全 文 ：稀土浸种对不同水分条件下苦
荞种子萌发和幼苗生长的影响
石艳华 1，张永清 1，2* （1.山西师范大学生命学
院，山西临汾 041004；2.山西师范大学城市与
环境科学学院，山西临汾 041004）
摘 要 [目的 ]研究稀土浸种对不同水分条
件下苦荞种子萌发和幼苗生长的影响。 [方法]
以“黑丰一号”苦荞为试验材料，采用水培实验
培养幼苗，取样测定各项指标。 [结果]①在正
常水分条件下，适宜浓度的稀土浸种能够提高
苦荞种子的发芽势、发芽率、发芽指数和萌发
指数；同时苦荞幼苗的叶面积、茎粗、总根长、
根重、叶片相对含水量、脯氨酸含量、可溶性糖
含量、可溶性蛋白含量、SOD 和 POD 活性以及
根系活力均显著高出对照（蒸馏水浸种），而叶
片相对电导率和 MDA 含量明显下降；②与正
常灌水相比较，当苦荞遭受干旱胁迫后，其种
子的发芽势、发芽率、发芽指数、萌发指数以及
幼苗的叶面积、茎粗、总根长、根重、叶片相对
含水量、脯氨酸含量、可溶性糖含量、可溶性蛋
白含量、SOD 和 POD 活性、根系活力均有所下
降， 而叶片相对电导率和 MDA 含量有所提
高，而且胁迫越深，其变化幅度越大但是在同
一水分梯度下， 采用不同的浸种物质浸种，其
变化幅度有所不同，稀土浸种能降低其变化幅
度。③在干旱条件下，采用 200 mg/L 的稀土浸
种与蒸馏水浸种能够极显著提高苦荞幼苗的
SOD、POD 活性、叶面积、总根长、叶绿素含量、
根系活力；在中度干旱和重度干旱下分别可使
叶片相对含水量提高 8.9%和 10.8%, 脯氨酸
含量提高 7.5%和 8.2%, 根系活力提高 13.8%
和 16.7%, 可溶性糖含量提高 10.4%和 7.9%。
[结论] 200 mg/L 的稀土为最佳的浸种浓度。
关键词 稀土; 浸种; 苦荞; 生理指标
基 金 项 目 国 家 自 然 基 金 面 上 项 目
（30871483）。
作者简介 石艳华 （1988- ），女 ，山西朔州
人 ，硕士研究生 ，研究方向 ：植物生理生态 ，
E-mail：yuxuan13141314@126.com。 * 通讯作
者，博士，教授，硕士生导师，主要从事土壤及
植物生理生态方面的教学与研究 ，E-mail：
yqzhang208@163.com。
收稿日期 2013-08-25
修回日期 2013-09-04
Effect of Seed Soaking with Rare Earth on the
Seed Germination and Seedling Growth of Tartary
Buckwheat under Different Water Conditions
Yanhua SHI1, Yongqing ZHANG1,2*
1. College of Life Science, Shanxi Normal University, Linfen 041004, China;
2. College of Urban and Environmental Science, Shanxi Normal University, Linfen 041004, China
Supported by the National Natural Science Foundation of China (30871483).
*Corresponding author. E-mail: yqzhang208@163.com
Received: August 25, 2013 Accepted: September 4, 2013A
Agricultural Science & Technology, 2013, 14(9): 1237-1243
Copyright訫 2013, Information Institute of HAAS. All rights reserved Agronomy and Horticultrue
Abstract [Objective] This study aimed to investigate the effect of soaked seed with
rare earth on the seed germination and seedling growth of tartary buckwheat under
different water conditions. [Method] A hydroponic experiment was carried out with
the seeds of tartary buckwheat variety Heifeng No.1 in the year 2012. [Result] ①
In the normal irrigation, suitable concentration of rare earth increased the germina-
tion rate, vital index, germination index and sprouting index of tartary buckwheat
seed; at the same time, the leaf area, stem thickness, total root length, root weight,
leaf relative water content, proline content, soluble sugar content, soluble protein
content, root activity, SOD activity and POD activity of seedling were significantly
enhanced, while the relative conductivity and MDA content of tartary buckwheat
were decreased obviously. ② Compared with water stress and normal irrigation, the
indices of germination potential, germination rate, vital index, germination index, the
leaf area, stem thickness, total root length, root weight, leaf relative water content,
proline content, chlorophyll content, soluble sugar content, root activity, SOD and
POD activity were reduced, while relative conductivity and MDA content were in-
creased, and the extents differed in the treatment of different chemical regulators,
and the varied range increased with the higher severity of soil water stress. ③ Un-
der water stress, soaking seeds with suitable concentration (200 mg/L) of rare earth
could significantly improve the SOD and POD activity, leaf area, total root length,
chlorophyll content and root activity compared with CK. They could increase leaf
relative water content by 8.9% and 10.8%, proline content by 7.5% and 8.2%, TTC
activity by 13.8% and 16.7%, and soluble sugar content by 10.4% and 7.9% under
mild and severe water stress, separately. [Conclusion] The appropriate concentration
of rare earth was 200 mg/L.
Key words Rare earth; Soaking seed; Tartary buckwheat; Physiological index
W ater stress is one of themost important environmen-tal factors that regulate plant
growth and development, and influ-
ence plant production. Plants can re-
spond and adapt to water stress
spontaneously by altering their cellular
metabolism and invoking various de-
fense mechanisms [1]. Survival under
this stressful condition depends on the
plant’s ability to perceive the stimulus,
generate and transmit the signals, and
initiate various physiological and
chemical changes[2-3].
Tartary buckwheat (Fagopyrum
tataricum Gaertn) is a dry fruit that be-
longs to the polygonaceae family. It is
an important functional food material.
It contains proteins with high biological
value and balanced amino acid com-
position, relatively high crude ber and
vitamins B1, B2, and B6. Besides, it
has more rutin than common buck-
wheat[1]. It always acts as a catch crop
for its short growth period, strong
adaptability, resistance against cold
weather and sterile soil [4]. In Shanxi
Province, especially its northern part,
tartary buckwheat has the regional ad-
vantage to process famous and excel-
lent tartary buckwheat. In general, the
tartary buckwheat is planted in the dry
DOI:10.16175/j.cnki.1009-4229.2013.09.019
Agricultural Science & Technology 2013
land, and drought becomes the main
factor which limits its yield. Therefore,
it is particularly important to study how
to improve the growth and yield of tar-
tary buckwheat under drought stress.
Keeping enough irrigation is a
good way to release water stress ,
and it is also effective to soak seeds
with some chemical regulators to im-
prove the crop self drought resis-
tance [5-6 ] . A great deal of researches
show that seed soaked with plant
growth regulator or chemical regula-
tors can make the morphology and
physiology of crop more suitable to the
adverse situation. For example, soak-
ing seed with gibberellin, ZnSO4, Mn-
SO4, proline and salicylic acid can in-
crease the crop’s drought-resistant
ability obviously[7]. The rare earth ele-
ments (REE) are a group of 17 chemi-
cal elements composed of scandium,
yttrium and the lanthanum (15 kinds),
which have widely been reported in
agricultural research [8]. As inorganic
metallicion, suitable concentration of
REE treatment can improve crops ab-
sorption, transformation and utilization
of nutritious elements, promote growth
and photosynthesis, adjust enzyme
activity, strengthen resistance and im-
prove product quality [9-10]. At present,
researchers mainly study the nutritive
value, medicinal value, component
content and sprouting product of tar-
tary buckwheat. Few studies have fo-
cused on the physiological response
under adversity stress. From the rea-
sons above, it is very essential to in-
vestigate the effect of soaked seed
with rare earth on the seed germina-
tion and seedling growth of tartary
buckwheat under different water con-
ditions, which guide the cultivation of
high yield and good quality of buck-
wheat.
Materials and Methods
Materials
The tested tartary buckwheat vari-
ety is “Heifeng No.1”, which is offered
by Shanxi Academy of Agricultural
Sciences. The soil for test is the calcic
cinnamon soil developed from the
loess parent material. REE is La(NO3)3
produced by Guangfu Fine Chemical
Industry Research Institute in Tianjin.
Design of experiment
The experiment is a complete
random design method with two fac-
tors: (1) different concentrations of La
(NO3)3: 0, 100, 200, 250 mg/L (Marked
as R1, R2, R3 and R4 respectively);
(2) different water conditions: normal
irrigation (no PEG), slight water stress
(10% PEG) and heavy water stress
(15% PEG), marked as B1, B2 and B3
respectively. There are 12 treatments
in all, and each treatment is repeated
three times.
Methods
Germination test After soaking
seeds with four different concen -
trations of La (NO3)3, seed germination
tests were carried out. One hundred
seeds for each treatment were placed
in a petri dish (10 cm in diameter) with
two pieces of filter paper, and each
experiment was replicated three times.
Then, seeds were incubated in an arti-
ficial climate box at 25 ℃ under alter-
nating cycle of 12 h illumination and 12
h darkness for 5 d. The distilled water
and statistical germination number
were added every day on time. After
germination, we determined the mor-
phology indices of the seedling.
Hydroponic experiment White
buckwheat seeds were surface-steril-
ized in 0.1% HgCl2 for 15 min, rinsed
thoroughly with deionised water and
germination in artificial climate box at
19/24 ℃ (day/night) for 7 d in petri dish
with water-moistened filter paper, and
the distilled water and statistical ger-
mination number were added every
day on time. Then the seedlings ob-
tained were placed in plastic contain-
ers (30 cm ×40 cm) with continuously
aerated nutrient solution for 12 d. The
compositions of the nutrient solution
were[19] KNO3 at 0.607 g/L, Ca(NO3)2·
4H2O at 0.945 g/L, MgSO4·7H2O at
0.493 g/L, NH4H2PO4 at 0.115 g/L, Fe-
EDTA at 0.020 g/L, H3BO3 at 2.860
mg/L, MnCI2·4H2O at 2.130 mg/L, Cu-
SO4·5H2O at 0.050 mg/L, (NH4)2MoO4
at 0.020 mg/L, and Na2SeO3 at 0.400
mg/L. In drought stress treatments,
PEG6000 was added to the nutrient
solution in proportion, and nutrient so-
lution free of PEG6000 was taken as
control.
Measurement indices According to
the international rules of seed germi-
nation.
(1) Germination energy =Normal
germinated seed number on the fourth
day/The total seed number;
(2) Germination rate =Normal
germinated seed number on the sev-
enth day/The total seed number;
(3) Sprouting index=ΣThe number
of germinated seed in some days ／The
corresponding number of sprouting
days;
(4) Vigor index= Germination in-
dex × The length of the seedling at the
final germination;
(5) Germination index=1.00 nd2+
0.75 nd4+0.50 nd6, in this formula, nd2,
nd4 and nd6 are the germination rates
on the second, fourth, sixth day re-
spectively, and 1.00, 0.75 and 0.50
are the drought-resistant coefficients
given by the corresponding days
respectively .
(6) Germination stress index= The
germination index of the treatment/The
germination index of the CK;
(7) Germination index of drought-
resistance = The sprouting index in the
water stress/The sprouting index in the
normal irrigation;
(8) The morphological index of the
seedlings: shoot and root length were
measured by using a meter scale;
stem diameter was measured by using
a vernier caliper; leaf area was mea-
sured with a leaf area meter; dry
weight was determined by drying the
plants at 75 ℃ for a period of 48 h until
constant weight.
(9) The physiological index of the
seedlings: total chlorophyll, chlorophyll
a and chlorophyll b were determined
according to Arnon[11]; leaf relative wa-
ter content (RWC) was identified by
weighing method; the relative electric
conductivity was determined by a
conductivity meter; the content of dis-
sociative proline was measured by
Acidity Ninhydrin; the soluble sugar
and protein contents were expressed
by Anthrone-sulfonic Acid method and
Coomassie Brilliant Blue Staining, re-
spectively; MDA content was analyzed
by Thiobarbituric Acid Test. SOD and
POD activity were determined by Ri-
boflavin treatment and Guaiacol col-
orimetric method, respectively; root
activity wasmeasured by TTCmethod.
Statistical analysis
Statistical analysis was performed
based on the SPSS (version 10.0)
program. All values were expressed as
mean value ± standard error (SE).
1238
Agricultural Science & Technology2013
Fig.1 Effect of soaking seeds with different
concentrations of rare earth on germi-
nation index under different water
conditions
Table 1 Effect of soaking seeds with different concentrations of rare earth on the
germination energy, germination rate, sprouting index and Vigor index under
different water conditions
Treatment Germination energy Germination rate Sprouting index Vigor index
R1W1 41.00±2.31 C 43.00±1.73 C 87.22±5.21 B 418.63±25.02 B
R2W1 54.00±1.45 AB 57.00±2.08 AB 83.71±2.87 B 452.03±15.49 B
R3W1 59.33±2.33 A 63.67±1.85 A 120.60±7.26 A 699.51±42.08 A
R4W1 45.33±1.45 BC 53.00±1.73 B 79.73±1.82 B 358.77±8.19 B
R1W2 20.33±2.33 B 28.00±1.73 B 42.61±3.70 B 161.90±14.05 C
R2W2 29.33±4.26 AB 37.33±4.05 B 64.65±8.77 AB 278.02±37.72 AB
R3W2 37.33±1.20 A 52.33±1.76 A 84.75±1.22 A 372.92±5.36 A
R4W2 31.00±3.21 AB 37.00±1.15 B 66.46±5.03 AB 245.91±18.61 BC
R1W3 12.33±1.45 B 20.67±2.60 B 27.42±2.21 B 85.01±6.84 B
R2W3 18.33±2.40 AB 31.00±2.08 AB 39.85±4.39 AB 139.49±15.37 AB
R3W3 24.67±1.45 A 34.33±2.33 A 52.43±4.31 A 188.78±15.51 A
R4W3 17.33±1.20 AB 26.33±3.18 AB 36.97±3.27 AB 110.91±9.82 AB
R1, H2O; R2, 100 mg/L La (NO3)3; R3, 200 mg/L La (NO3)3; R4, 250 mg/L La (NO3)3; W1,
normal irrigation (field water capacity of 65%-70%); B2, moderate drought stress (field
water capacity of 45%-60%); B3, serious drought stress (field water capacity of 30%-
45% ). Values within a column followed by a different capital or normal letter are
significantly different at P < 0.01 or P < 0.05, respectively.
Results and Analysis
Effect of soaking seeds with differ-
ent concentrations of rare earth on
the germination of seed under dif-
ferent water conditions
The results showed that the ger-
mination energy, germination rate,
sprouting index and vigor index were
reduced gradually with the increasing
water stress, but the extents differed in
the treatment of different concentration
of La (NO3)3, and soaking with H2O
changed most in all indices. The ger-
mination energy of tartary buckwheat
seeds soaked with H2O declined sig-
nificantly due to water stress treat-
ments. Well watered seeds showed
41.00% . The germination energy de-
clined signi cantly by 50.4% and
69.9% in mild and severe stress levels
respectively (Table 1). Effect of differ-
ent concentration of La (NO3)3 on ger-
mination energy was very obvious in
the water stress, and especially when
seeds were soaked with the 200 mg/L
La(NO3)3, effect appeared more at each
water stress level. In the normal irriga-
tion and mild water stress, it could in-
crease the germination energy by
44.7% and 83.6% respectively; in the
severe water stress, the germination
energy was doubled compared with
theCK(Table 1). The difference reached
the level of the most significance.
Being consistent with the germi-
nation energy results, seeds soaked
with La (NO3)3 could enhance the ger-
mination rate of tartary buckwheat un-
der different water gradients, and the
germination rate increased with the in-
creasing dosages of La (NO3)3 at first
and then reduced. The curves be-
tween the germination rate and treat-
ment dosages present obvious hump
shape. The results showed that the
germination rate was increased sig-
nificantly when seed were soaked with
200 mg/L La(NO3)3. Compared with the
control group, they were improved by
48.1, 86.9% and 66.1% in the normal
irrigation, mild water stress and severe
water stress respectively.
The results also showed that: ①
lower concentration (50-200 mg/L) of
La (NO3)3 has strong stimulating effect
on the seed germination energy, ger-
mination rate, sprouting index and vig-
or index of tartary buckwheat;② high-
er concentration (250 mg/L) of La(NO3)3
significantly inhibited the seed germi-
nation energy, germination rate,
sprouting index and vigor index of tar-
tary buckwheat.
Change trends of the sprouting
index during the water stress were
shown in Table 1. The decline of the
soil water content resulted in a signifi-
cant decrease of the sprouting index,
but the treatment of seeds soaked with
the 200 mg/L La(NO3)3 could make the
sprouting index of tartary buckwheat
remain at a higher level compare to
the treatment soaked with H2O. The
treatment can enhance the sprouting
index by 38.3% in the normal irrigation,
by 98.8% in the slight drought and by
91.2% respectively.
Different tartary buckwheat
seedlings were soaked with different
concentration of La (NO3)3. The result
showed that the vigor index of tartary
buckwheat seed increased notably, the
pretreatment with 200 mg/L La (NO3)3
for 12 h was the most effective. They
could add the vigor index by 67.1% in
the normal irrigation, in the mild and
severe drought. The vigor index was
1.3 and 1.2 times compared with the
CK, respectively.
Effect of soaking seeds with differ-
ent concentrations of rare earth on
germination index under different
water conditions
The effect of seed soaked with
different concentration of rare earth on
germination index under different wa-
ter conditions was revealed in the
Fig.1. All the three concentrations of
La (NO3)3 could increase the germina-
tion index compared with controls in
three water levels. There were no sig-
nificant differences in germination in-
dex except the treatments of 200 mg/L
La (NO3)3. It could enhance the germi-
nation index by 42.1% , 93.7% and
83.5% at normal irrigation, mild
drought and severe drought stress re-
spectively. It indicated that the treat-
ment of soaking seeds with 200 mg/L
La (NO3)3 is the most effective way to
increase the germination index of tar-
tary buckwheat seeds in the water
stress.
The germination stress index and
sprouting index of drought-resistant
are two important indices to evaluate
plant drought resistance. Soaking
seeds with appropriate concentrations
(50 -200 mg/L) of La (NO3)3 can in-
crease the index, but when the con-
1239
Agricultural Science & Technology 2013
Table 2 Effect of soaking seeds with different concentrations of rare earth on the
germination index and sprouting index of drought-resistant under two water stress
treatments
Treatment Germination stress index Sprouting index of drought-resistance
R1W2 0.50±0.02 c
R2W2 1.50±0.13 b 0.65±0.07 ab
R3W2 2.02±0.33 a 0.69±0.03 a
R4W2 1.56±0.05 b 0.68±0.03 a
R1W3 0.34±0.01 b
R2W3 1.44±0.09 b 0.42±0.04 ab
Values within a column followed by a different capital or normal letter are significantly
different at P < 0.01 or P < 0.05, respectively.
Table 3 Effect of soaking seeds with different concentrations of rare earth on morphologic
indexes of tartary buckwheat at seedling stage under different water conditions
Treatment Plant heightcm
Leaf area
cm2
Max length of
root∥cm
Stem
diameter∥cm
Seedling
index
R1W1 17.57±0.09 A 12.13±0.09 C 14.47±0.18 C 0.27±0.01 C 0.067±0.00 D
R2W1 16.97±0.12 B 13.77±0.09 B 17.07±0.26 B 0.31±0.01 B 0.076±0.00 C
R3W1 15.83±0.12 C 14.80±0.10 A 18.53±0.26 A 0.35±0.01 A 0.085±0.01 A
R4W1 14.33±0.32 D 13.73±0.03 B 17.37±0.16 B 0.29±0.01 BC 0.082±0.01 B
R1W2 16.23±0.17 A 10.33±0.09 D 13.07±0.07 C 0.21±0.01 C 0.052±0.00 C
R2W2 15.20±0.11 B 12.97±0.12 B 16.43±0.15 B 0.25±0.02 B 0.069±0.00 B
R3W2 14.20±0.17 C 13.53±0.15 A 17.63±0.07 A 0.28±0.01 A 0.080±0.01 A
R4W2 13.40±0.15 D 11.90±0.12 C 16.50±0.15 B 0.27±0.02 AB 0.067±0.00 B
R1W3 14.03±0.15 A 8.63±0.12 C 10.46±0.09 C 0.18±0.01 C 0.050±0.01 D
R2W3 13.70±0.21 A 11.30±0.15 B 15.36±0.09 B 0.23±0.01 B 0.056±0.00 C
R3W3 12.40±0.15 B 12.50±0.11 A 16.13±0.15 A 0.27±0.02 A 0.078±0.01 A
R4W3 11.37±0.19 C 11.27±0.07 B 15.40±0.06 B 0.23±0.02 B 0.064±0.01 B
Seedling index=( Stem diameter/ Plant height +Dry weight of the root/Dry weight of the
shoot) ×Dry weight of the plant. Values within a column followed by a different capital or
normal letter are significantly different at P < 0.01 or P < 0.05, respectively.
centrations of La (NO3)3 reaches 250
mg/L, it can inhibit the germination
stress index and sprouting index of
drought-resistant of the seeds. The
concentration of 200 mg/L La (NO3)3 is
the most effective to the increase of
the germination stress index and
sprouting index of drought-resistance
among the four treatments. Seed
soaked with the 200 mg/L La (NO3)3
can add the sprouting index of
drought-resistance by 38.0% in the
mild water stress and 29.4% in the
heavy water stress. It can also make
the germination stress index stay in a
high level to some extent.
Effect of soaking seeds with differ-
ent concentrations of rare earth on
the growth of seedling under dif-
ferent water conditions
Morphologic indices of seedling
As we can see in the Table 3, when
plants were subjected to mild and se-
vere water stresses, all growth and
biomass parameters (plant height, leaf
area, max length of root and stem di-
ameter) came down, and the declined
extent increased with the increasing
level of water stress. Among these pa-
rameters, the plant height of the
seedling reduced when treated with
La (NO3)3, and the inhibited effect was
enhanced with the adding concentra-
tions of La (NO3)3. On the contrary, the
leaf area, max length of root and stem
diameter are increased with the in-
creased concentrations of La(NO3)3 in
each water level. Taking max length of
root as an example, when seeds were
soaked with 200 mg/L La (NO3)3, the
max length of root could be enhanced
by 28.1% in the normal irrigation.
When the plants suffered from water
stress, the max length of root is de-
creased. However, compared with the
CK (soaking seeds with H2O), the de-
creasing extent was much smaller
then that treated with La (NO3)3, the
length of the treatment R1 is dropped
by 9.7% and 27.7% in mild and heavy
water stress, while that in treatment
R3 is dropped by 4.9% and 13.0% in
mild and severe water stress. The
length of treatment R3 is increased by
28.1% , 34.9% and 54.2% in the well
water, mild and heavy water stress
compared with the CK.
Seedling index is a comprehen-
sive index to reflect the quality of the
seedling. The effects of soaking seeds
with rare earth on seedling index under
different water conditions of tartary
buckwheat are listed in Table 3. The
seedling index gradually decreased at
first then raised with the increasing
concentrations of La(NO3)3 in any wa-
ter condition. The 200 mg/L La (NO3)3
is the best concentration, which can
significantly enhance the seedling in-
dex compared with the CK. After
soaking seeds with 200 mg/L La(NO3)3,
the seedling index can be increased by
26.9% in well water treatment, by
53.8% and 56.0% in mild and heavy
water stress.
Physiologic indices of seedling
The effects of water stress on the pro-
tective enzymes SOD and POD in tar-
tary buckwheat roots are shown in
Table 4. Under three different water
treatments, the activities of SOD and
POD in roots decreased drastically
during the seedling period of tartary
buckwheat. Compared with full water
supply (W1), the activities of SOD in
roots in treatment R3 decreased sig-
nificantly by 8.0% in heavy water
stress, which was much smaller than
those soaked with H2O (dropped by
11.1% ). The variance analysis re-
vealed that the treatment R3 signi
cantly enhanced the SOD activity
compared with the CK in each water
conditions. The activities of POD in
roots were enhanced when treated
with the rare earth at any water level.
Compared with treatment R1, POD ac-
tivity in roots increased significantly by
20.0% in the normal irrigation, by
24.1% in mild water stress and by
25.0% in severe drought. Among all
the treatments (R1, R2, R3 and R4),
R3 was the best.
The experimental result (Table 4)
indicated that water stress obviously
decreased the TTC activity in tartary
buckwheat roots. After rare earth were
applied, the damage of water stress on
TTC activity in root tend to be reduced
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Agricultural Science & Technology2013
Table 4 Effect of soaking seeds with different concentrations of rare earth on SOD activity,
POD activity, TTC activity, leaf relative conductivity and MDA content under
different water conditions
Treat-
ment
SOD activity
U/g
POD activity
U/(g·min)
TTC activity
μg/g
Leaf relative
conductivity∥%
MDA content
μmol/g
R1W1 531.97±1.33 D 480.00±27.71 b 43.81±0.51 C 88.52±1.67 a 6.66±0.06 A
R2W1 565.27±0.79 B 544.00±16.00 ab 46.85±0.36 B 85.83±0.45 ab 6.09±0.14 AB
R3W1 593.40±2.33 A 576.00±27.71 ab 50.26±0.39 A 82.89±1.56 b 5.09±0.06 C
R4W1 561.01±0.72 C 528.00±15.02 a 47.36±0.26 B 85.62±0.55 ab 5.71±0.41 BC
R1W2 514.52±8.35 BC 464.00±16.00 c 42.72±0.38 C 90.25±1.84 a 7.02±0.24 A
R2W2 554.88±23.73 AB 528.00±14.00 ab 45.71±0.07 B 88.06±0.95 ab 6.46±0.28 AB
R3W2 571.69±10.40 A 576.00±27.71 a 48.60±0.38 A 84.02±0.93 c 5.59±0.50 B
R4W2 495.74±7.34 C 496.00±16.00 bc 46.34±0.37 B 86.21±2.10 bc 6.10±0.22 AB
R1W3 472.86±22.79 BC 448.00±16.00 B 40.24±0.68 C 92.81±0.75 A 7.31±0.25 A
R2W3 529.21±12.55 AB 489.00±14.00 B 43.30±0.36 B 89.79±0.38 B 6.19±0.20 B
R3W3 545.92±13.12 A 560.00±32.00 A 46.97±0.26 A 86.51±0.45 C 5.96±0.19 B
Values within a column followed by a different capital or normal letter are significantly different at P <
0.01 or P < 0.05, respectively.
Table 5 Effect of soaking seeds with different concentrations of rare earth on soluble sugar
content, soluble protein content, proline content, chlorophyll content and leaf
relative water content under different water conditions
Treatment Soluble sugarcontent∥%
Soluble protein
content∥%
Praline
content∥μg/g
Chlorophyll
content∥mg/g
Leaf relative
water
content∥%
R1W1 6.53±0.36 B 20.15±0.08 B 48.08±0.79 C 3.46±0.10 C 84.02±0.92 B
R2W1 7.18±0.07 B 22.25±0.27 A 50.36±0.32 B 3.95±0.09 B 87.75±1.07 AB
R3W1 8.29±0.09 A 23.16±0.39 A 52.33±0.70 A 4.65±0.12 A 91.41±1.43 A
R4W1 7.89±0.12 A 20.64±0.39 B 47.49±0.16 C 4.12±0.05 B 86.12±2.36 B
R1W2 6.53±0.09 BC 19.12±0.54 B 44.78±0.32 C 3.07±0.05 C 78.15±1.72 B
R2W2 6.82±0.31 AB 19.67±0.65 B 47.39±0.71 AB 3.55±0.15 AB 83.23±0.96 AB
R3W2 7.21±0.07 A 21.74±0.10 A 48.13±0.36 A 3.87±0.08 A 85.09±1.61 A
R4W2 6.17±0.06 C 19.31±0.33 B 46.02±0.42 BC 3.45±0.08 B 83.18±2.10 AB
R1W3 5.82±0.13 B 16.79±0.33 C 41.84±0.26 B 2.35±0.06 C 73.52±1.05 C
R2W3 6.10±0.07 AB 17.36±0.10 BC 43.73±0.13 A 2.68±0.07 B 77.32±1.04 B
R3W3 6.28±0.12 A 19.74±0.46 A 45.28±0.49 A 3.16±0.04 A 81.45±0.88 A
R4W3 5.89±0.13 AB 18.09±0.20 B 40.95±0.94 B 2.59±0.02 B 75.92±0.92 BC
Values within a column followed by a different capital or normal letter are significantly
different at P < 0.01 or P < 0.05, respectively.
drastically, and the variation of TTC
activity in different treatments of soak-
ing with different concentrations of
La(NO3)3 was relative large, while com-
pare with the R1, the treatment of R3
(soaking with 200 mg/L La(NO3)3) was
the most effective, which could im-
prove the TTC activity by 14.7%, 13.8
and 16.7% under well watered, mild
and severe water stress, respectively.
After soaking seeds with rare
earth, the effects of leaf relative con-
ductivity of tartary buckwheat in the
drought stress clearly showed that leaf
relative conductivity of leaf first gradu-
ally decreased then raised with the in-
creasing concentrations of La(NO3)3 in
any water condition, and the 200 mg/L
La (NO3)3 was the best concentration,
which could remarkably lessen the leaf
relative conductivity of root compared
with the CK. After soaking seeds with
200 mg/L La (NO3)3, the leaf relative
conductivity could be reduced by 6.4%
in well watered treatment, by 6.9% and
6.8% in mild and heavy water stress.
MDA is one of the ultimate prod-
ucts as a result of lipid peroxidation
damage by free radicals. MDA content
was higher under water stress than
those in control environment for all
cultivars at seedling stage of tartary
buckwheat roots as shown in Table 4.
The treatment of seeds soaked with
200 mg/L La (NO3)3 could make MDA
content of root stay at a relative low
level in any water condition, they could
decrease the MDA content of root by
23.6% , 20.4% and 18.5% under well
watered, mild and severe water stress,
respectively. The variance analysis re-
vealed that the difference was very
significantly.
As shown in the Table 5, the total
soluble proteins and total soluble sug-
ar of buckwheat root decreased signi
cantly with increasing water stress.
Soaking seeds with rare earth could
clearly decline the degree of decline of
both total soluble proteins and total
soluble sugar, and soaking with 200
mg/L La (NO3)3 is the most effective
treatment compared with the others. It
significantly improved the total soluble
proteins and total soluble sugar in
leaves of tartary buckwheat under well
watered, mild and severe water stress
by 27.0% and 14.9%, 10.4% and 13.7%
and 7.9% and 17.6% compared to the
CK (soaking with H2O) respectively.
The proline content of buckwheat
root with different treatment of soaking
seeds with different concentration of
La (NO3)3 in different water conditions
are listed in Table 5. The proline con-
tent of all the treatment decreased un-
der the water stress, but soaking
seeds with rare earth could make the
proline content stay in a relative high
level compared with the CK at both
normal irrigation and water stress.
Soaking seeds with appropriate con-
centrations (50 -200 mg/L) of La(NO3)3
could increase proline content, but
when the concentration of La (NO3)3
reached 250 mg/L, it inhibited the
proline content of the root. Therefore,
the treatment of soaking with 200 mg/L
La(NO3)3 was most effective compared
with the others. It significantly im-
proved the proline content in tartary
buckwheat roots under well watered,
mild and severe water stress by 8.8%,
7.5% and 8.2% compared to the CK,
respectively.
Chlorophyll content under water
stress was lower than that in controlled
environment in all treatments at
seedling stages, and the degree of re-
duction varied depending on the
drought resistance of each treatment
(Table 5). Soaking seeds with 200
mg/L La (NO3)3 significantly enhanced
1241
Agricultural Science & Technology 2013
the total chlorophyll content in leaves
of tartary buck wheat under well wa-
tered, mild and severe water stress by
34.4% , 26.1% and 34.5% as com-
pared to the CK. The variance analysis
revealed that irrespective of water
stress level, soaking seeds with 200
mg/L La(NO3)3 significantly enhanced
the total chlorophyll content in leaves
than other treatments. Irrespective of
soaking seeds with different concen-
tration of La (NO3) 3 , the chlorophyll
content decreased signi cantly with in-
creasing level of water stress.
The tendency of leaf relative wa-
ter content of different soaking treat-
ment under different water condition is
similar to that of the chlorophyll con-
tent (Table 5). The leaf relative water
content of seeds soaking with 200
mg/L La(NO3)3 fell by 6.9% and 10.9%
in mild water stress and severe water
stress, which was smaller than that of
the treatment soaking seeds with H2O
(dropped by 7.0% and 12.5% in the
mild and severe water stress, respec-
tively). Soaking seeds with 200 mg/L
La (NO3)3 significantly added the total
relative water content in leaves of tar-
tary buckwheat under well watered,
mild and severe water stress by 8.8%,
8.9% and 10.8% as compared to the
CK (soaking with H2O), respectively.
Discussion and Conclusion
Plants can maintain normal
metabolisms by eliminating reactive
oxygen species (ROS) so that it can
avoid injury by the synergistic effect
of protective enzymes, such as super-
oxide dismutase (SOD), catalase (CAT),
peroxidase (POD), and non-enzyme
substances in plants as ascorbic
acid (ASA) and reduced glutathione
(GSH)[12-13]. Under water stress, ROS
accumulates and results in lipid peroxi-
dation in cell membrane, a series of
physiological and biochemical
changes associated with direct or indi-
rect oxidative stress in plants, and then
cell metabolic disorder to a serious
extent, which finally influence yield and
seed quality[14-15].
Extensive researches have been
carried out in recent years on the gen-
eration of ROS and its injury to plant
growth and development under water
stress [16 -17]. Photosynthetic apparatus
may be damaged under water stress,
which will lead to the reduction photo-
synthetic capacity. On one hand, ex-
cessive light causes an increase of
ROS in chloroplast which destroys the
defense system in which the SOD en-
zyme plays a major role, and decreas-
es the content of ant oxidation reduc-
tant (ASA)[18]. Consequently free radi-
cals attack alters the lipid composi-
tions in the cell membrane and
changes membrane structures which
results in increased cell conductivity
and MDA content [16-17]. On the other
hand, a series of adaptive responses
to water stress occur including the in-
duction of the protective enzymes
such as SOD, POD and CAT by the
increase of and H2O2 contents under
mild water stress, and leads to in-
creasing drought resistance. It was
shown that the activities of the protec-
tive enzymes increased more in
drought-resistant cultivars than those
in less-resistant cultivar in response to
drought[19-20].
An experiment conducted by Fu
et al. [21] to study the effects of water
stress on photosynthesis and associ-
ated physiological characters of cap-
sicum showed that under the water
stress condition, the growth of the
plants was inhibited; the total plant
dry weight declined significantly, but
root/shoot increased. This paper indi-
cates that leaf water potential, leaf rel-
ative water content and leaf pigment
decreased, while the contents of mal-
ondialdehyde, and the proline in-
creased. It also shows that the SOD
and POD activity is enhanced in the
water stress, which is different from
the result in this research, but it is
consistent with the result of Zhang et
al. [5] that the effect of soaking wheat
seed with 150 mg/L SA on the SOD
and POD activity of roots. The experi-
ment of Jie et al. [22] suggested that
MDA content in leaf was increased
under drought stress. MDA content
increased slowly in resistant varieties
while that increased rapidly in sensi-
tive ones, which is in accordance
with the result in this paper .
The past research showed that
after soaking sorghum seed with La
(Ⅲ ), the germination trends and per-
centage of peanut were promoted, and
the germination and vigor index were
also remarkably promoted [23]. The ger-
mination rate and its potential, average
growth potential and vitality index in-
creased after soaking seeds with
proper nitrate rare earth element solu-
tion. The period of emergence reduced
by one or two days, and the rate of
emergence was markedly increased[24].
All these are similar with the results in
this paper.
When soaking tartary buckwheat
seeds with 200 mg/L La (NO3)3, the
germination rate, vital index, germina-
tion index and sprouting index of tar-
tary buckwheat seed, the SOD activity
and POD activity, leaf area, total root
length, chlorophyll content and root
activity were significant improved,
while MDA content and leaf relative
conductivity decreased compared with
CK in different water conditions. That
is to say, soaking seeds with 200 mg/L
La (NO3)3 can improve the drought re-
sistance of tartary buckwheat.
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