Increase of in-dyke alluvial soil fertility, growth and yield of maize (Zea mays L.) by potent Rhodopseudomonas palustris strains

The present study was aimed to evaluate the effects of nitrogen (N) fixing Rhodopseudomonas palustris strains, VNW64, VNS89, TLS06 and VNS02 on soil fertility, growth and yield of hybrid maize cultivated on in-dyke alluvial soil (IDAS). The pot experiment followed a completely randomized block design with 10 treatments, 4 replicates for each treatment. The treatments comprised of (i) fertilization with 100% N following recommended fertilizer formula (RFF), (ii) fertilization with 85% N, (iii) fertilization with 70% N, (iv) fertilization with 55% N, (v) treatment i plus a mixture of four purple nonsulfur bacteria (MFPNSB), (vi) treatment ii plus MFPNSB, (vii) treatment iii plus MFPNSB, (viii) treatment iv plus MFPNSB, (ix) no chemical fertilization, and (x) Treatment ix plus MFPNSB. The result indicated that treatments supplied with MFPNSB enhanced soil properties, including soil pHWater, NH4+ content and total N uptake, in comparison with no supplemented bacteria, 6.11–6.15, 16.4–17.7 mg NH4+ kg-1 and 1.43–5.02 mg N pot-1 in comparison with 5.74–5.99, 11.3–12.7 mg NH4+ kg-1 and 0.82–3.11 mg N pot-1, respectively, for hybrid maize cultivated on IDAS. Inoculation of MFPNSB on maize seeds contributed to reduce 45% N of RFF, but still caused no decline in the grain yield of maize. At 100% N of RFF, the treatment supplemented MFPNSB possessed a grain yield of 20.2% higher than the treatment without supplemented MFPNSB. Additionally, the treatment fertilized with 85% N of RFF plus MFPNSB, the maize grain yield was increased by 12.5% compared to the treatment fertilized with 100% N of RFF.