Physiological studies on Macrophomin phaseolina (tassi) Goid isolates from different Hosts and their pathogenicity for Okra seedling

Abstract

The results showed that the Macrophomin phaseolina (tassi) Goid fungus was isolated from Okra , Sun flower , Cowpea , Sesame , Melon , Potato , Dedonia and Oleander plants . The isolates of M. phaseolina gave different morphological characters like the mycelia growth and sclerotial formation , The diameter growth of okra2 isolates was 8.5 cm in the third day from the inculoation at 27 + 2 c .It was found the sunflower 2 isolate of M. phaseolina produced a highest number of sclerotia on P.D.A. . The sclerotia numbers to above isolate were 100 , 188 and 244 sclrotia in third , forth and fifth day respectively . The isolates of M. phaseolina differed in the pathogenicity on the germination of Okra seeds . It was found the Okar2 isolate gave a high effect on planting pathogenicity while the lowest was by the oleander isolate.The antagonism of Al-Tahadi and Austarallan isolates of T.harzianum and Emericella nidulans against M. phaseolina showed differeat level of antagonisms. The antagonism distance of Al-Tahadi , Austarallan isolates and E.nidulans were 1.8 , 2.3 and 2.2 cm . The Austarallan isolate of T.harzianum gave ahigh ability to cover all the M. phaseolina colony by the parasitism on the pathogenic fungus .The best diameter growth and sclerotia formation were in 30 c while the growth and sclerotia formation were stopped in 0 and 50C . The study proved that the best diameter growth of M. phaseolina was in distilled water( 8.5 cm) and the best sclerotia formation was in level 10 ds . The best PH was 6.5 to produce best growth and number of sclerotia .The growth and sclerotia formation were increased in dark condition to reach 8.5 cm and 91.6 sclerotia respectively while the alternate dark and light condition gave 7.75 cm , 70 sclerotia respectively whereas the continous light treatment gave 2.25 cm , 29. 5 sclerotia respectively.