Inhibition of Nitrification by Root Exudates and Plant Materials fromBrachiaria humidicola

پژوهشهای زراعی ایران

Article 8, Volume 8, Issue 5 - Serial Number 19, November and December 2010, Pages 804-811   

Document Type: Research Article

DOI: 10.22067/gsc.v8i5.8022

Authors

M. K Souri^* ; M Arab; Gh Niuman

Abstract

Abstract
Nitrification inhibitors are synthetic or natural compounds highly specific in inhibiting ammonium oxidation to nitrate. Therefore, they are widely used in combination with ammonium fertilizers. Among plants, grasses always are interested for their role in controlling nitrification, and recently the form of nitrogen (ammonium vs. nitrate) was shown to be an important factor in release of natural nitrification inhibitors (NNI) from grasses. In this study production and release of natural nitrification inhibitors in Brachiaria humidicola was investigated. To study the effects of nitrogen forms on production and release of NNIs, brachiaria seedlings were grown in nutrient solution culture with either ammonium or nitrate, under controlled conditions. Root exudates were collected in two different mediums, distilled water or ammonium chloride, and with shoot and root homogenates were applied separately for their potential nitrification inhibition effect. The results, however, showed that when root exudates were collected in distilled water, there was no inhibitory effect on nitrification, but when root exudates were collected in a medium containing 1 mM NH4Cl, it showed significant nitrification inhibition in our soil nitrification test (bioassay). Leaf but not root homogenates also showed significant nitrification inhibition, independent of N form. This in turn suggests that synthesis of natural nitrification inhibitors in this grass is independent of nitrogen form.

Keywords: Nitrification, Root exudates, Ammonium, Nitrate, Brachiaria humidicola, Leaf and root homogenates