Vegetative and Reproductive Growth Responses of Three Strawberry Cultivars to Nitrogen1

Abstract

Abundant (‘Hood’ and ‘Benton’) and poor (‘Olympus’) runnering cultivars of strawberry ( Fragaria × ananassa Duch.) were grown in a milled-bark medium over an 8- or 16-fold range of slow-release ureaform N. Growth was poor or normal at low and intermediated rates of N, but inhibited at high rates. Number of leaves, crowns, and runners and subsequent inflorescence and flower production were frequently less than maximum at the highest level of N (4.8 gN/liter bark medium). Applied N had a significant effect on the number of crowns/plant, inflorescences/crown and flowers/inflorescence. In all cultivars, percent N in leaves in August, or in the entire shoot in November, showed a significant linear relationship with applied N. ‘Hood’ accumulated a higher concentration of N in both parts than ‘Olympus’ or ‘Benton’. Flower production in all cultivars was significantly correlated with the percent N in the shoot in November. Although the optimum range of applied N was similar for all cultivars, ‘Olympus’ was the most responsive to N in terms of increased leaf and flower production. When maximum values are compared, ‘Olympus’ in one year produced over 40% more leaves and 75% more flowers but at least 74% fewer runners than ‘Hood’ or ‘Benton’. ‘Benton’ was the only cultivar that at low and intermediate rates of applied N averaged less than one inflorescence/crown. Crown production by the 3 cultivars was not significantly different and high levels of applied N failed to increase the number of crowns available for flower initiation above those obtained at intermediate rates.