Rebecca L. Darnell, University of Florida Nitrogen in blueberry: A review Rebecca L. Darnell, University of Florida

Blueberry industry in FL Southern highbush blueberry Based on V. corymbosum Hybrids with wild species native to the southeastern U.S. V. elliottii / V. darrowii / V. virgatum

Nitrogen and Iron are two important nutrients in blueberry production Allocation of N - Storage vs current N uptake and assimilation Highbush vs sparkleberry

Seasonal N concentration in young blueberry canes and roots Decrease in cane and root N leading up to bloom in 2nd season Roots Continued decrease in cane N through harvest Nitrogen (µg/mg DW) 1-May 7-Jun 24-Jul 29-Oct 7-Feb 22-Apr 22-May 27-Jul 27-Oct 21-Jan Leaf senescence Budbreak Harvest Leaf senescence Modified from Banados et al., 2012

Nitrogen content in blueberry during fruiting Nitrogen (mg/plant part) Dormancy Bloom Early Mid Fruit devel devel harvest

Storage nitrogen content in blueberry during fruiting Nitrogen (mg/plant part) Dormancy Bloom Early Mid Fruit devel devel harvest

Nitrogen content in blueberry during fruiting Storage N Nitrogen (mg/plant part) Dormancy Bloom Early Mid Fruit devel devel harvest

Soil adaptation Blueberry soils Mineral soils Acidic (pH 4.5-5.5) High om - amended NH4 pH>6.0 Low om Accumulate NO3 over NH4

NH4 NO3

Dry weight (g) New Plant shoot Leaf Stem Root NH4 226.3* 9.0 66.6* 83.4* 67.2 NO3 167.2 9.4 36.4 64.2 52.2

NH4 vs NO3 uptake rates in blueberry 15N uptake (µg/g DW/h) 15NH4 15NO3 0 10 20 30 40 Time (h)

NH4 vs NO3 accumulation in blueberry Nitrogen (mg/plant) 15NO3 Time (h)

NO3 assimilation limited in blueberry 15N content (mg/plant) Total 15N Assimilated 15N Time (h)

N uptake and assimilation Amino acids/proteins NO2- NH4+ *NR NO3- NO2- 2H+ NO3- NH4+ *NR = nitrate reductase

NRA (nmol/g FW/h) Species Root Leaf HB blueberry 50-200 0 Strawberry 250-400 300 Apple 300 1810 Peach 200-400 2000 Calamondin 370 1000

Are there Vaccinium species native to higher pH (nitrate predominant N form), low om soils?

arboreum “Sparkleberry” Native to the southeastern US Vaccinium arboreum “Sparkleberry” Native to the southeastern US Tree-like growth habit Deep root system – drought tolerant Tolerates low organic matter soil, pH up to 6.7 N primarily in NO3 form

N uptake in sparkleberry vs blueberry N uptake (mmol/plant/day) sparkleberry blueberry NH4 NO3

Nitrate assimilation in sparkleberry vs blueberry NR activity (nmol/g FW/h) blueberry NH4 NO3

NO3 uptake and assimilation in sparkleberry is greater than in blueberry Can we use sparkleberry to increase adaptation of blueberry to more mineral soils?

1) Using sparkleberry in breeding 2) Using sparkleberry as a rootstock Two approaches: 1) Using sparkleberry in breeding 2) Using sparkleberry as a rootstock Other potential advantages: Drought tolerance Mechanical harvesting Courtesy: J. Spiers

Blueberry Trees?

Don Merhaut Eric Ostmark Gerardo Nunez Carol Hamilton Acknowledgements Don Merhaut Eric Ostmark Gerardo Nunez Carol Hamilton Bruno Casamali David Norden Robert Stacey Valerie Jones Paul Miller Jeff Williamson Jim Olmstead Paul Lyrene Steve Sargent Funding: USDA SCRI Grant 2009-02533