1. Mapping the Distribution of Navel
Oranges in Field 13B at the Citrus
Experiment Station (CES), UC Riverside
Emily Wieber

2. My Master Thesis: “Effect of Regulated Deficit Irrigation
on Navel Orange Physiology and Yield”
• The Citrus Collection at the Citrus Experiment Station (CES), Riverside
– Established in the early 1990s
– One of the premier citrus germplasm collections in the world with 1000 different citrus types
• My thesis objective was to reduce irrigation for citrus without compromising
yield:
– Citrus sinensis (L.) Osbeck (Smith’s Early Navel Orange)
– Applied regulated deficit irrigation (RDI) during citrus drought tolerant periods
• Jan. 2015 harvest indicated a variation in yield across the study site
• Using GIS to map and explain this pattern

3. Layout of Field Equipment
Navel Orange Study Site in the Citrus Experiment Station at UC Riverside

4. a
Layout of Field Equipment
Dendrometer Sap Flow Sensor
Layout of Field Equipment

5. Average Total Fruit Weight (kg) per
Tree

6. a
Layout of Field EquipmentAn Index Map Showing Distribution of Average Total
Fruit Weight (kg) and Tree Canopy Volume (m3)
y = 5.0564x + 13.498
R² = 0.4572
0
20
40
60
80
0 5 10 15
Yield(kg)
Tree Canopy Volume (m3)
Correlation between Yield
(kg) and Tree Canopy
Volume (m3)

7. a
Layout of Field EquipmentAn Index Map Showing Distribution of Average Total
Fruit Weight (kg) and Irrigation (mm)
y = 0.0247x + 20.8
R² = 0.1533
0
20
40
60
80
0 1000 2000
Yield(kg)
Irrigation (mm)
Correlation between Yield
(kg) and Irrigation (mm)

8. Conclusion
• Productivity (kg/tree) and sweetness are the same regardless
of irrigation treatments
• Tree canopy size is positively correlated with productivity
• Soil characteristics and water permeability are commonly
varied within the field, which could lead to variation in orange
yield across the study site (Mann et al. 2012)
AIC Citrus Research Center
© Marcos A. Machado
Treatment
Yield
(kg/tree)
Number
of
Fruit/Tree
Percentage of Weight Distribution of Different Fruit Size Across Treatments
Juice
Brim A
Very Tiny
50 – 59
mm
Tiny
60 – 63.4
mm
X-Small
63.5 –
68.9 mm
Small
69 – 74.9
mm
Medium
75 – 80
mm
Large
81 – 88
mm
X-Large
> 88
mm
Control 47.70 a 192 a .5 a 4.2 a 12.8 a 19.5 ab 25.9 a 20.3 a 5.6 a 10.85 a
RDI1 35.83 b 163 a 1.0 a 9.4 a 18.6 a 13.7 a 11.0 b 10.6 ab 2.6 a 10.81 a
RDI2 52.18 ab 212 a 1.2 a 5.7 a 20.9 a 26.1 b 28.8 a 14.2 ab 3.1 a 11.04 a
RDI3 42.22 ab 192 a 1.4 a 10.1 a 21.1 a 21.3 ab 13.1 b 7 b 4.9 a 11.17 a
Table 2: Effect of irrigation treatment on fruit yield and fruit size

9. Acknowledgements & Citation
• Data Source: collected field data
• With GIS Help from: Curtis Blondell, Prisco Blanco,
Gregory Beringer, and Sarah Taylor (former GIS student)
• Supplementary GIS Data from: ESRI
• Article from: Mann, K. , Schumann, A. , Obreza, T,
Harris, W., & Sartain, J. (2012). How to characterize soil
variability in Florida citrus groves as it relates to tree
growth and yield. IFAS Extension, SL556.
(http://edis.ifas.ufl.edu/ss557)