photosynthesis efficiency of date palm varieties grown in saudi arabia

‫ﺍﻟﻤﻤﻠﻜﺔ ﺍﻟﻌﺮﺑﻴﺔ ﺍﻟﺴﻌﻮﺩﻳﺔ‬
‫ﺟﺎﻣﻌﺔ ﺍﻟﻤﻠﻚ ﻓﻴﺼﻞ‬
‫ﻛﻠﻴﺔ ﺍﻟﻌﻠﻮﻡ ﺍﻟﺰﺭﺍﻋﻴﺔ ﻭﺍﻷﻏﺬﻳﺔ‬
‫اﻟﺘﻘﺮﻳﺮ اﻟﻔﻨﻲ اﻟﻨﻬﺎﺋﻲ ﻟﻠﻤﺸﺮوع اﻟﺒﺤﺜﻲ‬
‫‪PHOTOSYNTHESIS EFFICIENCY‬‬
‫‪OF DATE PALM VARIETIES‬‬
‫‪GROWN IN SAUDI ARABIA‬‬
‫ﺍﻟﺒﺎﺤﺜــــﻭﻥ‬
‫ﺩ‪ /.‬ﺴـــﻠﻴﻤﺎﻥ ﺒﻥ ﻋﻠﻲ ﺍﻟﺨﻁﻴﺏ )ﺒﺎﺤﺙ ﺭﺌﻴﺴﻲ(‬
‫ﺩ‪ /.‬ﻋﺒﺩ ﺍﻟﻠﻁﻴﻑ ﺒﻥ ﻋﻠﻲ ﺍﻟﺨﻁﻴﺏ )ﺒﺎﺤﺙ ﻤﺸﺎﺭﻙ(‬
‫ﺩ‪ /.‬ﺤﺴــﻥ ﻤﺯﻤل ﻋﻠﻲ ﺩﻴﻨــﺎﺭ )ﺒﺎﺤﺙ ﻤﺸﺎﺭﻙ(‬
‫ﻣﻘﺪم إﻟﻰ‬
‫ﻋﻤﺎدة اﻟﺒﺤﺚ اﻟﻌﻠﻤﻲ ‪ -‬ﺟﺎﻣﻌﺔ اﻟﻤﻠﻚ ﻓﻴﺼﻞ‬
‫‪١٤٢٤‬‬
‫‪١‬‬
PHOTOSYNTHESIS EFFICIENCY OF DATE
PALM VARIETIES GROWN IN SAUDI ARABIA
Al-Khateeb, S.A.* , A.A. Al-Khateeb** and H,M Ali-Dinar**
* Crops and Range Dept., College of Agric.& Food Sciences and ** Date Palm
Res.Center, King Faisal University P.O. Box 420, Al-Hassa, 31982, Kingdom of
Saudi Arabia.
SUMMARY
Gas exchange capacity was significantly affected by season
showing higher net photosynthesis in cold seasons(winter and spring) and
higher transpiration in hot season (summer). This trend was much related
to both stomatal and non stomatal component which affect water use
efficiency showing higher values in winter and lower in summer.
Although there was no much different in net photosynthesis among
cultivars Kheneizi ,Khalas,. Shahel, shisho and Helali had the higher
rates. Khalas CV showed lower rate of transpiration which reflected in
higher water use efficiency in this cultivar. Recently expanded leaves
showed higher rate of net photosynthesis and lower transpiration rate,
compared with fully expanded leaves and therefore showed higher water
use efficiency. Expanding leaves showed lower rate of activity inmost
parameters.
٢
INTRODUCTION
Photosynthesis is the source of organic carbon and energy for
plants. It is the source for the growth, production of biomass and yield
formation. Knowing the control of photosynthesis through leaves age is
of important variable to understand the relationship between production
and leaves age. Photosynthesis begins with the absorption of light energy
and using it resulting in a charge to the reaction contents which leas to the
reduction of C02 to carbohydrates. This reaction occurs within the
specialized structure of the chloroplast. It is suggested that as leaves age
the possibilities of a decreased in the ability of the chloroplast for C02
fixation is raises as will as chlorophyll concentration is decreased.
Although, there is a large amount of literature concerning the relationship
between photosynthises and gas exchange capacity and leaf age under
field conditions of many plants, there are few of these studies dealing
with date palm tree. Al-Waibi (1988) studied “Leaf C02 assimilation rate,
stomatal conductance and transpiration rate in the female cultivars Sikkeri
and Osaila from sunrise until dusk. His data suggested some variations in
these 3 parameters according to leaf surface (adaxial or abaxial), leaf age
and cultivar. The overall maximum of C02 assimilation was about 13%
higher in Osaila than in Sikkeri. Osalia also had a higher water use
efficiency (about 8%) than Sikkeri in spite of a higher chlorophyll content
and chlorophyll-a:b ratio in Sikkeri. These differences were probably due
to the high stomatal conductance of Osalia leaves which ranged from 207
to 254, while that found in Sikkeri ranged from 157 to 186 mmol H20 m-2
s-1.” However, in other palm trees Henson, (1992) measured standing dry
matter, DM production, leaf area, leaf photosynthesis parameters, and
dark respiration of the main plant organ for oil palms (Elaeis guineensis)
in the third year after planting (first cropping year) on 2 adjacent sites
٣
differing in ground water supply. He reported that productivity was
greater on the wetter site. Gross CO2 assimilation (GA) was obtained (1)
from the sum of DM production and total respiration (2) from DM
production alone, assuming this to be one-quarter of GA, and (3) as the
output of a simulation model of canopy photosynthesis. All 3 methods
produced similar GA values, but some adjustment of light interception
parameter values was needed to obtain a realistic output from the model.
Respiration was partitioned into growth and maintenance components and
general C budgets were constructed for the 2 sites. Dufrene and Saugier
(1993) reported that in experiment conducted in the La Me Oil Palm
Research station, Cote d’Ivoire, gas exchange in leaves of oil palm was
measured in the field over a range of photon fluxes, leaf temperatures and
leaf-air vapor pressure differences (VPD). There were no differences in
leaflet photosynthesis within one frond, but there was reduction with
frond age. Far fronds of the same age, between-tree variation was low.
The light-saturated rate of net CO2 assimilation was 20 mumol m-2s-1
when photosynthetically active radiation exceed 1100 mumol m-2s-1.
Apparent quantum yield averaged 0.051 mol/mol. When leaf temperature
increased from 30 to 38 0C, net CO2 uptake showed no variation as
transpiration rate and stomatal conductance increased slightly. A small
increase in VPD induced rapid stomatal closure and consequently a
reduction in the transpiration rate. A VPD> 1.8 kPa was required before
photosynthesis was reduced via stomatal closure in the case of plants
growing in a soil with adequate water supply. Again Dufrene and Saugier
(1993) measured leaf gas exchanged in 6-month-old and 10-year old oil
palms in the field (in the Ivory Coast) over a range of photon fluxes, leaf
temperatures and leaf-air vapor pressure differences (VPD). Leaflet
photosynthesis did not differ within frond, but did vary with frond age.
For fronds of the same age, between-tree variation was low. The light
٤
saturated rate of net CO2 assimilation was 20 mumol m-2s-1 when
photosynthetically active radiation (PAR) exceeded 1100 mumol m-2s-1.
Apparent quantum yield averaged 0.051 mol/mol. When leaf temperature
increased from 30 to 38 0C uptake showed no variation as transpiration
rate and stomatal conductance increased slightly. A small increased in
VPD induced rapid stomatal closure and consequently a reduction in the
transpiration rate. A VPD greater than 1.8 kPa was required before
photosynthesis was reduced via stomatal closure in the case of plants
growing in a soil with adequate water supply. Jayasekara et al (1996)
reported on photosynthesis, stomatal conductance, leaf temperature, light
compensation, dark respiration, intercellular CO2 concentration and
transpiration in seedlings of coconut palm (cultivars CRIC 60 and CRIC
65), growing in Sri-Lanka. Light saturated maximum rate of
photosynthesis in both cultivars was 1400 umol m-2s-1. The rate of
photosynthesis and N content of leaves decreased with increasing leaf
age.
Lamade
and
Setiyo
(1996)
observed
measurements
of
photosynthesis and stomatal conductance on oil palm (3 clones (MK10,
MK22 and MK04) with contrasting morphology and different genetic
origins) at the Marihat Research Station in North-Sumatra in Indonesia.
The results established a new level of reference for the maximal
photosynthesis of oil palm equal to 31.6 umol m-2s-1. Analysis of
variations of photosynthesis in response to environmental factors as
temperature or vapor pressure deficit (VPD) demonstrated the high
sensitivity of maximal photosynthesis to these factors in Sumatra
compared with observations in Cote d’Ivoire and in Benin. The
differences observed within clones for the photosynthetic response to
light and the sensitivity of maximal photosynthesis to variations in VPD
٥
and temperature demonstrate the possible use of these physiological
parameters for breeding. However, on other plants (Xizhen, et al, (1998)
reported that the chlorophyll content and photosynthetic rate of ginger
leaves increased with leaf expansion to reach a peak in 15-day-old leaves,
but subsequently declined gradually.
Thomas and Turner (1998), found that in bananas (cv. Williams)
grown in hot arid environment, net photosynthesis (Pn) did not differ
between the segments on the leaf except when they received different
photosynthetic photon flux density (PPFD). Pn reached a maximum of
20-25 umol CO2 m-2s-1, 9 days after the leaf had unrolled, that is when
another new leaf emerged and the measured leaf was in the second leaf
position. Leaf chlorophyll concentration stabilized 7 days after unrolling
but then increased slowly with time. The reduced rates of leaf gas
exchange of older leaves are most likely a result of shading by younger
leaves. In this study although Pn was lower in older leaves, the calculated
internal CO2 concentration did not increase even at high leaf temperatures
and leaf-to-air vapor differences. Therefore, they concluded that the
photochemistry of the chloroplast did not constrain Pn.
Prive et al (1997), studied seasonal changes in net CO2 exchange
rates of red raspberry. They found that net carbon exchange rate (NCER)
varied inconsistently between leaves which subtended fruiting lateral
branches (laterals) and those that did not. In leaves with fruiting laterals,
was lower on 3 dates, similar on 3 other dates and once greater than in
leaves without fruiting laterals. The leaf chlorophyll content increased
when fruiting laterals were present, but this did not produce a consistently
higher leaf NCER. The SPAD-501 meter provided a rapid and accurate,
nondestructive estimate of leaf chlorophyll content. They added that leaf
age did not influence leaf gas exchange until the leaves started to senesce.
٦
Therefore, good light interception throughout the canopy is needed to
optimize dry matter production in primocane fruiting raspberry.
Sobrado (1996), studied leaf photosynthesis and water loss as
influenced by leaf age and seasonal drought in an evergreen tree. He
found that maximum net photosynthetic rates (pmax) of about 9.5 mmol
m-2s-1 were observed in mature leaves during humid season. Expanding
and old leaves had lower maximum photosynthetic rate (Pmax). With
drought Pmax, stomatal conductances and water loss were reduced.
Therefore, this investigation was meant to measure the gas
exchange capacity, water use efficiently of the different Date Palm
varieties and to establish adequate standard and guidelines for leaf
removal in Date Palm. Seasonal changes in gas exchange capacity in Date
Palm to asses effectiveness of chlorophyll function with leaf age were
also considered.
٧
MAERIALS AND METHODS
Ten date palm cultivars (Khlas, Ghar, Kheneizi, Om-rhim, Shahel,
Ruzeiz, Nebout-sif, Sukari, Hilali and Shishi) between 5-7 years old were
selected for the study. All, trees were grown in the Date Palm Germplasm
Bank at the Date Palm Research Center; Ministry of agriculture
Experimental Station. Date Palm leaves were designated to these
categories:
1- Expanding leaves (about 1—3 months) L1.
2- Recently expanded leaves (about 3—6 months) L2.
3- Fully expanded leaves (about 9-12 months) L3.
Within the leaf, three leaflet edges were chosen for chlorophyll
determination as follows:
a) The young leaflets (the most upper leaflets at the top of the leaf.)
b) The middle leaflets
c) The oldest leaflets, the first leaflets from the base of the leaf.
Fig. (1): Diagram appearing leaf position on the stem of date palm
٨
In these leaves categories, all gas exchange and chlorophyll
measurements were obtained four times per year in June (Summer),
September (Autumn), December (Winter) and March (Spring). Four date
palm trees were used for each cultivar.
Gas exchange measurements:
All trees were labeled and the pointed leaves have been tagged for the
subsequent measurements. The photosynthesis gas exchange rate was
determined by infrared gas analysis techniques. All measurements were
carried out during sunny day between 9—11 A.M. in winter and spring
and 7-9 A.M. in summer and autumn. Photosyntethic active radiation
(PAR) was more than 1200 µmol/m2/s , which is expected to be above a
saturation photo irradiance of date palm. Calculation of photosynthesis
rate (P) in µmol/m2/s, stomatal conductance (C) in mmol/m2/s,
transpiration rate (E) in mmol/m2/s and intercellular CO2(Ci) in µmol/mol
was estimated according to Caemmerer and Furguhar (1981). Mesophyll
(residual) conductance (gs) in mmol/m2/s which is a composite measure
of all liquid plus.conductance to gas (Cell wall, Plasmatemma,
Cytoplasm, Chloroplast membranes) as well as the conductance
associated with carboxylation was calculated as:
gm=A/Ci mmol/nr/s
(Fites and Teskey, 1981).. Water use efficiently calculated as: WUE=A/E
Chlorophyll determination: Chlorophyll content was measured in intact
leaflet using chlorophyll meter (SPAD 502) which provides a rapid and
accurate nondestructive estimate of leaf chlorophyll content.
٩
RESULTS AND DISCUSSION
Chlorophyll content of the different leaf categories were shown in
Fig 1 &2. All the studied varieties show the same response with higher
chlorophyll content in expanding and recently expanded leaves and
showed slight reduction as leaf aged.Similar resultswere obtained by
Prive et al.,1997. However, the cultivar Sukari and Helaly showed very
low chlorophyll content in expanding leaves which were substantially
increased as leaf aged with no trend of a decrease in fully expanded
leaves (Fig. 1).
With regard to chlorophyll content within the leaf, i.e. leaflet
edges, Fig. 2 show that the oldest leaflet (A) had significantly higher
chlorophyll content in all studied varieties, except Helaly CV, which
showed the lowest chlorophyll content in the oldest leaflet. The middle
leaflet (B) had more or less equal content of chlorophyll , compared with
the the oldest leaflets. However, chlorophyll content showed slight
reduction in the young leaflet (C) (the most upper leaflets of the top of
the leaf). A mount of chlorophyll content was averaged 60 – 80 mg/cm2
in most varieties.
Net photosynthesis (P) rates were significantly higher in winter
season, compared with other seasons, followed by spring. It seeds that P
decreased with increasing temperatures showing lower values in autumn
and Summer (Table 1).Similar trend were obtained by Dufrene and
Saugier,1993 when temperature increased from 30 to 38 degrees.
Transpiration rate(E) showed lower values in winter and spring and
highest rate in Autumn and summer with the higher values in summer as
expected. This trend could be attributed to the higher transpiration stream
in these seasons.
١٠
١١
١٢
Stomatal conductance (gs) showed significantly higher rates in
summer and winter and lower rates in autumn and spring. Higher values
of gs in summer could explain the higher rate of transpiration in this
season, but interestingly did not fit with the lower transpiration in winter.
Similar results were obtained by Dufrene and Saugier,1993. However,
higher values of stomatal conductance could explain the higher net
photosynthesis reported in winter.
Intercellular CO2 concentrations were significantly lower in spring
which indicate higher rate of CO2 metabolic intake while higher values
were reported in autumn and spring (Table 1).
Mesophyll conductance (gm) was significantly higher in winter
which explain the higher rate of net photosynthesis in winter. Lower
stomatal conductance was reported in autumn which also had lower rate
of net photosynthesis. Most researchers reported that net photosynthesis
was also correlated with stomatal conductance or mesophyll conductance
(non stomatal component) (AlKhateeb 1997).
It seems that both stomatal and non stomatal components were
correlated with net photosynthesis in date palm (Alwhaibi, 1985).
Water use efficiency was higher in winter and spring , while the
lower values were reported in summer.
Net photosynthesis was almost unchanged in all date palm CVs
ranging from 4.17 µmol/m2/s in Ghar to 5.59 µmol/m2/s in Kheneizi.
Cultivars of Kheneizi, Shahel, Hilali, Khalas and Shishi had higher net
photosynthesis.
Transpiration was almost also unchanged in all cultivars with the
higher rates in Om-rahim and Shahil. However, Khalas had significantly
the lower ranspiration rate, compared with other cultivars. Stomatal
conductance showed similar trends reported in transpiration which
indicate the role of stomatal conductance in controlling transpiration
١٣
stream. However, stomatal conductance were much related to net
photosynthesis except in Khalas cultivar where other component rather
than stomatal conductance may also controling rate of net photosynthesis.
Intercelluar CO2 concentration (Ci) can be divided into three
categories. Kheneizi and Ruziz CVs which categorised by higher
concentration of Ci indicating higher rate of CO2 intake metabolism,
Ghar, Helali, Nebout Seif and Sukary categorised by lower concentration
of Ci and the others had intermediate concentrations.
Mesophyll conductance showed a trend oposite to that reported in
Ci.
Water use efficienct (WUE) was significantly higher in Khalas CV
which indicate the adaptation of this cultivar to arid and dry conditions.
Cultivar of Ghar and Om Rahim showed the lowest water use efficiency
while others showed intermediate rate of WUE.
With respect to leaf age, expanding leaves showed significantly
lower net photosynthesis rate while recently expanded leaves showed the
higher rate of net photosynthesis and atrend of declining net
photosynthesis appeared in fully expanded leaves (Xizhen et al.,1998).
Transpiration was significantly also lower in expanding leaves, but
was higher in fully expanded leaves. Stomatal conductance showed
similar trend as reported in transpiration rate.
Intercelluar CO2 concentration showed also similar trend as in
stomatal conductance with substantial concentration in expanding leaves
which indicate the unability of this leaf to metabolize CO2. Mesophyll
conductance showed higher rate in recently expanded leaves and no
activity was reported in expanding ones.
Water use efficiency was significantly higher in recently expanded
leaves which indicate that recently expanded leaves were the most active
leave in date palm.
١٤
Recently expanded leaves in spring and winter showed higher net
photosynthesis and transpiration rate and water use efficiency but lower
inter cellular CO2 concentration. This trend indicate that recently
expanded leaves in cold season showed higher activity in date palm.
Stomatal conductance showed higher rate in fully expanded and recently
expanded leaves in summer (Tabels 2-7).
Net photosynthesis was significantly higher in Kheneizi, Khalas
and Shishi in winter and Khalas in summer. On the other hand,
transpiration rate was significantly lower in Khalas particularly in winter
and spring. However, lower stomatal conductance was reported in Khalas
during cold seasons (winter and spring) which indicated the ability of
Khalas CV in controlling water loss through transpiration stream, and
therefore water use efficiency was higher in this cultivar.
Mesophyll conductance was significantly higher in Khalas ,
OmiRahim and Shishi CVs in winter showing the lowest intercellular
CO2 concentration due to high CO2 intake metabolism.
Net photosynthesis in Om-Rahim, Ruzeiz and Shahel was
significantly higher in recently expanded leaves showing rate more than
10 µmol/m2/s followed by Kheneizi, Hilali and Khalas.
Transpiration rate in Khalas cultivar in recently expanded leaves,
the most active leaves, was significantly lower among leaves of recently
and fully expanded of the different cultivars.
Higher net photosynthesis and lower transpiration rate in Khalas
CV in recently expanded leaves cause higher water use efficiency of this
cultivar. This trend was much related to lower stomatal conductance and
higher mesophyll conductance.
In Conclusion:
١٥
Intensive care should be taken to date palm in cold season to get
higher production since in this season date palm showed higher gas
exchange capacity activity. Khalas, Ghar, Shishi CVs showed higher net
photosynthesis and lower transpiration and consequently higher water use
efficiency indicating higher adaptation to dry regions. Removal of old
leaves of date palm may be done immediately after senescence since the
leaves showed lower water use efficiency especialy under the case of
water shortage as in Al-Hassa area. However, care should be taken, since
the old leaf considered a main source of nutrient recycling in date palm,
further investigation in this manner is highly recomended
١٦
Table (1): Averages of Photosynthesis rate (P), transpiration rate (E),
stomatal conductance (C); intercellular CO2 (Ci); water use
efficiency (WUE) and mesophyl conductance (gm) as affected
by the studied factors.
Season
P
E
C
C1
WUE
gm
Autumn
4.60
2.51 39.81
327.72
1.84
10.0
Spring
5.23
2.19 41.61
342.23
2.39
20.0
Summer
4.90
2.67 48.63
224.78
1.83
20.0
Winter
6.03
2.26 45.30
119.53
2.67
50.0
1.23
0.24
4.93
132.02
1.25
11.53
Ghar
4.17
2.20 34.42
161.95
1.89
30.0
Hilali
5.43
2.30 39.05
189.48
2.36
30.0
Kheneizi
5.59
2.45 50.36
387.86
2.28
10.0
Khalas
5.41
1.63 28.03
220.41
3.33
20.0
Nebout-Sif
4.99
2.22 45.78
183.74
2.25
30.0
Om-rhim
5.01
3.85 47.68
237.98
1.30
20.0
Ruzeiz
5.18
2.12 47.60
531.31
2.44
10.0
Shahel
5.49
2.65 51.44
237.63
2.07
20.0
Shishi
5.40
2.46 50.72
206.43
2.19
30.0
Sukary
5.25
2.21 43.31
178.85
2.37
30.0
1.93
0.32
7.74
208.62
2.03
18.2
Expanding
-0.74 0.99 19.99
536.15
-0.75
0.0
Fully expanded
7.09
3.20 58.24
122.28
2.21
60.0
Recently expanded
9.24
3.03 53.28
102.26
3.05
90.0
LSD (5%)
1.03
0.23
114.3
1.14
10.0
LSD (5%)
Date palm cultivars
LSD (5%)
Leaves age
١٧
4.23
Table (2): Photosynthesis rate (P) as affected by the interaction between
seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
-1.75
6.23
9.33
Season
Spring
Summer
-1.01
-0.28
6.51
7.27
10.20
7.72
Winter
0.06
8.34
9.70
2.08
Table (3): Transpiration rate (E) as affected by the interaction between
seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
1.49
3.42
3.09
Season
Spring
Summer
0.83
0.91
3.16
3.68
2.39
3.27
Winter
0.90
2.61
2.23
0.35
Table (4): Stomatal conductance (C) as affected by the interaction
between seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
22.54
50.04
46.85
Season
Spring
Summer
19.54
16.38
58.09
64.49
47.20
65.02
8.49
١٨
Winter
21.51
60.33
54.06
Table (5): Intercellular CO2 (Ci) as affected by the interaction between
seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
798.61
114.09
70.46
Spring
774.33
148.93
103.43
Season
Summer
392.09
138.74
143.52
Winter
179.57
87.38
91.63
228.63
Table (6): Water use efficiency (WUE) as affected by the interaction
between seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
-1.34
1.93
3.13
Season
Spring
Summer
-1.12
-0.29
2.00
1.99
4.22
2.26
Winter
0.07
3.13
2.93
2.17
Table (7): Mesophyll conductance (gm) as affected by the interaction
between seasons and leaves age.
Leaves age
Expanding
Fully expanded
Recently expanded
LSD (5%)
Autumn
0.0
50.0
130.0
Spring
0.0
40.0
100.0
Season
Summer
0.0
50.0
50.0
19.92
١٩
Winter
0.0
100.0
110.0
Table (8): Photosynthesis rate (P) of the evaluated date palm CVs during
the four growth seasons.
Ghar
Hilali
Kheneizi
Khalas
Nebout-Sif
Om-rhim
Ruzeiz
Shahel
Shishi
Sukary
LSD (5%)
Autumn
4.13
5.06
3.56
4.29
4.89
3.54
5.88
4.72
5.42
4.54
Season
Spring
Summer
6.69
4.20
5.60
4.49
4.81
5.92
3.02
7.36
4.71
4.70
6.25
3.91
5.46
4.66
6.11
4.52
4.30
4.22
5.40
5.07
Winter
1.67
6.59
8.09
6.99
5.67
6.33
4.74
6.61
7.64
6.00
3.79
Table (9): Transpiration rate (E) of the evaluated date palm CVs during
the four growth seasons.
Ghar
Hilali
Kheneizi
Khalas
Nebout-Sif
Om-rhim
Ruzeiz
Shahel
Shishi
Sukary
LSD (5%)
Autumn
1.62
1.82
2.85
1.69
2.77
3.90
2.23
2.95
2.74
2.51
Season
Spring
Summer
2.81
2.31
2.22
3.23
2.81
2.54
1.37
2.17
1.72
2.56
2.75
3.47
1.83
2.15
2.96
2.30
1.86
3.37
1.61
2.63
0.63
٢٠
Winter
2.08
1.94
1.60
1.28
1.81
5.27
2.29
2.39
1.88
2.10
Table (10): Stomatal conductance (C) of the evaluated date palm CVs
during the four growth seasons.
Ghar
Hilali
Kheneizi
Khalas
Nebout-Sif
Om-rhim
Ruzeiz
Shahel
Shishi
Sukary
LSD (5%)
Autumn
20.49
16.28
54.58
31.22
51.95
42.88
54.01
48.31
41.77
36.61
Season
Spring
Summer
40.36
35.87
48.63
46.33
55.38
46.37
25.00
33.57
33.91
57.35
46.38
63.06
43.93
43.53
44.67
44.36
42.10
59.79
35.75
56.09
15.50
Winter
40.96
44.94
45.12
22.32
39.91
38.41
48.92
68.44
59.22
44.77
Table (11): Intercellular CO2 (Ci) of the evaluated date palm CVs during
the four growth seasons.
Season
Summer
215.66
234.90
Hilali
Autumn
134.13
185.49
Spring
161.96
235.41
Kheneizi
247.94
918.08
208.91
176.53
Khalas
104.31
564.24
168.57
44.52
Nebout-Sif
182.78
203.63
236.52
112.02
Om-rhim
291.14
332.04
271.64
57.08
Ruzeiz
1526.06
203.63
222.49
173.06
Shahel
259.24
278.53
247.31
165.45
Shishi
159.70
350.16
223.36
92.52
Sukary
186.40
174.61
218.47
135.92
Ghar
LSD (5%)
417.42
٢١
Winter
136.06
102.11
Table (12): Water use efficiency (WUE) of the evaluated date palm CVs
during the four growth seasons.
Season
Spring
Summer
2.38
1.82
Ghar
Autumn
2.54
Hilali
2.78
2.52
1.39
3.40
Kheneizi
1.25
1.71
2.33
5.06
Khalas
2.55
2.20
3.39
5.47
Nebout-Sif
1.77
2.73
1.83
3.14
Om-rhim
0.91
2.27
1.13
1.20
Ruzeiz
2.64
2.99
2.17
2.07
Shahel
1.60
2.07
1.96
2.77
Shishi
1.98
2.31
1.25
4.06
Sukary
1.81
3.35
1.93
2.85
LSD (5%)
Winter
0.80
N.S
Table (13): Mesophyll conductance (gm) of the evaluated date palm CVs
during the four growth seasons.
Season
Spring
Summer
40.0
20.0
Ghar
Autumn
30.0
Hilali
30.0
20.0
20.0
60.0
Kheneizi
10.0
10.0
30.0
50.0
Khalas
40.0
10.0
40.0
160.0
Nebout-Sif
30.0
20.0
20.0
50.0
Om-rhim
10.0
20.0
10.0
110.0
Ruzeiz
0.0
30.0
20.0
30.0
Shahel
20.0
20.0
20.0
40.0
Shishi
30.0
10.0
20.0
80.0
Sukary
20.0
30.0
20.0
40.0
LSD (5%)
N.S
٢٢
Winter
10.0
Table (14): Photosynthesis rate (P) of the evaluated date palm CVs in the
different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
0.03
5.57
Recently
expanded
6.92
Hilali
-1.24
8.07
9.47
Kheneizi
-0.9
7.75
9.93
Khalas
-0.58
7.9
8.92
0.1
6.84
8.04
Om-rhim
-3.32
7.34
10.99
Ruzeiz
-1.2
6.33
10.43
Shahel
-0.58
6.19
10.85
Shishi
-0.24
7.66
8.77
Sukary
0.50
7.21
8.05
Nebout-Sif
LSD (5%)
3.28
Table (15): Transpiration rate (E) of the evaluated date palm CVs in the
different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
0.95
2.85
Recently
expanded
2.81
Hilali
0.76
3.3
2.85
Kheneizi
1.22
3.23
2.91
Khalas
0.67
2.27
1.94
Nebout-Sif
1.19
2.83
2.63
Om-rhim
1.49
4.38
5.67
Ruzeiz
0.8
2.91
2.65
Shahel
0.87
3.89
3.19
Shishi
1.16
3.25
2.97
Sukary
0.83
3.14
0.55
2.67
LSD (5%)
٢٣
Table (16): Stomatal conductance (C) of the evaluated date palm CVs in
the different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
15.49
40.57
Recently
expanded
47.2
Hilali
13.63
57.09
46.42
Kheneizi
29.39
58.74
62.95
Khalas
14.25
35.88
33.95
Nebout-Sif
23.65
57.38
56.31
Om-rhim
25.18
67.28
50.59
Ruzeiz
20.17
61.58
61.04
Shahel
16.55
77.38
60.4
Shishi
24.05
65.01
63.1
Sukary
17.56
61.47
13.41
50.89
LSD (5%)
Table (17): Intercellular CO2 (Ci) of the evaluated date palm CVs in the
different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
329.18
85.73
Recently
expanded
70.94
Hilali
342.91
79.5
146.02
Kheneizi
876.82
148.43
138.34
Khalas
518.74
59.78
82.71
Nebout-Sif
311.83
127.28
112.12
Om-rhim
497.02
125.63
91.28
Ruzeiz
1340.14
157.84
95.95
Shahel
451.69
176.24
84.97
Shishi
372.58
145.25
101.48
Sukary
320.6
117.18
361.24
98.77
LSD (5%)
٢٤
Table (18): Water use efficiency (WUE) of the evaluated date palm CVs
in the different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
0.03
1.96
Recently
expanded
2.46
Hilali
-1.62
2.45
3.32
Kheneizi
-0.74
2.4
3.42
Khalas
-0.86
3.48
4.61
Nebout-Sif
0.08
2.42
3.06
Om-rhim
-2.23
1.68
1.94
Ruzeiz
-1.5
2.17
3.94
Shahel
-0.67
1.59
3.41
Shishi
-0.21
2.35
2.95
Sukary
0.6
2.3
3.01
LSD (5%)
3.42
Table (19): Mesophyll conductance (gm) of the evaluated date palm CVs
in the different aged data palm leaves.
Leaves age
Date palm CVs
Expanding
Fully expanded
Ghar
0.0
60.0
Recently
expanded
100.0
Hilali
0.0
100.0
60.0
Kheneizi
0.0
50.0
70.0
Khalas
0.0
130.0
110.0
Nebout-Sif
0.0
50.0
70.0
-10.0
60.0
120.0
Ruzeiz
0.0
40.0
110.0
Shahel
0.0
40.0
130.0
Shishi
0.0
50.0
90.0
Sukary
0.0
60.0
80.0
Om-rhim
LSD (5%)
31.47
٢٥
EFERENCES
Al-Whaibi, M.H. 1988. Leaf C02 assimilation and conductance of two
date palm cultivars. Date palm J. 6: 2, 355-370.
Caemmerer, S. U. and Farguhar, G. 0. 1981. Some relations between the
biochemistry of photosynthesis and the gas exchange of
leaves. Planta. 153:376-387.
Dufrene, E. and Sugier, B. 1993. Gas exchange of oil palm in relation to
light, vapour pressure deficit, temperature and leafage.
Oleagineuz, Paris 48: 8-9, 347-356.
Fites, J. A. and Teskcy, R. 0. 1998. COz and water vapour exchange in
Pinus taeda in relation to stomatal behaviour: test of an
optimization hypothesis. Can. J. forest. Resc. 18: 150-157.
Henson, I. E. 1993. Carbon assimilation and productivity of young oil
palm (Elaeis Guinness). Elaeis. 1992, 4: 2, 51-59.
Jayasekara, C., Nainanayake-NPAD; Jayasekara-KS. 1996. Photo
synthetic characLensiics and productivity of the cocunut
palm.COCOS. 1996, 11; 96, 7 - 20.
Lamade, E.; Setiyo, E. 1996. Variation in maximum photosynthesis of oil
palm in Indonesia:
contrasting
clone.
comparison of three morphologically
Plantation,-Recherche,-Development.
1996, 3: 6, 429-438.
Prive, J. P.; Sullivan, J. A. and Proctor, J. T. A. 1997. Seasonal changes in
net carbon dioxide exchange rates of Autumn Bliss, a
primocane-fruiting red raspberry {Rubus idaeus L.). Can J.
Plant Sci. 77: 3, 427-431.
٢٦
Sobrado, M. A. 1966. Leaf photosynthesis and water loss as influence by
leaf age and seasonal drought in an evergreen tree.
Photosynthetica. 32: 4, 563-568.
Thomas, D. S., and Turner, D. W. 1998. Leaf age and environmental
effects on gas exchange in leaves of bananas (cv. Ivillians)
growing in a hot, arid environment. J. ofHort. Sci. And
Biotech. 73: 6, 774-780.
Xizher, A. 1998. Changes of photosynthetic rate, MDA content and the
activities of protective enzymes during development of
ginger leaves. Acta. Hort. Sinica. 25: 3, 294-296.
٢٧
Table (20): Photosynthesis rate (P) of the evaluated date palm Cvs in
different aged leaves during four growth seasons.
Treatments
CVs
Leaves age
Seasons
Autumn
Spring
Summer
Winter
Ghar
Expanding
-0.17
0.80
-0.31
-0.20
Ghar
Fully expanded
3.98
7.72
5.89
4.68
Ghar
Recently expanded
8.58
11.55
7.02
0.53
Hilali
Expanding
-0.60
-0.89
-0.82
-2.63
Hilali
Fully expanded
6.84
8.57
8.61
8.26
Hilali
Recently expanded
8.95
9.10
5.68
14.14
Kheneizi
Expanding
-1.90
-1.84
0.63
-0.50
Kheneizi
Fully expanded
5.90
6.00
6.64
12.46
Kheneizi
Recently expanded
6.67
10.26
10.49
12.30
Khalas
Expanding
0.88
-3.53
-0.53
0.86
Khalas
Fully expanded
4.97
5.69
10.94
10.00
Khalas
Recently expanded
7.03
6.89
11.67
10.10
Nebout-Sif
Expanding
0.17
-0.26
-0.43
0.92
Nebout-Sif
Fully expanded
7.15
5.33
7.86
7.03
Nebout-Sif
Recently expanded
7.36
9.06
6.66
9.07
Om-rhim
Expanding
-8.43
-2.23
-0.70
-1.92
Om-rhim
Fully expanded
7.24
9.12
6.24
6.78
Om-rhim
Recently expanded
11.81
11.85
6.18
14.13
Ruziz
Expanding
-5.39
-0.54
0.70
0.41
Ruziz
Fully expanded
5.98
6.79
5.64
6.90
Ruziz
Recently expanded
17.04
10.14
7.65
6.91
Shahel
Expanding
-1.83
-1.12
-1.14
1.76
Shahel
Fully expanded
6.79
4.99
6.14
6.86
Shahel
Recently expanded
9.20
14.46
8.55
11.20
Shishi
Expanding
0.47
-2.19
-0.52
1.27
Shishi
Fully expanded
7.07
4.82
6.28
12.47
Shishi
Recently expanded
8.73
10.27
6.89
9.20
Sukary
Expanding
-0.70
1.71
0.34
0.64
Sukary
Fully expanded
6.39
6.03
8.49
7.92
Sukary
Recently expanded
7.92
8.47
6.37
9.46
LSD (5%)
6.56
٢٨
Table (21): Transpiration rate (E) of the evaluated date palm Cvs in
different aged leaves during four growth seasons.
CVs
Treatments
Leaves age
Autumn
Seasons
Autumn
Autumn
Autumn
Ghar
Expanding
0.65
1.52
1.06
0.59
Ghar
Fully expanded
2.22
3.66
2.60
2.91
Ghar
Recently expanded
2.00
3.25
3.26
2.74
Hilali
Expanding
0.69
0.93
0.93
0.49
Hilali
Fully expanded
2.30
3.70
4.35
2.86
Hilali
Recently expanded
2.47
2.05
4.42
2.47
Kheneizi
Expanding
1.86
1.50
0.81
0.70
Kheneizi
Fully expanded
3.34
3.68
3.69
2.19
Kheneizi
Recently expanded
3.35
3.25
3.11
1.91
Khalas
Expanding
0.90
0.40
1.04
0.35
Khalas
Fully expanded
2.13
2.04
3.01
1.91
Khalas
Recently expanded
2.03
1.67
2.47
1.57
Nebout-Sif
Expanding
2.10
0.94
0.82
0.92
Nebout-Sif
Fully expanded
3.47
2.18
3.59
2.08
Nebout-Sif
Recently expanded
2.75
2.05
3.28
2.43
Om-rhim
Expanding
3.07
0.91
1.30
0.67
Om-rhim
Fully expanded
4.44
4.90
4.82
3.36
Om-rhim
Recently expanded
4.18
2.44
4.28
11.79
Ruziz
Expanding
0.65
0.54
0.53
1.50
Ruziz
Fully expanded
2.95
2.47
3.03
3.21
Ruziz
Recently expanded
3.09
2.47
2.89
2.15
Shahel
Expanding
0.83
0.99
0.65
1.02
Shahel
Fully expanded
4.45
4.50
3.75
2.84
Shahel
Recently expanded
3.56
3.38
2.50
3.30
Shishi
Expanding
1.54
0.74
1.65
0.69
Shishi
Fully expanded
3.49
2.74
3.98
2.80
Shishi
Recently expanded
3.18
2.09
4.46
2.16
Sukary
Expanding
0.79
0.58
0.65
1.29
Sukary
Fully expanded
3.56
2.74
3.79
2.47
Sukary
Recently expanded
3.17
1.52
3.45
2.56
1.09
LSD (5%)
٢٩
Table (22): Stomatal conductance (C) of the evaluated date palm Cvs in
different aged leaves during four growth seasons.
CVs
Treatments
Leaves age
Autumn
Seasons
Autumn
Autumn
Autumn
Ghar
Expanding
10.13
25.12
15.55
11.17
Ghar
Fully expanded
27.32
49.63
33.62
51.72
Ghar
Recently expanded
24.02
46.33
58.43
60.00
Hilali
Expanding
6.80
26.45
12.75
8.53
Hilali
Fully expanded
20.00
72.00
59.75
76.60
Hilali
Recently expanded
22.05
47.43
66.50
49.70
Kheneizi
Expanding
40.22
39.87
12.55
24.93
Kheneizi
Fully expanded
60.62
61.03
63.30
50.00
Kheneizi
Recently expanded
62.90
65.23
63.25
60.42
Khalas
Expanding
21.33
8.42
16.42
10.82
Khalas
Fully expanded
36.10
36.13
45.72
25.57
Khalas
Recently expanded
36.23
30.45
38.57
30.57
Nebout-Sif
Expanding
44.05
17.78
14.82
17.95
Nebout-Sif
Fully expanded
60.00
41.08
79.52
48.92
Nebout-Sif
Recently expanded
51.80
42.87
77.72
52.85
Om-rhim
Expanding
37.85
17.30
30.45
15.10
Om-rhim
Fully expanded
46.80
75.98
72.30
74.03
Om-rhim
Recently expanded
43.98
45.85
86.43
26.12
Ruziz
Expanding
14.60
14.30
10.32
41.47
Ruziz
Fully expanded
66.93
56.43
56.80
66.17
Ruziz
Recently expanded
80.48
61.07
63.47
39.13
Shahel
Expanding
14.18
15.08
11.27
25.67
Shahel
Fully expanded
75.42
68.55
74.95
90.62
Shahel
Recently expanded
55.33
50.38
46.85
89.03
Shishi
Expanding
23.80
17.53
27.97
26.92
Shishi
Fully expanded
55.40
60.48
72.80
71.35
Shishi
Recently expanded
46.12
48.28
78.60
79.38
Sukary
Expanding
12.38
13.57
11.75
32.53
Sukary
Fully expanded
51.85
59.53
86.13
48.35
Sukary
Recently expanded
45.60
34.15
70.40
53.42
26.80
LSD (5%)
٣٠
Table (23): Intercellular CO2 (Ci) of the evaluated date palm Cvs in
different aged leaves during four growth seasons.
CVs
Treatments
Leaves age
Autumn
Seasons
Autumn
Autumn
Autumn
Ghar
Expanding
297.02
295.77
394.78
329.13
Ghar
Fully expanded
75.17
117.00
121.47
29.30
Ghar
Recently expanded
30.20
73.12
130.72
49.73
Hilali
Expanding
506.15
387.68
467.83
10.00
Hilali
Fully expanded
10.00
133.48
71.63
102.90
Hilali
Recently expanded
40.33
185.08
165.25
193.43
Kheneizi
Expanding
416.00
2458.07
303.50
329.72
Kheneizi
Fully expanded
167.22
171.55
163.03
91.93
Kheneizi
Recently expanded
160.60
124.62
160.18
107.95
Khalas
Expanding
183.83
1452.48
376.72
61.93
Khalas
Fully expanded
82.38
110.35
36.37
10.00
Khalas
Recently expanded
46.72
129.88
92.63
61.62
Nebout-Sif
Expanding
318.15
369.25
396.57
163.33
Nebout-Sif
Fully expanded
137.03
112.45
153.77
105.85
Nebout-Sif
Recently expanded
93.17
129.20
159.22
66.88
Om-rhim
Expanding
701.68
787.65
432.75
66.00
Om-rhim
Fully expanded
98.95
133.38
174.95
95.23
Om-rhim
Recently expanded
72.80
75.10
207.23
10.00
Ruziz
Expanding
4328.33
384.28
388.02
259.92
Ruziz
Fully expanded
178.30
136.88
154.62
161.57
Ruziz
Recently expanded
71.53
89.73
124.83
97.70
Shahel
Expanding
524.45
573.90
491.32
217.10
Shahel
Fully expanded
176.13
195.37
187.30
146.15
Shahel
Recently expanded
77.13
66.33
63.30
133.10
Shishi
Expanding
295.35
755.87
317.02
122.07
Shishi
Fully expanded
115.20
223.40
176.97
65.42
Shishi
Recently expanded
68.55
71.20
176.10
90.07
Sukary
Expanding
415.15
278.33
352.40
236.52
Sukary
Fully expanded
100.52
155.45
147.30
65.43
Sukary
Recently expanded
43.53
90.03
155.72
105.80
N.S
LSD (5%)
٣١
Table (24): Water use efficiency (WUE) of the evaluated date palm Cvs
in different aged leaves during four growth seasons.
CVs
Treatments
Leaves age
Autumn
Seasons
Autumn
Autumn
Autumn
Ghar
Expanding
-0.26
0.52
-0.29
-0.34
Ghar
Fully expanded
1.79
2.11
2.27
1.61
Ghar
Recently expanded
4.29
3.55
2.15
0.19
Hilali
Expanding
-0.87
-0.96
-0.88
-5.33
Hilali
Fully expanded
2.97
2.32
1.98
2.89
Hilali
Recently expanded
3.62
4.45
1.28
5.72
Kheneizi
Expanding
-1.02
-1.23
0.77
-0.71
Kheneizi
Fully expanded
1.76
1.63
1.80
5.70
Kheneizi
Recently expanded
1.99
3.16
3.37
6.44
Khalas
Expanding
0.97
-8.82
-0.51
2.44
Khalas
Fully expanded
2.34
2.79
3.64
5.25
Khalas
Recently expanded
3.46
4.13
4.73
6.42
Nebout-Sif
Expanding
0.08
-0.28
-0.53
1.00
Nebout-Sif
Fully expanded
2.06
2.44
2.19
3.38
Nebout-Sif
Recently expanded
2.68
4.41
2.03
3.74
Om-rhim
Expanding
-2.75
-2.44
-0.54
-2.87
Om-rhim
Fully expanded
1.63
1.86
1.29
2.02
Om-rhim
Recently expanded
2.82
4.86
1.45
1.20
Ruziz
Expanding
-8.29
-1.00
1.33
0.27
Ruziz
Fully expanded
2.03
2.75
1.86
2.15
Ruziz
Recently expanded
5.52
4.10
2.65
3.21
Shahel
Expanding
-2.21
-1.13
-1.74
1.72
Shahel
Fully expanded
1.52
1.11
1.64
2.41
Shahel
Recently expanded
2.58
4.28
3.42
3.39
Shishi
Expanding
0.30
-2.96
-0.31
1.85
Shishi
Fully expanded
2.03
1.76
1.58
4.46
Shishi
Recently expanded
2.75
4.91
1.54
4.26
Sukary
Expanding
-0.89
2.96
0.52
0.50
Sukary
Fully expanded
1.79
2.20
2.24
3.21
Sukary
Recently expanded
2.50
5.57
1.85
3.70
N.S
LSD (5%)
٣٢
Table (25): Mesophyll conductance (gm) of the evaluated date palm Cvs
in different aged leaves during four growth seasons.
CVs
Ghar
Ghar
Ghar
Hilali
Hilali
Hilali
Kheneizi
Kheneizi
Kheneizi
Khalas
Khalas
Khalas
Nebout-Sif
Nebout-Sif
Nebout-Sif
Om-rhim
Om-rhim
Om-rhim
Ruziz
Ruziz
Ruziz
Shahel
Shahel
Shahel
Shishi
Shishi
Shishi
Sukary
Sukary
Sukary
Treatments
Leaves age
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Expanding
Fully expanded
Recently expanded
Autumn
-1.0
53.0
284.0
-1.0
684.0
222.0
-5.0
35.0
42.0
5.0
60.0
150.0
1.0
52.0
79.0
-12.0
73.0
162.0
-1.0
34.0
238.0
-3.0
39.0
119.0
2.0
61.0
127.0
-2.0
64.0
182.0
Seasons
Autumn
Autumn
3.0
-1.0
66.0
48.0
158.0
54.0
-2.0
-2.0
64.0
120.0
49.0
34.0
-1.0
2.0
35.0
41.0
82.0
66.0
-2.0
-1.0
52.0
301.0
53.0
126.0
-1.0
-1.0
47.0
51.0
70.0
42.0
-3.0
-2.0
68.0
36.0
158.0
30.0
-1.0
2.0
50.0
36.0
113.0
61.0
-2.0
-2.0
26.0
33.0
218.0
135.0
-3.0
-2.0
22.0
35.0
144.0
39.0
6.0
1.0
39.0
58.0
94.0
41.0
Autumn
-1.0
160.0
11.0
-263.0
80.0
73.0
-2.0
136.0
114.0
14.0
1000.0
164.0
6.0
66.0
136.0
-29.0
71.0
1413.0
2.0
43.0
71.0
8.0
47.0
84.0
10.0
191.0
102.0
3.0
121.0
89.0
62.69
LSD (5%)
 
٣٣

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