Yield and fruit quality of tomato as affected byrates and ratios of K and Ca in water culture
B. Nzanza , D. Marais & A.S. Claassens

September 2005

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Introduction
Fruit quality: crucial in greenhouse tomato
production
Quality factors driving consumer choice:¾Fruit size
¾Fruit color¾Fruit shape¾Shelf life
¾Etc.

Fruit quality is often affected by mineral nutrition
mainly K and Ca
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Introduction…
K plays a key role in fruit quality:¾Involved in metabolic and transport processes¾Generating turgor pressure¾Relates to fruit shape¾Increases fruit acid concentration¾Reduces ripening disorders¾Increases carotenoid concentrations¾Etc.

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Introduction…
Ca is also important in:¾Maintaining cell wall integrity¾Maintaining membrane permeability¾Enhancing pollen germination¾Activating numerous enzymes¾Affecting fruit quality and health of conductive
tissue¾Reduces physiological disorders¾Etc.

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Introduction…
K deficiencies lead to:¾Reduction of plant growth and dry matterproduction¾Effect fruit taste negatively¾Low fruit quality

Ca deficiencies cause:¾Reduced leaf size
¾Necrosis of young leaves¾Yield loss
¾Etc.
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Physiological disorders
yield loss andlow fruit quality
Cat Facing

Low
Ca?

Blotchy Ripening

Low
K?

Blossom End Rot

Fruit Cracking

Low
Ca?
Low
K?

Low Ca& Ca:K
ratios ?

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Problem statement
Sufficient K and Ca are needed for high yield andquality
Unfortunately K and Ca strongly interact duringuptake
High Ca decreases K uptake and vice versa
As result:Induced deficiencies are foundyield loss and low fruit quality
Physiological disorders = nutritional effects?

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

AimInvestigate the effects of K and Ca rates andratios on yield and quality of tomato

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Material and Methods
Experimental Farm (UP): GlasshouseTomato “ Money maker”:test cropTreatments consisted of:¾Two K concentrations (6 and 10 mmolc/l) combined¾With two Ca concentrations (12 and 16 mmolc/l )¾Giving four K:Ca ratios (6/12; 6/16; 10/12; & 10/16mmolc/l )Replication: 4 times
Experimental design: Completely Random Design
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Material and Methods…
Water culture system
10 liter pots on a rotating table Renewal ofsolution (Tables 1 and 2): every fortnightWater supplemented daily
Number of trusses allowed: 5
Pruning of lateral shoots

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Table 2. Hoagland no 2 solution
CompoundVolumeCa(NO3)28 mmolc.l-1

MgSO4

4 mmolc.l-1

KNO36 mmolc.l-1

NH4H2PO41 mmolc.l-1

Fe1 mg.l-1

Mn0.5 mg.l-1

Zn0.05 mg.l-1

Mo0.01 mg.l-1

B0.5 mg.l-1

Cl0.5 mg.l-1

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Results and Discussion

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 1. Effect of K:Ca ratios on fruit pH

4.25
a4.2

LSD 0.038

apH

4.15
bb10:16

10:12

4.1
4.05
43.95
06:16

06:12

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 2. Effect of K:Ca ratios on Titratable Acidity(TA) of tomato fruits
aa

10:16

10:12

73.5
72

LSD 4.28

TA (mmol.l-1)

70.5
69

a

a

06:16

06:12

67.5
66
64.5
63
61.5
60
K:Ca ratios

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 3. Effect of K:Ca ratios on Total Soluble Solidsof tomato fruits5.2
5aa

10:16

10:12

LSD 0.1409

aa

6:16

6:12

TSS (%)

4.8
4.6
4.4
4.2
4
K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 5. Effect of K:Ca ratios on fruit dry matter(%)
5.7

LSD 0.26

aaa

5.5

DM (%)

a5.3
5.1
4.9
4.7
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 6. Blossom-End Rot (BER) of tomato

High incidence on treatments with low Ca
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 7. Effect of K:Ca ratios on BER incidence ingreenhouse tomatoes
3.2aBER (%)

aLSD 1.89

2.4

1.6
b0.8
b0
6:12

6:16

10:12
K:Ca ratios

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 200510:16

Figure 8. Incidence of Blotchy Ripening ingreenhouse tomatoes

Disorder appear only in treatments with low K,
however, the incidence was very low
0.42 % for K:Ca 6:12
0.96 % for K:Ca 6:16
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 9. Incidence of Fruit Cracking ingreenhouse tomatoes

No relationships between Fruit Cracking and K:Ca
Disorder appears in all treatments (up to 2.59 %)Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 10. Incidence of Cat Facing in greenhousetomatoesNo relationships between Cat Facing and K:Ca ratios
Disorder appears in all treatments (up to 0.91 %)Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 11. Effect of K:Ca ratios on tomato yield (kgplant-1)
6

Yield (kg/plant)

5aaaa

6:16

6:12

10:16

10:12

4
3
2
1
0
K:Ca ratiosNzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Figure 12. Effect of K:Ca ratios on marketabletomato yielda94

Mark. Yield (%)

93

LSD 3.57

aa92
a91
90
89
88
87
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 13. Effect of K:Ca ratios on fruit N3LSD 0.40

aa2.5aaN (%)

21.510.5
0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 14. Effect of K:Ca ratios on fruit-P
LSD 0.04

0.5

aabab

P (%)

0.4

b0.3
0.2
0.1
0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 15. Effect of K:Ca ratios on fruit-Ca
LSD 0.060

0.2aaa6:16

6:12

aCa (%)

0.15

0.1

0.05

010:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 16. Effect of K:Ca ratios on fruit-K

3.75

aLSD 0.50

ab

K (%)

3.5
ab

3.25
b3
2.75
2.5
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 17. Effect of K:Ca ratios on fruit-Mg
LSD 0.0162

0.15aaaaMg (%)

0.1

0.05

006:16

06:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 18. Effect of K:Ca ratios on leaf-N

3.5

a3aLSD 0.72

N (%)

2.5b2b1.5
1
0.5
0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 19. Effect of K:Ca ratios on leaf-P

0.25

aLSD 0.09

a0.2aP (%)

a0.15

0.1

0.05

0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 20. Effect of K:Ca ratios on leaf-Ca
aa4
LSD 0.49

3.5

Ca (%)

32.5

b2b1.5
10.5
0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 21. Effect of K:Ca ratios on leaf-K
LSD 0.25

aaa1.2

K (%)

a0.8

0.4

06:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Figure 22. Effect of K:Ca ratios on leaf-Mg
LSD 0.13

0.8

aab

0.6

Mg (%)

bcc0.4

0.2

0
6:16

6:12

10:16

K:Ca ratios
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

10:12

Table 3. Effect of K:Ca ratios on mineral content ofgreenhouse tomatoes
K:Caratios

N (%)

P (%)

Ca (%)K (%)

Mg (%)

6:16

2.125 a0.35 b

0.14 a2.995 b0.115 a6:12

2.425 a0.475 a0.1475 a

3.575 a0.1225 a

10:16

2.25 a0.4 ab0.1325 a3.145 ab0.1175 a

10:12

2.525 a0.425 ab

0.18 a3.4425 ab

0.1225 aLSD0.40009

0.09430.060920.50030.0162CV11.161

14.87526.352

9.948

8.802

Means followed by the same letter in a column are not significantly different according to Turkey test at P<0.05
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Conclusions
Increased K from 6 to 10 mmolc/l resulted in:¾Decreased fruit pH (good)¾Increased Titratable Acidity (good)¾Increased Total Soluble Solids (good)¾Reduced incidence of Blotchy Ripening
Thus, High K improves fruit quality

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Conclusions…
High Ca reduced the incidence of Blossom-End Rotof tomato fruit
 K:Ca ratio (6:16 mmol.l-1) decreased the K
percentage in the fruitNo relationships has been established between Cat
Facing and K:Ca ratios
The cause of high incidence of Fruit Cracking might
not be the result of poor nutrition
Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005

Nzanza et Al.; IPI International Symposium on Fertigation; Optimizing the utilization of water and nutrients; Beijing, September 20-24, 2005