k effects on yield quality
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K EFFECTS ON YIELD QUALITY
Adolf Krauss
International Potash Institute
Basel, Switzerland
Contents Why quality? Where is the link between K and quality? What can we prove? Conclusion
… K effects on yield quality
Why quality?
… K effects on yield quality
… Why quality?
… because urbanisation is advancing
Regional urbanisation
0
10
20
30
40
50
60
70
80
90
100
1940 1960 1980 2000 2020 2040
sh
are
of
urb
an
ite
s
Brazil
EU-15
India
… Why quality?
… because urbanisation is advancing, that is more urbanites and less rural people - also in Brazil
Demographic development of Brazil as compared to EU-15
0
50
100
150
200
250
300
350
1940 1960 1980 2000 2020 2040
M in
ha
bit
an
ts Brazil urban
Brazil rural
EU-15 urban
EU-15 rural
… Why quality?
… the society is also rapidly ageing like in the OECD countries
Ageing society in OECD countries
0
200
400
600
800
1000
1200
1400
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
mill
ion
inh
ab
ita
nts
> 65 yr
15-64 yr
<15 yr
… Why quality?
… with income and ageing the food habit changes
Income
after KERN, 2000
subsistence food likecereals, fats, oils,
more meat, vegetables, fruits,quality comes into picture
packed/processed food, emphasison quality, safe/bio/functional food
food type
… why quality?
… less cereals and more fruits and vegetables ...
Change in the diet in Brazil compared to EU-15
0
50
100
150
200
250
300
1950 1960 1970 1980 1990 2000 2010
su
pp
ly k
g/c
ap
/ye
ar
Brazil cereals
Brazil fruits&veg
EU-15 cereals
EU-15 fruits&veg
… why quality
… less cereals and more fruits and vegetables ...
Per capita food supply 2000 in selected countries(FAO, 2004)
0
50
100
150
200
250
300
EU-15 Brazil India
kg
ce
rea
ls;
fru
its
&v
eg
eta
ble
s
cereals
fruits&veg
… why quality?
… and more vegetable oil with raising income ...
Relationship between per capita GDP and consumption of vegetable oil
(FAO/CIA 2004)
y = 0.5406x + 6.3747
R2 = 0.8866
0
5
10
15
20
25
30
0 10 20 30 40
GDP '000 USD per capita
kg
/ca
p v
eg
oil
… why quality?
… and customers look first for quality when selecting food
Relative importance of product attributes in product choice
after TRAILL, 1999
quality26%
price17%
reputation14%
freshness9%
guarantee9%
9 others25%
Why quality?
What is quality?
… K effects on yield quality
… what is quality?
Quality is
…an intrinsic property of food by which it meets predefined standard requirements. Determinants of food quality can be grouped into several properties. Food quality therefore refers to the value, which is subjectively or objectively attached to food with respect to quality properties…
(Alabaka, 1999)
… What is quality?
Nutritional properties Functional properties
Hygienic properties
Organo-leptic properties
Environmental compatibility Safe food
FOOD QUALITY
Why quality?What is quality?
Where is the link between K and quality?
… K effects on yield quality
… Where is the link between K and quality?
… for example, in N metabolism …
PEPNH3
protein
NO3NO3
K+Malate- K+NO3
K+K+
K+Malate-
Malate PyruvateHCO3
SHOOT
ROOT
KNO3
XYLEM
K+
Model for the circulation of potassium in relation to nitrate and malate transport (after MARSCHNER, 1995)
PHLOEM
CO2
… for example, in sugar transport
… Where is the link between K and quality?
… for example, in sugar transport
… Where is the link between K and quality?
Effect of K status of cane on sugar transport (exposure 4 hrs)
(after HARTT, 1969)
0
20
40
60
80
100
120
deficient K adequate K
pe
rce
nt
14C
tra
ns
po
rt f
rom
fe
d le
af
stalk
adjacent leaf
fed leaf blade
… unless excessive Cl- affects sucrose storage in cane stalks
Cl-+K+
Xylem TransportCl- and K+
Cl- and K+Sucrose
Synthesis
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Retrans
location Cl-
+K+
Exchange
processes
Leaves
Stalkstorage
cells
RootsCl-+K+
Exchange processes of Cl- and sucrose in sugarcane (KRAUSS, 1992)
… Where is the link between K and quality?
Relationship between Cl and sucrose in cane stalks
y = 71.015x2 - 171.67x + 110.17
R2 = 0.8278
0
5
10
15
20
25
30
35
40
0.5 0.7 0.9 1.1 1.3 1.5
Cl % in DM
su
cro
se
% in
DM
… unless excessive Cl- affects sucrose storage in cane stalks
Cl-+K+
Xylem TransportCl- and K+
Cl- and K+Sucrose
Synthesis
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Cl-+K+
Sucrose
Retrans
location Cl-
+K+
Exchange
processes
Leaves
Stalkstorage
cells
RootsCl-+K+
Exchange processes of Cl- and sucrose in sugarcane (KRAUSS, 1992)
… Where is the link between K and quality?
… for example, in water utilization
K 3K 1 K 2
Wilting of sugar beets as affected by K supply
… Where is the link between K and quality?
… K regulates stomata aperture
… Where is the link between K and quality?
Potassium and stomata aperture(from MARSCHNER, 1995)
0
50
100
150
200
250
300
350
400
450
open stomata closed stomata
K c
on
ten
t (1
0-1
4 m
ol/s
tom
ata
)
0
1
2
3
4
5
6
vo
lum
e (
10
-12 l)
K
guard cellvolume
… K is the insurance for quality formation even under climatic ... P
hoto
synt
hesi
s
(µm
ol C
O2
m-2 s
-1)
Drought Stress
Low K
Adequate K
0
10
20
30
40
50
LOW MILD SEVERE
From CAKMAK, 2003
… Where is the link between K and quality?
… or biotic stress
… Where is the link between K and quality?
Unbalanced
high Nsugar balanced
N sugar
Krebscycle
Krebscycle
secondarycompounds
secondarycompound
s
PhenolsQuinones
PhenolsQuinone
s
organic N
organic N
solubleorg N
compounds
solubleorg N
compounds
Synthesis of pathogen repellents in plants as affected by the level of N supply (after GRAHAM, 1983)
Why quality?What is quality?Where is the link between K and quality?
What can we prove?
… K effects on yield quality
… What can we prove?
… adequate K improves the nutritive value
- for instance in wheat - higher protein content and better appearance
+K-K
Yield and quality of wheat in India as affected by K
3.8
4
4.2
4.4
4.6
4.8
5
5.2
5.4
-K +K
t/h
a
10.4
10.6
10.8
11
11.2
11.4
11.6
11.8
% p
rote
in
grain yield
protein content
… What can we prove?
… adequate K improves the nutritive value
- with higher oil content, more people can get their daily need from the same field
+K -K
Yield and quality of oilseed rape in China as affected by K
2.6
2.65
2.7
2.75
2.8
2.85
2.9
-K +K
t/h
a
36.8
37
37.2
37.4
37.6
37.8
38
38.2
38.4
38.6
% o
il
seed yield
oil content
… What can we prove?
… adequate K affects the functional property
- with higher sugar content, less cane is required for the same sugar output and thus, less energy for transport and extraction
Relationship between soil K absorption ratio (K in % of CEC) and stalk size and sucrose content of cane in
Egypt
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
1.5 2 2.5 3 3.5
% K on CEC
kg
/sta
lk
17
17.5
18
18.5
19
19.5
20
su
cro
se
%
Poly. (sucrose %)
Poly. (stalk kg)
… What can we prove?
… adequate K affects the functional property
… the same applies to potato and starch production
Tuber yield and quality of potatoes in Poland
20
22
24
26
28
30
32
34
36
38
40
NP NPK NPK+Mg
tub
er
t/h
a
15.4
15.6
15.8
16
16.2
16.4
16.6
16.8
17
17.2
17.4
% s
tarc
h
tuber yield
starch content
… What can we prove?
… K is involved with organo-leptic properties
… amino acids are important components for tea quality ...
Impact of balanced fertilization with K and Mg on quality of tea (China)
24
25
26
27
28
29
30
NP NPK1 NPK2
am
ino
ac
ids
mg
/g m
ad
e t
ea
-Mg
+Mg
… What can we prove?
… K is involved with organo-leptic properties
… and potato crisps keep a bright colour when the tubers are fed with adequate K because it lowers the content of reducing sugars
-K +K
Color index of potato chips as affected by K supply
4
4.5
5
5.5
6
6.5
7
7.5
8
0 108 217 315
kg/ha K2O
colo
r in
dex
(10
=ex
celle
nt)
… What can we prove?
… K controls hygienic properties
… mouldy fruits, cracked tomatoes from K deficient plants are disliked by consumers ...
… What can we prove?
… K controls hygienic properties
… also black spots in potato tubers can be controlled by adequate K ...
Relationship between K supply and incidences of black spots in potato tubers
(Germany)
0
1
2
3
4
5
6
7
0 100 200 300
kg/ha K2O
bla
ck
sp
ot
inc
ide
nc
es
0
5
10
15
20
25
K m
g/k
g
tubers with black spot
K-content of tubers
NP control
NP + KMgS
O=C
HO-C
HO-C
H-C
HO-CH
CH2OH
… What can we prove?
… K enhances the content of functional compounds
… Vitamin C and antioxidant contents are improved by adequate K ...
Balanced fertilization increased yield and improved quality of cabbage in Russia
68
70
72
74
76
78
80
82
84
86
-K +K
He
ad
s t
/ha
235
240
245
250
255
260
265
270
275
Vit
C m
g/k
g
head yield
Vit-C content
OVit C
Effect of K on isoflavones in soybean seeds (BRUULSEMA*, 2002)
1650
1700
1750
1800
1850
1900
1950
2000
2050
2100
-K +K
tota
l is
ofl
av
on
es
pp
m (
ex
pre
ss
ed
as
ag
lyc
on
es
)
… What can we prove?
… K keeps plants healthy and hence the food
POTASSIUMCONTROL
-K
-K +K+K
… What can we prove?
… K improves the appearance and shelf-life of many crops
Economy of potato tubers in India (Bansal & Shahid, 1998)
5
10
15
20
25
30
VCR harvest VCR 2 weeks later VCR 4 weeks later
VC
R f
or
K2O
100 kg/ha K
150 kg/ha K
… What can we prove?
… K improves the appearance and shelf-life of many crops
Tuber yield and storage loss of potato tubers (Bansal & Shahid Umar, 1998)
15
17
19
21
23
25
27
29
31
33
0 100 150
kg/ha K2O
tub
er
yie
ld t
/ha
0
1
2
3
4
5
6
sto
rag
e lo
ss
% yield
storageloss (4weeks)
… What can we prove?
… K use meets the environmental requirements
… because at balanced fertilization, N use efficiency is improved
Residual NO3 in the subsoil (kg/ha) as affected by fertilization in China
0
20
40
60
80
100
120
140
160
farmers practice=excessive N
unbalancedhigh N
balanced NPK
Impact of Farmer's practice, FP and Site specific nutrient management, SSNM on
recovery efficiency of N fertilizers, REN, of rice in SE Asia
4.8
4.9
5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
FP(111-18-17 kg/ha N-P-K)
SSNM(120-22-66 kg/ha N-P-K)
gra
in y
ield
20
22
24
26
28
30
32
34
36
38
RE
N %
rice yield
REN
… growth limitation of the shoot e.g. at K deficiency signals to the roots to refrain from further N uptake, so, the plant cannot be forced to absorb N above its needs …
Low demand
high demand
shootshoot
root root
Growth Growth
Phlo
em
Phlo
em
Xyle
m
Xyle
m
Growth Growth
Nitrogen
after ENGELS & MARSCHNER, 1995
Nitrogen
… What can we prove?
… K effects on yield quality
In conclusion:
Producer • globalisation• trade liberalisation• competition• selective and
critical consumers• ...
Consumer • healthy food• cheap food• plenty food• protection of the
environment• safeguarding
natural resources• ...
• legislative measures• trade barriers• gaps in knowledge• agric. practice• quality auditing• confidence of
consumers
… K effects on yield quality
… Thank you
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