Phosphate Solubilizing Rhizobacteria Could Have a Stronger Influence on Wheat Root Traits and Aboveground Physiology Than Rhizosphere P Solubilization

Abstract

Limited P availability in several agricultural areas is one of the key challenges facing current agriculture. Exploiting P-solubilizing bacteria (PSB) has been an emerging bio-solution for a higher rhizosphere P-availability, meanwhile the above-and below-ground interactions that PSB would trigger remain unclear over plant growing stages. We hypothesized that PSB effects on plant growth may be greater on root traits that positively links with aboveground physiology more than the commonly believed rhizosphere P bio-solubilization. In this study, five contrasting PSB (Pseudomonas spp.) isolates (low "PSB 1 ", moderate "PSB 2 and PSB 4 " and high "PSB 3 and PSB 5 " P-solubilizing capacity "PSC") were used to investigate aboveand below-ground responses in wheat fertilized with rock P (RP) under controlled conditions. Our findings show that all PSB isolates increased wheat root traits, particularly PSB 5 which increased root biomass and PSB 3 that had greater effect on root diameter in 7-, 15-and 42day old plants. The length, surface and volume of roots significantly increased along with higher rhizosphere available P in 15-and 42-day old plants inoculated with PSB 4 and PSB 2. Shoot biomass significantly increased with both PSB 2 and PSB 5. Root and shoot physiology significantly improved with PSB 1 (lowest PSC) and PSB 4 (moderate PSC), notably shoot total P (78.38%) and root phosphatase activity (390%). Moreover, nutrients acquisition and chlorophyll content increased in inoculated plants and was stimulated (PSB 2 , PSB 4) more than rhizosphere P-solubilization, which was also revealed by the significant above-and below-ground inter-correlations, mainly chlorophyll and both total (R = 0.75, p = 0.001**) and intracellular (R = 0.7, p = 0.000114*) P contents. These findings demonstrate the necessity to timely monitor the plant-rhizosphere continuum responses, which may be a relevant approach to accurately evaluate PSB through considering below-and above-ground relationships; thus enabling unbiased interpretations prior to field applications.

Screening and Molecular Identification of Phosphate-Solubilizing Rhizobacteria from Mangrove Ecosystem of the Lombok Island

“…Ketersediaan P yang terbatas di beberapa wilayah pertanian merupakan salah satu tantangan utama yang dihadapi pertanian saat ini. Memanfaatkan bakteri pelarut P (PSB) telah menjadi solusi yang muncul untuk ketersediaan P rhizosfer yang lebih tinggi (Elhaissoufi et al, 2020). Fosfor (P) adalah salah satu unsur penting yang diperlukan untuk pertumbuhan dan perkembangan tanaman.…”

Will Phosphate Bio-Solubilization Stimulate Biological Nitrogen Fixation in Grain Legumes?

“…Altogether, nodule formation, nodule functioning, and the energy costs of BNF in legumes strongly depend on the P status in plants and nodule tissues, and inadequate P status will reduce potential BNF contribution to N uptake (Bargaz et al, 2018). Given all of the knowledge regarding the key role of P in enhancing plant growth either by boosting the size of the root system (i.e., root hair density, lateral root growth, root surface area, and nodulation) or by stimulating the BNF process, soil PSM represents a promising strategy that could be adopted to increase plant-accessible forms of P to maintain soil health, fertility and agricultural sustainability (Wani et al, 2007;Qureshi et al, 2011;Bargaz et al, 2018;Elhaissoufi et al, 2020).…”

Bioformulation of Silk-Based Coating to Preserve and Deliver Rhizobium tropici to Phaseolus vulgaris Under Saline Environments

“…The discovery of phosphate solubilizing bacteria has led to its use in agriculture as a potential biofertilizer. For example, it has been reported that phosphate solubilizing rhizobacteria strongly influences wheat root traits and aboveground physiology (Elhaissoufi et al, 2020 ). Although seed priming is facing many challenges related to the conservation of bioformulation, storage, and difficulties in upscaling management.…”