The effect of superabsorbent and different rates of the local fertilizer on garlic productivity in the forest-steppe of Ukraine

This study aimed to determine the effect of different rates of topical fertilizers on the background of superabsorbent polymers (absorbents; SAP) on plant growth, pigments content in leaves and activity of antioxidant enzymes in leaves and soil, yield and nutritional value of products. For this purpose, an absorbent at the rate of 15 kg ha–1 and fertilizers were applied, spread on the soil surface 100% (control), and locally in the furrows when planting at the rate of 25, 50, 75, and 100% of the recommended rate were applied. The results showed that the use of superabsorbent polymers (SAP) and the local application of fertilizers with increasing their rate, a significant increase in chlorophyll b and the number of chlorophylls. However, the use of SAP reduced the activity of antioxidant enzymes in the leaf (superoxide dismutase by 9.5–23.2%; glutathione S-transferase by 7.4–13.4%; peroxidase by 8.4–19.0%). The bulb’s weight with the absorbent increased by 31.2–45.4% compared to similar options without the introduction of absorbent. The local fertilizer without absorbent increased garlic yield by 3.5–13.9% relative to control. With the introduction of the absorbent, the local application of fertilizers contributed to the increase of yield by 4.2–25.4%. The application of fertilizers at the rate of 50 and 75% separately and together with the absorbent contributed to the improvement of nutritional value (dry matter, ash, proteins and carbohydrates, fat and caloric content of products). In conclusion, the combination of SAP with local fertilization in crop production technology can be used in today's dynamic climate conditions, due to their beneficial effects on plant productivity and savings and efficient use of water and fertilizers. Further research consists of a more detailed study of the rate of application of absorbents, the duration of their effective action, and the rate and ratio of nutrients.