Plant growth can be stimulated by a symbiotic relationship between arbuscular mycorrhizal fungi (AMF) and bacteria within the rhizosphere region. These interactions are crucial for increasing soil fertility, which leads to increased productivity and sustainability, as well as food security considering a high level of malnutrition. Six rice varieties were grown with (M+) or without (M-) AMF inoculation in a randomised complete block design with three replicates. The soil physic-chemical properties were determined using standard procedures. Bacteria were isolated from the soil samples and the colony count was determined during the early and late cropping seasons of rice. Specific soil properties (phosphate, pH, organic matter) increased dramatically in the presence of AMF, which led to significant rice yield in both seasons. Bacterial species isolated included Lactobacillus spp., Klebsiella aerogenes, Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens, Azospirillum brasilense, Bacillus subtilis, Staphylococcus aureus, Enterobacter cloacae, and Micrococcus sp. Rice exudates increased the bacterial population in the early season, while AMF treatment increased the bacterial population in the late season and generally increased the bacterial species richness in both seasons. Although the actual mechanism that increased the bacterial species richness was not accessed, this study, however, shows that AMF-bacteria interaction increased and sustained soil fertility which consequently increased rice yield. A further study is necessary to determine the mechanism of the interaction observed between AMF inoculation and bacterial population.

A field study was carried out in a vegetable research field of the National Horticultural Research Institute, Ibadan, Nigeria during the late raining season of 2015 to determine the appropriate okra/legume-based cropping system that will increase crop yield and farmer's income. The experiment was arranged in a randomized complete block design (RCBD) with three (3) replicates. The treatments comprised intercropping okra with groundnut or cowpea planted at varying spacings (60 cm x 30 cm, 60 cm x 40 cm, 60 cm x 50 cm and 60 cm x 60cm). Okra was planted at a spacing of 60 cm x 40 cm, the plot size was 3 m x 2.4 m (7.4 m 2). Data collected was subjected to analysis of variance (ANOVA) and significant means were separated using the least significant difference (LSD) test at the 5% probability level. Economic analysis of the cropping mixture was carried out using gross margin analysis, monetary advantage index and benefit to cost ratio analysis. Results revealed that the land equivalent ratio (LER) of 1.62 was recorded in okra/groundnut at 60 cm x 40 cm and LER of 1.74 was observed in okra/cowpea at 60 cm x 30 cm. Okra/cowpea intercropping system spaced at 60 cm x 30 cm was the most remunerative (N859,192/ha), followed by okra/cowpea spaced at 60 cm x 50 cm (N744,212/ha) while okra/cowpea spaced at 60 cm x 60 cm was the least remunerative. The highest gross margin of N2,188,961/ha was obtained in okra/groundnut spaced at 60 cm x 40 cm. The least return was obtained in okra/groundnut spaced at 60 cm x 60 cm (N700,103/ha). The economic analysis revealed that okra/cowpea spaced at 60 cm x 30 cm produced the highest gross margin of N859,192/ha and monetary advantage index of N450,447/ha while okra/groundnut spaced at 60 cm x 40 cm gave the highest gross margin of N2,188,961/ha and monetary advantage index of N924,642/ha.

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