Effect of mycorrhizal fungi and rock phosphate application on the growth of pinus roxburghii sarg. seedlings infected by Rhizoctonia solani

الملخص EN

This work was conducted to investigate the nature of tri- and tetra-partite systems among host plant, Ectomycorrhiza, VAM, (as symbiotic agents) and Rhizoctonia solani (as a pathogenic agent) alone or in combination and their effects on the survival (S) %, growth, biomass, dry weight of the seedlings of Pinus roxburghii Sarg.

The research was conducted in two successive growing seasons, of 2013 and 2014.

It was found that the infection % with EC+VAM was higher than the single inoculation with EC, owing to the synergistic effect of VAM, since the infection % was 40 and 20 %, respectively.

The inoculated seedlings with EC+VAM had brought about the highest S% (68.75%).

Uninoculated seedlings with R.

solani displayed the tallest shoot height (SH) (15.74 cm).

EC- inoculated seedlings and those dually inoculated ones, i.e., with EC+VAM had exhibited the highest SH (18.35 and 17.67cm, respectively).

The inoculated seedlings of P.

roxburghii with EC singly or dually with VAM which were fertilized with rock phosphate and uninoculated with R.

solani displayed the highest shoot growth rate (SGR) (2.92 and 3.12 cm/ month, respectively).

The inoculation of the seedlings with EC either singly or dually with VAM has brought about the highest root dry weight (RDW) (1.053 and 1.013g, respectively).

The inoculation with ectomycorrhiza either singly or dually with VAM, which were fertilized with rock phosphate and uninoculated with R.

solani displayed the highest shoot/root ratio as compared with the other treatments, since it was 3.481 and 3.559, respectively.

Concerning, the significant interaction among rock phosphate, inoculation with R.

solani and inoculation with symbiotic agents, the inoculated seedlings with ectomycorrhiza either only or with VAM, which were fertilized with rock phosphate and uninoculated with R.

solani displayed the highest total dry weight (TDW) as compared with the other treatments, since it was 4.46 and 4.46 g, respectively.

It has been concluded that the dual inoculation with EM and VAM combined with amendment of rock phosphate increased the resistance or mitigated the harmful effects off damping of the pathogenic- fungi and enhanced the survival as well as growth of P.

roxburghii Sarg.

seedlings.