Plant Growth Regulators Application Improves Spring Maize Yield by Improving Net Photosynthesis and Grain Filling Rate

Application of plant growth regulators can increase maize grain yield by improving its growth and development.Therefore, this study was conducted to investigate the effects of different plant growth regulators application on photosynthetic capacity, grain filling characteristics and grain yield of maize.Maize plants at six leaf stage were sprayed with two growth regulators viz., duntianbao (DTB) and compound of DCPTA (2,3,4-dichlorophenoxy triethylamine) and Ethephon (2chloroethylphosphonic acid) (KP) while distilled water spray was used as control (CK).The results disclosed that the KP and DTB treatments significantly improved the leaf area index (LAI) values in the late-growth stage and increased photosynthesis of maize.Additionally, the KP and DTB treatments increased the grain filling rate, prolonged the grain filling period and increased the grain weight, leading to an increase in grain yield of spring maize by 19.50 and 12.13%, respectively.Correlation analysis indicated that the grain yield was positively correlated with the PEPCase and RuBPCase activities, SPAD value, Pn, grain filling rate and increase in grain weight at the early-filling, middle-filling stage and latefilling stage.In conclusion, the spray of plant growth regulator KP i.e., a compound of DCPTA and Ethephon accelerated the maize yield due to substantial expansion in net photosynthesis and grain filling rates.