) Cultivation on Selected Physicochemical, Thermal and Rheological Properties of Starch

Foliar preparations are used in potato cultivation, and their use can affect starch properties, which are important for food production. Therefore, the aim of this study was to evaluate the effect of foliar application of preparations (biostimulants, fertilizers) during the growing season of potatoes (Solanum tuberosum L.), cultivar Concordia, on selected physicochemical, thermal, and rheological properties of starch. Eight commercial preparations (Basfoliar 12-4-6+S + ADOB PK (ADOB), Asahi SL, BlueN®, Megafol®, Quantis™, Qultivo, Rizoderma TSI, and Rizofos) were foliarly applied during the growing season. Potato starch was isolated using a laboratory method. Starch from potatoes grown without foliarly preparations served as a control sample. The research methodology included determination of amylose content and mean starch granule diameter. Thermodynamic characterization of gelatinization and retrogradation was performed using a DSC (differential scanning calorimeter), viscometric pasting characterization was performed with a Rapid Visco Analyzer (RVA), and flow curves were determined. A statistically significant effect of the type of foliar biostimulant/fertilizer applied on amylose content, starch grain size distribution, and rheological properties of the tested starches was observed. Amylose content ranged from 31.7% (BlueN) to 36.3% (ADOB). Starch from potatoes grown with ADOB had the largest grains, with the largest number of grains having a diameter >40 µm. The tested starches generally did not differ in terms of the onset, peak, and end temperatures of gelatinization determined using DSC. Similarly, slight differences were observed in the pasting temperature determined viscometrically. The RVA analysis showed that the highest maximum viscosity value was observed for starch obtained from the raw material stimulated with the Megafol preparation (3744 mPa·s), and the paste based on starch isolated from potatoes grown with the Asahi biostimulant was characterized by the highest rheological stability at 95 °C. The starch pastes obtained from the raw material stimulated with the Megafol and Quantis preparations were characterized by the lowest values of the consistency coefficient (15.7 Pa·sn), and the control starch had the highest value of this parameter (21.7 Pa·sn).