Increasing Plant Density in Eastern United States Broccoli Production Systems to Maximize Marketable Head Yields

Abstract

Increased demand for fresh market crown-cut broccoli (Brassica oleracea var. italica) has led to increased production along the eastern seaboard of the United States. Maximizing broccoli yields is a primary concern for quickly expanding eastern markets. Thus, a plant density study was carried out in Fall 2012 and 2013 using the hybrid cultivar Emerald Crown on a commercial farm in Summerton, SC, and in Fall 2013 using ‘Emerald Crown’ and another hybrid, ‘Durapak 19’, on a research farm in Charleston, SC. The objective was to determine the effect of variable within-row spacings of 4, 6, and 8 inches (using a system with double rows spaced 12-inches apart) on marketable yields and quality in the three environments. Our results indicated that increasing plant density by reducing within-row spacing to 4 inches significantly increased overall yield per hectare over the 6- and 8-inch spacing treatments at two of three environments. Stem diameter and average head weight were unaffected by plant density; however, heads harvested from plots with the highest plant densities had significantly (P < 0.01) lower bead uniformity in the Summerton 2012 trial, and significantly (P < 0.05) larger bead size in the two trials conducted in 2013. In general, the highest total marketable yields were from the 4-inch within-row spacing, but increased competition at the highest density may increase the risk of plants producing heads with lower quality characteristics. With the increased risk of producing lower quality marketable heads along with the increased production costs associated with the 4-inch spacing, yield and head quality attributes may be optimized at the 6-inch within-row spacing.