The influence of long-term crop rotations on vesicular-arbuscular mycorrhizae infection of spring wheat

Abstract

Vesicular-arbuscular mycorrhizae (VAM) play an important role in the nutrition of many agriculturally important crops. Because of the ubiquitous nature of the mycorrhizal association and the important role that VAM play in crop nutrition and growth, factors affecting this beneficial association need to be identified. Field studies were conducted to monitor the influence of long-term crop rotations on VAM infection of spring wheat. Wheat root samples were collected at regular intervals from Agriculture Canada long-term rotation studies located at Swift Current, Indian Head, Scott and Melfort, Saskatchewan. Root segments were stained, and percent infection was determined by microscopic observation. VAM infection was favoured by continuous wheat rotations at all but one location. The exception existed in the Brown Soil Zone were V AM infection was reduced in the continuous rotation. Likewise, the inclusion of summerfallow in the rotation sequence reduced VAM infection. Phosphorous application generally reduced levels of VAM infection. Factors influencing the VAM association included length of rotation and fertilizer application history.