Applying Biostimulants to Combat Water Deficit in Crop Plants: Research and Debate

Climate change has increased the severity of drought episodes by further reducing precipitation in vulnerable zones. Drought induces a substantial decrease in agricultural water, reducing crop yields. Consequently, addressing water consumption can increase farmers’ profits. This work describes lab-to-field research in Zea mays, using two biostimulants: glycine betaine (GB) and Lpyroglutamic acid (PG). The biostimulant optimal dosages were selected using a hydroponic system with 20% polyethylene glycol and nursery experiments under water-deficit irrigation. The established dosages were evaluated in field trials in which irrigation was reduced by 20%. Laboratory biostimulant optimisation showed in stressed treated seedlings (GB 0.1 mM; PG 1 mM) an increased dry weight, relative growth rate and water use efficiency, reducing seedling growth loss between 65 and 85%, respectively. Field trials using a GB-optimised dosage showed an increase in plants’ growth, grain yield and flour Ca content. In addition, grain flour carbohydrate content and protein remained similar to control well-watered plants. Finally, the economic aspects of biostimulant treatments, water consumption, water sources (ground vs. desalinated) and grain biomass were addressed. Overall, GB treatment demonstrated to be a valuable tool to reduce water consumption and improve farmers’ earnings.This work was financed by the project AHIDAGRO (MAC2/1.1b/279), Cooperation Programme INTERREG-MAC 2014–2020, with European Funds for Regional Development—FEDER. F.J.G.M. and A.G.G., PhD students at the University of La Laguna, were supported by research fellowship contracts from the Gobierno de Canarias. A.E.H is grateful for support from the project “Plants as a tool for sustainable global development” (CZ.02.1.01/0.0/0.0/16_019/0000827) and Erasmus + HE—2015 for her mobility grant. The authors thank Natalia Usenco for her technical support during field sample processing. The manuscript was revised by G. Jones, funded by Cabildo de Tenerife under the TFinnova Programme and supported by MEDI and FDCAN.Peer reviewe