Maize yield response to a phosphorus-solubilizing microbial inoculant in field trials

Abstract

SUMMARYFindings from multi-year, multi-site field trial experiments measuring maize yield response to inoculation with the phosphorus-solubilizing fungus, Penicillium bilaiae Chalabuda are presented. The main objective was to evaluate representative data on crop response to the inoculant across a broad set of different soil, agronomic management and climate conditions. A statistical analysis of crop yield response and its variability was conducted to guide further implementation of a stratified trial and sampling plan. Field trials, analysed in the present study, were conducted across the major maize producing agricultural cropland of the United States (2005–11) comprising 92 small (with sampling replication) and 369 large (without replication) trials. The multi-plot design enabled both a determination of how sampling area affects the estimation of maize yield and yield variance and an estimation of the ability of inoculation with P. bilaiae to increase maize yield. Inoculation increased maize yield in 66 of the 92 small and 295 of the 369 large field trials (within the small plots, yield increased significantly at the 95% confidence level, by 0·17 ± 0·044 t/ha or 1·8%, while in the larger plots, yield increases were higher and less variable (i.e., 0·33 ± 0·026 t/ha or 3·5%). There was considerable inter-annual variability in maize yield response attributed to inoculation compared to the un-inoculated control, with yield increases varying from 0·7 ± 0·75 up to 3·7 ± 0·73%. No significant correlation between yield response and soil acidity (i.e., pH) was detected, and it appears that pH reduction (through organic acid or proton efflux) was unlikely to be the primary pathway for better phosphorus availability measured as increased yield. Seed treatment and granular or dribble band formulations of the inoculant were found to be equally effective. Inoculation was most effective at increasing maize yield in fields that had low or very low soil phosphorus status for both small and large plots. At higher levels of soil phosphorus, yield in the large plots increased more with inoculation than in the small plots, which could be explained by phosphorus fertilization histories for the different field locations, as well as transient (e.g., rainfall) and topographic effects.

Soybean Response to Inoculation with Bradyrhizobium japonicum in the United States and Argentina

“…Yield data from the United States and Argentina were separately analyzed with the GLIMMIX procedure of SAS (Littell et al, 2006;SAS Institute, 2013). The analysis considered the effects of replicates and site (year × location combination) as random, and the effect of the inoculation treatment (IT) as fixed.…”

Effect of bioeffectors and recycled P-fertiliser products on the growth of spring wheat

“…PGPM may have the potential to enhance plant uptake of P from soil [14,18,19]. Improved growth under P-limiting soil conditions as a result of microbial inoculations has been observed in many different plant species, such as mung bean [17], bean [20], maize [21] and wheat [22]. In soil, a large proportion of the total P pool is not directly available for plant uptake [23], and the ability to solubilise phosphates in the rhizosphere has been viewed as an important function of PGPM [24].…”

“…Fungi of the genus Penicillium have been shown to have P-solubilising capabilities [31,32], and members of this genus have been observed to have a positive effect on biomass and P uptake of wheat and bean [20]. Wakelin et al [33] found that a strain of P. bilaii is both capable of increasing the yield of medic and lentil in the field and of significantly increasing the level of HCO 3 -extractable P in soil microcosms, and more recently P. bilaii has been found to increase yield in maize in field trials [21]. On the other hand, the positive effect of P. bilaii under P-limited conditions has also been linked in pea to an increase in the root adsorptive capacity under P-limited conditions rather than through increased P solubilisation [34].…”

Seed treatment with Penicillium sp. or Mn/Zn can alleviate the negative effects of cold stress in maize grown in soils dependent on soil fertility

“…As also found for Mn/Zn, there was no beneficial effect of Pen1 and Pen2 at the normal (control) temperature regime and inoculation with Pen1 and Pen2 actually led to a significant reduction in aboveground biomass at 51 DAS of plants grown in the high P soil (Figure ). Several studies have reported beneficial effects of seed inoculation with P. bilaii on plants grown under limited P availability (Asea et al., ; Leggett et al., ). However, in previous work we found that a minimum soil P and nutrient content is needed to ensure the persistence and activity of P. bilaii (Pen1) and to obtain a P. bilaii ‐induced increase in shoot length (Gómez‐Muñoz et al., n.d.), while under low P conditions we observed an increase in root growth due to inoculation with P. bilaii (Gómez‐Muñoz, Pittroff et al., ).…”