Study on the Effect of Indolebutyric Acid-Lanthanum Chelate on Vegetable Growth and Its Molecular Mechanism

In order to reduce the non-point source pollution caused by the large or excessive application of chemical fertilizers and pesticides, this study was aimed to develop new alternative functional substances. The effects of different concentrations of indolebutyric acid-lanthanum chelate on seed germination and tomato seedling growth were studied by germination test of cucumber and tomato seeds and pot experiment of tomato seedlings. The results showed that the optimum concentration of indolebutyric acid-lanthanum chelate could promote the germination and growth of tomato and cucumber seeds. Among them, 0.02 mg/L of indolebutyric acid-lanthanum chelate is the optimum concentration for tomato and cucumber seed germination. When the concentration is 0.1 mg/L, it is the optimum concentration for radicle and hypocotyl growth. In the pot experiment, when the optimum concentration of indolebutyric acid-lanthanum chelate on tomato seedlings was 0.5 mg/L, the plant height, stem diameter, aboveground biomass, underground biomass and leaf area of tomato seedlings could be significantly promoted. At the same time, the absorption of the main elements P, K, Mg and trace elements Fe, Mn, Cu, Zn and Na and their transfer from the underground part to the aboveground part of the seedlings were enhanced. The relative expression of the tomato expansion protein genes leEXP2, leEXP18 and leEXP5 was also significantly increased. Therefore, the suitable concentration of indolebutyric acid-lanthanum chelate has the effect of promoting root growth and promoting the quality of tomato seedlings.