Effect of Nitrogen on Bolting of Bunching Onion (Allium fistulosum L.)

Abstract

Effect of the nitrogen fertilizer level on growth and bolting of cv. ‘Kincho’ was investigated to clarify the involvement of nitrogen nutrition in flower initiation of bunching onion (Allium fistulosum L.). A low nitrogen level retarded the growth and promoted leaf sheath bulbing. Low nitrogen decreased both the nitrogen and carbon concentrations, but increased the C/N ratio. Low nitrogen promoted bolting when the plants were exposed to a low temperature for 21 days. However, the nitrogen level did not affect bolting when plants were exposed to a sufficiently low temperature for 35 days. In conclusion, low nitrogen is considered to be a supplementary factor for flower initiation of bunching onion.