Lipid peroxidation intensity in soybean and maize plants inoculated with PGPR

Abstract

The purpose of this work was to define the reaction of soybean and maize plants to inoculation with plant growth-promoting rhizobacteria (PGPR) [isolates of Azotobacter (AB), Streptomyces (S) and mixture of these (MIX)], by investigating lipid peroxidation intensity. Lipid peroxidation (LP) represents a valuable biomarker of cell degradation and oxidative stress secondary effects. It is analyzed as a response of plants exposed to various (a)biotic factors and in this work it is expressed as nmol malondialdehyde (MDA) equivalents in fresh leaves and roots of investigated plants. Seeds of soybean (cultivar Bečejka) and maize (hybrid NS 640) were inoculated with aqueous inoculums of tested PGPRs and grown under field conditions, without fertilization. Plants were harvested for biochemical analyses at three specific stages of development: 21-day-old seedlings, full bloom, seed beginning stage and, at the end of the experiments, yield was recorded. Inoculated plants had similar values of LP intensity as plants from control (35.1-98.9 nmol MDA g-1 fresh weight). There were no significant differences in LP intensity between control and treatments within the sampling stage, however the amount of MDA accumulated during the vegetation period (up to 60%), possibly because of the developmental processes in soybean and maize. As for seed yield (t ha-1), both investigated species had 5-7% higher yield when inoculated with MIX inoculum, which highlighted the coupled inoculation as possible potent biofertilizer in soybean and maize organic production.