Effects of inoculation with different ERM isolates on photosynthesis and chlorophyll fluorescence parameter of Rhododendron annae Franch. seedlings

Abstract:

[Objective] Twelve ericoid mycorrhiza (ERM) fungal strain isolates were used to inoculate 2-year-old ornamental Rhododendron annae Franch. sterile seedlings, plant growth, chlorophyll, photosynthetic parameters and chlorophyll fluorescence parameters in plant leaves were investigated. [Methods] Greenhouse pot experiments were conducted in this study to test the effect of 12 ERM strains which were isolated from the roots of wild R. annae. [Results] The results revealed that the colonization ratio was notably higher. There were substantial differences on the aboveground, underground part and total biomass index of inoculated seedlings compared with those of uninoculated seedlings (P<0.01). Compared with the control treatment, the chlorophyll a and b, total chlorophyll content, leaf net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) were higher significantly, along with the increase of intercellular CO2 concentration (Ci). Practical quantum yield (ΦPSⅡ) of inoculated seedlings’ leaves were significantly higher than those of the uninoculated except strain TY19, TY24 and TY34; PSⅡ electron transfer rate (ETR), PSⅡmaximum photochemical quantum yield (Fv/Fm), potential activity (Fv/Fo) and photochemical quenching (qP) were significantly higher than those of the control plants. Non-photochemical quenching (NPQ) were higher as well, and the difference was very significant except strain TY29. The correlation of ΦPSⅡ and Pn, Gs were significantly greater than those of Fv/Fm, qP and NPQ. The correlation of ETR Fv/Fm, Fv/Fo, NPQ, Pn and Tr were greater than the qP and Gs. The correlation of Pn and Gs were greater than Tr, but it had significant negative correlation with Ci (P<0.01). [Conclusion] Through inoculation treatment, photosynthetic parameters and chlorophyll fluorescence parameters in plant leaves were improved, and meanwhile the effective use of light were enhanced. Thus, there were significant increases in seedling biomass. As for the comprehensive inoculation effects, TY18, TY29, TY35, TY02, TY07 and TY12 are the superior strains isolates to cultivate R. annae mycorrhizal seedlings.