Impact of Arbuscular Mycorrhizal Fungi (AMF) on Colonization Rate and Growth of Crotalaria Retusa and Senna Occidentalis under Nitrogen Stress

Abstract

This study examines the impact of Arbuscular Mycorrhizal Fungi (AMF) on the colonization rates and growth of Crotalaria retusa and Senna occidentalis under varying nitrogen levels (low, medium, high). Conducted at Ahmadu Bello University, Zaria, the research used sterilized soil from a degraded site, filled into perforated buckets. AMF was applied using the Trench method. Root samples were collected, stored in 50% ethanol, and analyzed for mycorrhizal colonization following Brundett et al. (1994). Results indicated that the percentage rate of colonization (PRC) of AMF on C. retusa roots across different nitrogen levels was not statistically significant (p ≤ 0.218). Colonization was highest at low nitrogen (76.67±1.91%), followed by medium (72.83±3.89%) and high nitrogen levels (70.00±1.07%). Similarly, for S. occidentalis, the PRC was also not significant (p = 0.987) across nitrogen levels, with highest colonization at low nitrogen (76.50±2.39%), followed by high (76.00±3.02%) and medium (76.00±2.08%) levels. Overall, the study found that AMF colonization rates in C. retusa and S. occidentalis increased as nitrogen application decreased, regardless of whether the plants were inoculated with AMF. This suggests that lower nitrogen levels may favor higher AMF colonization in these species.