The Development and Condition of Selected Legume Species Depending on the Rate of Superabsorbent Under Conditions of Limited Irrigation

Legumes are among the most important crop species in the world. They are the foundation of global food security and, in addition to providing protein, improve soil fer-tility and sustainable agriculture. However, they are sensitive to climate change and une-ven rainfall distribution. Three two-factor pot experiments were conducted in MI-CRO-CLIMA phytotrons. The objects of the study were three legume species: faba bean, pea and soybean. The first factor was the superabsorbent (SAP) rate (0, 2, 4, 6 g·kg-1 of sub-strate), while the second factor was the watering frequency (the subjects were watered every 1, 3, 6, 9 days). The scope of the research included measurements of chlorophyll flu-orescence (Fv/Fm, PI), leaf greenness index (SPAD) and biometric measurements. The study showed a significant effect of superabsorbent application on biometric parameters of legumes. Faba bean and pea plants were significantly taller after superabsorbent appli-cation and developed greater root mass. The highest SAP dose reduced the Fv/Fm index in soybean and the PI index in faba bean and soybean. The lowest SPAD index in pea was recorded in the control treatment (without SAP), while the highest SAP dose in soybean resulted in a decrease in relative leaf chlorophyll content compared to the other treat-ments. Plants watered daily were significantly taller, developed a greater number of nodes, and had higher dry mass of both above-ground and underground parts compared to plants watered every 3, 6, and 9 days (only in soybeans the dry mass of the under-ground part was significantly higher in the treatment watered least frequently). Higher values of the Fv/Fm index were observed in soybean, and higher values of the PI index were observed in faba bean, pea, and soybean in the least frequently watered treatments. In all species studied, SPAD index was higher under conditions of the greatest water defi-cit (watering every 9 days) compared to plants watered every 1, 3, and 6 days.