Effects of the Timing of Fertilizer Application on the Number of Flowers of Japanese Pepper

Abstract

This study was conducted in three consecutive years to determine the appropriate timing of fertilizer application to increase the flower number of the Japanese pepper, Zanthoxylum piperitum (L.) DC. f. inerme Makino (known as ‘Budousanshou’ in Japan) cultivated in Wakayama Prefecture. The timing experiment involved three treatment options: fertilizer application in spring with two equal applications in May and June, a summer/autumn treatment of two equal applications in August and September, or a spring/summer/autumn treatment of four equal applications in May, June, August, and September. Each treatment consisted of an annual application of 300 kg·ha−1 nitrogen. The spring treatment resulted in increased flower number. It was suggested that the application of fertilizer in the May/June spring treatment resulted in a focused accumulation of nutrients prior to the floral evocation period and led to the subsequent increase in flower number and cluster number relative to the summer/autumn and spring/summer/autumn treatments.