Evaluation of Three Physiological Traits for Selecting Drought

Evaluation of Three Physiological Traits for Selecting Drought

J. Agric. Sci. Technol. (2005) Vol. 7: 81-87
Evaluation of Three Physiological Traits for Selecting Drought
Resistant Wheat Genotypes
R. Amiri Fahliani1 and M. T. Assad 2∗
ABSTRACT
Physiological traits are receiving increasing attention as screening tools for drought resistance. Two field experiments were conducted in 1998 at the Experimental Station of
College of Agriculture, Shiraz University at Badjgah, to evaluate the effectiveness of leaf
water potential, leaf osmotic potential and canopy temperature in screening resistant
bread wheat (Triticum aestivum L.) genotypes. Nine wheat cultivars consisting of drought
resistant, intermediate and susceptible genotypes were grown in two randomized complete block designs with three replications. The experiments only differed with respect to
their irrigation regimes. Leaf water potentials and leaf osmotic potentials at three developmental stages -stem elongation, booting and flowering - under water stress conditions,
and canopy temperature in non-stress conditions could discriminate between resistant
and susceptible cultivars. Although the drought susceptibility index could partly discriminate between resistant and susceptible cultivars, it was not evaluated as a reliable
index. The linear regression of grain yield on each trait was determined. The linear regressions of grain yield on leaf water potential; leaf osmotic potential and canopy temperature confirmed the above results.
Keywords: Triticum aestivum, Leaf water potential, Osmotic potential, Turgor potential,
Canopy temperature.
water-stressed treatment were much lower
than those of the well-watered control. They
also concluded that osmotic adjustment did
not contribute to the differences between
cultivars in response to water stress. However, Blume (1989) suggested that induced
osmotic adjustment under drought stress
might be an important component of drought
resistance in barley growth. Neumann
(1995) rejected the notation that a stressinduced reduction in cellular turgor pressure
is a primer cause of growth inhibition.
Hoffman and Jobes (1978) reported that the
relationship between crop yield and total
leaf water potentials was negative and linear.
Canopy temperature is another criterion,
which has been considered effective in
screening wheat (Blum et al., 1982; Pinter et
al. 1990; Golestani Araghi and Assad, 1998)
INTRODUCTION
Soil water deficit depresses agricultural
crop yield in many parts of the world. Plant
breeders search for effective and repeatable
criteria to screen germplasms, for drought
resistance in segregating populations. Plant
breeders have used selected physiological
parameters that are important in the plantwater relations of bread wheat (Triticum
aestivum L.) under stress conditions. Levitt
(1972), and Matin et al. (1989) reported that
total water potentials of plant tissue are different between drought-resistant and
drought-susceptible genotypes. Moustafa et
al. (1996) used leaf water and osmotic potentials to differentiate apparent drought tolerance among wheat cultivars. They reported that the leaf water potentials of the
_____________________________________________________________________________
1
Department of Agronomy, College of Agriculture, Yasuj University, Yasuj, Islamic Republic of Iran.
Department of Agronomy, College of Agriculture, Shiraz University, Shiraz, Islamic Republic of Iran.
∗
Corresponding author.
2
81
____________________________________________________________ Amiri Fahliani and Assad
middle rows were used for grain yield determination, and data were recorded on the
basis of 10 randomized selected plants in the
second and seventh rows. Fertilizer was applied at the rate of 80 Kg/ha N and 70 Kg/ha
P2O5. Crops received one half of N in urea
form and total amount of P2O5 at planting,
while the remaining N was applied at tillering stage.
The two experiments differed with respect
to their irrigation regimes. The non-stress
experiment received water when 40±5 mm
evaporation occurred from pan class A,
while the stress experiment was not irrigated
after plant establishment. The soil moisture
status in the non-stress experiment was
measured with a neutron probe (Troxler
Model 2651). The effective rainfall during
1998-9 and total irrigation for each experiment are given in Table 1.
Leaf water potential (ψw) was measured
using a PMS pressure bomb (PMS Instrument Co., Corvallis, OR) at stem elongation,
booting and flowering plant developmental
stages based on Zeidak`s Code in both experiments. The youngest fully expanded leaf
was detached and placed rapidly in a sample
chamber and the pressure was recorded. For
each developmental stage three randomly
selected plants were used. Measurements
were completed between 13.00 and 15.00
hours. To measure osmotic potential (ψs),
the youngest fully expanded leaf of each of
10 randomly selected plants was used for
each developmental stage. Leaves were
placed in plastic bags and rapidly packed in
and pearl millet (Singh and Kanemasu,
1983) genotypes resistant to drought. Plant
breeders have used selected physiological
parameters that play a role in the plant-water
relations of wheat under stress conditions
(Keim and Kronstad, 1981; Jaradat and
Konzak, 1983; Seropian and Planchon,
1984; Turner, 1986 a, b; Blum, 1989; Matin
et al. 1989). The objectives of this study
were to evaluate leaf water potential, leaf
osmotic potential, and canopy temperature
in differentiating wheat cultivars for drought
resistance and to find their relationships with
grain yield.
MATERIALS AND METHODS
Two field experiments were conducted in
1998 at the Experimental Station of College
of Agriculture, Shiraz University, at Badjgah
(Iran). Nine hexaploid wheat cultivars were
used in both experiments. According to the
ranking proposed by the Seed and Plant Improvement Institute and later approved by
Golestani Araghi and Assad (1998), three
drought resistant cultivars (Omid, Roshan,
and Kal-Haydary), three intermediate (Bayat, Niknejad, and M-75-5), and three
drought sensitive ones (Falat, Darab, and
Azadi Cross) cultivars were used. Cultivars
were planted on 6th November 1998 in two
experiments using randomized complete
block designs each with three replications on
a clay loam soil. Each plot consisted of eight
5m rows with the rows 25cm apart. The four
Table 1. Precipitation distribution and total irrigation for each experiment.
Month
November
December
January
February
March
April
May
June
Total
Total water used
Effective
Rainfall
19.7
126.8
26.1
165.8
60.4
50.7
5.0
454.5
Non-stress
140
200
100
440
894.5
82
Irrigation (mm)
Stress
140
140
594.5
Selecting Drought Resistant Wheat Genotypes ____________________________________
reduced under stress conditions, but the reductions in spike length were not significant.
Susceptible cultivars on average showed
higher drought susceptibility indices than
intermediate and resistant cultivars, however
there was some misclassification, especially
in respect to intermediate and resistant cultivars.
The leaf water potentials (ψw) of cultivars
at three developmental stages are given in
Table 3. The ψw values decreased with
maturation in both environments and cultivars showed significant differences in all
stages (p<0.01). Table 3 indicates that leaf
water potential apparently discriminated between drought resistant, intermediate, and
susceptible cultivars at the three stages in
both environmental conditions. Drought resistant cultivars showed lower ψw values as
compared to sensitive ones. This is in
agreement with the results obtained by others (Barlow et al., 1980; Keim and Kronstad, 1981; Matin et al. 1989; Entz and
Flower, 1990; Moustafa et al., 1996). The
linear relationship between ψw and grain
yield was significant under stress condition
only (Table 4). Although ψw in all stages
and conditions could classify cultivars in
respect to drought resistance, however, Table 3 shows that ψw values in stress conditions were more effective. The results obtained from linear regressions also confirmed these results.
The leaf osmotic potential (ψs) of cultivars
at different developmental stages in stress
and non-stress conditions are given in Table
3. The trend of variation in ψs values in different developmental stages was similar to
that of ψw. Cultivars were significantly different with regard to values in all stages, in
both environments (p<0.01). The ψs values
of drought resistant cultivars were, on average, lower than those of drought susceptible
ones in all conditions, indicating that ψs was
an effective technique in screening resistant
genotypes. Other investigators (Grumet et
al., 1987; Blume, 1989; Musick et al., 1994)
also reported that drought resistant cultivars
had lower ψs values as compared to
a box in order to avoid water-loss as vapor
from the sample and maintained at -15°C for
five hours. The frozen samples were then
thawed for approximately 30 minutes and
the freezing point (T) of collected saps was
measured using a digital thermometer
(Model ET - 2001). The osmotic potential
then was calculated (Kramer, 1995) by:
ψs = (-T / 1.86) × 2.27
The canopy temperature (TC) of each plot
was measured at three development al stages
at 13.00 to 15.00 hours in both experiments
using an infrared thermometer (Kane-May
Model Infratrace 800). The instrument was
pointed down at three random points in each
plot and held at an oblique angle to the canopy surface to minimize the influence of soil
exposure. The drought susceptibility index
(S) was also determined by the following
equation (Fischer and Mourer, 1978):
S = [1-( y D / y p)] / D
Where y D and y p , are the grain yield of
each cultivar at stress and non-stress conditions respectively, and D = 1- ( Y D / Y P). Y D
and Y P are the mean yield of all the cultivars under stress and non-stress conditions.
Analysis of variance in all the measurements
was conducted by Statistical Analysis System (SAS, 1985). Means were separated using the least significant difference (LSD).
The regression of grain yield on each
physiological index was also determined. To
compare the effects of stress and non-stress,
and cultivars by moisture conditions interaction, a combined analysis of variance was
used.
RESULTS AND DISCUSSION
The mean grain yield and some related
components for both experiments are
showed in Table 2. Cultivars did not differ
significantly in respect to grain yield under
non-stress conditions, however, the differences were significant under stress conditions (p<0.01). This emphasized the different responses of cultivars to drought conditions. All of the characters in Table 2 were
83
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Selecting Drought Resistant Wheat Genotypes ____________________________________
susceptible ones. Table 3 indicates that ψs
values in stress conditions could classify
genotypes better compared with non-stress
condition. The regressions of grain yield on
ψs were significant under stress condition
(Table 4). This indicated that leaf osmotic
potential might be a good trait for selecting
wheat genotypes resistant to draught in
stress conditions.
The differences in the canopy temperature
(Tc) of cultivars were highly significant in
both moisture conditions (p<0.01) and
growth stages, except stem-elongation in
non-stress conditions (Table 3). This exception may be due to similar transpiration activity of all cultivars under well-watered environmental conditions. Except for stem
elongation in non-stress condition, the linear
regressions of grain yield on canopy temperature were not significant in other cases
(Table 4). The canopy temperature of cultivars in flowering, under non-stress conditions, could help discriminate between resistant and susceptible cultivars better than at
other stages. Pinter et al. (1990) and Golestani Araghi and Assad (1998) also reported that (Ta-Tc) is a valuable technique in
screening drought resistant genotypes.
1. Barlow, E. W. R., Lee, J. W., Munns, R. and
Smart, M.G. 1980. Water Relations of Developing Wheat Grain. Aust. J. Plant
Physiol., 7: 519-525.
2. Blum, A. 1989. Osmotic Adjustment and
Growth of Barley Genotypes under Drought
Stress. Crop Sci. 29: 230-233.
3. Blum, A., Mayer, J. and Gozlan, G. 1982.
Infrared Thermal Sensing of Plant Canopies
as a Screening Technique for Dehydration
Avoidance in Wheat. Field Crop Res., 5:
137-146.
4. Entz, M. H. and Flower, D. B. 1990. Influence of genotype, water and N on leaf water
relations in No-till winter wheat. Can. J.
Plant Sci., 70: 431-441.
5. Fischer, R. A. and Maurer, R. 1978. Drought
Resistance in Spring Wheat Cultivars. 1:
Grain Yield Responses. Aust. J. Agr. Res.,
29: 897-912.
6. Golestani Araghi, S.and Assad, M. T. 1998.
Evaluation of four Screening Techniques for
Drought Resistance and Their Relationship
to Yield Reduction Ratio in Wheat.
Euphytica, 103: 293-299.
7. Grumet, R., Albrechtensen, R. S. and Hanson, A. D. 1987. Growth and Yield of Barley
Isopopulations Differing in Solute Potential.
Crop Sci., 27: 991-995.
8. Hoffman, G. J. and Jobes J. A. 1978. Growth
and Water Relations of Cereal Crops as Influenced by Salinity and Relative Humidity.
Agron. J., 70: 765-769.
9. Jaradat, A. and Konzak, C. F. 1983. Screening of Wheat Genotypes for Drought Tolerance: 1. Excised-leaf Water Retention. Cereal Res. Com., 11: 179-186.
10. Keim, D. L. and Kronstad, W. E. 1981.
Drought Response of Winter Wheat Cultivars Grown Under Field Stress Conditions.
Crop Sci., 21: 11-15.
11. Kramer, P. J., and J. S. Boyer. 1995. Water
Relations of Plant and Soils. Academic
press, Inc., New York, 494 pp.
12. Levitt, J. 1972. Response of Plants to Environmental Stress. Academic Press, New
York.
13. Matin, M. A., Brown, J. H. and Ferguson, H.
1989. Leaf Water Potential, Relative Water
Content, and Diffusive Resistance as Screening Techniques for Drought Resistance in
barley. Agron. J., 81: 100-105.
14. Moustafa, M. A., Boersma, L. and Kronstad,
W. E. 1996. Response of four Spring Wheat
CONCLUSION
This study showed that leaf water potentials and leaf osmotic potentials of wheat
plants at the three developmental stages
(stem elongation, booting, and flowering)
under water stress conditions, and canopy
temperature in non-stress conditions were
the best criteria for screening drought resistant genotypes. Although the drought susceptibility index could partly discriminate
between resistant and susceptible cultivars,
it was not evaluated as a consistent reliable
criterion alone. For more reliability of results use of more genotypes and seasons are
recommended.
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87
‫‪____________________________________________________________ Amiri Fahliani and Assad‬‬
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‫ارزﻳﺎﺑﻲ ﺳﻪ ﻣﻌﻴﺎر ﻓﻴﺰﻳﻮﻟﻮژﻳﻚ ﺟﻬﺖ ﮔﺰﻳﻨﺶ ژﻧﻮﺗﻴﭗﻫﺎي ﮔﻨﺪم ﻣﻘﺎوم ﺑﻪ ﺧﺸﻜﻲ‬
‫ر‪ .‬اﻣﻴﺮي ﻓﻬﻠﻴﺎﻧﻲ و م‪ .‬ت‪ .‬آﺳﺎد‬
‫ﭼﻜﻴﺪه‬
‫ﺻﻔﺎت ﻓﻴﺰﻳﻮﻟﻮژﻳﻚ ﺑﻪ ﻋﻨﻮان اﺑﺰاري ﺟﻬﺖ ﺗﺸﺨﻴﺺ ژﻧﻮﺗﻴﭗﻫﺎي ﻣﻘﺎوم ﺑﻪ ﺧﺸﻜﻲ ﻣﻮرد ﺗﻮﺟﻪ روز اﻓﺰون‬
‫ﻗﺮار ﮔﺮﻓﺘﻪ اﺳﺖ‪ .‬دو آزﻣﺎﻳﺶ در ﺳﺎل ‪ 1377‬در اﻳﺴﺘﮕﺎه ﭘﮋوﻫﺸﻲ داﻧﺸﻜﺪه ﻛﺸﺎورزي‪ ،‬داﻧﺸﮕﺎه ﺷﻴﺮاز‬
‫ﺟﻬﺖ ارزﻳﺎﺑﻲ ﺗﺎﺛﻴﺮ ﭘﺘﺎﻧﺴﻴﻞ آب ﺑﺮگ‪ ،‬ﭘﺘﺎﻧﺴﻴﻞ اﺳﻤﺰي ﺑﺮگ‪ ،‬و درﺟﻪ ﺣﺮارت ﺳﺎﻳﻪ اﻧﺪاز ﺑﺮ ﺗﺸﺨﻴﺺ‬
‫ژﻧﻮﺗﻴﭗﻫﺎي ﻣﻘﺎوم ﮔﻨﺪم )‪ (Triticum aestivum L.‬اﻧﺠﺎم ﮔﺮﻓﺖ‪ .‬ﻧﻪ رﻗﻢ ﮔﻨﺪم ﻣﻘﺎوم‪ ،‬ﻧﻤﻴﻪ ﻣﻘﺎوم و ﺣﺴﺎس‬
‫ﺑﻪ ﺧﺸﻜﻲ در دو ﻃﺮح ﺟﺪاﮔﺎﻧﻪ ﺑﻠﻮكﻫﺎي ﻛﺎﻣﻞ ﺗﺼﺎدﻓﻲ ﺑﻪ ﻛﺎر ﺑﺮده ﺷﺪ‪ .‬ﻳﻜﻲ از آزﻣﺎﻳﺶﻫﺎ ﺗﺤﺖ‬
‫ﺷﺮاﻳﻂ ﻣﻄﻠﻮب و دﻳﮕﺮي ﺗﺤﺖ ﺗﻨﺶ آﺑﻲ ﻗﺮار ﮔﺮﻓﺖ‪ .‬ﺻﻔﺎت ﻓﻴﺰﻳﻮﻟﻮژﻳﻚ ﻣﺰﺑﻮر در ﺳﻪ ﻣﺮﺣﻠﻪ رﺷﺪ‬
‫)ﻃﻮﻳﻞ ﺷﺪن ﺳﺎﻗﻪ‪ ،‬ﻏﻼف رﻓﺘﻦ و ﮔﻞ دﻫﻲ( ﮔﻴﺎه اﻧﺪازهﮔﻴﺮي ﺷﺪ‪ .‬رﮔﺮﺳﻴﻮن ﺷﺎﺧﺺ ﺣﺴﺎﺳﻴﺖ ﺑﻪ ﺧﺸﻜﻲ‬
‫ﺑﺮ ﻫﺮ ﻛﺪام از ﺻﻔﺎت ﻧﻴﺰ ﺗﻌﻴﻴﻦ ﺷﺪ‪ .‬ﭘﺘﺎﻧﺴﻴﻞ آب ﺑﺮگ و ﭘﺘﺎﻧﺴﻴﻞ اﺳﻤﺰي ﺑﺮگ در ﻫﺮ ﺳﻪ ﻣﺮﺣﻠﻪ رﺷﺪ ﺗﺤﺖ‬
‫ﺷﺮاﻳﻂ آﺑﻲ و درﺟﻪ ﺣﺮارت ﺳﺎﻳﻪ اﻧﺪازه ﺗﺤﺖ ﺷﺮاﻳﻂ ﻣﻄﻠﻮب در ﺗﺸﺨﻴﺺ ژﻧﻮﺗﻴﭗﻫﺎي ﺣﺴﺎس و ﻣﻘﺎوم‬
‫ﻣﻮﺛﺮ ﺑﻮدﻧﺪ‪ .‬ﻫﺮ ﭼﻨﺪ ﺷﺎﺧﺺ ﺣﺴﺎﺳﻴﺖ ﺑﻪ ﺧﺸﻜﻲ ﺗﺎ ﺣﺪودي در ﮔﺮوه ﺑﻨﺪي ارﻗﺎم ﺑﻪ ﺣﺴﺎس و ﻣﻘﺎوم ﻣﻮﺛﺮ‬
‫ﺑﻮد‪ ،‬وﻟﻲ ﻣﻌﻴﺎر ﻗﺎﺑﻞ اﻋﺘﻤﺎدي ﺗﺸﺨﻴﺺ داده ﻧﺸﺪ‪ .‬رﮔﺮﺳﻴﻮن ﺧﻄﻲ ﺷﺎﺧﺺ ﺣﺴﺎﺳﻴﺖ ﺑﻪ ﺧﺸﻜﻲ ﺑﺮ ﺗﻤﺎم‬
‫ﻣﻌﻴﺎرﻫﺎ ﺗﻌﻴﻴﻦ ﺷﺪ‪.‬‬
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