Field performance of native probiotic Pseudomonas applied to Triticum aestivum seeds under no-till management during two consecutive growing seasons

AGARAS, B; NOGUERA F; GONZÁLEZ ANTA G; WALL LG; VALVERDE CF

Rosario

Congreso; 7th World Congress on Conservation Agriculture; 2017

CAAPAS-AAPRESID

We have recently characterized a collection of 19 Pseudomonas spp. with direct and indirect plant probiotic traits in vitro that were isolated from agricultural fields under no-till management in the humid Pampas (Agaras et al 2015 Biol. Control 90:173?186). Here we present the output of a field test using a subset of 10 isolates, which were selected by their quantitative direct or indirect plant growth promoting potential. The experiment took place during two consecutive growing seasons (June-December 2015 and 2016), in two locations of Buenos Aires province (Pergamino and Ferré), with triplicate plots of 6×1.5 m (7 furrows) at every geographical site, using a randomized complete block design. Bacterial suspensions of washed cells were prepared at OD600= 1.0 in saline solution. One kg of wheat (Triticum aestivum var. Klein Yarará in 2015 and Baguette 601 in 2016) seeds were treated with 8 ml of each cell suspension + 2 ml of bacterial protectant (PremaxR, RASA). Besides, co-inoculation (or not) with 2 ml of the commercial biological fungicide Rizoderma (based on Trichoderma harzianum Th2 from RASA) was carried out. In control plots, seeds were untreated or inoculated only with Rizoderma. The average grain yield depended on the location in both experiments. Upon data analysis using linear general mixed models, considering the locations and season periods as random factors (InfoStat), we found that 15 out of 21 treatments significantly improved grain yield over the untreated control (p=0.0043, DGC with α=0.05), among which single inoculations with isolates SPSA2, RBBP4, RBAN4, SPAN5, RPAN5, SVBP6, SVBP8 or SMMP3, increased yield by 2.7-7.2%. Co-inoculations did not improve the effect of Rizoderma alone. The impact of bacterial seed treatment on plant, tiller and spikes density, and on NDVI was not statistically significant, but depended on the geographical location and the season period. Multivariate analysis (PCA) supported the positive effect of SPSA2, RBBP4, RBAN4, SPAN5, RPAN5 and SMMP3 mainly on yield, spikes and tiller values. Thus, single treatment of wheat seeds with any of these 8 pseudomonads had a positive impact on grain yield at these two locations with different soil properties during two consecutive growing seasons.