Bio-priming walnut seeds with novel PGPR strains enhances germination and drought resilience under osmotic stress

To explore how plant growth-promoting rhizobacteria (PGPR) can enhance drought tolerance in walnut (Juglans regia L.) seeds, the seeds of the 'SS2 ' and 'Chandler' genotypes were inoculated with Bacillus velezensis strain ZM39 and B. amyloliquefaciens strain Cha43. The seeds were germinated under stress imposed by polyethylene glycol (PEG6000), corresponding to an osmotic potential (Psi s) of -1.50 MPa. This osmotic pressure caused significant decreases in plumule and radicle length, as well as in dry and fresh weight, especially in 'SS2 ' seedlings. 'Chandler' seedlings exhibited better germination following inoculation with either bacterial strain. The ability of 'ZM39 ' and 'Cha43 ' to ameliorate stress effects in walnut seedlings was confirmed. Phenolic components such as salicylic acid, rutin, and epicatechin in both radicle and plumule tissues showed a significant correlation with the germination stress-tolerance index and germination rate index. The first and second factors of the principal component analysis accounted for 74.75 % and 12.44 % of the total variance, respectively. These results reveal the ability of two new bacterial strains to ameliorate PEG6000-induced osmotic stress in walnut seedlings. Considering the interplay between walnut genotype characteristics and the selected bacterial strains, bio-priming walnut seeds with these PGPR strains could be a valuable approach for the seed industry to enhance walnut seedling resilience in the face of an increasingly unpredictable climate.

Journal

SCIENTIA HORTICULTURAE

Year

2025

Volume

344

ISSN

0304-4238

eISSN

1879-1018

DOI

10.1016/j.scienta.2025.114073

WoS UID

WOS:001468969100001