V. NEW APPROACH TO WATER RELATIONS OF DESERT PLANTS
295
TABLE X X I I
CHLORIDE AND SULFATE FRACTION IN THE C E L L S A P ( P R E S S S A P ) OF SOME
XERO-HALOPHYTES"
Contributions to t h e
osmotic potential
Osmotic
Plants (from t h e Karroo,
potential
Chlorides
Sulfates
South Africa)
(atm)
(%)
(%)
Salsola&p.
—51 to —65
23
17
A triplex nummularia (cultivated)
—52 to —57
29
16
« After Walter (1939, p. 803).
The importance of concentration and composition of salts in soil in
growth and structure of plants was recently emphasized by Strogonov
(1964). He also mentioned the different effects of S0 4 and Cl ions. In
his experiments with halophytes and crop plants Strogonov controlled
the soil salt content by addition of chlorides and/or sulfates but did not
determine these ions in the plant leaves. Changes in physiological and morphological parameters of the plants were determined (Table XXIII). However, there is no simple correlation between ion composition of the soil
solution and ion uptake. Chloride and sulfate halophytes may grow beside
TABLE X X I I I
PLANT DEVELOPMENT AND TRANSPIRATION OF Gossypium herbaceum IN RELATION
TO SOIL SALINITY«·
6
Parameter
Water content (in % of fresh weight)
Fresh weight of 100 cm
2 leaf area (in gm)
Amount of water in 100 cm
2 leaf area
(in gm)
Amount of dry matter in 100 cm
2 leaf area
(in gm)
Transpiration (in g m / m
2 / hour)
Transpiration (in % of water content)
Leaf area per plant in cm
2
Dry matter of roots per plant (in gm)
Control
78.16
2.08
1.60
0.48
188.4
120.6
3628
4.34
Sulfate
salinity
78.48
2.53
1.98
0.55
243.6
135.0
2505
3.22
Chloride
salinity
83.34
4.00
3.40
0.60
109.8
35.4
685
1.46
a From Strogonov (1964, p . 105, Tables 40, 43, 45).
b The water content of t h e soil is 70% of field capacity; the salt content of the soil
was brought to 1 % of t h e soil dry weight.