PHOTOSENSITIZATION PROCESS WITH LASER AND SUNLIGHT FOR CONTROL OF RHIZOCTONIA SOLANI

Abstract

Rhizoctonia so/ani, the most widely recognized species of Rhizoctonia was originally described by Julius Killin on potato in 1858. R so/ani Is a very common soil borne pathogen with a great diversity of host plants. R so/ani can survive for many years by producing small (1 to 3 mm

diameter), irregular-shaped, brown to black structures (called sclerotia) in soil and on plant tissue.

In this work, the results of testing of hematoporphyrine as photofungicide, these compound have been already approved for medical use in the photodynamic therapy of tumors and other disease, HP becomes toxic only when it is activated by sunlight. We used natural o.nd artificial light with porphyrine derivative and laser

radiation for controlling R . so/ani

Hematoporphyrine (IX) several favorable features for such application as photofungicide due to:

1)- it is endowed a high quantum yield for generation of highly cytotoxic intermediates. 2)- absorb essentially all wavelengths in the sun emission spectrum.

3)- typically act at the level of cell membranes minimizing the induction of mutagenic effects. 4)- have high photosensitizing activity towards biological systems in addition, its already approved for medical use in photodynamic therapy of tumors and another disease.

The efficiency of the photosensitization reaction depends on the concentration ofHP, the fluence rate of irradiation and exposure time.

The result reveal that, the sclerotia of R so/ani treated with lowest concentration of HP and photoirradiated by solar simulator at highest intensity rate was exhibited 100% mortality during exposure time (3 hour).

But the highest concentration was more efficiency when the sample which exposed to direct sunlight, it is found that the survival percentage of linear growth of R. so/ani was zero % when irradiation at sunlight for 4 hour (fluence rate 504 w/m2) after treatment·with concentration 1o-2 ofHP.

It is found that the average solar irradiation in a sunny day in Cairo about

650 W/m2 and 250 WI m2 in summer and winter respectively.

On another hand the laser radiation reaction depended on the exposure time and power of radiation, as show in result the mortality increased by increase the exposure time, the power radiation.