Inoculation with Phosphate Solubilizing Bacterial Consortia Enhanced Rock P Agronomic Efficiency and Yield of Wheat Under Low P Conditions

Phosphate-solubilizing bacteria (PSB) are well known to enhance P availability and crop yield. However, profound understanding of crop responses to inoculation under contrasting conditions and throughout crop growth stages are so far incomplete. That is the case when employing bacterial consortia, which involve intricate species interactions likely ensuring complementary functions for a better plant growth and nutrient acquisition. This study, therefore, aimed to evaluate agro-physiological responses of durum wheat (under different growth stages) to the combined application of three PSB consortia (BC_a, BC_b, and BC_c) and rock P (RP) versus three uninoculated control treatments (unfertilized “P₀”, fertilized with RP and orthophosphate “OrthoP”) under controlled and field conditions. Overall, BC inoculation significantly enhanced grain yield, nutrient uptake, and physiological performance under both controlled and field conditions, and at a comparable level to OrthoP application. Particularly, BC_c significantly enhanced biomass and number of spikes under field conditions yielding 2-times higher grain yield than uninoculated RP treatment. This improvement can be attributed to enhanced biomass of shoots (40.6 and 102.1%) and roots (37.3 and 156.5%) under both conditions compared to uninoculated RP-fertilized plants. Spikes nutrient content also increased significantly (P “81%”, N “72%”, and K “71%”) along with grain yield (average of 68.3%) in response to BC (mainly BC_c), which can be attributed to the capacity of BC to enhance rhizosphere available P through induced acid phosphatases activity and growth traits of roots. However, across plant growth stages (30-, 75-, and 95-day old) there was a noticed decrease in rhizosphere available P (51.5, 47.6 and 25.3%) concomitantly to increased soil microbial biomass P (60.3, 107.8, and 86.7%) compared to uninoculated RP-fertilized plants. The increase of both soil microbial biomass P and wheat agro-physiological performance can be directly attributed to positive impacts of BC across different stages of plant growth, demonstration a significant ecological contribution to sustain wheat production under low P conditions.