Figure 1. The effect of inoculation with R. irregularis on plant growth and leaf photochemical activity of the pea cv. Finale at different stages of plant development.

The stages are: I: 7 days post inoculation (DPI) when the second leaf is fully unfolded with one pair of leaflets and a simple tendril; II: 21 DPI at first leaf with two pairs of leaflets and a complex tendril; III: 32 DPI when the floral bud is enclosed; IV: 42 DPI at the first open flower; V: 56 DPI when the pod is filled with green seeds; and VI: 90-110 DPI at the dry harvest stage. Bars represent standard errors. p ≤ 0.05. (A) The number of internodes between cotyledons and the youngest completely formed leaf (pcs.) and parameters of arbuscular mycorrhiza development in the inoculated plants: M% is the intensity of intraradical mycelium development (no differences were observed between the mean values for stages I and II, as well as between those for stages IV and V), a% is the arbuscule abundance in mycorrhizal root fragments (no differences found between the mean values for the stages II and III, as well as between those for stages IV and V). (B) Average dry weight (g) 1) of shoots 2) of seeds per plant 3) per seed (at stage VI). (C) Photochemical activity of the youngest completely developed leaf (one leaflet). Ik is the light saturation and minimum saturating irradiance, ETRmax is the maximum electron transport rate. (A, C) The values, which are not significantly different from each other, are marked with the same letter. (B) * indicates a significant difference between control and inoculated plants. contr signifies control plants, AM signifies plants inoculated with R. irregularis.