Using two plant growth promoting bacteria to sustainably reduce the drought-induced loss in Triticum aestivum yield

Abstract

In a greenhouse experiment, the inoculated and uninoculated grains with Azospirillum brasilense NO40 or Stenotrophomonas maltophilia were sown in unsterilized sandy soil and watered normally till the 8th day. Thereafter, the drought stress was initiated by watering pots once every 10 days while the unstressed pots were irrigated normally once every 5 days. Samples of spikes and dry grains were collected after 120 days from sowing. The results indicated that the inoculated-drought-stressed plants maintained significantly higher values of all of the measured yield parameters, where the yielded grains had higher amounts of the direct reducing sugars, sucrose, starch; lower contents of total soluble proteins and the total free amino acids, and altered protein patterns compared to those of the uninoculated-drought-stressed plants. SDS-PAGE of the yielded grains showed that drought led to the appearance of some newly synthesized stress protein bands and disappearance of others. Inoculation with PGPB resulted in the re-appearance of some of the disappearing bands and the synthesis of new others. Meanwhile, wheat inoculation under normal conditions resulted in significantly promoted grain yields with higher contents of carbohydrates, total soluble proteins and total free amino acids than that of the uninoculated control. It has been proved that treating wheat plants with the PEG-tolerant Azospirillum brasilense NO40 or Stenotrophomonas maltophilia that were compatible with the systems into which they were introduced and possess multiple plant growth promoting traits, can be an efficient strategy to enhance wheat growth and productivity, not only under normal conditions, but also under drought stress.