Identification and allelopathy of chemical compositions of peanut root exudates

Objective To analyze peanut root exudates and study the allelopathic effects of peanut root exudates.

Method Compounds extracted from peanut root exudates were identified by GC-MS technique. The allelopathic effects of peanut root exudates on the peanut seeding growth were analyzed using biological test at the concentrations of 0, 1 × 10^-5, 1 × 10^-4 and 1 × 10^-3 mol·L^-1.

Result and conclusion The peanut root exudates included organic acid, alcohol, ester, ketone, aldehyde, benzene, hydrocarbon and so on. Benzaldehyde and 4-ethylbenzoic acid, which showed an allelopathic effect on peanut, were found to be the major components of peanut root exudates. 1 × 10^-5mol·L^-1 Benzaldehyde, 4-ethylbenzoic acid and ferulic acid promoted or weakly inhibited peanut seeding stem length, root length, dry mass of root and shoot. Compared with the control, 1 × 10^-3 and 1 × 10^-4 mol·L^-1 benzaldehyde, 4-ethylbenzoic acid and ferulic acid significantly inhibited peanut seedling growth (P < 0.05). The SOD activity, POD activity and MDA content of two peanut varieties leaf showed a rising trend to varying degrees at different concentration levels of benzaldehyde, 4-ethylbenzoic acid and ferulic acid, and there was significant difference between the high concentration treatment (1 × 10^-3 mol ·L^-1) and the control (P < 0.05). In conclusion, there are allelophathic substances in peanut root exudates, which is one of the main factors of continuous cropping barrier of peanut.