Evaluación de la eficiencia de micorrizas aplicada en la fase vegetativa en el cultivo de banano ( musa x paradisiaca l).

Abstract

This thesis evaluated the efficiency of inoculation with arbuscular mycorrhizae (AM) during the vegetative phase of banana (Musa × paradisiaca L.) cultivation, using rhizotrons for non‐destructive monitoring of the root system. The study was carried out at the “Santa Inés” Experimental Farm of the Technical University of Machala, at 7 m a.s.l., under warm tropical climate conditions and sandy‐loam soils with moderate compaction. The general objective was to determine the effect of three inoculum levels (1 g, 2 g, and 3 g per plant) compared to a non‐inoculated control on foliar growth parameters, root biomass, and mycorrhizal colonization. The experimental design was completely randomized with four treatments (T1 = 1 g, T2 = 2 g, T3 = 3 g, and T4 = 0 g) and five replicates per treatment, totaling 20 experimental units. Glass‐window rhizotron boxes filled with representative sandy soil were used. At transplanting, each seedling received the designated inoculum dose suspended in 200 mL of distilled water, applied directly to the rhizosphere. Over six weeks, plant height (cm) and the number of active leaves were measured weekly; at the end of the vegetative phase, rhizotrons were dismantled to extract and classify roots by live, dead, and diseased biomass (g). Additionally, AM spore counts (×10³) were performed on adhered soil samples using KOH clearing techniques and microscopic observation. Data were subjected to one‐way analysis of variance (ANOVA) for each variable at a significance level of p ≤ 0.05; multiple comparisons were made using Tukey’s test. Results showed that none of the inoculum doses produced significant differences in plant height (means: 105.8–115.4 cm) or leaf number (5.6–6.2 leaves per plant) compared to the control (108.3 cm and 5.9 leaves). Similarly, total root biomass ranged from 363.8 g to 431.9 g without statistically relevant differences; the live, dead, and diseased root fractions exhibited numerical variations that were not significant (p > 0.05). In contrast, AM colonization was dose‐dependent: the 2 g treatment achieved the highest sporulation (6.60 × 10³ spores), followed by 3 g (4.60 × 10³) and 1 g (1.80 × 10³); the control lacked viable spores. This pattern suggests an optimal symbiosis point near 2 g per plant, beyond which the response declines, possibly due to rhizosphere competition or substrate saturation with inoculum. The absence of significant effects on agronomic parameters may be due to the short evaluation period, the soil’s high baseline fertility, or suboptimal experimental conditions for expressing AM benefits in vegetative growth. However, the clear increase in sporulation indicates effective root colonization by the mycorrhizae, which in a longer crop cycle or in low‐fertility soils could translate into improved phosphorus and water uptake and enhanced stress tolerance. It is recommended to deepen the study by including intermediate doses (e.g., 1.5 g and 2.5 g), extending the experiment’s duration, and measuring colonization intensity (% of root colonized) alongside foliar phosphorus and water content analyses. Likewise, validating the protocol under field conditions and in organic production systems is essential to determine its economic and agronomic viability. The use of rhizotrons proved to be a valuable tool for observing root dynamics; its application in future studies will allow detailed monitoring of symbiosis and root development under different management practices.