132 Fertilization Methods to Match Nutrient Supply with Demand for Potted Chrysanthemum

Abstract

A greenhouse study was conducted in Autumn 1998 using standard cultural practices for potted chrysanthemum [Dendranthema × grandiflorum (Ramat.) Kitamura] to determine how fertilization affected plant growth and quality and nutrient leaching. Fertilization treatments included constant liquid fertilization until anthesis (LFA), constant liquid fertilization until disbud (LFD), slow-release resincoated fertilizer (SRF), and no-fertilizer control. Frequency of irrigation was determined gravimetrically, and leaching fractions maintained near 0.2. Plant growth and quality for LFA, LFD, and SRF met commercial crop standards. Nearly 60% of the total nitrogen applied with LFA was applied during the 4 weeks between disbud and anthesis, due to increased water demand. During the same period when liquid fertilization was discontinued for LFD, leachate electrical conductivity (EC) levels dropped from 4 to <1 dS·m-1. Leachate EC levels for LFA at anthesis remained high, but were <1 dS·m-1 for the other treatments. LFD and SRF drastically reduced the total amount of nutrients applied during the course of production compared with LFA. Use of an appropriate slow-release fertilizer or discontinued use of liquid fertilizer at disbud allow soluble salt levels to decrease during the latter weeks of the mum production cycle, when nutrient demand is low and water demand is high.