Effects of temperature and pH on mycelium growth of Phoma sorghina (Sacc.) Boerema Dorenbosch and Van Kesteren in vitro.

Abstract: The effects of temperatures 22, 28, 32, 36 and 40 degrees C and those of pH 5, 6.5 and 6 were evaluated on 11 isolates of P. sorghina on malt agar medium. The optimal mycelium growth of the most isolates is noted at 28 degrees C. At 32 degrees C, we have recorded a significant reduction of mycelium growth of all the isolates tested when compared with the control at 22 degrees C. At this same temperature, P. sorghina isolates can be group on sensitive isolates, on moderately isolates and on resistant isolates to temperature. The mycelium growth of all the isolates is inhibited at 36 degrees C. On the other hand, the temperature of 40 degrees C kills the mycelium of all the isolates of P. sorghina. The results of our work also show that, least variation of pH (6.5-6) significantly reduced the mycelium growth of P. sorghina isolates at 22 and 28 degrees C. At pH 5 most of the isolates tested are well adapted and the mycelium growth is more important when compare with that at pH 6.