No escape? Costs and benefits of leaf de-submergence in the pasture grass Chloris gayana under different flooding regimes

STRIKER GG; CASAS C; KUANG G; GRIMOLDI AA

FUNCTIONAL PLANT BIOLOGY

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2017 vol. 44 p. 899 - 906

1445-4408

Elongation-induced leaf emergence is one way for plants to deal with completesubmergence by ?escaping? from water. This growth strategy is hypothesized to be more beneficial under single long-term submergence than under repeated short-term submergence events (i.e. fluctuating environment), as costs of repeated plant ?adjustment? would exceed the initial benefits of shoot elongation. To test this idea, 2-week-old plants of Chloris gayana cv. Fine Cut (a submergence-tolerant cultivar firstly selected by a screening experiment) were grown for 4 weeks under (i) control conditions, (ii) two 1-week submergence cycles, or (iii) one 2-week submergence cycle. Additionally, a set of plants were placed below nettings to assess the cost of remaining forcedly submerged. Impeding leaves emergence through nettings did not compromise survival when submergence was 1-week long, but determined the death of all plants when extended to 2 weeks. Growth as affected by flooding regime revealed that under one 2-week submergence event, plants accumulated a 2.9-fold higher dry mass than when they experienced the same submergence duration in separate events along 1week. The ?escape? strategy in the grass C. gayana, by which leaf contact with air is reestablished, is essential for its survival, and it is more beneficial for plant growth under long-term submergence than under repeated short-term submergence cycles.