Seed bio-priming with Pseudomonas fluorescens isolates enhances growth of pearl millet plants and induces resistance against downy mildew

Abstract

Biopriming pearl millet seeds with Pseudomonas fluorescens isolates resulted in improved growth of the plants and also induction of resistance against downy mildew disease caused by the fungus Sclerospora graminicola. Although all of the test isolates reduced disease severity and promoted growth both under greenhouse and field conditions, high variability was observed in their efficiency. Treatment due to Pseudomonas fluorescens resulted in enhancement of: germination, seedling vigour, plant height, leaf area, tillering capacity, seed weight (measured for 1000 seeds) and yield. The time required for flowering was advanced by 5 days. Isolate UOM SAR 14 registered higher levels of vegetative and reproductive growth; most importantly there was a 22% increase in grain yield. The isolates also effectively induced resistances against downy mildew disease both under greenhouse and field conditions. The isolates offered protection ranging from 20 to 75%. However, the level of disease control was less than that achieved by the systemic fungicide Apron. UOM SAR 14 offered 71 and 75% and remained consistent under all test conditions. Further studies showed that the resistance induced was systemic, required a minimum of 3 days to build up, and was sustained throughout the plant's life.