LAUSR

Abstract The study investigated the possibility of growth-promoting rhizobacteria to enhance plant growth capacities of Amaranthus hybridus and A. viridis in ferruginous ultisols comparative to humus. The experimental setup was divided into two groups; the first comprised of 2 weeks old plants that were inoculated using the rhizobacteria – Pseudomonas putida, P. fluorescence and a combination of both in the ratio of 1:1, in both humus (HMS) and ferruginous red (FRS) soils. The second consisted of seeds of the test plants bioprimed with the bacteria in filtrates of HMS and FRS respectively. Germination percentage in the Pseudomonas-exposed seeds was better when seeds were primed for 24 h than for 3 h in both plant species. Further, results showed that plants sown in the ferruginous soil were short-lived compared to those sown in humus containing soil irrespective of microbial treatments. The growth parameters of plants inoculated with the Pseudomonas species were better than the uninoculated plants and plants sown in the humus soil. Qualitative assessment of phytochemicals showed the presence of saponins, phenolic, tannins, terpenoids, alkaloids, and flavonoids in both species notwithstanding inoculation. The presence of glycosides in plants inoculated with P. pseudomonas was reported, but not in the control plants. Significant reduction in total phenols upon inoculation of plants with P. putida was also reported. Following the failure of FRS-exposed plants to subsist, in-vitro growth studies were conducted to compare seed growth response. Results suggest that seeds sown in FRS-filtrates performed better than those in HMS-filtrates. Pseudomonas species improves the growth, development and stress tolerance of Amaranthus species in humus soil.