全 文 ：1 Introduction
Palms are widely distributed in tropical and
subtropical area, which have been widely introduced in
Southern China[1-2]. Low temperature in winter is the major
hazards to palm species grown in the field[3]. There have
been numerous studies on the cellular, andphysiological
changes of palmsunder low temperature [4-11]. Furthermore,
It becomes more and more important to seek the
techniques to enhance the cold tolerance in them.
Rare earth elements fertilizer has been extensively
applied on agriculture since 1970 s [12]. We have found
that La （NO3）3 can increase the activity of POD and
reduce the relative conductivity of leaves in banana
seedlings under cold condition [13]. Our present research
in order to find whether direct spraying of La（NO3）3 can
reduce cold injury in L. chinensis and to provide the
theoretical basis for palms cultivation.
2 Materials and methods
2.1 Plant materials and samples collection
The 2 -year -old of L. chinensis seedlings were
planted in nursery of Xiamen Botanical Garden
（longitude 118° 04′ 04″E and latitude 24° 26′ 46″N）,
located at an altitude of 108 m above sea level, with
approximately 1 140 mm rainfall annually, with average
temperature ranging from 12.6 ℃ in January to 28.2 ℃
in July. Seedlings were arranged in random with three
replications. Growth medium contained fertile sandy
热带作物学报 2012， 33（2）： 243-247
Chinese Journal of Tropical Crops
收稿日期： 2011-11-13 修回日期： 2012-01-24
基金项目： 厦门市科技计划项目（No. 3502Z20092019）。
作者简介： 阮志平（1969 年—）， 男， 博士， 高级农艺师。 研究方向： 植物生理生态学和植物保护学。 E-mail: rzp20012001@yahoo.com.cn。
Effect of La（NO3）3 on the Physiological Indices of Cold
Tolerance in Livistona chinensis Seedlings
RUAN Zhiping， WANG Fenfen
Xiamen Botanical Garden, Xiamen, Fujian 361003, China
Abstract The effect of La（NO3）3 on the physiological indices of cold tolerance in Livistona chinensis seedlings
was conducted, The L. chinensis seedlings were sprayed with 0, 100, 200, 300, 400, 500, 600 mg/L La （NO3）3
solution, the contents of malondialdehyde （MDA）, soluble sugar, chlorophyll and chlorophyll a/b ratio of L.
chinensis seedlings were determined under 20, 5, 12 and 10 ℃ for 24 h, respectively, The results of the MDA
contents with La （NO3）3 treatments were lower than those of the control, and changed slowly under temperature
stress, and the contents of soluble sugar, chlorophyll and chlorophyll a/b ratio increased compared with the control.
It was concluded that La（NO3）3 agents could boost the physiological indices of cold tolerance in L. chinensis. And
the appropriate concentration which significantly affected the physiological indices of cold tolerance was 300 mg/L.
Key words La（NO3）3; Livistona chinensis; Cold tolerance; Physiological indices
doi 10.3969/j.issn.1000-2561.2012.02.008
硝酸镧对蒲葵幼苗耐寒性生理指标的影响
阮志平， 王芬芬
厦门市园林植物园, 福建厦门 361003
摘 要 用 0、 100、 200、 300、 400、 500、 600 mg/L 硝酸镧溶液喷施蒲葵幼苗叶片作为处理， 每天喷施 1 次，
连续 3 d。 在 20、 5、 12 和 10℃下分别处理 24 h 后测定叶片的丙二醛、 可溶性糖和叶绿素含量以及叶绿素 a/b 的
比值。 结果表明： 硝酸镧溶液处理的幼苗丙二醛含量都比对照低， 而且随温度变化幅度小， 而可溶性糖和叶绿素
含量及叶绿素 a/b比值均比对照高。 硝酸镧处理可有效改善上述蒲葵幼苗的耐寒性生理指标， 其中 300 mg/L 硝酸
镧溶液对提高蒲葵幼苗的耐寒性生理指标具有显著的效应。
关键词 硝酸镧； 蒲葵； 耐寒性； 生理指标
中图分类号 S687 文献标识码 A
第 33 卷热 带 作 物 学 报
Treatment/(mg/L) 20 ℃ 5 ℃ 12 ℃ 10 ℃
CK (24.54±0.36) a (25.96±3.46) c (17.45±0.80) c (19.22±0.83) c
100 (25.94±3.71) a (31.47±4.89) ab (20.82±2.05) b (30.26±0.44) b
200 (26.35±5.43) a (35.64±3.54) ab (19.94±1.56) b (32.37±5.71) b
300 (23.57±1.44) a (40.49±2.65) a (25.38±2.09) a (35.18±1.35) a
400 (24.58±3.93) a (40.64±1.13) a (22.09±1.23) a (36.80±4.28) a
500 (26.39±2.75) a (38.32±3.25) a (18.17±4.11) ab (33.19±2.51) b
600 (25.02±0.84) a (34.47±3.44) ab (25.34±3.66) a (35.5±6.71) a
Table 2 Effect of La(NO3)3 on soluble sugar concents (mmol/L) in L. chinensis seedlings
Note: Different letters in the same columns represent statistically sigriificant differenles fron at p＜0.05 the same below。
Treatment /(mg/L) 20 ℃ 5 ℃ 12 ℃ 10 ℃
CK (22.56±3.01) a (35.80±2.54) a (27.07±1.35) a (31.41±0.26 ) a
100 (22.24±8.36) a (28.68±3.02) b (17.07±0.66) b (26.12±7.01) b
200 (21.84±0.13) a (28.14±2.80) b (14.13±0.48) c (22.42±3.05) c
300 (22.18±6.57) a (24.73±0.47) c (13.17±0.05) c (22.07±3.14) c
400 (21.67±4.18) a (24.94±1.69) c (14.78±0.18) c (23.13±0.73) c
500 (23.12±4.93) a (30.51±2.97) b (15.30±3.87) bc (27.86±2.04) b
600 (23.43±0.86) a (35.10±5.04) a (17.36±0.87) b (27.59±0.71) b
Table 1 Effect of La（NO3）3 on MDA contents(umol/g)in L. chinensis seedlings
loam soil, which were kept saturated during the
experiment period.
2.2 Treatment and Determination
The leaves were sprayed evenly with 0, 100, 200,
300, 400, 500, 600 mg/L La（NO3）3 solution until drops
began to fall once a day for three consecutive days in
January 2011. The seedlings were proceeded in
chambers at 20, 5, 10, 12 ℃ for 24 h, respectively, and
were randomly sampled to analyzed immediately. The
contents of malondialdehyde （MDA）were determined
with the improved method of thiobarbituric acid （TBA）
and soluble sugar contents were measured by common
anthrone colorimatric methods and chlorophyll contents
were determined with spectrophotometer （UV -2450/
2550）described in refs[14].
2.3 Statistical analysis
All measurements were replicated three times and the
data shown were the mean values±standard errors（SE）.
Significant differences between La（NO3）3 treatments and
the control were analyzed using ANOVA test, the
statistical analysis was performed using the statistical
software package SPSS17.0 for Windows（p<0.05）.
3 Results and Analysis
3.1 Change of MDA contents under different La
（NO3）3 treatments
MDA has widely been used as an indicator of cold
injury under temperature stress[15]. The dynamic changes
of MDA contents in the leaves of L. chinensis seedlings
were shown in Table 1. The contents were similar
under 20 ℃ （p >0.05）, varying from 21.67 μmol/g to
23.43 umol/g. When under 5 ℃ cold stress, MDA
contents of 100 mg/L, 200 mg/L, 300 mg/L, 400 mg/L
and500mg/LLa（NO3）3 treatmentsdecreased significantly
in contrast with those in the control （p<0.05）, and the
300 mg/L La （NO3）3 treatment reached its minimum of
24.73μmol/g. When under 12℃ and 10℃, the maximum
of MDA level was observed with 27.07 μmol/g and 31.41
μmol/g, respectively. La（NO3）3 treatment could decrease
the accumulation of MDA. TheMDA contents of 300 mg/L
and 400 mg/L La （NO3）3 treatments remained stable
under different temperatures. Therefore, 300 mg/L and
400 mg/L La （NO3）3treatments could play an important
role in keeping the cell from damage under the low
temperature stress.
3.2 Change of soluble sugar contents under
different La（NO3）3 treatments
The accumulation of soluble sugar can function in
preventing plants from being damaged caused by
osmotic stress, protecting protein and scavenging
244- -
第 2 期
Treatment/(mg/L) 20 ℃ 5℃ 12℃ 10℃
CK (14.28±1.98) a (11.10±0.17) b (13.33±1.46) b (10.64±0.07) c
100 (14.66±2.21) a (12.26±1.02) b (13.55±3.41) b (12.29±2.36) b
200 (14.90±2.18) a (14.76±0.30) a (15.15±3.36) a (14.31±1.94) a
300 (15.05±4.83) a (14.57±7.63) a (15.65±4.52) a (14.23±0.27) a
400 (14.97±1.23) a (12.85±2.86) ab (13.36±0.36) b (12.39±1.18) b
500 (14.43±2.66) a (12.13±1.07) b (13.40±1.13) b (12.83±0.81) b
600 (14.46±2.05) a (12.10±1.48) b (13.39±0.23) b (12.81±0.87) b
Table 3 Effect of La(NO3)3 on chlorophyll contents(ug/g)in L. chinensis seedlings
Treatment/(mg/L) 20 ℃ 5℃ 12℃ 10℃
CK (2.14±0.10) a (1.44±0.04) d (1.64±0.01) bc (1.48±0.11) c
100 (2.31±0.03) a (2.08±0.19) ab (2.19±0.16) a (2.11±0.37) a
200 (2.39±0.04) a (2.24±0.02) a (2.32±0.29) a (2.28±0.31) a
300 (2.27±0.13) a (2.13±0.04) a (2.21±0.49) a (2.16±0.20) a
400 (2.28±0.04) a (2.10±0.28) a (2.17±0.07) a (2.12±0.37) a
500 (2.33±0.31) a (2.04±0.02) ab (2.16±0.36) a (2.09±0.23) a
600 (2.19±0.08) a (1.81±0.09) c (1.87±0.45) b (1.77±0.04) b
Table 4 Effect of La(NO3)3 on chlorophyll a/b ratios in L. chinensis seedlings
oxidative free radicals when under temperature stimuli.
As seen from Table 2, The results demonstrated the
generally similar levels of soluble sugar under 20 ℃（p>
0.05）. The soluble sugar contents differed substantially
under 5℃（p<0.05）, ranged from 25.96 mmol/L to 40.64
mmol/L, 300 mg/L and 400 mg/L La（NO3）3 treatments
possessed the contents of 40.49mmol/L and 40.64 mmol/L,
increased by 16.92 mmol/L and 16.06 mmol/L,
respectively, compared to the control which increased
only1.42 mmol/L. Soluble sugar contents drop rates of
300 mg/L and400mg/L and500mg/LLa（NO3）3 treatments
declinedby15.11mmol/L,18.55mmol/L and 20.15 mmol/L,
respectively, while the control dropped by 8.51 mmol/L
from 5 ℃ to 12 ℃ . The increase rates of 300 mg/L and
400 mg/L and 500 mg/L La （NO3）3 treatment were
38.61%, 83.97% and 82.66%, respectively, compared to
the control value 10.14% from 12 ℃ to 10 ℃ . Soluble
sugar contents of 300 mg/L and 400 mg/L and 500 mg/L
La （NO3）3 treatments altered drastically than the other
treatments during the variation of the temperature.
3.3 Change of chlorophyll contents under different
La（NO3）3 treatments
As shown in Table 3. The chlorophyll contents in the
200mg/L and 300mg/L La（NO3）3agents treated seedlings
from 20 ℃ to 5 ℃ stress only decreased by 0.09% and
3.19% , respectively, which showed little variation of
chlorophyll contents, While the content of the control
dropped drastically by 22.27% reaching its minimum
value of 11.10 μg/g. When temperature varied from
12 ℃ to 10 ℃ , the 200 mg/L and 300 mg/L La （NO3）3
treatments showed significantly high chlorophyll
contents （p<0.05）. This suggested that 200 mg/L and
300 mg/L La （NO3）3 treatments had higher chlorophyll
accumulation under varied temperatures. So it was
demonstrated that the chlorophyll contents of 200 mg/L
and 300 mg/L La （NO3）3 treatments were relatively
stable under the temperatures stress for L. chinensis.
3.4 Change of chlorophyll a/b ratios under different
La（NO3）3 treatments
As shown in Table 4. The chlorophyll a/b ratios
varied with temperatures. Their differences were not
significant by test at the temperature of 20 ℃（p>0.05）,
200 mg/L treatment had the maximum chlorophyll a/b
ratio of 2.39. When under 5 ℃ stress, 200, 300 mg/L
and 400 mg/L treatments only decreased by 6.28% ,
6.17% and 7.89%, respectively, chlorophyll a/b r atios
were markedly higher than those of the other treatments
and the control （p<0.05）. The chlorophyll a/b ratio of
the control dropped drastically to its minimum of 1.44.
When under 12 ℃ and 10 ℃, the chlorophyll a/b ratios
阮志平等： 硝酸镧对蒲葵幼苗耐寒性生理指标的影响 245- -
第 33 卷热 带 作 物 学 报
of 100, 200, 300, 400 mg/L and 500 mg/L La （NO3）3
treatments still kept much higher than those of 600 mg/
L treatment and the control. So it was demonstrated that
200, 300 mg/L and 400 mg/L of La （NO3）3 treatments
were major factors to influence chlorophyll a/b ratios.
4 Discussion
It could be drawn a conclusion from above results
that La （NO3）3 could alleviate cold injury in a certain
extent, which indicated that La （NO3）3 had protective
function from the damage.The optimum concentration
impacted the L. chinensis seedlings was 300 mg/L, and
further increase concentrations seemed to be less
effective. So La （NO3）3 could be a promising agent on
cold tolerance in palm plant.
Some studies had reported that MDA was a byproduct
of membrane lipid peroxidationand, an indicator
characterizing detrimental degree of plants under
adverse environment[16-18]. La（NO3）3agent could ameliorate
the MDA contents in the L. chinensis seedlings during
the temperature variation, whose mechanism maybe
related to the decrement of reactive oxygen in the
seedlings.
Sugar had been considered to be one of the important
factors in cold tolerance [19]. Soluble sugar acted as
osmoprotectant interacting with the lipid bilayer [20]. The
accumulation of soluble sugar could be a cold tolerance
indicator and had been shown to function as protectants
of plasma membranes and proteins from the effects of
low temperature [21]. La （NO3）3 treatments induced the
accumulation of sugar contents in low temperature, and
the changes could reversed rapidly by improving
temperature.
It was reported that rare earth elements could
improve the chlorophyll contents in the plant. La3+ could
promote the absorption of N, P, Mg, and induced the
synthesis of large amount of Pchlide. Pchlide synthesis
was inhabited under the cold stress. The results in the
experiments were consistent with the data above[22, 23].
The results of the present study were in conformity
with those of the report[12]. Further studies need be done
to investigate the La（NO3）3 triggering acclimated mech
anisms in plant under temperature stress. The complex
process may involve in many biochemical and
physiological changes which include alterations in gene
expression and hormone levels.
Acknowledgements
We are indebted to thank Prof. LI Zhenji of Xiamen University for
valuable comments for the manuscript, and thank LIN Min and Zen
Meijiao of Xiamen Botanical Garden for parts of experiments.
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阮志平等： 硝酸镧对蒲葵幼苗耐寒性生理指标的影响 247- -