Carnation yield patterns: The effects of plant density and planting-date

Abstract

Carnations, cultivar ‘White Sim’, were planted on 17 January, 12 March, 11 July, 12 September and 7 November, at densities of 12.9, 25.8, 51.7 and 103.3 plants m −2. For each planting-date, yields within a year from planting were asymptotically related to plant density. The mid-winter plantings gave the highest yields and the July planting the lowest. Yield patterns, derived from a weighted moving average, were affected by both the date and the density of planting. At high density, a major part of the year's yield came from the first flush, accounting for 48% of the total yield in the September planting and 75% in the March planting. At the low density, the first flush was only 26–31% of the year's yield. After the first flush, crop yields were suppressed more at higher densities, especially in the November, January and March plantings. Densities of 25.8 and 51.7 plants m −2 gave the best continuity of production per unit area, whilst the lowest density gave the best continuity of production per plant. The suppression of flower initiation was related to the amount of light; in November less than 20% of the incident light penetrated the canopy of a high-density September planting. Continuous light did not materially increase the number of shoots per plant that initiated flowers, its greatest effect being to produce earlier initiation.