Application of water-saving irrigation and biostimulants on the agronomic performance of maize (Zea mays)

Water deficit can limit maize yield; therefore, appropriate choices of irrigation schemes or water-saving irrigation strategies to maximize WUE are needed for sustainable agriculture in response to environmental challenges and climate change. The objectives of our study were to evaluate and compare the effects of regulated deficit irrigation (RDI) and partial root-zone drying irrigation (PRDI) schemes with various field capacity (FC) conditions on yield components, water use efficiency (WUE), photosynthesis capacity, and chlorophyll fluorescence parameters of the maize plant in a pot experiment. Moreover, we also investigated foliar application of glycine betaine (B, 50 mM) and soil-treated chitin (C, 2 g/kg) to plants against water supply limitations and highlighted their potential for the sustainable production of maize. Significantly higher plant height, cob fresh and dry weights, and total dry weight of maize were observed in RDI with the 75 % FC condition compared to the control (full irrigation with 100 % FC). PRDI treatment resulted in significantly higher economic yield, WUEyield, and WUEbiomass compared to RDI treatment. Total water used in PRDI at 50 % FC saved 72 % of water resources compared to the control. Furthermore, values for effective quantum yield (ФPSII), photochemical quenching (qP), and electron transfer rate (ETR) of maize subjected to 75 % FC were higher than under 50 % FC and the control, while maximal quantum efficiency (Fv/Fm) levels of maize were higher under 50 % FC than under 75 % FC. All agronomic traits, chlorophyll content (as SPAD value), transpiration rate, net photosynthesis value, WUEyield, and WUEbiomass of plants subjected to PRD-50 %FC with spraying B alone showed higher values compared to other chemical applications and no chemical treatment. Applying C alone to maize plants under PRDI-50 % FC increased qP and Fv/Fm compared to other chemical treatments. Evaluating water deficits with non-destructive measurements are applicable to large-scale water management of maize plants, thereby enabling scarce water resources to be conserved.