تاثير نيترات بر تثبيت بيولوژيك نيتروژن و رشد گياه شبدر زيرزميني

Effect of nitrate on growth and biological nitrogen fixation in subterranean clover (Trifolium subterraneum.L)

In order to investigate the effect of nitrate (KNO3) on growth and biological nitrogen fixation (BNF) in subterranean clover (Trifolium subterranum var Goss), an experiment was conducted using a compeltely randomized design with 3 replications, the treatments were 0, 1, 2.5 and 5 mM KNO3 in Hogland solution with sand culture. Results showed that with increasing nitrate nodulation and nodule growth severly decrease. Nodule growth was more sensitive than nodulation. Nitrate treatment resulted in greater leaf area per plant. The highest plant dry weight was obtained in 2.5 mM KNO3. Ratio of root/shoot decreased with rising nitrate level. The highest total nitrogen percentage was obtained in 2.5 mM KNO3. The increasing total nitrogen content was as a result of nitrate ion accumulation (not BNF).