全 文 ：Received 1 Mar. 2004 Accepted 13 Sept. 2004
Supported by the National Natural Science Foundation of China (40205005).
http://www.chineseplantscience.com
Acta Botanica Sinica
植 物 学 报 2004, 46 (12): 1387-1392
Response of Corn to Climate Warming in Arid Areas in Northwest China
WANG Run-Yuan1, ZHANG Qiang1, WANG Yao-Lin2, YANG Xing-Guo1, HAN Yong-Xiang1, YANG Qi-Guo1
(1. Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China;
2. Gansu Desert Control Institute, Wuwei 733000, China)
Abstract: Based on surface observations, response of corn (Zea mays L.) to climate warming in the Hexi
Corridor in the arid northwest of China was investigated. Results show that in the last 20 yr and more the
response of corn to climate warming took the form that its growing season came in advance and its growth
period became shorter period. And such response is related to the critical temperature. In case the mean
temperature during the corn’s growth period was less than the critical temperature, an increase in tem-
perature shortened its growth period. When the mean temperature was higher than the critical temperature,
then a rise in temperature no longer showed a tendency of shortening. The continuous increase in
temperature in future may cause the mean temperature of corn’s growth period to exceed the critical
temperature, thus leading to lengthening of corn’s growth period. In addition, response of corn to climate
warming varied in its different growing stages. An increase in temperature shortened corn’s phase of
vegetative growth prior to the tasselling phase, prolonged the generative growth phase in the tasselling-
milk stage, and cut down the generative growth phase in the milk-maturity stage. These characteristics
may correlate with the climatic condition in the arid areas in the northwestern of China, the crop’s
physiological properties, and the variation of temperature increase in various seasons.
Key words: arid areas in Northwest China; growth period; corn; climate warming; response
The study of global change, started in the 1980s, has
drawn great attention from the governments of various
countries, the scientific circle and the public due to its vital
environmental and scientific importance to future develop-
ment (Zhang et al., 1997; Zhang and Sun, 1999; Ye et al.,
2002). The change of terrestrial ecosystem and its relation
to change in non-bio process are the essential part of the
study on global change (Zhang et al., 1997; Zhang and
Sun, 1999; Shang, 2000; Ye et al., 2002; Gao et al., 2003).
With the rapid development of scientific research, monitor-
ing and computer simulation, the study on the response of
the terrestrial vegetation to climate change has been one of
the important scientific research subjects and has achieved
much progress in respect to various zonal, seasonal and
species response in recent years.
Studies have shown that climate warming varies greatly
in regions and seasons in China, featuring the north warm-
ing and the south cooling versus winter warming and sum-
mer cooling (Sha et al., 2002). The response of vegetation
to climate changes in China also differs in regions and
seasons. Both the terrestrial net primary production (NPP)
and the normalized difference vegetation index (NDVI)
showed an increasing trend in the four seasons from 1982
to 1999. Spring was the season with the largest increasing
rates of NPP and NDVI while summer had the greatest
increment of NPP. The response of vegetation to climate
change was mainly characterized by the forward growing
season over the last 18 yr in China; the regions where the
increment of vegetation principally takes place in summer
were located in the arid northwest of China and the Qinghai-
Xizang (Tibet) Plateau. In the eastern monsoon climate re-
gion the growing season was advanced and in the north-
ern part of the Daxinganlin (Da Hinggan Ling) Mountains
and the north slope of the Tianshan Mountain the growing
season in autumn extended (Xie et al., 2002; Piao and Fang,
2003; Piao et al., 2003). The response of vegetation to tem-
perature change in the Northern Hemisphere also varies
distinctly in regions and seasons (Melillo et al., 1993; Zhou
and Zhang, 1996; Myneni et al., 1997; Fang et al., 2001;
Gong et al., 2002; Gong and Shi, 2004). Artificially con-
trolled experiments suggested that the response of seed-
lings of three dominant shrubs to climate warming differed
in the Ordos Plateau; a rise in temperature had a positive
effect on seedling growth of Caragana korshinskii and
Hedysarum froticusum and had a minor effect on Artemisia
ordosica (Xiao et al., 2001). Field observations showed
that various climatic factors had different effects on grow-
ing periods of the prairie plants in the Ordos Plateau and
one climatic factor might affect differently on their various
growth stages as well (Huang et al., 2001). An increase in
Acta Botanica Sinica 植物学报 Vol.46 No.12 20041388
temperature gave rise to the shortening of the growth pe-
riod (from seeding to maturity), and a decrease in the dry
matter accumulation and yield of winter wheat in Yongning
and Guyuan (Gao et al., 1995). Many studies on the re-
sponse of vegetation to climate change has been carried
out; the majority of the studies has been conducted on
large space scale, which is helpful in probing into the over-
all response of vegetation to global warming. However due
to the lack of surface observations, only a few studies on
the response of specific regions and specific ecosystems
to global warming, and on the bio-mechanism of the re-
sponse have been undertaken. Therefore to carry out fur-
ther studies on the response of specific regions and spe-
cific ecosystems, particularly the agro-ecosystem, which is
highly related to human activities, to global warming, and
on bio-mechanism of the response will be of great signifi-
cance in research into the global changes in future (Zhang
et al., 1997; Ye et al., 2002).
1 Data Source
All the data concerning corn employed in this study
were collected in the period of 1981 to 2002 from Wuwei
Agricultural Experimental Station of Gansu, located in the
east of the Hexi Corridor in the arid northwest of China. The
data concerning corn development were collected in the
period from 1981 to 2002 and those related to biomass were
collected during 1994 and 2001. Meteorological data were
collected in the period of 1981 to 2002 from Wuwei Meteo-
rological Station.
All the data were collected in line with Agricultural
Meteorological Observation Criterion issued by China
Meteorological Administration. The site for the data col-
lection of corn, 300 m away from the meteorological obser-
vation site, had remained unchanged for 22 yr. The regres-
sion equations in this study have all been tested at the
confidence level (95%).
2 Seeding Time and Rises of Early Temperature
After comparing the sowing data over the period of 1981
to 2002, the earliest seeding time of corn was on 4 April.
And March was chosen to represent the season of tem-
perature changes prior to corn’s seeding. The seeding time
and the mean temperature changes in March over the 22 yr
are presented in Fig.1. During the 22 yr (1981-2002) the
mean temperatures of March showed an increasing trait
while the seeding time of corn tended to get earlier. The
correlation between the seeding time and the mean tem-
peratures of March is expressed as y = -2.14 x +14.03 (where
y is the seeding time and x the mean temperature of March),
R2 = 0.473. Every increment of 1 ℃ corresponded to 2 d
forward of the seeding time. Compared with the first 11 yr
(1981-1991), likewise the mean temperature of March in
the last 11 yr (1992-2002) had risen by 1.0 ℃ and the seed-
ing time had been 2 d earlier than the normal phase. This
showed that a rise in temperature before sowing in spring
brought forward the growing season of corn in the Hexi
oases, which is in agreement with the principal way of the
response of vegetation to climate change in China (Piao
and Fang, 2003).
Fig.1. Seeding time and mean temperature changes.
3 Growth Periods and a Rise in Temperature
Within Them
A growth period refers to the span within which crops
complete their lifecycle, i.e. from seeding to maturity. Re-
gardless of variety, the correlation between the growth
period of corn and the change of the mean temperature
within the period from1981 to 2002 are presented in Fig.2a
(labeled as Integrated). In order to find out the responses
of different corn varieties in the same growth period to
climate warming, the correlation between the growth pe-
riod of corn variety Zhongdan 2 and Zhangye 488, and the
mean temperature change within the growth period are re-
spectively presented in Fig.2b, c. The results indicated
that there was an overall shortening of the growth period
of corn with the mean temperature rising, i.e. an increment
of 1 ℃ against a 5 d cut of the growth period on average.
The findings reveal that a temperature rise cuts down the
growth period of corn in the Hexi oases, which is consis-
tent with the conclusion of the related study on wheat (Gao
et al., 1995).
Yet further analysis showed a figure of a conic express-
ing the response of corn’s growth period to temperature
change. When the mean temperature of corn’s growth pe-
riod was less than the critical temperature (expressed as
X0), with an increase in temperature, corn’s growth period
shortened accordingly; if the mean temperature of corn’s
WANG Run-Yuan et al.: Response of Corn to Climate Warming in Arid Areas in Northwest China 1389
growth period was higher than the critical temperature, with
a rise in temperature, corn’s growth period no longer
showed the trend of shortening as a result. This property
had nothing to do with different varieties, although vari-
ous varieties of corn showed difference in their individual
critical temperatures. Irrespective of the factor of variety,
the critical temperature X0 as Integrated was 18.8 ℃. The
critical temperature for Zhangye 488 corn was 18.2 ℃ and
that for Zhongdan 2 was 19.4 ℃. This suggested that the
response of corn to a temperature rise was a complicated
process. The rise in temperature in most of the 22 yr has not
made the mean temperature in the growth period of corn
exceed the critical temperature. Therefore a temperature in-
crease tended to cut down the growth period of corn by
and large, which may cover up the complexity of the re-
sponse of corn to climate warming. According to UN IPCC
predictions from the third assessment report, the mean glo-
bal surface temperature is predicted to rise by 1.4-5.8 ℃
during the period of 1990-2100 (Sun et al., 2002). Yet the
mean temperature of corn’s growth period in the 22 yr in
the Hexi oases was 17.9 ℃, which may exceed the critical
temperature in most years in the future. As a result, the
response of corn to climate warming may be an extension
of corn’s growth period in the main with the increase in
temperature.
The characteristics of the response of corn to a rise in
temperature may be related to its physiological property.
The normal development of crops goes on within a certain
optimal temperature range. When the actual environmental
temperature is beyond either the upper or lower limits of
the optimal temperature, it will handicap the development
of crops (Wang et al., 2003). Seasonal changes of the envi-
ronmental temperature and difference in response of a rise
in temperature in various seasons may cause the environ-
mental temperature in a certain phase of the growth period
of corn to exceed the optimal upper limit, which will form an
obstacle to the development of corn (Wang and Lin, 2003),
hence the growth period will be prolonged. As a result, if
the environmental temperature in all phases of the growth
period is below the optimal upper limit, a rise in temperature
will promote a rapid growth of corn, and may shorten the
growth period in the oases in northwest China. The exten-
sion of the growing season of natural vegetation in autumn
caused by a rise in temperature is probably the result of
postponement of the lower limit of growth temperature and
that of corn’s growth period presumably results from the
temperature exceeding the upper limit of growth tempera-
ture during its growth period. Therefore the biological
mechanisms, leading to the two changes, are different.
4 Development Stages and Temperature
Variation
In order to present directly the relation between devel-
opment phases of corn and temperature changes, the mean
temperature during the growth period of corn over the 22 yr
were displayed in an increasing order and labeled from No.
1 to No.22, simultaneously the days of different develop-
ment phase in corn growth periods, and the mean tempera-
ture corresponding with No.1- 11 and No.12-22 are listed
statistically in Table 1.
The results showed that corn exhibited different re-
sponses to temperature changes in its different phases of
development in the Hexi oases. The responses in the growth
period consisted of three stages on the whole, viz. the sow-
ing-tasselling, tasselling-milk and milk-maturity stage. In
both the sowing-tasselling and milk-maturity stages, with
the temperature rise, all the development phases were
moved up and days of all the development phases reduced
or unchanged. In the tasselling-milk stage with the tem-
perature mounting up, all the phases were advanced and
days of all the phases increased. This suggested that the
Fig.2. The growth period of corn and temperature change. a.
Corn, Integrated. b. Corn, Zhangye 488. c. Corn, Zhongdan 2.
Acta Botanica Sinica 植物学报 Vol.46 No.12 20041390
climate warming made all the development phase of corn
get earlier, shortened the vegetative phase before the tas-
selling phase, extended the reproductive growth phase in
the tasselling-milk stage, cut down the reproductive growth
phase in the milk-maturity stage, and reduced the whole
growth period in the arid northwest of China. The response
of corn in all its development phases to climate warming in
the arid northwest of China is partly the same as that of
other crops in other regions (Gao et al., 1995; Monteith et
al., 1997; Sun et al., 2002).
This is likely related to the characteristics of the climate
in the Hexi oases, physiological property of corn and the
difference in temperature rise in various seasons. The opti-
mal temperature for corn growth ranges from 18 ℃ to 24 ℃
while the mean temperature was 15.3 ℃ over the years from
April to June in the oases where the observation spot is
situated. Taking into account a rise in temperature and the
big diurnal temperature range, the mean temperature is still
in the range of optimal temperature of corn. Temperature
adaptation in corn’s vegetative phase is not very strict. A
rise in temperature quickens corn’s growth, shortens its
growth stage, and makes its development phases get ear-
lier as well. The mean temperature of the stage of July to
August was 20.7 ℃, due to the wide range of diurnal tem-
perature and the frequent attacks of consecutive high tem-
perature of 30 ℃ during daytime lasting for 3 to 5 d or more,
an increase in temperature might further increase this kind
of disaster. The reproductive phase of corn is more sensi-
tive to temperature changes. A temperature rise hampered
its development (Wang and Lin, 2003), by extending the
tasselling-milk stage during which the advancing of the
development phases resulted from the moving up of the
preceding development phase. The mean temperature of
September was 15 ℃; an increase in temperature expedited
corn’s growth, shortened its growth stage and made its
development phase earlier as well.
5 Biomass in the Development Phases and
Temperature Changes
Data on the leaf areas, leaf area indices, biomass of
leaves, blade sheaths, stems, ears, and the whole plants of
corn in its different development phases in the Hexi oases
during the period from 1994 to 2001, and the temperatures
in the corresponding development phases had been col-
lected and tested.
No significance of correlation (a > 0.5) was found be-
tween leaf area, leaf area index, biomass of leaves, stems
etc., and temperature change. This indicated that the re-
sponse of biomass of corn to temperature change was not
significant, which may be related to either inadequate data
acquisition or insensitive to temperature change. The Hexi
oases are typical irrigated agricultural area; without
irrigation, there would be no agricultural production (Zhang
and Hu, 2002). As the climate in this area is getting drier, the
shortage of water resource becomes a serious problem. Con-
sequently irrigation is a restraint to crop growth.
Despite of the non-significance in the biomass in all the
developmental phases of corn and the corresponding an-
nual temperature changes between 1994 and 2002, a com-
parison showed that with a continuous rise in temperature,
there was an increasing trend of the leaf area indices in all
the development phases, and the greatest increment was in
the shooting-tasselling stage (Fig.3), i.e. the largest incre-
ment was in July in the Hexi oases, which is in agreement
with the studies related (Piao and Fang, 2003). With an
increase in temperature the fresh weight of leaves, leaf
sheaths, and stem were increased before the shooting phase
and decreased after the tasselling phase. With the tempera-
ture increase the weight (fresh and dry) of corn increased
before the tasselling phase and then decreased afterwards.
This may be related to the nutrition transfer in different
developmental phases and high temperature impacts in the
Hexi oases (Wang and Lin, 2003; Wang et al., 2003 ) as well.
Table 1 Corn’s development phases vs. days, mean temperatures
No.1-11 No.12-22 No.12-22-No.1-11
Development phases Date Days Temperature Date Days Temperature Date Days Temperature
(d/m) (d) (℃) (d/m) (d) (℃) (d) (d) (℃)
Seeding 12/4 - - 11/4 - - -1 - -
Seedling emergence 3/5 21 11.7 1/5 20 12.1 -2 -1 0.4
Seven leaf 4/6 32 16.2 2/6 32 17.1 -2 0 0.9
Shooting 1/7 27 19.2 28/6 26 20.2 -3 -1 1.0
Tasselling 28/7 27 21.1 24/7 26 22.3 -4 -1 1.2
Milk maturity 27/8 30 21.5 25/8 32 22.9 -2 2 1.4
Maturity 26/9 30 15.3 20/9 26 17.4 -6 -4 2.1
Seeding-maturity - 167 17.4 - 162 18.6 - -5 1.2
WANG Run-Yuan et al.: Response of Corn to Climate Warming in Arid Areas in Northwest China 1391
6 Conclusions
(1) A rise in temperature made corn’s growing season
get earlier and shortened its growth period in the Hexi oases.
(2) When the mean temperature of corn’s growth period
was less than the critical temperature, an increase in tem-
perature cut down the growth period of corn but if the
mean temperature of corn’s growth period was higher than
the critical temperature; with a rise in temperature, the growth
period no longer showed a trend of shortening.
(3) The response of corn to temperature rise varied in its
different development phases. A rise in temperature short-
ened its vegetation phase before the tasselling phase, ex-
tended the reproductive phase in the tasselling-milk stage
and cut down the reproductive phase in the milk-maturity
stage.
(4) Likewise in the last 20 yr or so, the response of corn
to climate warming in the Hexi oases mainly took the form
of the growing season getting earlier and the growth pe-
riod shorter as well. However the continual increase in tem-
perature in the future may prolong the growth period of
corn in the arid northwest of China.
(5) In the recent years the study on response of the
terrestrial vegetation to climate warming has progressed
greatly by analysis of remote sensing data (Piao and Fang,
2003), which has brought about a new approach for re-
search into global change. A combination of surface obser-
vations and remote sensing data will be more helpful in
obtaining more details and biological mechanism of re-
sponse of vegetation to climate warming.
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