PJB-2008-288
SEASONAL DYNAMICS OF AM FUNGI IN SUGARCANE (SACCHARUM OFFICINARUM L. CV. SPF-213) IN RELATION TO RED ROT (COLLETOTRICHUM FALCATUM) DISEASE FROM PUNJAB, PAKISTAN
GHAZALA NASIM 1, AMIR ALI2, ASIFA MUNAWAR3 AND RUKHSANA BAJWA1
Abstract
In this study we have observed the seasonal spore dynamics of 15 species of AM fungi prevalent in (cv. SPF-213) sugarcane fields in and around District Jhang, Punjab, Pakistan through out the growing season. Maximum number of spores per 10g sample soil was recorded for G. mosseae, G. fasciculatum and G. monosporum towards the end of growth period. However the pattern for highest values of propagule number in rhizosphere soil was variable for rest of the species. Maximum spore abundance for G. mosseae, G. fasciculatum and G. monosporum was noticed at the time of crop harvest. However figures close to the peak values were observed even during the growth period. The presence of 2 Gigispora spp. (Gi. nigra and Gi. minuta,) was recorded only in February. Lowest propagule number for G. mosseae, G. monosporum and G. fasciculatum was in October, September and November respectively. The difference between highest and lowest spore densities was statistically significant for G. mosseae and G. monosporum and Gi. nigra and Gi. minuta, at 5% level and insignificant for G. fascicultum and G. mosseae. There was a positive correlation between average number of spores and average percentage frequency of G. mosseae, G. fasciculatum and G. monosporum, while this relationship was not apparent for rest of the species. In interspecific interactions it was observed that in a particular sample higher number of propagules of one species was associated with significantly lower values of spore number of some other species. In order to assess the AM colonization of sugarcane plants in relation to Red Rot, 4 categories of plants for disease incidence were identified as healthy, partially diseased, diseased and severely diseased. A significant change in pattern of AM colonization was recorded. Percentage frequencies of arbuscules, vesicles and intra-matricle mycelium exhibited a gradual increase from slightly diseased to severely diseased. Various AM structures showed a significant variation with the passage of time in the extent of infection. Alongwith AM and pathogenic fungi, Dark septate endophytic fungi were also observed in 80% of the samples particularly in the severely diseased specimen. Heavy colonization suggest a significant role of these fungi as biocontrol agent
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