The Effect of
Foliar Fertilization
with Potassium
and Magnesium
on Fruit Quality
in Plums (Prunus domestica L.)
Eivind Vangdal, Sigrid Flatland and Ingvild Mehl
Bioforsk Vest Ullensvang, Norway
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
1
This presentation includes:
• Why use foliar fertilization
• Present status of major nutrients in plum and
present recommendations for foliar
fertilization in plums in Norway
• Results from field experiments
• Conclusions
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
2
Why use foliar fertilization?
• Strong focus on fruit quality
• Good foliar fertilizers are available
• Are fruit trees in high density orchards able
to get the nutritients needed through their
roots for optimum fruit quality?
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
3
Standard fertilization in plums in Norway:
• N-P-K mineral fertilizer on the soil in the spring
Contains some calcium and magnesium
and trace elements like Manganese, Boron, Zink
etc.
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
4
Leaf analysis of plums:
Element
Nirogen*
Phosphorus*
Potassium*
Calcium*
Magnesium*
Boron**
Manganese**
Zink**
Recommended Average in field
range
experiment
2,3 – 2,8
2,37
0,15 – 0,3
0,24
2,2 – 2,8
2,59
2,0 – 3,0
2,22
0,25 – 0,40
0,31
20 – 50
30 – 60
20 - 150
*) Per cent of DM; **)ppm of DM
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Standard fertilization in plums in Norway:
• N-P-K mineral fertilizer (6-5-20 or 11-5-18) on
the soil in the spring
• Foliar fertilization:
– Calcium (every second week from two weeks after
petal fall until 2 weeks prior to estimated harvest date)
– Boron (once after harvest, once two weeks prior to
flowering
– Nirogen (urea after harvest)
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
6
Field experiment with foliar fertilization with
Mg and K
A: Foliar fertilization programme with N, P, K, Ca,
Mg, Cu, S, B, Mn, Zn (Reduced N-P-K on the
ground)
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
7
Foliar fertilization programme:
Stadium
week N
P
Ca
Other nutrients
D / 54
16
3 kg
urea
1 kg Cu
E2 / 57-58
18
3 kg
urea
1 kg MAP
2 kg S + 1 kg Solubor
End of
flowering
21
1 kg
urea
1 kg MAP
2 kg S + 5 kg MgSO4
After
flowering
24
1 kg
urea
1 kg MAP 2,5 kg CaCl2
0,5 l Mantrac + 0,2 l Zintrac
27
2,5 kg CaCl2
30
2,5 kg CaCl2
31
3 kg MKP
33
Postharvest
38
2,5 kg CaCl2
5 kg
urea
1 kg MAP
5 kg MgSO4 + 0,5 l Mantrac
0,2 l Zintrac + 1 kg Solubor
Field experiment with foliar fertilization with
Mg and K
• A: Foliar fertilization programme with N, P, K,
Ca, Mg etc. (in additon to N-P-K on the
ground)
• B: As A + 2 x 5 kg MgSO4 (week 24 and 27)
• C: As A + 2 x 3 kg MKP (week 29 and 32)
• D: As A + both Mg and K as in C and D
• Cultivars: Avalon, Excalibur and Reeves
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
9
Results: yield, fruit size and colour
Control
Yield
Fruit
(tons/ha) size (g)
18,4
55
Ground
colour
Blush
clour
4,8
5,0
+ 2 x Mg
23,7
56
5,2
4,9
+2xK
25,7
54
4,6
5,1
+ 2 x both
Mg and K
P-value
18,9
51
4,4
4,6
n.s.
n.s.
n.s.
n.s.
Results: internal quality factors
Firmness
Soluble
solids
content
Titratable
acidity
Control
73
12,3
1,26
SSC:
acidity
ratio
9,64
+ 2 x Mg
73
12,1
1,26
9,55
+2xK
74
12,1
1,26
9,57
+ 2 x both
Mg and K
P-value
74
12,3
1,28
9,61
n.s.
n.s.
n.s.
n.s.
Results: leaf analysis
N
P
K
Mg
Ca
Control
2,37
0,25
2,56
0,32
2,30
+ 2 x Mg
2,36
0,22
2,5
0,32
2,26
+2xK
2,36
0,23
2,72
0,30
2,18
+ 2 x both
Mg and K
2,31
0,24
2,66
0,32
2,25
Results: fruit analysis
N
P
K
Mg
Ca
Control
0,74
0,15
1,33
0,070
0.140
+ 2 x Mg
0,74
0,15
0,98
0,070
0,090
+2xK
0,77
0,13
1,23
0,043
0,063
+ 2 x both
Mg and K
0,78
0,16
1,23
0,056
0,107
Results: yield, fruit size and colour
Control
Foliar
fertilizing
programme
Yield
Fruit
(tons/ha) size (g)
16,1
41
19,2
39
Ground
colour
Blush
clour
6,2
5,5
5,5
5,3
Results: internal quality factors
Firmness
Soluble
solids
content
Titratable
acidity
Control
63
11,3
1,41
SSC:
acidity
ratio
8,01
Foliar
fertilizing
programme
65
11,1
1,42
7,82
Results: fruit analysis
N
P
K
Mg
Ca
Control
0,83
0,16
1,33
0,069
0.140
Foliar
fertilizing
programme
0,99
0,11
0,99
0,045
0,090
Concluding remarks:
• The results shown in this presentations do not
indicate strong effects of foliar application with
Magnesium and Potassium
• Previous research and observations show good
effects of foliar applications of Calcium, Boron
(and in some situations) Nitrogen
• The fieled experiment with foliar fertilization with
Mg and K will be repeated this year including
studies of effects on shelf life of plums
ISHS Plum and Prune Symposium;
Palermo, Italy 17.-19.03.08
17
Thank you for your attention!