Effect of nitrogen- boron interaction on plant growth and tissue nutrient concentration of canola (Brassica napus L.)

Pot experiments were conducted in the greenhouse on a calcareous soil to study the effect of nitrogen on the alleviation of boron toxicity in canola (Brassica napus L.). The treatments consisted of factorial combination of six levels of B (0, 2.5, 5, 10, 20, and 40mg kg(-1) as boric acid), and four levels of nitrogen (N) (0, 75, 150 and 300mg kg(-1) as urea) in a completely randomized design with three replicates. Boron (B) application significantly reduced the yield, whereas N addition alleviated the growth suppression effects caused by B supplements. Boron concentration increased with addition B. However, boron concentration in shoot declined with increasing N levels. Increasing N and B rates increased N concentration. Soil application of B increased proline concentration. However, the supply of N decreased it. Generally, application of B decreased potassium (K):B and calcium (Ca):B ratios, chlorophyll concentration, while N application increased them. It is concluded that N fertilization can be used effectively in controlling B toxicity in canola grown in B-affected soils.