Evaluation of electrical conductivity of the fertiliser solution on growth and flowering of a <i>Cymbidium</i> hybrid

Abstract

The effects of three fertiliser solutions (20:20:20, 15:5:25 and 12:30:10 NPK) with electrical conductivity (EC) of 1, 1.5 or 2 mS cm^-1 on growth and flowering of Cymbidium ‘Sleeping Nymph’ were investigated over three years. One-year-old tissue-cultured propagules of ‘Sleeping Nymph’ were planted singly in plastic pots in a polyhouse. Plant height, leaf length, pseudobulb length and girth, and number of pseudobulbs per clump were highest in treatment T5 (20:20:20 NPK at 1.5 mS cm^-1). The EC of the fertiliser solution had a significant influence on the number of spikes per plant, number of florets per spike, spike length and rachis length. The number of florets per spike and spike length were highest with fertiliser solution with an EC of 1.0 mS cm^-1. The number of spikes per plant, florets per spike, spike length and rachis length (1.75, 11.25, 46.3 cm and 22 cm, respectively) were highest in treatment T4 (12:30:10 NPK at 1 mS cm^-1). Plant nutrient content was highest with fertiliser solution with an EC of 2.0 mS cm^-1. An EC of 0.8–1.0 mS cm^-1 for the pour-through leachate from the growing medium was optimal for highest-quality flowering of the Cymbidium hybrid.

Keywords: Cymbidium hybrid, electrical conductivity, flowering, nutrition

South African Journal of Plant and Soil 2013, 30(1): 33–39