Growth promotion and protection from drought in Eucalyptus grandis seedlings inoculated with beneficial bacteria embedded in a superabsorbent polymer

CHAIN JM; TUBERT E; GRACIANO C; CASTAGNO LN; RECCHI M; PIECKENSTAIN FL; ESTRELLA MJ; GUDESBLAT GE; AMODEO G; BAROLI I

Virtual

Congreso; Plant Biology; 2021

American Society of Plant Biologists

Eucalyptus grandis is a globally planted tree crop. Improvements in this species management can have a considerable economic impact, but it is also necessary to develop management practices that are environmentally friendly and sustainable. Greenhouse-grown tree seedlings often face water deficit after outplanting, which can affect their survival and establishment severely. This can be alleviated by the application of superabsorbent hydrophilic polymers (SAPs). Growth-promoting bacteria can also improve crop abiotic stress tolerance; however, their use in trees is limited, partly due to difficulties in the application and viability loss. In this work, we evaluated the improvement of the drought tolerance of E. grandis seedlings after inoculating with two Pseudomonas strains (named M25 and N33), carried by an acrylic-hydrocellulosic SAP. We observed significant bacterial survival in the seedling rhizosphere 50 days after inoculation. Under gradual water deficit conditions, we observed a considerable increase in the water content and wall elasticity of M25-inoculated plants and a trend towards growth promotion with both bacterial strains. Under rapid water deficit conditions, which caused partial defoliation, both strains significantly enhanced the formation of new leaves, while inoculation with M25 reduced the transpiration rate. Co-inoculation with M25 and N33 substantially increased growth and photosynthetic capacity. We conclude that the selected bacteria can benefit the early growth of E. grandis and can be easily inoculated at transplant by using an acrylic-hydrocellulosic SAP.