Ascophyllum nodosum seaweed extract in Inga edulis seedlings under drought and the potential of phenotypic plasticity

Abstract Studies aiming alleviating the effect of drought on plants have increased, and the use of seaweed extract has been a sustainable and promising management for stress tolerance. Thus, this work aimed to evaluate the role of Ascophyllum nodosum (L.) Le Jolis seaweed extract (ANE) in Inga edulis Mart. seedlings under drought and post-stress. The seedlings were cultivated under: 1) control (daily irrigation), 2) drought by water restriction – WR (irrigation suspension), 3) WR + 15 mL L-1 ANE, 4) WR + 30 mL L-1 ANE, and 5) WR + 45 mL L-1 ANE, and evaluated in two periods: i) SWD - when the seedlings showed symptoms of water deficit, and ii) REC: recovery (post-stress) - resumption of irrigation for 60 days. The application of 45 mL ANE contributed to the N content of seedlings under drought and post-stress. The order of nutritional requirement was similar for N, Ca, and Mg, but P and K varied according to the evaluation periods under drought. The application of 30 and 45 mL L-1 ANE contributed in the post-stress, favoring the quantum efficiency of photosystem II in response to the higher nutrient content in plant tissue, reflecting on growth in the REC. ANE increased proline content as osmoprotection mechanism during SWD and promoted an efficient recovery. The application of 30 and 45 mL ANE contributes to induction of stress tolerance in I. edulis seedlings under drought, and it favors recovery of plants in the post-stress due to phenotypic plasticity, which becomes a promising management for this species.