The forage grass Paspalum dilatatum tolerates partial but not complete submergence either caused by deep water or repeated defoliation

MANZUR ME; GRIMOLDI AA; STRIKER GG

Crop and Pasture Science

CSIRO

Año: 2020 vol. 71 p. 190 - 198

1836-0947

Grazing, flooding and their combination are major disturbances that could affect plant performance in humid grasslands. We performed two experiments to study the tolerance of the forage grass Paspalum dilatatum Poir., to different submergence depths and defoliation frequencies. First, we addressed whether this species can shift from the escape strategy to ?quiescence? when completely submerged (CS) for 30 days. Second, we explored to what extent partial (PS) or complete submergence (CS) produced by defoliation, compromise plant regrowth. The results showed that regardless of the depth of water at submergence, P. dilatatum always responded by attempting to expose its leaf area above water, by increasing the tiller angle and/or blade length (i.e. tiller height). PS plants showed a reduction in starch concentration (89%) but biomass was unaffected, while CS plants did not survive. After one defoliation event, 77% of aerial biomass of PS plants was removed and the concentration of carbon reserves (water-soluble carbohydrates and starch) decreased to a half of the one of controls. A second event of defoliation (20 days later) of plants with few reserves removed 50-52% of shoot biomass and compromised plant survival, with plants dying before the end of the experiment. In conclusion, P. dilatatum does not tolerate prolonged complete submergence conditions, either caused by deep water columns or by repeated defoliation.