Impacts of Banding Ammonium Fertilizer on Canola and Wheat Seedling Root and Root Hair Growth and Development.

Dryland wheat and canola cropping systems have the option of N fertilization at planting to meet crop N needs. While the potential toxicity of seed placed N is well recognized, impacts of N banding are less well understood.  High levels of ammonium/ammonia in the root zone can be toxic to plant roots. The root architectures of canola and wheat respond differently to the effects of below seed N banding. Fertilizer banding was observed causing stunted root growth, die back of young root hairs, and  apical necrosis of the seminal root axis. Root growth stops at a distance of around 1 cm from the fertilizer band and is followed by shrinking of the seminal root and root hair dieback. The multi-seminal axes of wheat roots enabled wheat to better evade the fertilizer band than the tap root system of the canola reducing the impacts of the fertilizer band on the overall structure of the developing wheat root system.