Effects Of Arbuscular Mycorrhizal Fungi On Robinia Pseudoacacia Under Water Stress

We inoculated two strains of arbuscular mycorrhizal fungi (Glomus intraradices and G.mosseae) to Robinia pseudoacacia seedlings in pot cultures, in an attempt to study the effectsof arbuscular mycorrhizal fungi (AMF) on R. pseudoacacia under different water conditionscontrolled by weighing. Results showed that:1. Both G. intraradices and G. mosseae can colonize in the root of R. pseudoacaciaeffectively under well watered condition and water stressed condition, with no significantdifference noticed between them under the same condition. Colonization rates of G.intraradices and G. mosseae were affected negatively by water stress, dropping from81.33%and76.33%to59.00%and56.33%respectively. R. pseudoacacia showed differentdependence upon AMF, with a higher one on G. mosseae, especially under water stressedcondition.2. Both G. intraradices and G. mosseae can boost the growth of R. pseudoacacia well,enhancing the growth parameters, altering the morphology of R. pseudoacacia up and downthe ground, however had little influence on the ratio between root and shoot. The two fungishowed different mycorrhizal effects on growth and morphology and mainly affected thenumber of leaves and lateral root under water stressed condition. Besides, G. mosseae wasbetter than G. intraradices did in increasing the dry mass of R. pseudoacacia up and downthe ground, with higher plant height and stem diameter.3. AMF promoted the growth of R. pseudoacacia via different mechanisms underdifferent water conditions and under water stressed condition mainly through improving thephotosynthesis. Under water stressed condition and the other, mycorrhizal R. pseudoacaciahad more photosynthetic pigments, higher net rate of photosynthesis, especially under waterstressed condition. AMF increased photosynthesis related parameters of R. pseudoacaciasuch as stomatal conductance, intercellular CO2concentration, transpiration rate, Fm, Fv/Fmand qP. G. intraradices affected the photosynthetic pigments content, net photosynthetic rateand gas exchange parameters of R. pseudoacacia more, showed a better mycorrhizal effect onphotosynthesis of R. pseudoacacia.4. The inoculation of AMF notably decreased, especially in roots, the contents of O2-andMDA in leaves and roots of R. pseudoacacia, lowered the oxidative damage imposed bywater stress. Activities of SOD and POD, contents of soluble protein in leaves and roots of mycorrhizal R. pseudoacacia were higher than that of non-mycorrhizal R. pseudoacaciaunder water stressed condition, and also those in leaves were higher. Compared to R.pseudoacacia inoculated with G. intraradices, R. pseudoacacia inoculated with G. mosseaehad higher enzyme activities and soluble protein contents, in leaves or in roots.