nghiên cứu một số chỉ tiêu sinh lý, hóa sinh liên quan đến tính chịu hạn, năng suất và phẩm chất hạt của một số giống vừng (sesamum indicum l) trồng ở khu vực hà nội bản tóm tắt tiếng anh

MINISTRY OF EDUCATION AND TRAINING
HA NOI NATIONAL UNIVERSITY OF EDUCATION





TRAN THI THANH HUYEN




RESEARCH ON SOME PHYSIOLOGICAL AND BIOCHEMICAL
INDEXES RELATED TO DROUGHT TOLERANCE,
PRODUCTIVITY AND QUALITY OF SOME SESAME VARIETIES
(SESAMUM INDICUM L.) CULTIVATED IN HANOI




Major: Plant physiology
Code: 62. 42. 30. 05



Summary of doctoral thesis of biology

HA NOI - 2011


The thesis completed at
Hanoi National University of Education



Scientific supervisor:

1. Prof. Dr. NGUYEN NHU KHANH
2. As. Prof. Dr. NGUYỄN VAN MUI




Reviewer 1: Prof. Dr. Hoang Minh Tan



Reviewer 2: Prof. Dr. Do Ngoc Lien

Reviewer 3: Prof. Dr. Le Tran Binh









Thesis defense will be at the Council for State Level Thesis Marking at Hanoi National
University of Education
At (time) on … (date)…… 2011









The thesis can be found at:
- National Library of Viet Nam
- Library, Hanoi National University of Education

Publications related to the thesis

1. Tran Thi Thanh Huyen, Nguyen Nhu Khanh, Nguyen Thi Lan Phuong,

Hoang Thi Thu Phuong (2008), “Comparison of amino acid composition,
nutritional value of sesame seed proteins in some local and imported
sesame cultivars in Vietnam”, Journal of Science, Ha Noi National
University of Education, Volume 53 No

5, pp. 122-127.

2. Tran Thi Thanh Huyen, Nguyen Nhu Khanh, Nguyen Thi Lan Phuong,
Hoang Thi Thu Phuong (2008), “Seed quality of some local and imported
black sesame (Sesamum indicum L.) cultivars in Vietnam”, Proceedings of
the 4
th
National Coference on Biochemistry and Molecular Biology, pp.
183-186, Science and Technics Publishing House.

3. Tran Thi Thanh Huyen, Lê Thi Thuy, Nguyen Nhu Khanh (2010), “
Fluctuation of proline content in relationship to drought resistance ability at
the young age of 20 sesame varieties in artificial drought condition”, Journal
of Science, Ha Noi National University of Education
,
Volume 55, No 3, pp
137-142
.


4. Tran Thi Thanh Huyen, Chu Thi Ngoc, Trinh Thi Thu Phuong (2010),
“Evaluation of drought tolerance of 20 sesame varieties (Sesamum indicum
L.)”, Journal of Science, VietNam National University, HaNoi, Volume 26,
No 2S, pp. 145-151.

5. Tran Thi Thanh Huyen, Nguyen Nhu Khanh, Nguyen Thi Thanh Thuy,
Nguyen Thi Minh Nguyet (2010), “Study in genetic diversity of sesame
(Sesamum indicum L.) using RAPD”, Journal of Biotechnology, Volume
8, No 4, pp. 1847-1853.


6. Tran Thi Thanh Huyen, Nguyen Nhu Khanh (2011), “Study on
indicators of water exchange that related to drought resistance of 20
sesame varieties”, Journal of Science, VietNam National University, HaNoi


1

INTRODUCTION
1. Background
During the living process, plants are always influenced by external factors such
as drought, cold weather, heat, salinity, flooding, insects, etc. Among these factors,
high temperature, cold weather, wind and drought are considered the main causes to
the dehydration in plants. A long drought can affect relevant metabolistic reactions,
different stages of plant growth and development leading to low productivity and
quality of agricultural products and possible dead plants. Drought is a complicated
phenomenon and is widely regarded as the most important factor to optimise plant
production.
Sesame (Sesamum indicum L.) is among terrestrial plants with a wide range of
adaptation and traditionally cultivated in different types of soil. Sesame is known as
“the queen of oil producing plants” with high nutritional values. In sesame seeds, the
high lipid content of 45 – 54%, especially with presence of unsaturated fatty acids
(oleic, linoleic, linolenic), essential amino acids, antioxidant compounds (sesamin,
sesamol, sesamolin and vitamin E), has increased values of sesame seeds. Many
studies in the world have been carried out to evaluate these characteristics of sesame.

In Vietnam, few studies on sesame has been conducted so far, especially typical
features of sesame on drought tolerance have not been systematically explored in
depth. In the mean time, there have been quite many studies on drought tolerance in
other cropping plants such as sweet grass, paddy rice, mung bean, tobacco, green
bean, maize, etc. Drought tolerance of a plant depends on its own genotypes,
agrobiological charateristics, physiological and biochemical characteristics.
Therefore, it is necessary to study on the relationship between physiological and
agrobiolocial characteristics, and further more at the molecular level, the
characteristics related to drought tolerance of sesame. Moreover, since Vietnam is
located in the monsoon tropical region, drought which is a frequently found factor
that affects growth and development of crop plants, crop production and its quality.
Therefore, studying to analyse influences of droughts, to assess and select varieties
which are of high drought tolerance is an effective and necessary measure to
minimise drought effects on crop plants in general, and sesame, in particular. On that
basis, drought tolerance mechanisms, directions to improve and to select potential
sesame varieties with high drought tolerance, high yield, stability and adaptability for
unfavourable natural conditions in a range of different ecological regions will be
identified.
From the above reasons, we have carried out the study:
“Research on some physiological and biochemical indexes related to drought
tolerance, productivity and quality of some sesame varieties (Sesamum indicum L.)
cultivated in Hanoi”.
2. Objectives of the study
- To identify differences between some physiological and biochemical criteria
related to drought tolerance of sesame varieties of good and poor drought tolerance.
2

Through this study, to recommend criteria which are characterised by drought
tolerance of sesame varieties to be as a basis for selection of sesame varieties of high
drought tolerance.

- To identify genetic relationships between sesame varieties of good and poor
drought tolerance among the 20 pre-screened sesame varieties.
- To assess yield and seed quality of some drought tolerant sesame varieties
selected during experiments of the study conducted in Hanoi.
3. Scientific and practical significance of the study
Scientific significance
- Data collected in the study will be scientific evidence on physiological and
biochemical reactions related to drought tolerant ability of sesame varieties under the
study.
- Study results identified the genetic relationship between sesame varieties of
high and poor drought tolerance among 20 sesame varieties under the study.
- The results of sesame seed analysis will have additional contributions of
scientific evidence, which is significantly important to nutritional values and uses of
sesame seeds.
Practical significance
- Differences between physiological and biochemical criteria of high and poor
drought tolerant varieties can be used for selection and generation of high drought
tolerant varieties with high yield and good quality so as to reduce input materials and
labour in selecting drought tolerant varieties.
- Study results on sesame seeds are also a criterion of reference for selections
of sesame varieties with both drought tolerance and good seed quality to be used in
industries of sesame exploitation and processing as well as in medicine and
pharmacy.
4. New contributions of the thesis
- Identified physiological and biochemical differences between high and poor
drought tolerant varieties. On that basis, classified sesame into different groups of
sesame with drought tolerance at different levels. Proposed V5 and V14 varieties
which are highly drought-tolerant but can give stable production and good seed quality.
- Combined the assessment of drought tolerance with the analysis of
genotypes with RAPD techniques and showed different sesame varieties with

genetically high and poor drought tolerance.
- Analysed some criteria on nutritional quality of sesame seeds such as contents of
minerals, amino acids, lipids, acid indexes, especially 3 unsaturated fatty acids (oleic,
linoleic and linolenic).

CHAPTER I. RESEARCH REVIEW
1.1. General introduction on sesame
1.2. Crops’ drought tolerance
1.3. Research situation of genetic diversity of sesame
3


CHAPTER II. RESEARCH SUBJECT AND METHODOLOGY
2.1. Research subject
Sesame varieties were obtained from Department of Seed Gene Bank –
Vietnam Institute of Agriculture Science and Technology.
2.2. Methodology
2.2.1. Identification of physiological criteria: Rapid assessment of drought
tolerance, identification of soil’s wilting coefficient, water content in tissues when
plants are withered, and associated water content were performed applying Dhopte
method. Leaf tissues’ water-retaining capacity (identified with Kozushco method),
osmotic pressure of cells, fluorescent chlorophyll were identified by OPTI-Sciences
OS-30 Chlorophyll Flourmeter. Total chlorophyll content was identified with
methods of Wintermans, De Mots, while associated chlorophyll content was
identified based on Shmatco.
2.2.2. Identification of biochemical criteria: saccharose content and α-amylase
activity were determined by Miller G.L method; proline content, by Bates method;
lipid content, by Soxlet method. Amounts of minerals and unsaturated fatty acids
were analyzed by gas chromatography. Total essential amino acid content in sesame
seeds was identified by HP-Amino Quant series II.

2.2.3. Identification of genetic diversity by RAPD (Random Amplified
Polymorphic DNA): DNA isolation was based on Doyle method; RAPD-PCR was
carried out using the method of William et al with 26 random primers
CHAPTER III. RESULTS AND DISCUSSIONS
3.1. Assess dehydration resistance of 20 sesame varieties in researched area
3.1.1. Impacts of drought on physiological criteria
3.1.1.1. Rapid assessment of drought tolerance
We rapidly assessed drought tolerance of 20 sesame genotype during seedling
period in laboratory including: rate of un-withered plant, rate of recovered plant and
drought tolerance indexes. V14 and V5 had the highest drought tolerance indexes,
which reached 22085 and 21541, respectively. Two varieties had the lowest drought
tolerance indexes were V4, V8, which reached 13675 and 12646 (the higher the
drought tolerance index is, the higher the drought tolerance capacity is)
Based on drought tolerance indexes in the table 3.1, initially we divided 20
varieties into three groups: the good drought tolerance group has two varieties: V14
and V15; low drought tolerance group has two varieties: V4 and V8; other 16 varieties
have medium drought tolerance indexes including: V18, V17, V13, V16, V12, V19, V11,
V6, V15, V2, V1, V9, V10, V3, V7, V20 varieties.





4

Table 3.1. Drought tolerance indexes of 20 sesame varieties
One day after
drought
treatment
Three days

after drought
treatment
Five days after
drought
treatment
Sesame
varieties

%
UWP
% RP %
UWP
% RP %
UWP
% RP
Drought
tolerance
index
Drought
tolerance
ranking
V1 97.98 100.00 85.14 70.00 77.89 55.34 17084 13
V2 100.00 100.00 83.21 83.12 69.63 50.40 17135 12
V3 95.97 100.00 79.15 63.17 64.89 42.79 14502 16
V4 93.45 100.00 78.94 62.50 55.34 40.00 13675 19
V5 100.00 100.00 99.06 100.00 80.23 66.11 21541 2
V6 98.87 100.00 89.23 75.12 67.24 57.62 17378 10
V7 96.25 100.00 80.23 60.44 63.69 43.33 14408 17
V8 94.41 100.00 73.33 55.79 49.65 38.68 12646 20
V9 98.24 100.00 87.89 70.00 66.66 58.78 16940 14

V10 100.00 100.00 90.34 73.55 60.45 54.62 16838 15
V11 97.34 100.00 94.12 74.14 62.50 59.13 17410 9
V12 95.17 100.00 93.24 80.12 69.53 60.43 18114 7
V13 100.00 100.00 90.16 82.14 76.11 61.14 18809 5
V14 100.00 100.00 96.67 99.12 84.61 72.42 22085 1
V15 96.87 100.00 88.78 79.56 66.67 53.77 17201 11
V16 100.00 100.00 87.99 87.56 64.67 62.75 18402 6
V17 100.00 100.00 91.26 84.34 76.44 61.56 19108 4
V18 99.12 100.00 92.13 83.15 78.22 64.15 19340 3
V19 100.00 100.00 89.45 77.84 76.24 49.67 17578 8
V20 94.37 100.00 72.42 63.69 64.75 43.66 14012 18
(% UWP: rate of un-withered plant; % RP: rate of recovered plant)
3.1.1.2. Soil’s wilting coefficient
We identified soil’s wilting coefficient in order to determine water absorption
capacity from the soil of different sesame varieties. The minimal point of soil
moisture the plant requires not to wilt is defined as soil’s wilting coefficient. If
moisture decreases to this or any lower point a plant wilts and thus can no longer
recover its turgidity. The physical definition of the wilting point (symbolically
expressed as θ
pwp
or θ
wp
) is defined as the water content at −1500 J/kg (or −15 bars)
of suction pressure, or negative hydraulic head. The results are indicated in the Table
3.2.
For soil’s wilting coeficient, V5 and V14 were withered when water content in
soil was low, which was only 10.89% and 11.04% compared to undried soil. V3 and
V8 were withered when water content in soil was higher, reaching 14.92% and
15.08%, respectively.

5


Table 3.2. Humidity of withered plants and soil’s wilting coefficient









Wilting coeficient of 20 sesame varieties fluctuated from 3.41 – 4.85g H
2
O/100g
dried soil. Wilting coeficients were lowest for V5 and V14 varieties. Of which V5
had the lowest wilting coeficient, which was 3.41g H
2
O/100g dried soil. Two
varieties V3 and V8 showed the highest wilting coeficients, which were 4.85 and
4.80g H
2
O/100g dried soil, respectively. That means, water content in soil, which V5
and V14 could not absorb, was lower than water content in soil, which V3 and V8
varieties could not absord. In the same soil type, the variety which can survive with
lower water content in the soil, have better drought tolerance and vice versa. The
results showed that V5 and V14 have the best drought tolerance and V3 and V8 have
the worst drought tolerance.

3.1.1.3 Impacts of drought on water content in tissues
At diferent drought levels, water content in tissues is different between
varieties. Water content in tissues inffluences physical actitives in general and in leaf
tissues in particular. Therefore, the water content in plant at wilting point is critial for
Varieties
Humidity of
withered plant

Soil’s wilting
coefficient (g
H
2
O/100g dried soil)
Drought
tolerance
ranking
V1 11.29
a
3.54 a* 4
V2 13.34
b
4.25 b* 11
V3 15.08 f

4.85 e* 20
V4 14.37
c
4.61 c* 18
V5 10.89
d

3.41 a* 1
V6 12.63
e
4.01 d* 10
V7 14.35
c
4.60 c* 16
V8 14.92
f
4.80 e* 19
V9 12.56
e
3.98 d* 9
V10 11.14
g
3.49 a* 3
V11 12.48
e
3.95 d* 8
V12 13.52
b
4.31 b* 14
V13 14.08
h
4.51 b*c* 15
V14 11.04
d
3.46 a* 2
V15 13.52
b

4.31 b* 13
V16 12.07
i
3.81 f* 6
V17 11.32
a
3.55 a* 5
V18 13.45
b
4.29 b* 12
V19 12.11
i
3.83 f* 7
V20 14.16
h
4.53 b*c* 17
6

supplementary water for plants, minimizing harmful effects of drought on crops and
through this amount of water we can assess water dificit torelance capacity.
Table 3.3. Water content in leaf tissues when plant withered
Water content in tissue when plant withered (%)
Sesame
varieties


Normal
condition
Drought
condition

Rate comparing with
normal condition
(%)
Drought
tolerance
ranking
V1 82.76
a
69.53
a*
84.01 8
V2 79.53
b
66.54
b*
83.66 6
V3 84.31
c
73.32
g
86.96 19
V4 79.56
b
68.24
c*
85.77 16
V5 85.05
f
68.15
c*

80.12 1
V6 83.03
c
69.91
c*
84.19 10
V7 82.67
a
70.69
a*
85.50 14
V8 81.03
e
70.26
a*
86.70 18
V9 81.74
c
70.13
a*
85.79 17
V10 81.53
e
67.27
e
82.50 4
V11 80.61
b
68.53
c*

85.01 11
V12 82.56
a
70.23
a*
85.06 12
V13 83.05
c
70.67
a*
85.09 13
V14 83.78
c
68.25
c*
81.46 2
V15 82.17
a
70.12
a*
85.33 15
V16 80.49
b
67.16
e
83.43 5
V17 83.56
c
68.32
a*

81.76 3
V18 83.04
c
69.78
a*
84.03 9
V19 82.15
a
68.85
c*
83.81 7
V20 85.75
d
75.46
f
88.00 20
The data showed that: under impact of drought, water content in leaf tissues of
all varieties was reduced in comparison to normal condition. Water content in leaf
when plants were withered ranges from 80.12 to 88% in comparison with those of
insufficient water. Of which, water content in leaf tissue when plant withered was
lowest for V5 variety and was 80.12 (compared to this value when plant do not wilt).
This value is 81.46 for V14 variety. Water content in leaf tissue was the highest for
V20 variety (88.00%) and V3 variety (86.96%). At the wilting point, variety which
has lower water content in leaf tissue per water content at normal condition has
higher drought tolerance. That means V5, V14 varieties can resist to drought better
than V5, V20 varieties.
3.1.1.4. Impact of drought on associated water content in leaf
In the drought condition, water in plant has a trend to increase associated water
content and increase free water content. Therefore, associated water content and
water-retaining capacity of leaf tissue have very important meaning for tolerance

7

capacity in water deficit condition. Associated water content in normal and drought
condition is presented in table 3.4.
Table 3.4. Associated water content in sesame leaf in normal and drought
condition
Associated water content in sesame leaf (%)
Sesame
varieties


Normal
condition
Drought
condition
Rate to compare
with normal
condition (%)

Drought
tolerance
ranking
V1 22.76
a
37.53
a*
164.85 14
V2 22.53
a
36.54

a*
162.16 15
V3 21.78
a
33.25
b*
152.66 20
V4 19.49
b
31.16
c*
159.87 17
V5 23.25
c
43.86
d
188.64 2
V6 20.03
a
33.91
b*
169.29 11
V7 22.53
a
39.27
e
174.30 7
V8 23.56
c
37.32

a*
158.40 18
V9 18.74
b
32.13
f
171.45 9
V10 22.67
a
40.69
g
179.48 4
V11 21.61
a
37.53
a*
173.66 8
V12 22.56
a
36.23
a*
160.59 16
V13 23.05
c
38.67
e
167.76 13
V14 23.31
c
44.32

d
190.13 1
V15 19.17
b
34.12
b*
177.96 5
V16 20.56
a
36.24
a*
176.26 6
V17 21.03
a
38.26
e
181.93 3
V18 23.04
c
38.78
e
168.31 12
V19 22.15
a
37.85
a*
170.88 10
V20 23.46
c
36.16

a*
154.13 19
Associated water content in leaf of all researched varieties increased in
comparison to that in the normal condition. This index increases to about 52.66 –
90.13%. Associated water content in tissue is the highest for V14, which increases to
90.13% in comparison with that in the normal condition; it is followed by V5, which
increases to 88.64%. Groups of varieties whose associated water content slightly
increased include V3, V20; with V3 gaining the lowest increase (52.66%). This
higher associated water content in tissues of these varieties suggested that these
varieties may have better tolerance against drought.
Under the drought condition, to reduce dehydration, a part of water in tissues
shifts to associated water. At the same time dehydration also increases the ratio of
associated water in plants. Moreover, the increased associated water ratio in tissue
under the drought condition can be explained by the increase of dissolved molecular
concentration (ions of minerals, saccharose, organic acids, amino acids…). The
8

drought condition also increases the content of absorption associated water. This is
absorption adjustment, and is the main mechanism to maintain turgor pressure in
almost all plants to deal with dehydration and helps plant continuously absorb water
and maintain water for metabolism.
3.1.1.5. Impact of drought on water-retaining capacity of leaf tissue
Under drought condition, water-retaining of leaf tissue is a mechanism to
support plants to resist water deficit. Content of water loss during the same period
from one amount of sample higher, the water-retaining capacity is lower and lead to
resistant capacity to disadvantage environment is lower and otherwise hydration of
plant tissue slower, water-retaining capacity is higher, resistance capacity to stress
environment higher. When leaf tissue lost water to one restriction level, leaf cells
produce water-retaining mechanism to sustain water to assist plants to against water
deficit.

Table 3.5. Water-retaining capacity of leaf tissue in drought condition of 20
researched sesame varieties
Water-retaining capacity of leaf tissue (% content of lost water/ total
water content)
Sesame
varieties

One day
after
drought
treatment
Drought
tolerance
ranking
Three days
after
drought
treatment
Drought
tolerance
ranking
Five days
after
drought
treatment
Drought
tolerance
ranking
V1 29.46
a

13 16.26
a*
7 40.21
a**
14
V2 26.05
b
5 15.72
a*
5 40.27
a**
15
V3 32.26
c
19 18.12
b*
17 43.72
c**
20
V4 31.01
d
17 17.17
b*
12 42.11
b**
19
V5 24.17
e
2 14.27
e*

2 36.17
g
2
V6 26.87
b
7 18.95
b*
19 40.21
a**
13
V7 27.34
b
9 16.78
a*
10 40.15
a**
11
V8 33.14
c
20 17.41
b*
14 41.68
b**
18
V9 31.34
c
18 15.63
a*
4 40.01
a**

9
V10 26.34
b
6 16.05
a*
6 39.34
d
7
V11 27.36
b
10 17.04
b*
11 38.75
f
5
V12 30.21
c
16 16.53
a*
8 41.68
b**
17
V13 28.09
b
12 18.05
b*
16 40.11
a**
10
V14 23.68

e
1 13.07
e*
1 35.69
h
1
V15 25.67
e
4 15.26
a*
3 38.62
f
4
V16 27.21
b
8 17.31
b*
13 39.67
d
8
V17 25.15
e
3 16.58
a*
9 37.04
e
3
V18 27.86
b
11 17.51

b*
15 39.23
d
6
V19 29.75
a
14 18.63
b*
18 40.18
a**
12
V20 30.17
c
15 19.02
b*
20 41.15
b**
16
9

Water-retaining capacity of leaf tissue is expressed by amount of lost water (%
water lost/ total water content). Therefore, to assess water deficit resistance of
researched sesame varieties, we identified water-retaining capacity of leaf tissue at
different period after drought treatment (one day, three days and five days).
Data collected in the table 3.5 indicates that water-retaining capacity of leaf
tissue changes over time (number of days) of droughts.
Amount of lost water after three drought treatment days of all 20 researched
varieties is less than content of lost water after one drought treatment day indicating
water-retaining capacity increased. However, after 5 drought treatment days, content
of lost water increases more than the content of lost water after three drought

treatment days, or after five drought treatment days. Water-retaining capacity of leaf
of all researched varieties is reduced. At the same drought treatment period, the
varieties which have smaller content of lost water/ total water content will have better
water-retaining capacity.
Collected data illustrated that: at three point of time, after 1, 3 and five drought
treatment days, content of lost water is the smallest for V14 variety; following is V5
meaning that these two varieties have the best water-retaining capacity.
The group, which has the worst water-retaining capacity, does not identically
fluctuate. In particular: after one drought treatment day, position of ranking order 20
belongs to V8; after three drought treatment days this position belongs to V20; and
after five drought treatment days is V3. Therefore, it is clear that all three varieties
V3, V8, and V20 belong to groups, which have the worst water-retaining capacity or
the lowest drought tolerance.
Together with relative drought tolerance capacity, the water-retaining capacity
of leaf tissue also has similar results for some groups such as: V5, V14 which have
the highest water-retaining capacity while V3, V8, V20 have the worst water-
retaining capacity.
3.1.1.6. Impacts of drought on content of chlorophyll and fluorescent chlorophyll
of sesame leaf
In the drought condition, then content of chlorophyll is different in each
variety. The indicator of chlorophyll content, especially the content of relative
pigments can be used to evaluate photosynthesis activity and resistance capacity of
crop. We calculated content of total chlorophyll and content of relative chlorophyll of
20 researched sesame varieties and realized that:
The content of total chlorophyll of all 20 sesame varieties is reduced when
drought occurs. The two varieties V5 and V14 reaches the highest value of
chlorophyll content (1.934 mg/g leaf and 1.930 mg/g leaf). These two varieties are
also slightly impacted by water deficit (reached 90.53% and 88.44% in comparison to
the normal condition). Therefore, they rank the first and the second position
respectively. V3 and V13 are the most seriously influenced by water deficit, which

have amount of total chlorophyll reduced to 67.49% and 74.29% as compared with
normal condition.
10

11


Changing of relative chlorophyll level is related to changing of relative
chlorophyll a and b level. Experimental results proved that relative chlorophyll level
is reduced in drought condition and varies in different sesame varieties, which
reached from 70.00 to 90.00% as compared with the normal condition. Varieties V5
and V14 have clearly higher content of relative chlorophyll level a+b than the
remaining varieties (1.01 mg/g and 1.00mg/g), chlorophyll level of these two
varieties in drought condition also change less than other varieties. Relative
chlorophyll level a+b is remarkably reduced when water deficit condition occurs for
V3 and V4 (70.00% and 73.68%).

In chloroplast, chlorophyll closely relates to protein and lipid to create a

complex system, which is photosynthesis system. Chlorophyll and others organizes
such as associated pigment, enzyme and electronic transport system play a critical
role in photosynthesis activity and resistance capacity of plants. The variety, which
has higher relative chlorophyll level, is little changed, and more stable under pressure
of disadvantages, usually can photosynthesize more effective and have better
resistance capacity.
Beside the chlorophyll level, the effectiveness of photosynthesis activity also
expresses through fluorescent chlorophyll indicator. Fluorescent chlorophyll is a
parameter that indicates biophysical condition of photosynthesis system under stress
condition. Of which, altered fluorescent (F
vm
) directly relates to photosynthesis
effectiveness. Varieties which have stable F
vm
when environment changes usually
have better resistance capacity.
The effectiveness of altered fluorescent (F
vm
) reflects the effectiveness of using
solar energy in photochemistry reaction in PSII.
When water is enough, F
vm
is not different for almost all varieties. When water
deficit occurs, F
vm
reduces differently for each variety. V5, V14 reduce the least
(98.75% and 97.50%); F
vm
reduces the most for V8 and V10 (89.33% and 88.46%).
Changing of F

vm
means that PSII’s activity decreases leading to the decrease of
using effectiveness of energy in photosynthesis.
Based on the indicator of the fluorescent chlorophyll level, it can be affirmed
that: drought resistant capacity of V5 and V14 are the highest; V3 and V8 have the
lowest drought tolerance.
Many researches indicated that: the impact of drought and water deficit on
developing tissue leads to inhibit photosynthesis. In detail, when water deficit occurs,
plants react with quick closing stoma to reduce water loss. At the same time, reduced
CO
2
diffusion into leaf also leads to the decreased absorption CO
2
of ribulose1,5
diphosphate and impact on photosynthesis effectiveness. Drought can have direct
impact on activity of ribulose 1,5 diphosphates cacboxylase enzyme /oxygenate, or
ATP synthesize. Photosynthesis electron which transports through PSII also is
inhibited. These are causes of declining using effectiveness of energy in
photosynthesis in PSII and reducing of photosynthesis effectiveness.
12

3.1.1.7. Impacts of drought on osmotic pressure.
Capacity of osmotic presure adjusment to balance water between cell and
surrounding environment is a critical quality and also is water deficit adaptable
measurement of many varieties.
When soil is dry, osmotic pressure of soil-liquid is very high so crops need to
adjust their osmotic pressure to be higher soil-liquid’s osmotic pressure to obtain a
little water remained in the soil.
Therefore, osmotic pressure determaination has critical meaning in evaluation
of water absorption capacity and holding-water capacity of crops. Osmotic pressure

of leaf tissue in drought and normal condition is presented in table 3.9.
Table 3.9. Osmotic pressure of sesame leaf’s tissue in drought and normal
condition
Osmotic pressure of sesame leaf’s tissue
(atm) Sesame
varieties

Normal
condition
Drought
condition
Ratio to compare
to normal
condition (%)
Drought
tolerance
ranking
V1 1.02 2.91 285.29 8
V2 1.28 3.65 285.15 9
V3 1.26
a
2.96
a*
234.92 20
V4 1.15 3.04 264.34 16
V5 1.20
b
3.71
b*
309.16 2

V6 1.11 3.24 291.89 6
V7 1.23
c
3.08
c*
250.40 19
V8 1.20 3.17 264.16 17
V9 1.08 3.04 281.48 12
V10 1.12
d
3.39
d*
302.67 4
V11 1.07 2.90 271.02 13
V12 1.29 3.70 286.82 7
V13 1.25 3.38 270.40 14
V14 1.14
e
3.58
e*
314.03 1
V15 1.06 3.02 284.90 10
V16 1.03 2.92 283.49 11
V17 1.16
f
3.52
f*
303.44 3
V18 0.94 2.77 294.68 5
V19 1.01 2.69 266.33 15

V20 1.19 3.05 256.30 18
Osmotic pressure in water deficit condition significantly increases as compares
with the normal condition. The higher this rate is, the more crops can absorb water
and the higher crops also have drought tolerance capacity. Two varieties V5, V14
have the highest rate of osmotic pressure rising as compared to other researched
varieties. These two varieties’ osmotic pressure increase to 209.16% and 214.03% as
13

compared to the normal condition. In addition, osmotic pressure of V10 and V17
varieties also highly increase (202.67% and 203.44%), ranked number 3 and 4 which
are followed by V5 and V14; osmotic pressure of varieties V3 and V7 slightly
increase, reaching 134.92% and 150.40%. V3 variety’s osmotic pressure increases
the least (134.92%). Therefore, if depending on the osmotic pressure indicator, the
group with the highest drought tolerance capacity includes V5, V14; the group with
the lowest drought capacity includes V3, V7
Osmotic pressure adjustment by assembling dissolves substances in cell and
leads to the increased osmotic pressure of cell-liquid. Assembling ions to adjust
osmotic pressure mainly occurs in vacuole so that ions do not influence enzyme
activity in cytoplasm. Therefore, related to osmotic pressure it is needed to account
presence of dissolved substances such as saccharoses, organic acids, amino acids
(proline), ions (mainly K
+
)… When disadvantages happens (drought, cold weather,
salinity…), cells gradually hydrates, organic substances disperse into sacchoroses,
amino acids. These dissolve substances accumulated in cytoplasm lead to increasing
osmotic pressure. This is caused by resisting water potential energy lost and
increasing plasma’s water retaining capacity or preventing Na
+
from penetrating. In
addition, they also replace water role, where biochemical reactions occur, interact

with protein and lipid in cell membrane to prevent cell membrane from destroying.
In summary, one of factors has impact on osmotic pressure, water absorption
capacity and holding-water capacity of cells is the dissolved saccharoses, proline
amino acid. Clearly, there are relationships between two these factors and cells’
osmotic pressure, and crops’ drought tolerance capacity. This relationship would be
more clearly discussed in following indicators.
Determination of crops’ drought tolerance capacity does not only depend on
water exchange indicators but they also are results of many other factors. Therefore,
it is necessary to analyse biochemical indicators to determinate crops’ drought
tolerance in general and sesame’s drought tolerance in particular.
3.1.2. Impact of drought on biochemical indexes
3.1.2.1. Evaluation of drought tolerance through deoxidized saccharose level in
sesame’s leaf
Saccharose has an important role in life such as structure, energy providing,
especially saccharose play a critical role in osmotic pressure adjustment in cell liquid.
This is an advantage when crops deal with unfavourable conditions. Many researches
reveal that in unfavourable conditions such as heat, cold weather, drought …
saccharose level has a trend to increase. Therefore, it is needed to study changing of
saccharose level to find relationship between this level and crops’ resistance capacity.
The rate of sacchorase in drought and normal condition is presented in table 3.10.
Collected data in the table 3.10 reveal that all 20 sesame varieties have a trend
to increase saccharose level after drought treatment. Variety reaching the highest
increase of saccharose level is V14 (327.10%); following is V5 (309.52%); the
lowest level are V3 and V8, reaching 175.10% and 178.04%, respectively (lower than
14

other remaining varieties). In the drought condition, under influence of hydrolysis
enzyme, dispersion process of some organic substances such as protein, hydrate
carbon increases.
In particular, amylase enzyme activity increased to hydrolyze starch into

saccharose. Increased hydrolyzed saccharose leads to saccharose concentration in
cytoplasm raised. Thus osmotic pressure (main cause of water-obtaining capacity of
roots), crops can obtain water more easily, created favorable conditions for
biophysical activities to occur, crops have better resistance capacity in disadvantage
condition, especially drought.
If depending on saccharose level increasing to rank drought capacity, two
varieties V5 and V14 took to first place. Varieties V3 and V8 belong to the low
drought tolerance group. These results are similar with studied results on leaf tissue’s
water-retaining capacity.
Table 3.10. Leaf’s deoxidized saccharose level in drought and normal condition
Deoxidized saccharose level (%)
Sesame
varieties
Normal
condition
Drought
condition
Rate as compare
with normal
condition (%)
Drought
tolerance
ranking
V1 1.19 2.68 225.21 11
V2 1.09 3.02 277.06 6
V3 1.23
a
2.19
a*
178.04 19

V4 1.38 2.64 191.30 16
V5 1.05
b
3.25
b*
309.52 2
V6 1.38 2.82 204.34 14
V7 1.82 3.34 183.51 18
V8 1.76
c
3.09
c*
175.56 20
V9 1.17 2.76 235.89 10
V10 1.09
d
3.08
d*
282.56 4
V11 1.51 3.71 245.69 9
V12 1.23 2.51 204.06 15
V13 1.19 3.16 265.54 7
V14 1.07
e
3.50
e*
327.10 1
V15 1.12 2.42 216.07 13
V16 1.21 3.43 283.47 3
V17 1.01 2.21 218.81 12

V18 1.12 3.12 278.57 5
V19 1.01 3.67 264.35 8
V20 1.22 2.32 190.16 17
3.1.2.2. Evaluation of drought tolerance capacity through α-amylase activity
level
Amylase in one of enzyme can disperse starch into saccharose. Activity of α-
amylase is significantly influenced by surrounding environment. Therefore, based on
15

α-amylase activity changing it is possible to have preliminary assessment of
researched sesame varieties’ drought capacity (table 3.11)
In the drought condition, α-amylase activity remarkably increases as compared
with the normal condition (from 153.98% to 233.75%). Activity of α-amylase of V5
and V14 varieties more highly increase than the remaining varieties. The data in table
3.11 illustrated that: V5 and V14’s α-amylase enzyme activity most highly increase
(230.92% and 233.75%). Varieties of V3 and V8 have the lowest increase, reaching
153.98% and 159.63%.
Increasing of α-amylase ezyme activity increases saccharose level because of
starch hydrolysis. Thus it influences osmotic pressure adjustment capacity when
drought happens, leading to increased crops’ resistance capacity.
Table 3.11. Activity of α-amylase enzyme in drought and normal condition
Activity of α – amylase enzyme (UI)
Sesame
activities
Normal
condition
Drought
condition
Ratio as compared
with normal

condition (%)
Drought
tolerance
ranking
V1 0.115 0.331 287.82 13
V2 0.128 0.385 300.78 7
V3 0.113
a
0.287
a*
253.98 20
V4 0.118 0.320 271.18 15
V5 0.152
b
0.503
b*
330.92 2
V6 0.149 0.481 322.81 4
V7 0.121 0.318 262.80 17
V8 0.109
c
0.283
c*
259.63 19
V9 0.120 0.354 295.00 11
V10 0.143
d
0.468
d*
327.27 3

V11 0.146 0.415 284.24 14
V12 0.126 0.373 296.03 10
V13 0.243 0.724 297.94 9
V14 0.157
e
0.524
e*
333.75 1
V15 0.101 0.270 267.32 16
V16 0.151 0.482 319.20 6
V17 0.117 0.340 290.59 12
V18 0.135 0.404 299.25 8
V19 0.142 0.456 321.12 5
V20 0.130 0.339 260.76 18
In summary, based on changing of α-amylase activity in normal and drought
condition, drought tolerance of twenty varieties could be ranked as follows: the first
group with the highest drought tolerance level: 2 varieties V5 and V14; the second
group with the medium drought tolerance level: V14, V5, V10, V6, V19, V16, V2,
V18, V13, V12, V9, V17, V1, V11, V4, V15, V7, V20, V8, V3; the lowest drought
16

tolerant level V3 and V8. These results also are similar with drought tolerance
ranking based on saccharose level.
3.1.2.3. Evaluation of drought tolerance level based on proline level
Proline is an amino acid, which can be absolutely dissolved in water. It
supports cell to retain water and absorb water. In nitrogen complexes, proline has a
critical role in cells’ osmotic pressure adjustment.
It is necessary to base on variously different indicators to evaluate drought
tolerance capacity. However, proline can be considered as a primary indicator of
plant’s drought tolerance level, or proline concentration is a criterion of adaptation

reflection of plants in water deficit condition. Proline level in sesame leaves at the
seedling stage in normal and drought condition is compared in table 3.12.
Table 3.12. Proline level in sesame leaves in normal and drought condition
(increased percentage increase or number of times increases as compared with
drought condition)
Proline (µ
µµ
µmol/mg)
Sesame
varieti
es

Normal
conditio
n
Droug
ht
toleran
ce level

One day
after
drought
treatment
Drough
t
toleran
ce level

Two days

after
drought
treatment
Drough
t
toleran
ce level

Three days
after
drought
treatment

Drough
t
toleran
ce level

V1 0.278 11 0.521 5 0.867 7 1.054 9
V2 0.273 12 0.493 9 0.871 6 1.001 13
V3 0.264 16 0.482 11 0.798 17 0.906 18
V4 0.229
b
18 0.401
b*
18 0.754
b**
18 0.896
b***
19

V5 0.341
a
1 0.663
a*
1 0.962
a**
1 1.254
a***
1
V6 0.323 3 0.552 3 0.864 8 1.116 5
V7 0.271 13 0.494 8 0.803 14 0.954 16
V8 0.198
b
20 0.347
b*
20 0.654
b**
20 0.856
b***
20
V9 0.298 5 0.485 10 0.904 3 1.043 10
V10 0.285
c
10 0.512 6 0.879 5 1.057 7
V11 0.267 14 0.478 12 0.802 15 1.123 4
V12 0.253 17 0.502 7 0.835 9 1.056 8
V13 0.267 15 0.423 15 0.827 11 1.102 6
V14 0.328
a
2 0.635

a*
2 0.914
a**
2 1.245
a***
2
V15 0.319 4 0.528 4 0.798 16 1.206 3
V16 0.293 7 0.421 16 0.817 13 1.023 11
V17 0.295
c
6 0.452 13 0.901 4 1.011 12
V18 0.287 8 0.402 17 0.821 12 0.987 15
V19 0.286 9 0.435 14 0.832 10 0.995 14
V20 0.201
b
19 0.357
b*
19 0.708
b**
19 0.945 17
Gain results in table 3.12 indicated that proline level in leaf increases based on
period of drought treatment and it is different to various sesame varieties. Proline
level ranges from 0.198 – 0.341µmol/mg in normal condition. One day after drought
17

treatment, this level increases from 0.347 to 0.663µmol/mg, and then continuously
increases after two and three day of drought treatment in range of 0.654 – 0.962
µmol/mg and 0.856 -1.254µmol/mg, respectively. Proline level of V5 reached the
highest value in comparison with other varieties during all drought treatment periods.
This indicator most highly increases in normal condition (0.341µmol/mg) and obtains

0.663, 0.962 and 1.254 µmol/mg at one day, two days and three days after drought
treatment respectively. V14’s proline level also increases higher than other varieties
(V14’s level increase is lower than only V5) for all control experiments, at all periods
of time. At one, two and three days after drought treatment, this indicator increases
by 1.93 times, 2.78 times, 3.79 times as compared to normal condition, respectively.
In conclusion, depending on leaf’s proline level group, which has the highest
ptoline level at different period of drought treatment, correlates to the best drought
tolerance capacity including V5 (the first position ranking) and V14 (the second
position ranking).
V8 has the lowest proline at all drought treatment periods (in normal condition
was 0.198 µmol/mg, one day after drought treatment reaches 0.347µmol/mg, two
days after drought treatment reaches 0.654 µmol/mg and three days after drought
treatment was 0.856µmol/mg). Following is V20, which have proline level higher
than only V8 at three situations: normal condition and two days after drought
treatment.
If based on proline level, low drought capacity group (correlated to the lowest
proline level at different periods of drought treatment) includes three varieties, which
are categorized gradually reduced proline level are V4, V20 and V8.
Proline level parameter also correlates to cell’s osmotic pressure, which is
presented in previous section (table 3.9).
3.1.3. General evaluation of drought tolerance capacity and biophysical,
biochemical indicators
Based on researched biophysical and biochemical indicators, we evaluated
twenty sesame varieties’ drought tolerance on a basis of appearance frequency at
ranking position from the first position to 20
th
position (in table 3.13).
Results in table 3.13 proved that: two varieties V14 and V5 always take place at the
first and second position following drought tolerance ranking. It is followed by
varieties V10, V17. Two varieties V3, V8 frequently appear at 19

1th
and 20
th
position
at almost all indicators. Therefore, to evaluate twenty sesame varieties’ drought
tolerance at various levels, we divided the twenty varieties into three groups based on
collected data: the first group with the highest drought tolerance level: 2 varieties V5
and V14; the second group with medium drought tolerance level: V10 and V17; the
third group with the lowest drought tolerant level: 5 varieties V3 and V8.
To examine genetic relationship between different varieties, which are ranked
based on biophysical and biochemical indicators, we applied PCR method based on
indicator of RAPD to determine genetic diversity of sesame varieties.
18

19

3.2. Studied results of genetic polymorphism analysis of twenty sesame varieties
The phylogenetic tree generated from RAPD data indicates

In this research we amplified 26 selected RAPD primers to investigate polymorphic
of representative varieties. Among them 18 primers were polymorphic, the rest
primers did not issue polymorphic results between varieties, produced blurred
banners or did not produce PCR. Thus we rejected these outcomes. Eighteen
polymorphic primers were continuously amplified to analyze genetic diversity of
twenty researched sesame diversity.
Among of 169 collected banners (table 3.14) only 140 (82.8%) were
polymorphic (table 3.14). Number of banner per primer ranged from 4 to 20 banners/
primer (average was 9.4 banners/ primer). Polymorphic level arrayed from 42.8 –
100%, primers OPA-01, OPA-11, OPA-15 and OPM-13 reached the highest rate
(100%); primer OPM-06 obtained the lowest polymorphic level (42.8%). Collected
data from 18 primers was listed and analyzed by using NTSYS pc2.1 software
program. Obtained results presented in matrix and polygenetic tree diagram to
expressed genetic relationship between researched varieties. Varieties, which had
close genetic relationships, would be at close position, high similar indicators.
Otherwise, varieties, which have different genetic relationship would have longer
distance between them and be further in the polygenetic tree diagram. Polygenetic
tree diagram illustrated genetic similarities of twenty researched sesame. With
similarities among samples at 62%, 20 analyzed varieties have been clustered into 2
distinct.

Diagram 3.8. The polygenetic tree diagram on genetic relationship of twenty
researched sesame varieties. Numbers in diagram are correlative
in order in table 2.1
II
III
I
Nhóm 2
Nhóm 1
20

Group 1 consists of 15 varieties which are split into 3 subgroups (at 65% genetic
similarities): subgroup 1 has variety No.1; the subgroup 2 includes 6 varieties: variety
No.2, 16, 9, 11, 13, 18; the subgroup 3 includes 8 varieties: variety No. 6, 17, 19, 10,
12, 14, 15. The group 2 consists of the rest 5 varieties: variety No. 3, 4, 7, 8, 20.
3.3. Evaluation of productivity and quality of six sesame varieties
3.3.1. Productivity
We determined above indicators of 6 varieties, which were considered having
the best, medium and the lowest drought tolerance capacity, based on numbers of
fruits per tree, number of firmed seeds per fruit, and quantity of 1000 seeds.
Table 3.15. Factors forming productivity and net productivities of the six
researched sesame varieties
Order

Varieties

No. of
fruits/ tree
No. of
firmed seed/
fruit
Quantity of
1000 seeds
Net
productivity
(100kg/ha)
1 V3 30.4
a
83.2
a
2.275
a
14.64
a

2 V5 35.6
b
98.4
b
2.787
b
17.60
b

3 V8 31.3
a
84.7
a
2.365
a
15.29
a

4 V10 33.2
a
87.4
a
2.558
c
16.25
c

5 V14 36.1
b
97.8
b
2.894
b
18.15
b

6 V17 28.2
a
86.5

a
2.454
c
16.67
c

Net productivities of six researched sesame varieties calculated by 100kg/ha,
this indicator ranged from 14.64 to 18.15 (100kg/ha), among two varieties V5 and
V14 gained the highest productivity, reaching 17.6 and 18.15 (100kg/ha). This result
can be explained by higher forming productivity factors of these varieties to compare
to other varieties. The two lowest drought tolerance varieties (V3 and V8) also had
the lowest productivities, which were 14.64 and 15.29 (100kg/ha). Therefore,
obtained results proved that six researched sesame varieties’ drought tolerance were
correlative with their net productivities. This result brings practically important
meaning in seedling selection to choose cultivar which having high productivity also
having good drought tolerance capacity.
3.3.2. Lipid content and lipid indexes
Lipid content was calculated by percentage of lipid content per seed’s quantity.
Fatty indexes reflect oil quality, which is a basic indicator to classify oil and select oil
maintain measurement. For sesame, acid indexes, iodine indexes, soap indexes were
most concerned.
The data in table 3.16 indicated that, lipid content varied from 47.14 to
53.32%. V5 had the highest lipid content (accounted for 53.32%); following was V17
(accounted for 52.52%); and V3 had the lowest lipid content (consisted 47.14%). The
remaining varieties V8, V10, V14 had the lowest lipid level, accounted for 49.76%,
48.67% and 50.78 respectively.


21

Table 3.16. Lipid content and lipid indexes in sesame seed
Order

varieties

Lipid
content
(%)
Lipid
indexes
Soap
indexes
Iodine
indexes
1 V3 47.14
a
3.36
a*
65.8
a**
130.2
a***

2 V5 53.32
b
2.64
c*
64.3
a**
131.9

a***

3 V8 49.76
a
3.24
a*
62.8
a**
136.5
a***

4 V10 48.67
a
3.02
a*b*
65.7
a**
132.7
a***

5 V14 50.78
bc
2.57
c*
63.5
a**
133.5
a***

6 V17 52.52

bc
2.85
a*b*
60.7
a**
135.3
a***

Fatty acid composition was most concerned among above analyzed lipid
indexes. This is also standards to evaluate sesame quality and maintaining
measurement. This index is lower, sesame quality is better, sesame is easier to
maintain and does not need complicated process. All three sesame varieties, which
had high fatty acid composition (V5, V14, V17), had acid index lower than 3. V3
variety had the highest acid index (3.36), this is also low drought tolerance variety
and V3’s fat content and acid index do not fulfill export requirements of fat content
and acid index. These indexes of two sesame varieties V8 and V10 were 3.24 and
3.02, respectively.
3.3.3. Fatty acid composition in sesame seed
Unsaturated fatty acids help crops absorb better, presence of these unsaturated
fatty acids enhance sesame oil quality in particular and plant oil in general. We
analyzed content of five main fatty acids to determine the role of these acids in
sesame seeds. Gained results are presented in table 3.17.
Table 3.17. Fatty acid composition in sesame seeds
Fatty acid compositions (%) Order

Varieties

Plasmatic

Stearic

Linoleic

Oleic Linolenic
1 V3 6.35
e
3.43
d
40.35
a
32.68
b

0.37
c

2 V5 6.18
e
4.05
d
40.67
a
34.25
b

0.50
c

3 V8 5.86
e

3.98
d
39.45
a
32.53
b

0.44
c

4 V10 6.28
e
3.95
d
40.33
a
33.70
b

0.54
c

5 V14 5.79
e
4.21
d
39.78
a
33.29
b

0.47
c

6 V17 6.12
e
3.79
d
39.60
a
33.28
b

0.49
c

Data in table 3.17 indicated that these unsaturated fatty acids content accounted
for 82.18% - 85.65% total fatty acids in sesame oil. Among that, oleic and linoleic
acids composition accounted for higher portion to compare to other fatty acids,