The effects of three different plant growth regulators on the proportion of reproductive branches, inflorescence yield, endogenous hormones, soluble sugar and protein of Lithocarpus litseifolius were determined.

The 7-year-old L. litseifolius superior clone plantation was used as the material, and different concentrations of sodium nitrophenolate, chlormequat and paclobutrazol were sprayed on the leaves for 6 consecutive times before physiological differentiation. The dynamic changes of endogenous hormones, soluble sugar and soluble protein contents in leaves, the proportion of reproductive branches and inflorescence yield were measured and analyzed with water spraying as the control.

There were significant or extremely significant differences in the proportion of reproductive branches and inflorescence yield among different plant growth regulators. The proportion of reproductive branches was significantly reduced by more than 20% compared with the control. The total inflorescence yield was the highest in the treatment of 1 000 mg·L^-1 compound sodium nitrophenolate, which was 332.73 g·m^-2. The yield of male and female mixed inflorescence treated with 1 000 mg·L^-1 paclobutrazol was the highest, which was 6.56 times higher than that of the control. The effects of different plant growth regulators on the contents of IAA, ABA, GA₃, ZR, soluble sugar and soluble protein in the leaves of L. litseifolius at different stages were significantly different. The IAA content of spraying paclobutrazol treatment showed a trend of decreasing first and then increasing, while other treatments showed the opposite trend. The contents of GA₃, soluble protein and soluble sugar increased with the increase of paclobutrazol treatment concentration in the early and late stages. The contents of ABA and ZR in different treatments showed a downward trend as a whole. There was a significant negative correlation between the proportion of reproductive branches and IAA. The total yield of inflorescence per unit area and the yield of male inflorescence per unit area were significantly positively correlated with ZR, and the yield of mixed inflorescence per unit area was significantly positively correlated with GA₃. Soluble sugar was significantly positively correlated with IAA and GA₃.

In the experimental level range, the best treatment to improve the yield of L. litseifolius inflorescence and the yield of male and female mixed inflorescence were 1 000 mg·L^-1 sodium nitrophenolate and 1 000 mg·L^-1 paclobutrazol, respectively. Plant IAA hormone content regulates the proportion of reproductive branches and soluble sugar content, and the increase of ZR and GA₃ hormone content will promote inflorescence yield. In the production, appropriate plant growth regulators should be adjusted according to the demand to improve the inflorescence yield and the proportion of reproductive branches.