Morphophysiological responses of Zygia cataractae (Kunth) L. Rico in flooding and submersion conditions

Abstract

Soil flooding can reduce the oxygen available in the soil and around the roots, resulting in physiological and morphological changes in response to such conditions. The species Zygia cataractae (Kunth) L. Rico, Fabaceae, is frequently found in dense forest with drained soil, igapó forest, with moist sandy soil, floodplain forest, and in riparian forests, as near the Paraná River areas. The species has an occurrence restricted to the margin range, which makes it an interesting model in studies aiming to evaluate the physiological responses under flooding and total submersion conditions. For this, young Z. cataractae plants were kept in a greenhouse, under control conditions (CT), under flooding (FL) and under total submersion (TS) for the assessment of physiological responses. Analyses were performed after 15, 30, and 60 days of water treatment (DAWT). In addition, a germination test was carried out, under laboratory conditions, with submerged seeds, using gerbox boxes. Flooded plants showed adventitious roots only after 50 days of treatment. However, roots of Z. cataractae total submerged plants presented higher total stem diameter at 15 and at 50 days of treatment. We observed growth reduction and lower a,b, and total chlorophyll contents in flooded and totally submerged plants. We also observed an increase in the levels of total sugars and sucrose contents in roots of flooded and totally submerged plants. The totally submerged seeds presented higher germination than non-submerged. The results show that this species presents adaptations that ensure its permanence and colonization in environments subject to periodic flooding.