Effect of Nitrogen on the Alleviation of Boron Toxicity in Rice (Oryza Sativa L.)

Pot experiments were conducted in the greenhouse on a calcareous soil to study effect of nitrogen (N) on the alleviation of boron (B) toxicity in rice. The treatments consisted of factorial combination of six levels of B (0, 2.5, 5, 10, 20, and 40 mg kg^?1 as boric acid), and four levels of N (0, 75, 150, and 300 mg kg^?1 as urea) in a completely randomized design with three replicates. Boron addition (higher than 2.5 mg kg^?1) significantly reduced the seeds yield. Nitrogen addition alleviated the growth suppression effects caused by B supplements. Yield was increased by application of 2.5 mg B kg^?1 at all N levels, but at higher levels, B significantly decreased the yield of rice. Boron concentration declined with increasing N levels. Boron application increased the concentrations of B, potassium, phosphorous (P), and zinc. Nitrogen application decreased the concentration of Zn and increased the concentration of N and P.