The effect of plant growth promoting rhizobacteria on seed germination and seedling growth of maize

Seed quality is one of the most important factors influencing crop quality and yield. Seed germination and vigour, components of seed quality, are therefore important characteristics that need to be considered by farmers before planting. Seed lots from two maize cultivars were evaluated in germination and vigour tests and the seed lot with lower vigour was used in the trials. Seven PGPR isolates viz. T19, T29, A32, S6, S7, A08 and T22, were applied as seed treatments in a seed germination bioassay to determine their effect on a low vigour seed lot of cultivar, PAN 6Q-308B, in two experimental runs. Isolate T22 significantly increased germination by up to 8% in both experimental runs. Treatment with isolate S6 resulted in the highest increase in shoot dry mass (35.2%) and shoot length (25%) in both experimental runs. Isolate A32 also enhanced both shoot length and shoot dry mass significantly, by 21.7 and 27.7%, respectively. None of the PGPR isolates enhanced root length significantly except for isolate T19 which promoted root length by 23.5% in experimental run 2. Isolate S7 significantly enhanced root dry mass by 40.7% (average of experimental runs 1 and 2) compared with the untreated control. Isolate T19 also showed a tendency to enhance dry root mass in experimental run 1 and caused a significant increase (39.4%) in dry root mass in experimental run 2. These findings show the ability of PGPR isolates T22, S6, S7, A32 and T19 to enhance the early growth parameters of maize with low seed vigour, when applied as seed treatments, and therefore demonstrate their potential use in the seed industry and sustainable farming.