IMPACT OF LAND USE ON DISTRIBUTION AND DIVERSITY OF FUSARIUM SPP. IN TAITA TAVETA, KENYA

Abstract

The effect of Land Use Types (LUTs) on distribution and diversity of soil Fusarium species was carried out in Taita Taveta district, Kenya. Soil samples were collected from sixty sampling points across a land use gradient covering six different LUTs, at the depths of 0 to 10 and 10 to 20 cm. Using Fusarium-selective media, a total of 1865 Fusarium isolates were recovered from the soil samples which resulted into 26 Fusarium species. Fusarium oxysporum and Fusarium solani were the dominant species in this area. Difference in Fusarium abundance, diversity and richness across the LUTs was significant (P<0.001) with horticulture being the richest and the most diverse LUT. The top soil layer had significantly higher Fusarium abundance and richness (P<0.05). Principal Component Analysis (PCA) based on the relative Fusarium species abundance differentiated the LUTs with 79.69 % variance explained by the first and second components. The influence of soil chemical characteristics on distribution and diversity of soil Fusarium species was also analysed using regression analysis. There was significant positive correlation between P and pH levels with Fusaria abundance, richness and diversity (P<0.001). Abundance and diversity of Fusarium was also positively correlated with soil Mg and K (P<0.05). However, a significant negative correlation between exchangeable soil acidity and abundance (r=-0.605), richness (r=-1.317) and diversity (r=-0.16) was observed (P<0.05). Negative correlation was also observed between Nitrogen and richness (r=-2.94) and diversity (r=-0.67) of Fusarium species. The soil C, Ca, Cu, Fe and Mn had no significant effect on soil Fusaria abundance, richness and diversity (P>0.05).