1. EFFECTS OF HIGH CONCENTRATION OF NaCl IN THE NUTRIENT SOLUTION OF
HYDROPONIC TOMATOES ON YIELD, WATER EFFICIENCY AND POTASSIUM
ABSORPTION
25th Scientific Conference of the Greek Society for Horticultural Science,
Cyprus, 2011
K. Koni1, D. Tarnavas1, I. Lycoskoufis1,2, G. Mavrogianopoulos1
1Laboratory of Agricultural Constructions, Department of Natural Resources Management & Agricultural Engineering, Agricultural University of
Athens, 75 Iera Odos, P.O. 118 55, Athens, Tel. +30 210 529 4008, Fax: +30 210 529 4016, E-mail: ilycoskoufis@aua.gr, mav.g@aua.gr
2School of Agricultural Technology, Technological Educational Institute of Peloponnese, Antikalamos,
P.O. 24 100, Kalamata, Tel. +30 27210 45160
Introduction
The aim of the current project is to research the effects of high salinity
in the nutrient solution, on hydroponic tomatoes, when partly or all the
root system is under high salinity conditions.
Materials and Methods
For this purpose tomato plants (Lycopersicon esculentum Mill., cv. ‘Rally
F1’) were cultivated on a closed hydroponic N.F.T. System on three
different cases: in Case (A) the roots of the plants were supplied with
regular nutrient solution of 2 dS m-1 of electrical conductivity, in Case
(B) the roots were supplied with saline nutrient solution of 12 dS m-1
E.C. ( regular nutrient solution + 100 mΜ NaCl), while in Case (C) the
roots were divided on two segments, one was supplied with regular
nutrient solution (2 dS m-1 E.C.) and the other with saline nutrient
solution (12 dS m-1 E.C.). To the regular solution Rb was added as a
detection element of potassium absorption.
Results-Discussion
Exposuring the tomato plants in NaCl high salinity conditions, as it was
expected, reduced significantly their growth by reducing their height,
their leaf area and their production. The decrease in the leaf area of
the plants emerged from the reduction of the size of the leaves, as well
as from the reduction of the amount of leaves per plant. The decrease
of production came from the decrease of the average weight per fruit.
Exposuring part of the root system of the plants that were exposed in
salinity conditions, on a regular nutrient solution eliminated the
negative effects of high salinity, in the development of the leaf area and
in the yield of the tomato plants, while it significantly confined its
negative effect on the height of the plants (Graph 1).
Also, in comparison with Case (A), the fruit quality was improved due
to the increase in the concentration of total soluble solids (Graph 2).
Water efficiency, as to the quantity of fresh product produced, was
greater in Case (C), with the split root system. The amount of water
absorbed in Case (C), originated at 81% in the root growing with
regular nutrient solution and 19% in the root growing with saline
nutrient solution (Graph 3a). Leaves conciseness on Rb+ and K+, in Case
(A), confirmed that the two elements are absorbed on the same rate.
Based on the previous statement it was calculated that in Case (C),
where one part of the root system has grown with regular nutrient
solution and the other with saline nutrient solution, the part with the
regular nutrient solution absorbed the greater amount of Κ+ (70%)
(Graph 3b).
Conclusions
Exposing only part of the root system of a plant that is in a saline
environment to regular nutrient solution, prevents the decrease in
tomato yield, while it improves the quality of fruits, through the
increase in the concentration of total soluble solids and enhances the
efficiency of irrigation water. In such conditions the plant absorbs both
water and potassium from the area with the least electrical
conductivity.
Graph 1. Salinity implications, in the root system of tomatoes or part of it, (a) in
height, (b) on leaf area per plant, (c) on average leaf area και (d) in number of
leaves per plant.
0,0
0,2
0,4
0,6
0,8
1,0
1,2
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
m2
CASES
Leaf Area per Plant
A B C
2,5 dS m-1 12 dS m-1 Split Root
12
13
14
15
16
17
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
CASES
Number of Leaves per Plant
A B C
2,5 dS m-1 12 dS m-1 Split Root
500
550
600
650
700
750
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
cm2
CASES
Average Leaf Area
A B C
2,5 dS m-1 12 dS m-1 Split Root
0
40
80
120
160
200
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
g
CASES
Average Fruit Weight
A B C
2,5 dS m-1 12 dS m-1 Split Root
(c)
20
24
28
32
36
40
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
CASES
Number of Fruits per Plant
A B C
2,5 dS m-1 12 dS m-1 Split Root
0
2
4
6
8
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
kgperplant
CASES
Yield
A B C
2,5 dS m-1 12 dS m-1 Split Root
4,0
4,3
4,6
4,9
5,2
5,5
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
%brix
CASES
Total Soluble Solids (d)
A B C
2,5 dS m-1 12 dS m-1 Split Root
Graph 2. Salinity implications, in the root system of tomatoes or part of it, (a) on
yield, (b) on number of fruits per plant, (c) on average fruit weight and (d) in
total soluble solids of tomatoes.
(α)
(a)
(c) (d)
(b)
0
1
2
3
4
5
6
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
m
CASES
Plant Height
A B C
2,5 dS m-1 12 dS m-1 Split Root
(a)
10
11
12
13
14
15
Μάρτυρας
2,5 dS m-1
NaCl
12 dS m-1
Διαχωρισμένη
ρίζα
l kg-1
CASES
Water Efficiency (a)
Graph 3. Salinity implications, in the root system of tomatoes or part of it, (a)
on water efficiency and (b) on relative potassium absorption in uneven salinity
conditions.
0
20
40
60
80
Κανονικό θρεπτικό διάλυμα
2,5 dS m-1
Αλατούχο θρεπτικό
διάλυμα 12 dS m-1
%
Root System
Κ+ Absorption
Regular Nutrient Saline Nutrient
Solution Solution
2,5 dS m-1 12 dS m-1
(b)
A B C
2,5 dS m-1 12 dS m-1 Split Root
(b)