Abstract: The Hanmai 19 wheat variety widely popularized in the production of wheat in the northern Huanghuai region was used as the test material to study the regulation of stalk traits and grain yield in wheat by spraying plant growth regulators at different growth periods. The results showed that compared with the control, the plant growth regulator could significantly reduce the plant height, the height of the center of gravity and the length of the first and second internodes at the base of wheat, improve the mechanical strength of the second internode at the base, and reduce the lodging index. And the adjustment effect of thickness and diameter varied with the spray period and the type of chemical control agents. Among them, paclobutrazol could reduce the plant height by 6.4~12.3 cm, the height of the center of gravity could be reduced by 6.18%~18.12%, the mechanical strength could be increased by 5.66%~9.53%, and the first and second nodes at the base could be shortened by 1.98~2.93 cm and 0.66~1.03 cm respectively, the lodging index decreased by 15.03%~21.66%. Plant growth regulators could increase grain yield. Among them, spraying paclobutrazol at the rising stage had a significant effect of increasing yield, with a yield increase of 5.15%. The comprehensive analysis showed that spraying paclobutrazol during the stand-up period was the best treatment,which provided a scientific basis for the rational selection of chemical control agents for high-yield wheat.

Key words: plant growth regulators, stem characteristics, yield