Corn Yield and Phosphorus Use Efficiency Response to Phosphorus Rates Associated With Plant Growth Promoting Bacteria

Nathália Cristina Marchiori Pereira,Emariane Satin Mortinho,Fernando Shintate Galindo,Raíssa Pereira Dinalli Gazola,Poliana Aparecida Leonel Rosa,Elisângela Dupas,Marcelo Carvalho Minhoto Teixeira Filho

doi:10.3389/fenvs.2020.00040

Abstract

The use of plant growth promoting bacteria that can solubilize phosphorus (P) has shown potential to improve nutrient availability in grass crops such as corn (Zea mays L.) This study was developed to investigate if inoculation with Azospirillum brasilense, Bacillus subtilis or Pseudomonas fluorescens associated with P2O5 rates can improve phosphorus use efficiency (PUE) reflecting on greater corn development and yield. The field trial was set up in a Rhodic Hapludox under no-till system under Savannah conditions, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five P2O5 rates (0 to 105 kg ha-1) and ii) four PGPB seed inoculation (Control – without inoculation, A. brasilense, B. subtilis or P. fluorescens). Inoculation was found to increase grain yield by 17.5% when B. subtilis was inoculated associated with 70 kg P2O5 ha-1 and by 34.7% when A. brasilense was inoculated with application of 105 kg P2O5 ha-1. In addition, inoculation with B. subtilis and A. brasilense were found to increase biomass and grain P uptake, number of grains per row, stem diameter, ear length and PUE. The results of this study showed positive improvements in P uptake as a result of B. subtilis and A. brasilense inoculation, with an increase of 86.9 and 40.6% on PUE, respectively; while the P. fluorescens inoculation were less evident. Further research should be conducted under biotic or/and abiotic conditions to better understand the role of PGPB, inoculated alone or in combination as the co-inoculated method.

Highlights

Phosphorus (P) is one of the most limiting nutrients in agricultural cropping systems (Roberts and Johnston, 2015; Guignard et al, 2017; Khan et al, 2018)
Statistical analysis showed that leaf P concentration, biomass P uptake, grain P uptake, plant height, ear length, ear diameter, number of grains per row, and grains per ear, mass of 100 grains, phosphorus use efficiency (PUE) and grain yield were significantly affected by the interaction between P2O5 rates × plant growth promoting bacteria (PGPB) inoculation (Table 2)
Control plots associated with low and average P2O5 application rates (0, 17.5 and 35 kg ha−1) resulted in greater leaf P concentration compared to A. brasilense, P. fluorescens and B. subtilis inoculated plots (Figure 2A)

Summary

Introduction

Phosphorus (P) is one of the most limiting nutrients in agricultural cropping systems (Roberts and Johnston, 2015; Guignard et al, 2017; Khan et al, 2018). P can precipitate as minerals of Fe, and Al (Penn and Camberato, 2019) Both minerals decrease the availability of P for plant growth (Dhillon et al, 2017). Clay fractions such as amorphous hydrated oxides of Fe and Al, in addition to gibbsite, goethite, and kaolinite are responsible for the greatest P fixation (Dhillon et al, 2017). Fertilizer application is one of the highest input costs for cereal crops and yet most of the P-fertilizer used to supplement crops is lost into the environment, due to the low PUE in cereal crops (Metson et al, 2016; Li et al, 2017)

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