EFFECTS OF FOLIAR APPLICATIONS OF UREA OR NUTRIPHITE ON FLOWERING AND YIELDS OF VALENCIA ORANGE TREES

ALBRIGO, L. GENE

Abstract


Valencia orange yields have been related to the number of flowers in the spring bloom, and the number of induced flower buds is determined by climatic stress factors such as cold and drought. Winter foliar sprays of urea have been reported to enhance the number of flower buds, flowers per inflorescence and yields under California conditions. Sprays of urea (28-31 kg N/ha) or Nutriphite (6.1 l/ha of 0-28-26 product) were applied to mature Valencia trees in two locations in South Florida in 1994-95. Urea or Nutriphite applied between the dates of 25 Dec. and 11 Jan. increased flowers. With continued annual treatment for 4 yr, Nutriphite treatment increased yields whether applied annually in the winter or later, just before full bloom. Winter urea sprays on the same plots for 4 consecutive years significantly increased yields. Orange juice soluble solids per ha were increased by both treatments when compared to the control plots. Possible mechanisms for these yield responses are discussed.

Keywords


phosphorous acid; flower bud induction; fruit set; soluble solid/box

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283