Foliar Application of Zinc Improves Safflower Yields More than Glycine Betaine

In arid regions, yields from safflower plants are appreciably lower than normal. Foliar application of zinc or glycine betaine has been reported to increase yields in other grown crops. A field experiment was conducted to compare the specific effects and mechanisms of foliar-applied zinc or glycine betaine on safflower yield in this study. Seven foliar spraying treatments were implemented, including a control (spraying water), three concentrations of zinc sulfate (Zn1: 0.6 g L−1, Zn2: 0.8 g L−1, Zn3: 1.0 g L−1), and three concentrations of glycine betaine (GB1: 0.23 g L−1, GB2: 0.47 g L−1, GB3: 0.70 g L−1). Results showed that Zn1 treatment had the highest grain yield at 2197 kg ha−1, which was 45.4% higher than the control. GB3 treatment resulted in a grain yield at 2127 kg ha−1, which was 40.8% higher than the control. The yield increase mechanism for the zinc treatment was primarily due to optimized plant morphology and improved photosynthetic performance, while glycine betaine improved yield mainly through antioxidant regulation. This study has important implications for water-saving and sustainable agriculture development in arid regions.