沙漠研究 24-1, 129-132 (2014)
Ἃ₍◊✲ 24-1, 129 - 132 (2014)
Journal of Arid Land Studies
Journal of Arid Land Studies－ DT11 Refereed Paper －㸫DT11 Refereed Paper㸫

Deficit Irrigation in Winter Wheat- The U.S. Southern High Plains and North China Plain Baozhen HAO1), Qingwu XUE*1), Yinghua ZHANG2), B. A. STEWART3) and Zhimin WANG2)
Abstract: Winter wheat is a major crop in the U.S. Southern High Plains (SHP) and North China Plain (NCP). In both regions,water is the most important limiting factor for wheat production. Drought stress often significantly reduces wheat yield and water use
efficiency (WUE) since the seasonal precipitation only can partially meet the evapotranspiration (ET) requirement for high yields.
Irrigation can help to maintain high yields and productivity in wheat. However, the dramatic increase in water extraction for crop
irrigation resulted in a significant decline in the water table in both regions. Deficit irrigation, application of less water than required
for full ET and maximum yield, has shown to be a viable management practice for improving wheat yield and WUE in the SHP and
NCP. We compare the relationships among yield, ET and WUE in the two regions and explore the physiological mechanisms forincreasing yield and WUE under deficit irrigation. Wheat yield increases linearly with increasing ET in both regions. The
relationship between WUE and yield is a linear in NCP but a curvilinear in SHP. Although higher WUE generally can be achieved
with higher yields, the curvilinear relationship between WUE and yield in the SHP indicates that WUE may not be the highest whenyield was in the high range. For both regions, maintaining high available soil water at planting, applying irrigation at critical stages,
and achieving high harvest index are important for successful practice of deficit irrigation.
Key Words: Drought, Evapotranspiration, Triticum aestivum L., Water use efficiency

1. Introduction
In the U.S. Southern High Plains (SHP), winter wheat isgrown under a wide range of water regimes for producing bothgrain and cattle forage (Musick et al., 1994). In 2013, about
14 million ha of wheat were harvested in the SHP (NASS,2013). The region has a semi-arid climate with annual
rainfall ranging from 380 to 580 mm. Growing season
precipitation averages about 250 mm.
The seasonalevapotranspiration (ET) for wheat growth ranges from 700 to
950 mm under full irrigation (Howell et al., 1995). Therefore,
the seasonal rainfall can only meet one-third of the ET required
for maximum yield. As a result, wheat yield and water-use
efficiency (WUE, the ratio of yield and ET) are primarily
limited by drought stress from late spring to early summer(Musick et al., 1994). Under dryland conditions, wheat
production is largely determined by the amount and effective
use of soil water storage and seasonal rainfall (Jones andPopham, 1997). However, dryland wheat yields are generally
much lower than irrigated wheat (Musick et al., 1994).
Winter wheat is also a major crop in the north China Plain(NCP). The region produces about 69% of wheat in thewhole country on about 14 million ha of arable land (Mo et al.,2009). The average annual rainfall in the region ranges from500 to 650 mm.
However, the majority of precipitation occurs during thesummer months (Jul.-Sep.). Rainfall during the wheat
growing season ranges from 100 to 180 mm, or approximately
25-40% of crop water requirement over the growing season(Zhang et al., 1999). Therefore, drought is also an importantfactor affecting dryland wheat yield.
Irrigation application provides a means to maintain highyields in wheat in the SHP and NCP. For both regions,
irrigation water is mainly from underground. In the SHP,
irrigation from Ogallala Aquifer significantly increased during
the 1950’s. However, the dramatic increase in water
extraction for crop irrigation resulted in a significant decline in
the water table. In the meantime, irrigated land area has
decreased from a peak of 2.4 million ha in 1974 to 1.9 million
ha in 2000 in the Texas High Plains (Colaizzi et al., 2008).
Similarly, groundwater levels have decreased considerably in
the NCP due to irrigation (Zhang et al., 2003). Since watertables will continue to decrease, application of less irrigation
will be the primary practice for wheat production in SHP and
NCP. Deficit irrigation, application of less water than it isrequired for full ET and maximum yield, has shown to be a
viable management practice for improving wheat yield and㸦Received, September 15th, 2013; Accepted, January 1st, 2014㸧

* Corresponding Author: qxue@ag.tamu.edu
6500 Amarillo Blvd. W., Amarillo, TX 79106, USA
1) Texas A&M AgriLife Research at Amarillo
2) Department of Agronomy, China Agricultural University

3) Dryland Agriculture Institute, West Texas A&M University

130

WUE. In this article, we briefly review the long-term fieldresearch on deficit irrigation in wheat in US SHP and China’s
NCP. Our objective is to better understand the ecological andphysiological basis for improving yield and WUE underwater-limited conditions.

Deficit irrigation is defined as the application of less water
than it is required for full ET and maximum yield (English etal., 1990; Musick, et al. 1994). It is called by a variety ofother names such as partial irrigation, regulated deficit
irrigation, ET deficit irrigation, and limited irrigation (English
et al., 1990; Kang et al., 2002). The overall goal of deficit
irrigation is to increase WUE, either by reducing irrigation
frequency or by eliminating the least productive irrigations.
Management of deficit irrigation is very different from full
irrigation management. Rather than working to minimize
crop water stress, plants must be allowed to certain levels ofwater stress (English et al., 1990; Zhang et al., 1998).

8

Yield(MghaͲ1)

2. Definition of Deficit Irrigation

10

6

4

SHPͲI

2

SHPͲD
NCP

0
0

200

400
600
Evapotranspiration(mm)

800

1000

Fig. 1. The linear relationship between yield and evapotranspiration(ET) in the U.S. Southern High Plains (SHP) and North
China Plain (NCP).
I-irrigated; D-dryland. Regression
equations: SHP-Y=0.0106X-1.7393, R2=0.75, p<0.001;
NCP-Y=0.0117X+2.1945, R2=0.31, p<0.001 (Data sources: Xueet al., 2012; Zhang et al., 1998, 2003, 2004; Hu et al., 2005; Qiu
et al., 2008; Hao and Wang 2013, personal communications).
2.4

3. Yield, Evapotranspiration (ET) and Water Use Efficiency

2.0

1.6

WUE(kgmͲ3)

In the U.S. SHP, the long-term dryland wheat yields were
mostly 1-2 Mg ha-1 (Jones and Popham, 1997). However,dryland yields in irrigation studies were frequently over 3 Mg
ha-1 (Xue et al., 2006). The irrigated wheat yields ranged
from 3.0 to 7.7 Mg ha-1 and ET from 400 to over 900 mm,
depending on irrigation timing and frequency (Xue, 2012).
Wheat yields under full irrigation were in the range of 5.3-7.7
Mg ha-1 and required about 700-950 mm ET (Howell et al.,1995). Under dryland conditions, WUE ranged from 0 to 0.8
kg m-3, with an average of 0.4 kg m-3. The WUE in irrigatedwheat was higher and ranged from 0.5 to 1.2 kg m-3 (Musick etal., 1994; Xue et al., 2006). In the NCP, wheat yields ranged
from 2.9 to 9.5 Mg ha-1 and ET from 200 to 600 mm. The
WUE in NCP was much higher than SHP, ranging from 0.9 to
2.3 kg m-3 (Zhang et al., 1998, 2003, 2004, 2010; Hu et al.,2005; Qiu et al., 2008; Hao and Wang, 2013, personalcommunications).
Figure 1 shows that there was asignificant linear relationship between yield and ET for bothareas. The data in NCP were more scattered because of themulti-locations across the NCP while data in SHP were mainly
from Bushland, Texas. The linear regression of yield and ET
in NCP had a greater slope (1.17 kg m-3) in NCP than that in
SHP (1.06 kg m-3).
Figure 2 shows the relationship between WUE and wheatyield. The WUE-yield relationship was a quadratic function
when the full range of yield was considered for SHP. The
WUE increased linearly when yield increased up to 4-5 Mg

1.2

0.8
SHPͲI
0.4

SHPͲD
NCP

0.0
0

2

4
6
Yield(MghaͲ1)

8

10Fig. 2. The relationship between WUE and yield in the U.S.
Southern High Plains (SHP) and North China Plain (NCP).
I-irrigated; D-dryland. Regression equations: SHP-Y = -0.0267X2+ 0.3138X, R2 = 0.79, p<0.001; NCP-Y = 0.1338X + 0.7482, R2 =0.40, p<0.001) (Data sources: see Fig. 1).

ha-1. When yield increased further, WUE maximized andeven tended to decrease. In NCP, the WUE increased linearly
as yield increased.
Figure 2 indicates that higher WUE generally can beachieved with higher yields.
However, curvilinear
relationship between WUE and yield in the SHP showed that
WUE might not be the highest when yield was in the highrange. The ET demand could be as high as 12 mm per day
and was frequently over 60 mm per week in irrigated wheat
due to high winds and associated high vapor pressure deficit(Howell et al., 1995). In the NCP, daily ET was generally
less than 10 mm (Liu et al., 2002; Hu et al., 2005).

131

4. Improving Yield and WUE under Deficit Irrigation
In the SHP, Schneider and Howell (2001) studied the
responses of wheat yield, WUE, ET, irrigation water use
efficiency (IWUE) and harvest index (HI) to different irrigationlevels (from deficit to full irrigation) in two growing seasons at
Bushland, TX. Irrigation application increased wheat yield
and WUE as compared to dryland treatment. Deficit
irrigation (25% and 50% ET requirement of full irrigation)
resulted in highest WUE and IWUE. For 50% ET treatment,
yield was 86-95% of full irrigation (100% ET). In anotherfield study at the same location, Xue et al. (2006) showed that
deficit irrigation of 100 mm at booting stage increased yield by
46% and WUE by 23% as compared to dryland treatment.
Compared to full irrigation of 400 mm, a deficit irrigation of
220 mm at jointing and anthesis achieved 84% of the yield atfull irrigation and resulted in 45% irrigation water savings. In
the NCP, Zhang et al. (1998) showed that wheat yield at
one-irrigation (80 mm) were 84-100% that under four
-irrigation (320 mm). As a result, WUE was increased to1.55 kg m-3 at one-irrigation treatment from 1.22 kg m-3 atfour-irrigation treatment (Zhang et al., 1998). More recent
studies confirmed the above results in the NCP (Qiu et al.,2008; Zhang et al., 2011).

5. Mechanisms for Increased WUE under Deficit Irrigation
Many field studies have been conducted in both the SHP
and NCP to elucidate the mechanisms for increased yield and
WUE under deficit irrigation. First, maintaining highavailable soil water (ASW) at planting and allowing soil drying
at early stage are important for successful practice of deficit
irrigation. Musick et al. (1994) showed that wheat yield
increased linearly as ASW at planting increased. High ASW
at planting not only ensured the vigorous early shoot growth
but also resulted in deep root system. Xue et al. (2003)
showed that mild soil water stress in the spring promoted root
growth and development. For example, root length density
along the soil profile was higher in dryland than in irrigatedtreatment at booting. With the deep root system, irrigation
can be delayed until booting stage or anthesis if only
one-irrigation is allowed (Xue et al., 2003). Similarly, Zhang
et al. (1998) and Zhang et al. (2011) also reported that mild
water stress at early stage led to a relatively deeper root system
in NCP environment.
Second, irrigation must be applied at critical stages forwheat yield determinations when only limited irrigation isallowed. Critical growth stages for irrigating winter wheat
generally occur from early spring growth to early grain
development in the SHP. When only one-irrigation allowed,

irrigation between jointing and anthesis resulted in same yield
and WUE. However, irrigation at grain filling did notincrease yield and WUE (Xue et al., 2003, 2006). Irrigation
at critical stage also reduced the severity of soil water stressand allowed plants to use more water during grain filling(Zhang et al., 1998; Xue et al., 2003, 2006). Xue et al. (2003,
2006) demonstrated that one-irrigation at booting stage
maintained high soil water content and significantly reduced
water stress at anthesis. As a result, plants in one-irrigation atbooting stage had higher photosynthetic rate and stomatal
conductance than dryland and one-irrigation at jointing (Xue etal., 2006). Similar results were also found in the NCP (Zhang
et al., 1998; Zhang et al., 2011).
Third, increased yield and WUE under deficit irrigation isrelated to increased harvest index (HI). HI is determined
during grain filling by both current photosynthesis andremobilization of pre-anthesis carbon reserve from stems.
For the maintenance of current photosynthesis to meet the
carbohydrate supply, higher photosynthesis rate and longer
green leaf area duration are advantageous under drought
conditions. Zhang et al. (2011) showed that deficit irrigation
changed wheat canopy structure and increased the proportionof non-leaf organs for photosynthesis. As a result, canopy
photosynthetic capacity was improved during grain filling andgrain yield was increased under deficit irrigation. Whenphotosynthesis is reduced by drought stress during grain filling,remobilization of carbon reserves can be important. The
contribution of remobilized carbon reserves to grain yield in
wheat varied from 5% to 90%, depending on environmental
conditions (Asseng and van Herwaarden, 2003; Xue et al.,2006). The increased HI under appropriate deficit irrigation
was due to increases in both the current photosynthesis and theremobilization of pre-anthesis carbon reserves (Xue et al.,2006; Zhang et al., 2013). The best example is perhaps atreatment (T-6) in a field study by Xue et al. (2006). This
treatment received irrigations at both jointing and anthesis.
Irrigation at jointing increased the number of spikes and stems,
and irrigation at anthesis increased seed weight. The morestems allowed plants to remobilize pre-anthesis carbon reservesto grains at late grain filling. As a result, the treatment had
higher WUE and HI, and the yield only reduced 16% ascompared to the full irrigation treatment (Xue et al., 2006).

6. Future Perspectives
The declining irrigation water continues to challenge theirrigated wheat production in the SHP and NCP. Althoughseveral management factors (improved cultivars, fertilizationand pests control, etc.) contributed to higher yield and WUE,
irrigation still plays a vital role to increase wheat yield and132

WUE in these areas. For example, irrigated wheat yields canbe 2-4 times higher than dryland yields in the SHP (Fig. 1).
Therefore, irrigation will be an important management practicefor long time. Since the irrigation water becomes limiting,deficit irrigation will be the primary practice in the future for
irrigated wheat production. The future challenge will be
integration of new irrigation technologies and better managing
crops under drought stress.
In the SHP, irrigation
technologies have been improved significantly over the
decades (e.g., from furrow to sprinkler and sub-drip irrigation).
However, the technologies in the NCP need more
improvements since the majority of irrigation practices are stillflood irrigation. Nevertheless, adoption of cultivars withmore drought resistance will lead to more water savings andmaintain yields as evidenced in both regions (Zhang et al.,2010; Xue et al., 2013). Improving drought resistancethrough breeding will provide benefits but is a long-term task.
The current challenges are identifying important physiologicaltraits and looking for high throughput field phenotyping tools.
Currently we are conducting new field studies to address someof these challenges.

References
Asseng S., van Herwaarden A.F. (2003): Analysis of the benefits
to yield from assimilates stored prior to grain filling in a range
of environments. Plant Soil, 256: 217-229.
Colaizzi P.D., Gowda P.H, Marek T.H., Porter D.O. (2008):
Irrigation in the Texas High Plains: A brief history andpotential reductions in demand. Irrigation and Drainage, 58:
doi:10.1002/ird.418.
English M.J., Musick J.T., Murty V.V.N. (1990): Deficit
irrigation. In Hoffman G.J., Howell T.A., Solomon K.H. eds.,
Management of Farm Irrigation Systems. American Societyof Agricultural Engineers, St. Joseph, MI. p 631-663.
Howell T.A., Steiner J.L., Schneider A.D., Evett S.R. (1995):
Evapotranspiration of irrigated winter wheat: Southern High
Plains. Trans ASAE, 38: 745-759.
Hu C., Delgado J.A., Zhang X., Ma L. (2005): Assessment ofgroundwater use by wheat (Triticum aestivum L.) in the
Luancheng Xian Region and potential implications for water
conservation in the Northwestern North China Plain. Journalof soil and water conservation, 60: 80-88.
Jones O.R., Popham T.W. (1997): Cropping and tillage systems
for dryland grain production in the Southern High Plains.
Agronomy Journal, 89: 222-232.
Kang S., Zhang L., Liang Y., Hu X., Cai H., Gu B. (2002):
Effects of limited irrigation on yield and water use efficiencyof winter wheat in the Loess Plateau of China. Agricultural
Water Management, 55: 203-216.
Liu C., Zhang X., Zhang Y. (2002): Determination of daily
evaporation and evapotranspiration of winter wheat and maize
by large-scale weighing lysimeter and micro-lysimeter.
Agricultural and Forest Meteorology, 111: 109-120.

Mo X., Liu S., Lin Z., Guo R. (2009): Regional crop yield, water
consumption and water use efficiency and their responses toclimate change in the North China Plain. Agriculture,
Ecosystems and Environment, 134: 67-78.
Musick J.T., Jones O.R., Stewart B.A., Dusek D.A. (1994):
Water-yield relationships for irrigated and dryland wheat in
the U.S. Southern Plains. Agronomy Journal, 86: 980-986.
NASS (National Agricultural Statistics Service) (2013): Small
Grains 2013 Summary (http://usda01.library.cornell.edu/usda/
current/SmalGraiSu/SmalGraiSu-09-30-2013.pdf).
Qiu G., Wang L., He X., Zhang X., Chen S., Chen J., Yang Y.
(2008): Water use efficiency and evapotranspiration of winterwheat and its response to irrigation regime in the north China
plain. Agricultural and Forest Meteorolog, 148: 1848-1859.
Schneider A.D., Howell T.A. (2001): Scheduling deficit
irrigation with data from an evapotranspiration network.
Transaction of the ASAE, 44: 1617-1623.
Xue Q., Liu W.Z., Stewart B.A. (2012): Improving wheat yield
and water-use efficiency under semiarid environment: The US
Southern Great Plains and China’s Loess Plateau. In Lal R.,
Stewart B.A. eds., Advances in Soil Science: Soil Water andAgronomic Productivity. Taylor & Francis, New York.
Xue Q., Rudd J.C., Liu S., Jessup K.E., Devkota R.N., Mahan
J.R. (2014): Yield determination and water use efficiency ofwheat under water-limited conditions in the U.S. SouthernHigh Plains. Crop Science, 54: 34-47.
Xue Q., Zhu Z., Musick J.T., Stewart B.A., Dusek D.A. (2003):
Root growth and water uptake in winter wheat under deficit
irrigation. Plant Soil, 257: 151-161.
Xue Q., Zhu Z., Musick J.T., Stewart B.A., Dusek D.A. (2006):
Physiological mechanisms contributing to the increased
water-use efficiency in winter wheat under deficit irrigation.
Journal of Plant Physiology, 163: 154-164.
Zhang H., Wang X., You M., Liu C. (1999): Water - yield
relations and water-use efficiency of winter wheat in the North
China Plain. Irrigation Science, 19: 37-45.
Zhang J.H., Sui X.Z., Li B., Su B.L., Li J.M., Zhou D.X. (1998):
An improved water-use efficiency for winter wheat grownunder reduced irrigation. Field Crops Research, 59: 91-98.
Zhang X., Chen S., Sun H., Wang Y., Shao L. (2010): Water use
efficiency and associated traits in winter wheat cultivars in the
North China Plain. Agricultural Water Management, 97:
1117-1125.
Zhang X., Pei D., Hu C. (2003): Conserving groundwater for
irrigation in the North China Plain. Irrigation Science, 21:
159-166.
Zhang Y., Kendy E., Yu Q., Liu C., Shen Y., Sun H. (2004):
Effect of soil water deficit on evapotranspiration, crop yield,
and water use efficiency in the North China Plain.
Agricultural Water Management, 64: 107-122.
Zhang Y.P., Zhang Y.H., Wang Z., Wang Z.J. (2011):
Characteristics of canopy structure and contributions of
non-leaf organs to yield in winter wheat under different
irrigated conditions. Field Crops Research, 123: 187-195.