Radiation Preparation of Oligo-Alginate for Utilization as Plant Growth Promoter on Peanut

Aqueous solutions of alginate (4%) with or without hydrogen peroxide (0-2% H2O2) were irradiated under Co-60 source. Effect of dose rate on the radiation chemical yield of degradation (Gs) of resulting degraded alginate was determined. At the dose of 20 kGy, Gs of irradiated alginate decreased with dose rate, but for the alginate irradiated at the same dose rate, its Gs value increased with radiation dose and H2O2 concentration. Molecular weight (Mw) and polydispersity index (PI) of irradiated alginate rapidly decreased with the increase of radiation dose and further decreased by H2O2 treatment. The oligoalginate was obtained by radiation degradation of native alginate in 2% H2O2 at 20 kGy. Radiation scission of glycosidic bonds and formation of carbonyl groups with C=O double bond were indicated in UV and FTIR spectra of irradiated alginate. Peanut seedlings were fertilized with oligoalginate solution of 0, 40, 60 and 80 ppm, and the results showed that all growth parameters of the treated plants were better than those of the control. Thus, oligoalginate prepared by gamma irradiation can be applied as plant growth promoter for peanut.