Water shortage was the key factor that was restricting the spring wheat production in
Desert-oasis of northwest China. So, if the water resources sustainable development was
realized and the efficient or water-saving oasis agriculture was build that the growth
characteristics and the pattern water requirement of spring wheat was mastered. And
finding the reasonable effective water-saving measures and determines optimal irrigation
system for soil and climate conditions in the region and establishes the optimum planting
pattern. This paper analyzed the relationship between water use efficiency, water
consumption and production as well as influencing factors of water use efficiency which
based on the analysis of spring wheat growth characteristics, water requirement and light
characteristics. And then clarify the water consumption and the interactions of growth
characters under the various control modes. This study set six irrigation treatments and
four mulch modes. such as, W1(240mm)、W2(300mm)、W3(360mm)、W4(420mm)、
W5(480mm)、W0(0mm)；Film mulch(B)、Straw mulch(M)、Stone mulch(S)and CK. The
irrigation quantity of mulch treatments was 360mm. The mainly results as follow:
(1)The irrigation quota directly affected the plant height, leaf area index and
aboveground and belowground biomass and grain yield of spring wheat. The grain yield in
descending order was: W4>W5>W3>W2>W1>W0. The descending order of the water use
efficiency (WUE) was W4>W3>W1>W2>W5>W0. There were quadratic curve equation
between yield and water consumption (ET), water use efficiency (WUE).the maximum
value of water use efficiency and grain yield was W4 (420mm) treatment so that it was
best suitable for irrigation in the region.
(2)The grain yield and thousand grain weights in descending order was: B>S>CK>M.
Comparing the CK treatment, the grain yield of B treatment was increased by 2.2%~10.9%.
And the grain yield of S treatment was increased by 0.86%~0.35%. The grain yield of M treatment was increased by -6.9%~9.4%. So, B treatment compared with other treatments
was better to improve crop yields, under the same conditions to achieve high purposes.
(3) According to the water balance method, the wheat water consumption of spring
wheat was 490mm to 650mm under the different irrigation treatment. The maximum
values of Water consumption was in the periods of the jointing late~pre-heading and
heading late~pre-filling stage. The evapotranspiration (ET) in descending order was
W5>W4>W3>W2>W1>W0. Respectively, crops transpiration (T) of W0 accounted for
66.16% of total ET. W1 accounted for 79.60% of total ET. W2 accounted for 80.64% of
total ET. W3 accounted for 81.25% of total ET. W4 accounted for 80.58% of total ET. W5
accounted for 81.26% of total ET. Mulch treatments, the water consumption of spring
wheat in descending order was CK>S>B> M.
(4)The diurnal variations of spring wheat’s photosynthetic rate in the descending
order was W4>W5>W3>W2>W1>W0; the diurnal variations of photosynthetic rate
showed a single peak curve trend in W3, W4, and W5. But photosynthetic rate of W1, W2,
and CK showed bimodal curve, the “lunch break " phenomenon. So, higher water
irrigation treatments could effectively restrain the "lunch break" phenomenon of spring
wheat.Jointing and filling stage was the peak periods of spring wheat photosynthetic
rate .In mulch treatments, the diurnal variations of spring wheat’s photosynthetic rate were
in the descending order. Such as, was B>S>CK>M. and photosynthetic rate showed a
single peak curve characteristics. Excessive drought and excessive irrigation were not
beneficial to improve the photosynthesis of spring wheat.There were the quadratic
relationship between Transpiration rate (Tr), stomatal conductance (Cond), soil water
content (W), solar radiation (PAR) and leaf net photosynthetic rate (Pn). The result of
principal component analysis showed that the key affected environmental factors of the
water use efficiency of spring wheat were the photosynthetic rate, transpiration rate, and air
temperature and soil moisture under different irrigation treatments. However, under
different mulching treatments, leaf temperature, 5cm soil temperature and soil moisture
were the important environmental factors affected the water use efficiency of spring wheat.
Film mulch (B) treatments were better to maintain soil temperature than other treatments.
It was beneficial to help maintain soil moisture by Straw mulch (M).
(5)Farquhar model was used to simulate net photosynthetic rate (Pn) of different irrigation and mulch treatments of Spring Wheat. And the light compensation point and
light saturation point, and other photosynthetic parameters could be calculated by the
Farquhar model. Experimental data showed that the maximum photosynthetic rate of W4
treatment had a maximum light saturation point (39.8μmol CO 2 •m -2 •s -1 ) and a minimum
light compensation point (2.32μmol CO 2 •m -2 •s -1 ). Film mulch (B) was more conducive to
improving maximum net photosynthetic rate of spring wheat than others. Therefore, W4
(240mm) Irrigation and Film mulching (B) treatment of spring wheat had a better the light
ecological adaptability than any other treatments.
(6)The growth characteristics of spring wheat plant height, leaf area index, and
aboveground biomass were conforming to the characteristics of classic Logistic curve with
analysis. So, the new modified Logistic modes were built by plant height (H) as the
independent variable. The leaf area index (L) and aboveground biomass (B) can be
calculated easily by the new modified Logistic model. And according to the parameters
characters of the CK and mulching treatments, a cover factor k was proposed. Therefore,
the functional relationship between CK and mulching treatments was established by the
classic Logistic. By The error test and correlation analysis, simulation and measured values
had a higher degree of agreement. The amendment logistic model can well simulate crop
leaf area index and aboveground biomass by the faction of height as the independent
(7) Aquacrop models was used to simulate the soil moisture, canopy cover,
aboveground biomass and grain yield of the spring wheat under different irrigation
treatments in Desert-oasis. The results showed that the simulated values were agreed well
with the observed values. And the simulation accuracy of the high water irrigation
treatments is better than the low water irrigation treatments. Therefore, Aquacrop model
can be used to simulate the crop growth and soil moisture change process in this region.
KEY WORDS: spring wheat; water use efficiency (WUE); photosynthetic characteristics;
Logistic model; AquaCrop model