Recently, Volkameriana seedlings rootstock are introduced to Egypt for propagation of citrus trees
In this research endomycorrhizae ((Glomus macrocarpum), biological control agent (Trichoderma harzianum), Rhizoclonia sol ani fungi and combination of them were used to study the effect of inoculation with G. macrocarpum and T. harzianum in the presence of R. solani on growth and chemical constituents of volkameriana
Obtained results showed that total microbial flora and actinomycetes populations were increased with the increasing of growth period of volkameriana to reach their maximum values during the period ranged between 60-90 days and 120-150 days for total microbial flora and actinomycetes counts respectively then gradually decreased thereafter. In contrast, the counts of total fungi in rhizosphere region gradually decreased with the increasing of growth period in various investigated treatments.
The highest populations of total microbial flora were observed in the treatment of (G. macrocarpum combined with R. solani + T. harzianum. Highest actinomycetes populations were observed in the treatment included mycorrhizal fungus alone. Whereas, the highest count of fungi was observed in the treatments included either R.solani alone or untreated one (control). Inoculation with either (G.macrocarpum or T. harzianum as well as the combination of them led to sharp decrease in the populations of fungi
Volkameriana seedlings inoculated with mycorrhizae and '/ harzianum either in infested or uninfested soil with R solani showed a significant increase
in plant height and top and root dry weights as well as in leaves contents of chlorophyll a and b during two seasons of study.
Statistical analysis clearly showed that mycorrhizal inoculation increased N, P, K, Mg and Ca contents of leaves and roots as compared to control (uninoculated plants). However, T. harzianum fungus had no effect on leaves and roots macro -nutrients content in comparison with the control plants In contrast, R. solani alone reduced the values of macro-nutrients content of leaves and roots. In general, combination treatment ('/’. harzianum + G. macrocarpum+ R. solani) improved leaves and roots macro - nutrients content as compared to either 7. harzianum + R. Solani or G. macrocarpum + R solani treatments.
The infection percentage and colonization intensity of mycorrhizae fungus reached to the highest level in root seedlings inoculated with G. macrocarpum + T. harzianum + R. solani. Obtained results clearly show that mycorrhizal inoculation either alone or in combination with T harzianum in the presence of R. Solani improved growth characters and chemical constituents of volkamariana plants. This result could be attributed to G. macrocarpum and T. harzianum can antagonize R. Solani and consequently reduce its harmful effect. |
