MICROALGAE/BACTERIA SEED INOCULATION INCREASES BREAD WHEAT (Triticum aestivum) GRAIN YIELD UNDER DROUGHT STRESS IN THE FIELD

SANCHEZ RIZZA LARA; MOLINA FAVERO, CELESTE; MARONICHE GM; POLIZZI MAURO; CREUS CECILIA; CURATTI LEONARDO; PAGNUSSAT LA

Congreso; SAMIGE 2023; 2023

Water is essential to life and agricultural production is heavily influenced by its availability, and its deficiency could lead to a significant decrease of up to 60% in bread wheat production. Plant growth-promoting bacteria (PGPBs) inoculation is an accepted approach for improving crop performance under stressful conditions. Pseudomonas putida LSR1 and Azospirillum. argentinense Az39 are PGPBs that increase plant growth. Strain Az39 is also known as capable of mitigating the harmful effects of water scarcity on crop productivity. Microalgae are organisms that produce exopolysaccharides (EPS), that aggregate into an extracellular matrix. Because of their hygroscopic nature, these compounds may capture water from rain and fog, resulting in a positive water balance in their surrounding environment. Trials were conducted in both a growing chamber and under field conditions to evaluate PGPB root colonization and the performance in PGPB/microalgae-inoculated wheat crops (Triticum aestivum, cultivar MS INTA 221) under drought stress. Thus, wheat seeds were inoculated with Az39, LSR1, C1S, Az39/LSR1, Az39/C1S, LSR1/C1S or Az39/LSR1/C1S.PGPB root colonization was evaluated in 4 days post-germination radicles by cell counting and confocal microscopy. Az39 colonization was significantly higher in Az39/LSR1 and Az39/LSR1/C1S inoculated roots, while LSR1 remained similar in all treatments. Both bacteria were primarily localized to root hairs. Upon moderate drought stress conditions (MSC, 40% field capacity) in a growing chamber (16:8 light:dark, 25°C), plant aerial dry weight (ADW) after 8 and 11 days of MSC was higher in plants inoculated with Az39, LSR1, Az39/C1S and Az39/LSR1, compared to the non-inoculated control. No effects of inoculation on root dry weight were observed, but there were clear differences in its architecture. In addition, after 8 days of MSC, plant leaves inoculated with Az39, LSR1, C1S, and Az39/LSR1 consortia had a higher relative water content than the control.Field traits were performed under agroecological management in the 2022-2023 season (EEA-Balcarce). According to the INTA weather station, the plants were subjected to drought stress throughout the crop cycle as a result of unusually low rainfall in relation to historical records. The trial was performed with a completely randomized design with four repetitions and six treatments: Az39, Az39/C1S, Az39/LSR1, C1S, Az39/LSR1/C1S, and control without inoculum. The results showed an increase in the number of tillers per plant with C1S and Az39/LSR1/C1S treatments, as well as a higher root dry weight in C1S and Az39/C1S ones. Also, the Az39/LSR1/C1S treatment had a greater grain yield (kg/ha). The set of results presented here reveals a clear inoculation-dependent mitigating effect of water stress, both under controlled and field conditions, opening up new biotechnological perspectives for extensive crops inoculation with microalgae-bacteria consortia.