Open AccessEffects of Raising Lowbush Blueberry Leaf Cu Concentration on Growth and Yield
Author(s) -
John M. Smagula,
Ilse Fastook
Publication year - 2005
Publication title -
hortscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.518
H-Index - 90
eISSN - 2327-9834
pISSN - 0018-5345
DOI - 10.21273/hortsci.40.4.1107b
Subject(s) - randomized block design , chemistry , yield (engineering) , ammonium sulfate , horticulture , botany , biology , materials science , metallurgy , chromatography
Two experiments evaluated the Trevett (1972) Cu standard of 7 ppm by raising leaf Cu concentrations in a commercial blueberry field having low (∼4 ppm) leaf Cu concentrations. A foliar spray of Cu Keylate (5% Cu) (Stoller Enterprises, Inc.) in a volume of 627 L·ha -1 applied 0, 0.56 1.12, 1.68, or 2.24 kg·ha -1 of Cu. Ammonium sulfate at 3.1 kg·ha -1 was added to the solutions to enhance Cu absorption. A preemergent soil application of Micromate Calcium Fortified Mix (Stoller Enterprises, Inc.), a micronutrient mixture containing Cu (0.3%), was also tested at 14 kg·ha -1 . These 6 treatments were replicated 7 times in a randomized complete-block design in 2001. Treatments were reapplied in 2003 in a split-plot design with Cu treatments as the main plots and an application of DAP at 448 kg·ha -1 as the split plots. In 2001, leaf Cu concentrations increased linearly, up to 12 ppm, with increasing rates of Cu, but Micromate had no effect. Leaf N and P concentrations were below the standards of 1.6% and 0.125%, respectively, and could explain why raising leaf Cu concentrations had no effect on growth or yield. In 2003, DAP corrected the N and P deficiency and leaf Cu concentrations were raised to above the 7 ppm standard with 2.24 kg·ha -1 of Cu, but again, no effect on growth or yield was found. The Cu standard appears to be too high.