BIOFERTILIZERS IN MEXICAN LIME (Citrus aurantifolia (Christm.) Swingle): ARBUSCULAR MYCORRHIZAL FUNGI AND Azospirillum brasilense IN GREENHOUSE

Abstract

Background: The majority of terrestrial plants have evolved in symbiosis with beneficial microorganisms, which help them acquire minerals that are scarce in soil, such as phosphorus and in some cases nitrogen. Thus, the development and use of biofertilizers based on microorganisms is important for partial or total replacement of chemical fertilizers. The use of arbuscular mycorrhizal fungi (AMF) and Azospirillum brasilense helps to boost Mexican lime (Citrus aurantifolia) plant growth, making them more vigorous and productive. Objective: To evaluate the effect of beneficial microorganisms in Mexican lime plant growth in a greenhouse. Methodology: An experiment with Mexican lime was established under greenhouse conditions and a completely randomized bifactorial design: (A) beneficial microorganism with four levels: consortium HMA Cerro del Metate; Rhizophagus intraradices (Ri); Azospirillum brasilense (Ab); and without microbial inoculum (WI); (B) chemical fertilization N-P-K (nitrogen-phosphorus-potassium) with four levels: high (180-180-180 kg ha-1); intermediate (90-90-90 kg ha-1); low (45-45-45 kg ha-1) and without fertilization. In total, 16 treatments with seven replicates were performed; plant growth and microbiological response variables were evaluated with an analysis of variance (ANOVA) and Tukey’s multiple comparison of means tests. Results: Significant effects (Tukey, P≤0.05) of the mycorrhizal consortium Cerro del Metate were found, followed by R. intraradices and lastly A. brasilense, which proved that these microorganisms promoted plant growth. Mycorrhization significantly increased (P≤0.05) plant growth rate, as well as dry biomass, observing a mycorrhizal colonization from 16 to 30%. Fertilization only showed a significant interaction (Tukey, P≤0.05) with A. brasilense. Implications: The use of native microorganisms and preferably consortia may have better adaptability than commercial ones, which can be explained in part by the effects found in this study. Conclusion: Mexican lime plants showed a significantly positive (P≤0.05) response to inoculation with AMF, showing greater plant growth than the other treatments.

Keywords

• beneficial microorganisms
• growth promoting bacteria
• chemical fertilization
• rhizosphere.