Articles
EFFECTS OF TIMING OF N AND PHI FOLIAR SPRAYS ON LOWBUSH BLUEBERRY LEAF NUTRIENT CONCENTRATIONS, GROWTH, AND YIELD
Article number
810_97
Pages
733 – 740
Language
English
Abstract
Foliar sprays of N and potassium phosphite (Phi) were evaluated in a commercial lowbush blueberry (Vaccinium angustifolium Ait.) field with a known history of low leaf N and P. Applications of foliar N (13.4 kg N/ha) and Phosphite (Phi) (13.4 kg P205/ha), following a soil application of diammonium phosphate (DAP) (448 kg/ha), were evaluated to determine their effects on stem growth and branching, flower bud formation, and berry yield.
One plot received only DAP and a control plot received no fertilizer.
The most beneficial time for the application of N, Phi, or N + Phi foliar sprays was studied through applications on 9 June, 29 June, 19 July, 8 August, 2 September, or 21 September, 2005. Leaf N and P concentrations were raised by DAP. Leaf tissue samples taken two weeks after each foliar application indicated that foliar N and Phi sprays raised both N and P concentrations, with a linear or quadratic seasonal trend for N and P, respectively.
DAP increased the percentage of branched stems by 11% and foliar sprays applied before July, when branching begins, increased that by an additional 3-10%, depending on treatment and application date.
Height of branched stems and length of branches were increased by DAP but not by the foliar sprays.
DAP increased flower bud formation on branched but not on unbranched stems.
Flower buds on unbranched stems were increased by foliar treatments of N and Phi on 28 June and N alone on 8 August and 21 September, compared to the controls.
Flower buds on branched stems were increased by DAP alone, compared to the controls; but foliar sprays did not increase the flower bud formation compared to DAP alone.
Flower bud density (number per 0.03m2) was greater with the 9 and 28 June N + Phi foliar sprays and 28 June Phi foliar spray, compared to DAP. Berry yield was almost doubled from 6,079 kg/ha for the controls to 11,808 kg/ha for plots receiving application of DAP alone.
The foliar N or Phi sprays did not result in larger yields than DAP alone.
One plot received only DAP and a control plot received no fertilizer.
The most beneficial time for the application of N, Phi, or N + Phi foliar sprays was studied through applications on 9 June, 29 June, 19 July, 8 August, 2 September, or 21 September, 2005. Leaf N and P concentrations were raised by DAP. Leaf tissue samples taken two weeks after each foliar application indicated that foliar N and Phi sprays raised both N and P concentrations, with a linear or quadratic seasonal trend for N and P, respectively.
DAP increased the percentage of branched stems by 11% and foliar sprays applied before July, when branching begins, increased that by an additional 3-10%, depending on treatment and application date.
Height of branched stems and length of branches were increased by DAP but not by the foliar sprays.
DAP increased flower bud formation on branched but not on unbranched stems.
Flower buds on unbranched stems were increased by foliar treatments of N and Phi on 28 June and N alone on 8 August and 21 September, compared to the controls.
Flower buds on branched stems were increased by DAP alone, compared to the controls; but foliar sprays did not increase the flower bud formation compared to DAP alone.
Flower bud density (number per 0.03m2) was greater with the 9 and 28 June N + Phi foliar sprays and 28 June Phi foliar spray, compared to DAP. Berry yield was almost doubled from 6,079 kg/ha for the controls to 11,808 kg/ha for plots receiving application of DAP alone.
The foliar N or Phi sprays did not result in larger yields than DAP alone.
Publication
Authors
J.M. Smagula, L. Kreider
Keywords
Vaccinium angustifolium Ait., nutrition, fertilizer, phosphite, foliar spray
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