Hydric stress index of sunflower irrigated with water replacement fractions and magnetically altered water

Resumen

The objective was to evaluate the water sensitivity of sunflower (Helianthus annuus L.) using the crop water stress index (WSI) and leaf area (AF), when subjected to soil water variation and using normal and magnetized water in irrigation. The experiment was conducted in pots with cv BRS 323 grown in red latosol. The design was randomized blocks (DBC) in a 4 x 2 x 4 factorial scheme with 4 replications, with 4 water replacement fractions (100, 75, 50, 25% - RH); 2 types of irrigation water (normal and magnetized) and 4 evaluation periods (20, 40, 60 and 80 days after emergence - DAE). The magnetization occurred through the Sylocimol magnetizer constantly deposited in a different reservoir and the RHs were administered with the fractions of the crop's real evapotranspiration (ETrc) obtained by the water balance. In calculating the WSI, the air temperature was measured using a maximum and minimum thermometer and the leaf temperature was measured using a digital infrared thermometer. FA was calculated indirectly after measuring leaf lengths. Magnetized water reduced AF and increased WSI. Greater plant hydration reduced WSI, regardless of the type of water. The highest WSI occurred at HRs of 25% and 50% at 68 and 84 DAE, respectively. The maximum AF is only obtained at a RH of 127.5%, that is, outside the water range imposed in the study, resulting from its quality.