Biostimulation of Maize (Zea mays) and Irrigation Management Improved Crop Growth and Water Use under Controlled Environment

Abstract

Water deficits during the growing season are a major factor limiting crop production. Therefore, reducing water use during crop production by the application of regulated deficit irrigation (RDI) is crucially important in water resources. There are few reports on the biostimulants used for growth and water use efficiency (WUE) in maize (Zea mays Linn.) under RDI. Therefore, the influence of betaine and chitin treatments, alone and in combination, on maize cultivar ‘White Pearl’ was assessed by observing changes in the physiology and morphology of plants exposed to RDI. Plants were grown in plastic pots in greenhouses and maintained under full irrigation (FI) for 1 week until imposing RDI and biostimulants. Plants were then subjected to FI (no water deficiency treatment, field capacity >70%) and RDI (field capacity <50%) conditions until the end of each experiment. Plant agronomic performance, photosynthesis parameters, and WUE values were recorded weekly for 8 weeks and three individual experiments were carried out to assess the efficacy of biostimulants and irrigation treatments. Betaine (0, 50, and 100 mM/plant) was foliage-treated every 2 weeks during Experiment 1, but chitin (0, 2, and 4 g/kg) was applied to the soil at the beginning of Experiment 2. The optimal concentration of each chemical alone or in combination was then applied to the plants as Experiment 3. A factorial experiment design of two factors with different levels under a completely randomized arrangement was used in this investigation. Betaine (50 mM) or chitin (2 g/kg) treatments alone significantly elevated total fresh weight (63.03 or 124.07 g/plant), dry weight (18.00 or 22.34 g/plant), and cob weight (3.15 or 6.04 g/plant) and boosted the water-stress tolerance of the maize under RDI compared to controls. However, a combination treatment of 50 mM betaine and 2 g/kg chitin did not increase plant height, fresh shoot and root weights, dry cob weight, and total dry weight under RDI compared to controls. Soil-plant analysis development (SPAD) values (>30) were effective in detecting plant growth performance and WUE values under RDI. These findings may have greater significance for farming in dry lands and offer information for further physiological studies on maize WUE and water stress tolerance