Both uniconazole and 5-aminolevulinic acid increase maize ( L.) yield by changing its ear morphology and increasing photosynthetic efficiency and antioxidants in saline-alkali land.

Saline-alkaline stress is one of the most detrimental abiotic stresses that restrict the yield and physiological activity of maize ( L.). In the present study, maize was planted on saline-alkali land, while 25 mg L uniconazole (S3307) and 40 mg L 5-aminolevulinic acid (ALA) were sprayed at the stage of nine expanded leaves. Our results showed that both S3307 and ALA applications significantly increased all ear width, volume, and mass in the maturity stage. Both applications also upregulated photosynthetic efficiency increasing the chlorophyll content, net photosynthetic rate, transpiration rate, and stomatal conductance, as well as reduced the intercellular CO concentration after the silking stage. In addition, both applications upregulated further the antioxidant system enhancing the activity of antioxidants and contents of soluble protein and sugar, as well as reducing the malondialdehyde content after the silking stage. Thus, both S3307 and ALA applications can improve maize yield in saline-alkali land enhancing ear morphology and increasing photosynthetic efficiency and antioxidants.