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Effects of irrigation before sowing and plastic film mulching on yield and water uptake of spring wheat in semiarid Loess Plateau of China
Agricultural Water Management 67 (2004) 77–88
Effects of irrigation before sowing and plastic film mulching on yield and water uptake of spring wheat in semiarid Loess Plateau of China Feng-Min Li a,b , Ping Wang a , Jun Wang c , Jin-Zhang Xu a,∗ a
b
Laboratory of Arid Agroecology, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China State Key Laboratory of Soil Erosion & Dryland Farming on the Loess Plateau, Institute of Soil & Water Conservation, CAS and Ministry of Water Resources, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi Province 712100, China c Department of Environmental Science, Northwest University, Xian, Shaanxi Province 710069, China Accepted 2 February 2004
Abstract To improve crop yield in semiarid areas, it is valuable to combine irrigation of harvested rainwater with plastic film mulching technology. Limited irrigation after mulching is not usually practiced. This research was to study the combination of pre-sowing irrigation and film mulch and its effect on spring wheat grain yield in semiarid Loess Plateau in China. Four treatments were employed: (1) C—control, without pre-sowing irrigation and without mulching; (2) I—pre-sowing irrigation of 30 mm without mulching; (3) M—plastic film mulching without pre-sowing irrigation; and (4) IM—30 mm pre-sowing irrigation plus mulching. Plastic films in mulched plots were removed at 60 days after sowing (DAS). Although soil water evaporation in the mulched treatments is reduced by film mulch, soil water content in the mulched treatments was lower than in the non-mulched treatments by 60 DAS. Pre-sowing irrigation increased evapotranspiration, but the percentage of water supply from the soil profile in the overall evapotranspiration is just within the range from 7.1 to 33.5%. Rainfall and irrigation during the growing period provide most of the water for evapotranspiration, especially in very dry years. The grain yield was 29.4% greater in treatment IM in 1999 and 112.4% greater in 2000 compared with control, and 35.7% greater in 1999 and 47.3% greater in 2000 compared with the treatment M. Correlation analysis revealed that the spikelet number and the fertile spikelet number were the key factors determining grain yield formation, at least in these two years. The greatest water-use efficiency (WUE) was found in treatment IM for both years, and was significantly higher than in other treatments. The WUE was higher in the wet year of 1999 than in the dry year of 2000.
∗
Corresponding author. Tel.: +86-931-8912848; fax: +86-931-8912848. E-mail addresses: [email protected], [email protected] (J.-Z. Xu). 0378-3774/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2004.02.001
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The combination of pre-sowing irrigation with film mulching increased the soil temperature in the seedling stage, reduced the water deficit, and achieved the highest shoot biomass, grain yield, and water-use efficiency of the 2 years. It is, therefore, concluded that the combination of pre-sowing irrigation with plastic film mulching works well in increasing plant growth and yield of spring wheat and can be adopted for spring wheat production in the semiarid areas. © 2004 Elsevier B.V. All rights reserved. Keywords: Loess Plateau; Plastic film mulch; Irrigation; Spring wheat; Water use; Grain yield
1. Introduction Most of the semiarid areas in China are located on the ecotone belts between humid and arid regions. In arid areas where there is little precipitation, agriculture depends on irrigation from underground water or from rivers descending from mountains. In humid areas, crop water needs can be provided by both rain and irrigation. In many semiarid areas, however, crops are mainly rainfed even though rain is limited and it varies from year to year and within seasons. This results in a low and unstable productivity (Li, 1999). To tackle the problems of water shortages and rainfall fluctuations, a rainwater harvesting system has been developed in the semiarid Loess Plateau of China, allowing limited irrigation for cropland in the last few years (Zhao, 1996; Li et al., 1999b). Rainwater harvesting uses an integrated technological system to supply supplemental irrigation to crops. This generates a significant increase in crop productivity (Li et al., 1999b). In addition to rainwater harvesting, soil mulch technology with plastic film, developed in the semiarid Loess Plateau of China, is another approach to improvements in water use efficiency and grain yield. Previous research (Li et al., 1999a) has shown that plastic film mulching reduces soil evaporation and increases water uptake, water-use efficiency and dry matter production. It also increases topsoil temperature and prolongs the reproductive growth that is positively associated with grain yield (Li et al., 1999a; Niu et al., 1998). To improve the grain yield further in semiarid areas, it is clearly valuable to combine irrigation of harvested rainwater with plastic film mulching technology. Even limited irrigation after mulching is not practicable because (1) water loss by evaporation is high when irrigating on top of the plastic film, and (2) pipe irrigation under the film is too expensive for farmers in the area. Irrigation before sowing and mulching overcomes these problems. Because of the very thick topsoil layer in the research area, profile soil water content in the early growth stage of spring wheat significantly influences dry matter partition between shoots and roots (Li et al., 2001a). In fact, early irrigation gives a higher grain yield than regular irrigation using the same total amount of water (Li et al., 2001b,c). From a field experiment in 1997, it was also found that 30 mm irrigation at pre-sowing in this area increased the grain yield by 174% (Li et al., 2001c). Folk wisdom for the semiarid areas of China suggests that the soil water content before sowing is important for the grain yield. Therefore, this research was designed to examine the effect on spring wheat yield of combining pre-sowing irrigation with plastic film mulch so as to determine the feasibility of application in semiarid Loess Plateau.
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2. Material and methods 2.1. Research site The field experiment was conducted in 1999 and 2000 at the Tangjiabu Agricultural Experimental Station located in a typical area of semiarid Loess Plateau, in Dingxi County, Gansu province of China. It has a medium temperate climate and an altitude of 1970 m, a mean annual air temperature of 6.2 ◦ C and a mean annual precipitation of 420 mm (rain and snow) over the previous 17 years. Sixty-eight percent of the precipitation occurs between June and September, with annual variability in precipitation of 24 and a 48% probability of at least 400 mm precipitation. The underground water is more than 10 m deep and is not a feasible supplementary source. Fig. 1 shows precipitation during the experimental periods. The soil was a loess-like loam with a bulk density of 1.25 g cm−3 , a field capacity of 26% (gravimetric), and a permanent wilting coefficient of 7.5%. 2.2. Treatments Four treatments were designed as follows: (1) C—control, with no irrigation pre-sowing and with no mulching; (2) I—30 mm irrigation pre-sowing without mulching; (3) M—plastic film mulching with no irrigation pre-sowing; and (4) IM—30 mm irrigation pre-sowing plus mulching. In consideration of no precipitation occurred for five months before sowing in 1999, 86.5 mm of water was applied in the irrigation experiments (I and IM) and 56.5 mm in the non-irrigation treatments (C and M) 3 days before sowing to ensure normal seedling emergence. Thus, there was 30 mm more water in I and IM than in C and M treatments. Plastic films in the mulched plots were removed 60 days after sowing (DAS). Each treatment was replicated in three plots each 5.6 m long and 3.3 m wide, in a randomized arrangement. In accordance with local practice, 75 kg N ha−1 and 52.4 kg P ha−1 were applied each year.
Fig. 1. Rainfall for the 1999 and 2000 growing seasons at the Tangjiabu Agricultural Experimental Station, Dingxi, Gansu, PR China. Mean is the averaged value of the rainfall in recent 17 years. The rainfall during the period between 101 and 120 days after sowing in 2000 was not shown because the crop was harvested.
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The averaged precipitation during the spring wheat growth period for recent 11 years is 223 mm. The precipitation during the growing season was 234 mm in 1999, but only 91 mm in 2000 (Fig. 1). Obviously 2000 was an exceptionally dry year, and a light wet year in 1999. To facilitate the experiment in 2000, all plots were irrigated with 27 mm water on 12 May (50 DAS) and 32 mm on 24 May (62 DAS). Spring wheat (Triticum aestivum L. c.v. Longchun 8139-2) was sown with a hole-seeding machine driven by manpower on 23 March in 1999 and 2000. Rows were spaced 15 cm apart and 11 cm between the holes in a row. The seeding rate was 250 kg ha−1 . Before sowing, plastic film (PE film, 1.4 m wide and 0.0075 mm thick) was used as mulch on the soil surface with the edges closed tightly under the soil. The film was drilled through for dropping seeds to the sowing depth by hole-seeding machine when sowing. 2.3. Measurements The soil temperature at 5 cm depth was recorded daily at 8:00, 14:00, and 20:00 h. The mean daily soil temperature was calculated as the average of the three daily readings and the 8:00 h reading the following morning. The soil water content was measured gravimetrically at intervals of 20 cm within the 0–100 cm depth at 30 DAS, 60 DAS, and 90 DAS, and at the start and the harvest date for 0–200 cm soil depth. Because rainfall is too low to cause drainage below the root zone, drainage need not be considered in this area. Therefore, evapotranspiration (ET) can be calculated as follows: ET = P + I + W where P, I and W are the precipitation, irrigation and the difference in soil water content between the beginning and the end of the experimental period, respectively. Fifteen plants were sampled randomly in sampling area of each plot at 30, 60, 90 DAS and at harvest, dried for 48 h at 75 ◦ C for shoot biomass measurement. The remaining plants were harvested on 26 July in 1999 and on 16 July in 2000, and grain yields and yield components were recorded for each plot. All statistical analyses were made with the SAS procedure ANOVA (Hui and Jiang, 1996).
3. Results 3.1. Topsoil temperature The mean difference in topsoil temperature at 5 cm depth between the mulched (M and IM) and non-mulched treatments in 1999 was 5.09 ◦ C for 1–15 DAS, 1.77 ◦ C for 16–30 DAS, and 1.25 ◦ C for 31–60 DAS, all significant at P = 0.05 probability level (Fig. 2). In 2000, the difference was 2.75 ◦ C for 1–15 DAS, 1.10 ◦ C for 16–30 DAS and 0.93 ◦ C for 31–60 DAS. The topsoil temperature in 1999 was slightly lower in the irrigated treatments (I and IM) than in the non-irrigated treatments (C and M). The mean topsoil temperature difference between irrigated (I and IM) and non-irrigated treatments (C and M) was 1.22 ◦ C
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Fig. 2. Soil temperature at 5 cm depth in the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
for 1–15 DAS, 0.96 ◦ C for 16–30 DAS and 0.96 ◦ C for 31–60 DAS. These results imply that irrigation 3 days before sowing reduced the topsoil temperature. 3.2. Soil water content Soil water content at all depths was significantly greater in the irrigated (I and IM) treatments than in the non-irrigated (C and M) treatments in both years at the start of the experiment (Fig. 3). This soil water content difference from 0 to 100 cm depth maintained until 60 DAS in 1999, and 45 DAS in 2000. In 1999, a wet year, mulching increased the soil water content at 0–20 cm and 20–100 cm at 30 DAS when compared to no mulch. Soil water content, however, was significantly lower at 90 DAS in the M treatment than in C, and significantly lower in the IM than in I treatment at 60 and 90 DAS and at harvest. In 2000, a dry year, the soil water content was significantly lower in IM than in I from 45 DAS, but no significant difference was found between M and C for the same period. This indicates that, although the mulch depresses soil water evaporation in the mulched treatments, film mulching does not increase soil water
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60
1999 0-20cm
45 30 15 0
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IM
60 90 Days after sowing
Soil water content
Soil water content
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Soil water content
150 130 110
C M
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Soil water content
I IM
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60 90 Days after sowing C
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30 60 90 Days after sowing
I IM
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C M
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70
45
0
120
2000 0-20cm
120
2000 0-100cm
180
C M
I IM
150 120 90
0
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60 90 Days after sowing
120
Fig. 3. Profile soil water content (mm) in 0–20, 20–100, and 0–100 cm depths for the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Error bars represent LSD at P = 0.05.
content in the later growth period, since it promotes plant growth, which leads to greater transpiration and greater soil water consumption. 3.3. Duration of the growth stage In 1999, seedlings emerged 2 days earlier for I, 9 days earlier for M, and 10 days earlier for IM treatment (Table 1). The jointing period lasted 5–8 days longer in I, M, and
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Table 1 Phenostages phonological growth stages of spring wheat in control and different treatments, Dingxi, China Seedling
Jointing
Heading
Anthesis
Maturing
Total LDs
DAS
LDs
DAS
LDs
DAS
LDs
DAS
LDs
DAS
LDs
1999 C I M IM
18 16 9 8
– – – –
59 62 56 57
41c 46b 47b 49a
78 80 72 74
19a 18a 16a 17a
84 86 78 80
6a 6a 6a 6a
123 127 124 126
39b 41b 46a 46a
105c 111b 115a 118a
2000 C I M IM
18 17 16 15
51 50 49 48
33a 33a 33a 33a
72 71 72 70
21a 21a 23a 22a
77 77 77 75
5a 6a 5a 5a
113 113 113 113
36a 36a 36a 38a
95a 96a 97a 98a
DAS and LDs refer to days after sowing and lasting days during two different stages, respectively. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Values followed by different letters (a, b, and c) in superscript in a column differ significantly at P = 0.05.
IM than in C, and no difference was found in the heading and anthesis periods between C and other treatments. The two mulched treatments (M and IM) entered the maturation period earlier, but the maturation period lasted 5 days longer than the C. The IM treatment showed the longest growth stage, 13 days longer than the C. In the drought year of 2000, mulching and pre-sowing irrigation advanced seedling emergence by only 1–3 days when compared to C, and no significant difference was found between treatments in other stages. 3.4. Dry matter accumulation In 1999, shoot dry matter was consistently higher in the irrigated treatments (I and IM) than in the non-irrigated treatments (C and M). The difference in biomass between the IM and M treatments was significant, but no significant difference was found between I and C treatments (Fig. 4). The shoot biomass at harvest in both years was significantly higher in the IM treatment than in the others, and no significant difference was found among C, I, M treatments in 1999. In 2000, the shoot biomass was higher in I and IM treatments than in C and M treatments, although the difference was not significant (Fig. 5). The shoot biomass was significantly higher in 1999 than in 2000, as expected. 3.5. Yield and yield components No significant difference in grain yield was recorded among I, M, and C treatments, but grain yield was significantly higher for the IM treatment when compared to the others in 1999. Grain yield was significantly higher in I when compared to the C and significantly higher in IM when compared to the M. In both years, the greatest grain yield was obtained in treatment IM. Grain yield for IM was 29.4% higher in 1999 and 112.4% higher in 2000
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Shoots biomass g m
-2
2000 C I M IM
1500 1000 500 0 20
50
80 Days after sowing
110
140
Fig. 4. Shoot biomass dynamics of the various treatments in 1999. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
Fig. 5. Shoot biomass in the various treatments at harvest stage in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
compared to the C, and 35.7% higher in 1999 and 47.3% higher in 2000 when compared to treatment M (Fig. 6). Correlation of grain yields with yield components using all the treatment data is shown in Table 2. In both years, a significant correlation was found between the grain yield and the spikelet number, and between the grain yield and the fertile spikelet number. Spikelet
Table 2 The significance level (P) of correlation analysis between spring wheat yields and yield components
1999 2000 Two years
Harvest index
Spikelet number per spike
Fertile spikelet number per spike
Grain number per spike
Spike weight (g per plant)
Weight per grain (g)
0.91 0.94 0.034
0.022 0.054 9E−5
0.036 0.024 5.8E−5
0.11 0.088 2.7E−4
0.28 0.11 5.0E−3
0.36 0.13 0.021
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Fig. 6. Grain yield in the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
number and fertile spikelet number are, therefore, the most important factors determining the grain yield. Obviously, the soil water content and topsoil temperature in early growth period, as well as the nutrient status affected by the improvement of water-thermal environment, influence these two parameters, and therefore, they are important for achieving a good yield. 3.6. Water use and water-use efficiency In 1999, evapotranspiration was 40 mm higher in treatment I when compared to the C, and 60 mm higher in treatment IM when compared to the M (Table 3). The mean difference in evapotranspiration between the irrigated treatments (I and IM) and the non-irrigated treatments (C and M) was 50 mm, which was greater than the amount of irrigation before sowing. This implies that irrigation pre-sowing causes the plants to use more soil water Table 3 Soil water supply (W), evapotranspiration (ET) and water use efficiency (WUE) of spring wheat in control and different treatments, Dingxi, PR China Treatment (in 1999)
W (mm) ET (mm) WUE (kg m−3 )
Treatment (in 2000)
C
I
M
IM
C
I
M
IM
56.70b 296.6b 0.861b
96.77b 336.7b 0.720b
61.47b 301.4b 0.808b
121.1a 361.0a 0.916a
59.33ab 209.4ab 0.398c
47.10b 197.2b 0.698b
52.67b 202.8b 0.593b
66.84a 216.9a 0.817a
DAS and LDs refer to days after sowing and lasting days during two different stages, respectively. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Values followed by different letters (a and b) in superscript in a column differ significantly at P = 0.05.
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beyond the amount applied in irrigation, especially in treatment IM. In the drought year of 2000, in contrast, evapotranspiration was just 14 mm higher in treatment IM than in M, less than half the amount of irrigation applied before sowing. The proportions of water supply from the soil to the total evapotranspiration in 1999 was 19.1, 28.7, 20.4, and 33.5% for the C, I, M, and IM treatments, respectively. In 2000, the proportions were 7.1, 23.9, 26.0, 30.8, respectively. The mean percentages were 25.4% in 1999 and 21.9% in 2000. This means that although pre-sowing irrigation is important in increasing evapotranspiration and grain yield, the proportion of soil water supply in the total evapotranspiration is very low, and rainfall and irrigation during the growing period provide most of the water loss for evapotranspiration, especially in very dry year. The greatest water-use efficiency (WUE) was found for treatment IM in both years, which was significantly higher than the other treatments. No significant difference in WUE was found among treatments C, I, and M in 1999, but WUE in 2000 was significantly higher in treatments I and M when compared to the C. It is clear that WUE was greater in the wet year of 1999 than in the dry year of 2000.
4. Discussion On the semiarid Loess Plateau, plastic film mulching can improve the soil water content and thermal conditions in the early growth stage of spring wheat, advancing seedling emergence and promoting the accumulation of shoot biomass (Li et al., 1999a). However, the faster establishment of the plant canopy leads to greater transpiration from the crop canopy and more water consumption from the soil profile. A study with spring corn also found that the plant transpiration increased after plastic film mulching (Wang et al., 1998). Soil water content in the mulched treatments decreased, and was significantly lower than in non-mulch treatments in the later growth stage, though soil water evaporation was restrained by the plastic film mulch. The soil in the Loess Plateau is very deep, up to 100–300 m. It is easy for surface water to infiltrate down into the subsoil (Shan and Chen, 1993). Water from pre-sowing irrigation can, therefore, reach the deeper soil layers and remain there. Film mulching can promote the development of plant roots to reach deeper and improve their water absorption capacity (Boatwright et al., 1976; Cumbus and Nye, 1985). Soil water content at depths of 20–100 cm was increased significantly by pre-sowing irrigation; this reduced the water deficit and clearly increased water use. Soil water content before sowing is considered to be of equal importance to rainfall during the growing season (Chen et al., 1992; Shi et al., 2000). Wheat yield increased significantly with increased soil water storage, ranging from 250 to 360 mm before sowing (Chen et al., 1992). Soil water content before sowing may be accountable for about 30% of the grain yield of spring wheat (Mo et al., 1991). A study with winter wheat showed that the wheat yield increased by 120–180 kg ha−1 for every 10 mm increase in the available soil water content (Gao et al., 1999). However, the soil surface temperature in 1999 decreased significantly after the pre-sowing irrigation, especially during 1–15 DAS. A low soil temperature in early spring not only influences seed germination and seedling growth, but also has significant indirect effects on other physiological processes (Rawson and Bagga, 1979; Chaudhary
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and Chopra, 1983). Here, the lower soil temperature slowed plant growth and reduced the seedling biomass in 1999; film mulching after pre-sowing irrigation solves this problem, and achieved a significantly higher grain yield by increasing the topsoil temperature. The year 2000 was a serious drought year, soil water content was the most important factor determining the grain yield; the higher soil water content in I treatment led to greater grain yield and water-use efficiency when compared to the C treatment. In treatment IM, the soil temperature and soil water content in the seedling stage were increased by film mulching and pre-sowing irrigation, respectively. The greatest shoot biomass accumulation, grain yield and water-use efficiency were obtained consistently in IM treatment in both years. This indicates that combining pre-sowing irrigation with plastic film mulching works well to facilitate plant growth and yield of spring wheat.
Acknowledgements The authors thank Drs. S.Q. Li and Q.H. Song for their partial contribution to the field experiment, and Drs. Xinyuan Ben Wu and Huilian Xu for editing the manuscript. National Important Basic Research Pre-arrangement Special Project, NSFC (39970148), and Talent Training Program of China Education Ministry supported this research.
References Boatwright, G.O., Ferguson, H., Sims, J.R., 1976. Soil temperature around the crown node influences early growth, nutrient uptake, and nutrient translocation of spring wheat. Agron. J. 68, 227–281. Chaudhary, T.N., Chopra, U.K., 1983. Effect of soil covers on growth and yield of irrigated wheat planted at two dated. Field Crops Res. 6, 293–304. Chen, P.Y., Li, Y., Jiang, Y.L., 1992. Study of fertility pattern on winter wheat responsive type in loess dryland. In: CAS Bureau of Resources and Environment (Ed.), The Integrated Father and Development of Small Watershed in Loess Plateau. China Science and Technology Press, Beijing, pp. 503–520. Cumbus, I.P., Nye, P.H., 1985. Root zone temperature effects on growth and phosphate absorption in Rape Brassica napus CV. Emerald. J. Exp. Bot. 36, 219–227. Gao, Z.Q., Yin, J., Miao, G.Y., Gao, F.W., 1999. Effects of tillage and mulch methods on soil moisture in wheat fields of Loess Plateau, China. Pedosphere 9 (2), 161–168. Hui, D.-F., Jiang, C.-J., 1996. Application Guide for SAS. Beihang University Press, Beijing. Li, F.M., 1999. On agricultural productivity and ecosystem’s sustainability in semiarid areas of China. Resour. Sci. 21 (5), 25–30. Li, F.M., Guo, A.H., Wei, H., 1999a. Effects of plastic film mulch on yield of spring wheat. Field Crops Res. 63, 79–86. Li, F.M., Wang, J., Zhao, S.L., 1999b. The rainwater harvesting technology approach for dryland agriculture in semi-arid Loess plateau of China. Acta Ecol. Sin. 19 (2), 259–264. Li, F.M., Liu, X.L., Guo, A.H., 2001a. Effects of early soil moisture distribution on the dry matter partition between root and shoot of winter wheat. Agric. Water Manage. 49, 163–171. Li, F.M., Song, Q.H., Liu, X.L., Li, F.R., Liu, H.S., 2001b. Effects of pre-sowing irrigation and phosphorus application on water use and yield of spring wheat under semi-arid conditions. Agric. Water Manage. 49, 173–183. Li, F.M., Yan, X., Li, F.R., Guo, A.H., 2001c. Effects of different water supply regimes on water use and yield performance of spring wheat in a simulated semiarid environment. Agric. Water Manage. 47, 27–37. Mo, X.M., Chen, G.L., Zhao, K.X., 1991. The water ecology character of spring wheat farmland and its improving approach in dry land of loess area. Mem. ISWC 11, 56–63.
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Niu, J.Y., Gan, J.W., Zhang, J.W., Yang, Q.F., 1998. Post-anthesis dry matter accumulation and redistribution in spring wheat mulched with plastic film. Crop Sci. 38, 1562–1568. Rawson, H.M., Bagga, A.K., 1979. Influence of temperature between floral initiation and flag-leaf emergence on grain number in wheat. Aust. J. Plant Physiol. 6, 391–400. Shan, L., Chen, G.L., 1993. The Theory and Practices of Dryland Agriculture in Loess Plateau. Science Press, Beijing. Shi, G.A., Wei, L.Y., Chen, M.C., 2000. A path analysis of relative yield characters of winter wheat in dryland under simulated rainfall conditions. China J. Agric. Res. Arid Area 18 (3), 64–69. Wang, X.Q., Li, S.X., Gao, Y.J., 1998. Effects of film mulch on physi-ecology and yield of spring corn. Acta Agron. Sin. 24 (3), 348–353. Zhao, S.L., 1996. Introduction to Rainwater Harvesting Agriculture. Shaanxi Science and Technology Press, Xi’an.
Effects of irrigation before sowing and plastic film mulching on yield and water uptake of spring wheat in semiarid Loess Plateau of China Feng-Min Li a,b , Ping Wang a , Jun Wang c , Jin-Zhang Xu a,∗ a
b
Laboratory of Arid Agroecology, School of Life Science, Lanzhou University, Lanzhou, Gansu Province 730000, China State Key Laboratory of Soil Erosion & Dryland Farming on the Loess Plateau, Institute of Soil & Water Conservation, CAS and Ministry of Water Resources, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi Province 712100, China c Department of Environmental Science, Northwest University, Xian, Shaanxi Province 710069, China Accepted 2 February 2004
Abstract To improve crop yield in semiarid areas, it is valuable to combine irrigation of harvested rainwater with plastic film mulching technology. Limited irrigation after mulching is not usually practiced. This research was to study the combination of pre-sowing irrigation and film mulch and its effect on spring wheat grain yield in semiarid Loess Plateau in China. Four treatments were employed: (1) C—control, without pre-sowing irrigation and without mulching; (2) I—pre-sowing irrigation of 30 mm without mulching; (3) M—plastic film mulching without pre-sowing irrigation; and (4) IM—30 mm pre-sowing irrigation plus mulching. Plastic films in mulched plots were removed at 60 days after sowing (DAS). Although soil water evaporation in the mulched treatments is reduced by film mulch, soil water content in the mulched treatments was lower than in the non-mulched treatments by 60 DAS. Pre-sowing irrigation increased evapotranspiration, but the percentage of water supply from the soil profile in the overall evapotranspiration is just within the range from 7.1 to 33.5%. Rainfall and irrigation during the growing period provide most of the water for evapotranspiration, especially in very dry years. The grain yield was 29.4% greater in treatment IM in 1999 and 112.4% greater in 2000 compared with control, and 35.7% greater in 1999 and 47.3% greater in 2000 compared with the treatment M. Correlation analysis revealed that the spikelet number and the fertile spikelet number were the key factors determining grain yield formation, at least in these two years. The greatest water-use efficiency (WUE) was found in treatment IM for both years, and was significantly higher than in other treatments. The WUE was higher in the wet year of 1999 than in the dry year of 2000.
∗
Corresponding author. Tel.: +86-931-8912848; fax: +86-931-8912848. E-mail addresses: [email protected], [email protected] (J.-Z. Xu). 0378-3774/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.agwat.2004.02.001
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The combination of pre-sowing irrigation with film mulching increased the soil temperature in the seedling stage, reduced the water deficit, and achieved the highest shoot biomass, grain yield, and water-use efficiency of the 2 years. It is, therefore, concluded that the combination of pre-sowing irrigation with plastic film mulching works well in increasing plant growth and yield of spring wheat and can be adopted for spring wheat production in the semiarid areas. © 2004 Elsevier B.V. All rights reserved. Keywords: Loess Plateau; Plastic film mulch; Irrigation; Spring wheat; Water use; Grain yield
1. Introduction Most of the semiarid areas in China are located on the ecotone belts between humid and arid regions. In arid areas where there is little precipitation, agriculture depends on irrigation from underground water or from rivers descending from mountains. In humid areas, crop water needs can be provided by both rain and irrigation. In many semiarid areas, however, crops are mainly rainfed even though rain is limited and it varies from year to year and within seasons. This results in a low and unstable productivity (Li, 1999). To tackle the problems of water shortages and rainfall fluctuations, a rainwater harvesting system has been developed in the semiarid Loess Plateau of China, allowing limited irrigation for cropland in the last few years (Zhao, 1996; Li et al., 1999b). Rainwater harvesting uses an integrated technological system to supply supplemental irrigation to crops. This generates a significant increase in crop productivity (Li et al., 1999b). In addition to rainwater harvesting, soil mulch technology with plastic film, developed in the semiarid Loess Plateau of China, is another approach to improvements in water use efficiency and grain yield. Previous research (Li et al., 1999a) has shown that plastic film mulching reduces soil evaporation and increases water uptake, water-use efficiency and dry matter production. It also increases topsoil temperature and prolongs the reproductive growth that is positively associated with grain yield (Li et al., 1999a; Niu et al., 1998). To improve the grain yield further in semiarid areas, it is clearly valuable to combine irrigation of harvested rainwater with plastic film mulching technology. Even limited irrigation after mulching is not practicable because (1) water loss by evaporation is high when irrigating on top of the plastic film, and (2) pipe irrigation under the film is too expensive for farmers in the area. Irrigation before sowing and mulching overcomes these problems. Because of the very thick topsoil layer in the research area, profile soil water content in the early growth stage of spring wheat significantly influences dry matter partition between shoots and roots (Li et al., 2001a). In fact, early irrigation gives a higher grain yield than regular irrigation using the same total amount of water (Li et al., 2001b,c). From a field experiment in 1997, it was also found that 30 mm irrigation at pre-sowing in this area increased the grain yield by 174% (Li et al., 2001c). Folk wisdom for the semiarid areas of China suggests that the soil water content before sowing is important for the grain yield. Therefore, this research was designed to examine the effect on spring wheat yield of combining pre-sowing irrigation with plastic film mulch so as to determine the feasibility of application in semiarid Loess Plateau.
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2. Material and methods 2.1. Research site The field experiment was conducted in 1999 and 2000 at the Tangjiabu Agricultural Experimental Station located in a typical area of semiarid Loess Plateau, in Dingxi County, Gansu province of China. It has a medium temperate climate and an altitude of 1970 m, a mean annual air temperature of 6.2 ◦ C and a mean annual precipitation of 420 mm (rain and snow) over the previous 17 years. Sixty-eight percent of the precipitation occurs between June and September, with annual variability in precipitation of 24 and a 48% probability of at least 400 mm precipitation. The underground water is more than 10 m deep and is not a feasible supplementary source. Fig. 1 shows precipitation during the experimental periods. The soil was a loess-like loam with a bulk density of 1.25 g cm−3 , a field capacity of 26% (gravimetric), and a permanent wilting coefficient of 7.5%. 2.2. Treatments Four treatments were designed as follows: (1) C—control, with no irrigation pre-sowing and with no mulching; (2) I—30 mm irrigation pre-sowing without mulching; (3) M—plastic film mulching with no irrigation pre-sowing; and (4) IM—30 mm irrigation pre-sowing plus mulching. In consideration of no precipitation occurred for five months before sowing in 1999, 86.5 mm of water was applied in the irrigation experiments (I and IM) and 56.5 mm in the non-irrigation treatments (C and M) 3 days before sowing to ensure normal seedling emergence. Thus, there was 30 mm more water in I and IM than in C and M treatments. Plastic films in the mulched plots were removed 60 days after sowing (DAS). Each treatment was replicated in three plots each 5.6 m long and 3.3 m wide, in a randomized arrangement. In accordance with local practice, 75 kg N ha−1 and 52.4 kg P ha−1 were applied each year.
Fig. 1. Rainfall for the 1999 and 2000 growing seasons at the Tangjiabu Agricultural Experimental Station, Dingxi, Gansu, PR China. Mean is the averaged value of the rainfall in recent 17 years. The rainfall during the period between 101 and 120 days after sowing in 2000 was not shown because the crop was harvested.
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The averaged precipitation during the spring wheat growth period for recent 11 years is 223 mm. The precipitation during the growing season was 234 mm in 1999, but only 91 mm in 2000 (Fig. 1). Obviously 2000 was an exceptionally dry year, and a light wet year in 1999. To facilitate the experiment in 2000, all plots were irrigated with 27 mm water on 12 May (50 DAS) and 32 mm on 24 May (62 DAS). Spring wheat (Triticum aestivum L. c.v. Longchun 8139-2) was sown with a hole-seeding machine driven by manpower on 23 March in 1999 and 2000. Rows were spaced 15 cm apart and 11 cm between the holes in a row. The seeding rate was 250 kg ha−1 . Before sowing, plastic film (PE film, 1.4 m wide and 0.0075 mm thick) was used as mulch on the soil surface with the edges closed tightly under the soil. The film was drilled through for dropping seeds to the sowing depth by hole-seeding machine when sowing. 2.3. Measurements The soil temperature at 5 cm depth was recorded daily at 8:00, 14:00, and 20:00 h. The mean daily soil temperature was calculated as the average of the three daily readings and the 8:00 h reading the following morning. The soil water content was measured gravimetrically at intervals of 20 cm within the 0–100 cm depth at 30 DAS, 60 DAS, and 90 DAS, and at the start and the harvest date for 0–200 cm soil depth. Because rainfall is too low to cause drainage below the root zone, drainage need not be considered in this area. Therefore, evapotranspiration (ET) can be calculated as follows: ET = P + I + W where P, I and W are the precipitation, irrigation and the difference in soil water content between the beginning and the end of the experimental period, respectively. Fifteen plants were sampled randomly in sampling area of each plot at 30, 60, 90 DAS and at harvest, dried for 48 h at 75 ◦ C for shoot biomass measurement. The remaining plants were harvested on 26 July in 1999 and on 16 July in 2000, and grain yields and yield components were recorded for each plot. All statistical analyses were made with the SAS procedure ANOVA (Hui and Jiang, 1996).
3. Results 3.1. Topsoil temperature The mean difference in topsoil temperature at 5 cm depth between the mulched (M and IM) and non-mulched treatments in 1999 was 5.09 ◦ C for 1–15 DAS, 1.77 ◦ C for 16–30 DAS, and 1.25 ◦ C for 31–60 DAS, all significant at P = 0.05 probability level (Fig. 2). In 2000, the difference was 2.75 ◦ C for 1–15 DAS, 1.10 ◦ C for 16–30 DAS and 0.93 ◦ C for 31–60 DAS. The topsoil temperature in 1999 was slightly lower in the irrigated treatments (I and IM) than in the non-irrigated treatments (C and M). The mean topsoil temperature difference between irrigated (I and IM) and non-irrigated treatments (C and M) was 1.22 ◦ C
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Fig. 2. Soil temperature at 5 cm depth in the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
for 1–15 DAS, 0.96 ◦ C for 16–30 DAS and 0.96 ◦ C for 31–60 DAS. These results imply that irrigation 3 days before sowing reduced the topsoil temperature. 3.2. Soil water content Soil water content at all depths was significantly greater in the irrigated (I and IM) treatments than in the non-irrigated (C and M) treatments in both years at the start of the experiment (Fig. 3). This soil water content difference from 0 to 100 cm depth maintained until 60 DAS in 1999, and 45 DAS in 2000. In 1999, a wet year, mulching increased the soil water content at 0–20 cm and 20–100 cm at 30 DAS when compared to no mulch. Soil water content, however, was significantly lower at 90 DAS in the M treatment than in C, and significantly lower in the IM than in I treatment at 60 and 90 DAS and at harvest. In 2000, a dry year, the soil water content was significantly lower in IM than in I from 45 DAS, but no significant difference was found between M and C for the same period. This indicates that, although the mulch depresses soil water evaporation in the mulched treatments, film mulching does not increase soil water
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60
1999 0-20cm
45 30 15 0
0
30
C
I
M
IM
60 90 Days after sowing
Soil water content
Soil water content
60
Soil water content
150 130 110
C M
90
Soil water content
I IM
30
60 90 Days after sowing C
210
I
M
0
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30 60 90 Days after sowing
I IM
130 110 90 0
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IM
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C M
2000 20-100cm
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1999 0-100cm
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70
45
0
120
2000 0-20cm
120
2000 0-100cm
180
C M
I IM
150 120 90
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60 90 Days after sowing
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Fig. 3. Profile soil water content (mm) in 0–20, 20–100, and 0–100 cm depths for the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Error bars represent LSD at P = 0.05.
content in the later growth period, since it promotes plant growth, which leads to greater transpiration and greater soil water consumption. 3.3. Duration of the growth stage In 1999, seedlings emerged 2 days earlier for I, 9 days earlier for M, and 10 days earlier for IM treatment (Table 1). The jointing period lasted 5–8 days longer in I, M, and
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Table 1 Phenostages phonological growth stages of spring wheat in control and different treatments, Dingxi, China Seedling
Jointing
Heading
Anthesis
Maturing
Total LDs
DAS
LDs
DAS
LDs
DAS
LDs
DAS
LDs
DAS
LDs
1999 C I M IM
18 16 9 8
– – – –
59 62 56 57
41c 46b 47b 49a
78 80 72 74
19a 18a 16a 17a
84 86 78 80
6a 6a 6a 6a
123 127 124 126
39b 41b 46a 46a
105c 111b 115a 118a
2000 C I M IM
18 17 16 15
51 50 49 48
33a 33a 33a 33a
72 71 72 70
21a 21a 23a 22a
77 77 77 75
5a 6a 5a 5a
113 113 113 113
36a 36a 36a 38a
95a 96a 97a 98a
DAS and LDs refer to days after sowing and lasting days during two different stages, respectively. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Values followed by different letters (a, b, and c) in superscript in a column differ significantly at P = 0.05.
IM than in C, and no difference was found in the heading and anthesis periods between C and other treatments. The two mulched treatments (M and IM) entered the maturation period earlier, but the maturation period lasted 5 days longer than the C. The IM treatment showed the longest growth stage, 13 days longer than the C. In the drought year of 2000, mulching and pre-sowing irrigation advanced seedling emergence by only 1–3 days when compared to C, and no significant difference was found between treatments in other stages. 3.4. Dry matter accumulation In 1999, shoot dry matter was consistently higher in the irrigated treatments (I and IM) than in the non-irrigated treatments (C and M). The difference in biomass between the IM and M treatments was significant, but no significant difference was found between I and C treatments (Fig. 4). The shoot biomass at harvest in both years was significantly higher in the IM treatment than in the others, and no significant difference was found among C, I, M treatments in 1999. In 2000, the shoot biomass was higher in I and IM treatments than in C and M treatments, although the difference was not significant (Fig. 5). The shoot biomass was significantly higher in 1999 than in 2000, as expected. 3.5. Yield and yield components No significant difference in grain yield was recorded among I, M, and C treatments, but grain yield was significantly higher for the IM treatment when compared to the others in 1999. Grain yield was significantly higher in I when compared to the C and significantly higher in IM when compared to the M. In both years, the greatest grain yield was obtained in treatment IM. Grain yield for IM was 29.4% higher in 1999 and 112.4% higher in 2000
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Shoots biomass g m
-2
2000 C I M IM
1500 1000 500 0 20
50
80 Days after sowing
110
140
Fig. 4. Shoot biomass dynamics of the various treatments in 1999. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
Fig. 5. Shoot biomass in the various treatments at harvest stage in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
compared to the C, and 35.7% higher in 1999 and 47.3% higher in 2000 when compared to treatment M (Fig. 6). Correlation of grain yields with yield components using all the treatment data is shown in Table 2. In both years, a significant correlation was found between the grain yield and the spikelet number, and between the grain yield and the fertile spikelet number. Spikelet
Table 2 The significance level (P) of correlation analysis between spring wheat yields and yield components
1999 2000 Two years
Harvest index
Spikelet number per spike
Fertile spikelet number per spike
Grain number per spike
Spike weight (g per plant)
Weight per grain (g)
0.91 0.94 0.034
0.022 0.054 9E−5
0.036 0.024 5.8E−5
0.11 0.088 2.7E−4
0.28 0.11 5.0E−3
0.36 0.13 0.021
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Fig. 6. Grain yield in the various treatments in 1999 and 2000. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching.
number and fertile spikelet number are, therefore, the most important factors determining the grain yield. Obviously, the soil water content and topsoil temperature in early growth period, as well as the nutrient status affected by the improvement of water-thermal environment, influence these two parameters, and therefore, they are important for achieving a good yield. 3.6. Water use and water-use efficiency In 1999, evapotranspiration was 40 mm higher in treatment I when compared to the C, and 60 mm higher in treatment IM when compared to the M (Table 3). The mean difference in evapotranspiration between the irrigated treatments (I and IM) and the non-irrigated treatments (C and M) was 50 mm, which was greater than the amount of irrigation before sowing. This implies that irrigation pre-sowing causes the plants to use more soil water Table 3 Soil water supply (W), evapotranspiration (ET) and water use efficiency (WUE) of spring wheat in control and different treatments, Dingxi, PR China Treatment (in 1999)
W (mm) ET (mm) WUE (kg m−3 )
Treatment (in 2000)
C
I
M
IM
C
I
M
IM
56.70b 296.6b 0.861b
96.77b 336.7b 0.720b
61.47b 301.4b 0.808b
121.1a 361.0a 0.916a
59.33ab 209.4ab 0.398c
47.10b 197.2b 0.698b
52.67b 202.8b 0.593b
66.84a 216.9a 0.817a
DAS and LDs refer to days after sowing and lasting days during two different stages, respectively. C is control (without pre-sowing irrigation or mulching), I is pre-sowing irrigation of 30 mm without mulching, M is plastic film mulching without pre-sowing irrigation, and IM is 30 mm pre-sowing irrigation plus mulching. Values followed by different letters (a and b) in superscript in a column differ significantly at P = 0.05.
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beyond the amount applied in irrigation, especially in treatment IM. In the drought year of 2000, in contrast, evapotranspiration was just 14 mm higher in treatment IM than in M, less than half the amount of irrigation applied before sowing. The proportions of water supply from the soil to the total evapotranspiration in 1999 was 19.1, 28.7, 20.4, and 33.5% for the C, I, M, and IM treatments, respectively. In 2000, the proportions were 7.1, 23.9, 26.0, 30.8, respectively. The mean percentages were 25.4% in 1999 and 21.9% in 2000. This means that although pre-sowing irrigation is important in increasing evapotranspiration and grain yield, the proportion of soil water supply in the total evapotranspiration is very low, and rainfall and irrigation during the growing period provide most of the water loss for evapotranspiration, especially in very dry year. The greatest water-use efficiency (WUE) was found for treatment IM in both years, which was significantly higher than the other treatments. No significant difference in WUE was found among treatments C, I, and M in 1999, but WUE in 2000 was significantly higher in treatments I and M when compared to the C. It is clear that WUE was greater in the wet year of 1999 than in the dry year of 2000.
4. Discussion On the semiarid Loess Plateau, plastic film mulching can improve the soil water content and thermal conditions in the early growth stage of spring wheat, advancing seedling emergence and promoting the accumulation of shoot biomass (Li et al., 1999a). However, the faster establishment of the plant canopy leads to greater transpiration from the crop canopy and more water consumption from the soil profile. A study with spring corn also found that the plant transpiration increased after plastic film mulching (Wang et al., 1998). Soil water content in the mulched treatments decreased, and was significantly lower than in non-mulch treatments in the later growth stage, though soil water evaporation was restrained by the plastic film mulch. The soil in the Loess Plateau is very deep, up to 100–300 m. It is easy for surface water to infiltrate down into the subsoil (Shan and Chen, 1993). Water from pre-sowing irrigation can, therefore, reach the deeper soil layers and remain there. Film mulching can promote the development of plant roots to reach deeper and improve their water absorption capacity (Boatwright et al., 1976; Cumbus and Nye, 1985). Soil water content at depths of 20–100 cm was increased significantly by pre-sowing irrigation; this reduced the water deficit and clearly increased water use. Soil water content before sowing is considered to be of equal importance to rainfall during the growing season (Chen et al., 1992; Shi et al., 2000). Wheat yield increased significantly with increased soil water storage, ranging from 250 to 360 mm before sowing (Chen et al., 1992). Soil water content before sowing may be accountable for about 30% of the grain yield of spring wheat (Mo et al., 1991). A study with winter wheat showed that the wheat yield increased by 120–180 kg ha−1 for every 10 mm increase in the available soil water content (Gao et al., 1999). However, the soil surface temperature in 1999 decreased significantly after the pre-sowing irrigation, especially during 1–15 DAS. A low soil temperature in early spring not only influences seed germination and seedling growth, but also has significant indirect effects on other physiological processes (Rawson and Bagga, 1979; Chaudhary
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and Chopra, 1983). Here, the lower soil temperature slowed plant growth and reduced the seedling biomass in 1999; film mulching after pre-sowing irrigation solves this problem, and achieved a significantly higher grain yield by increasing the topsoil temperature. The year 2000 was a serious drought year, soil water content was the most important factor determining the grain yield; the higher soil water content in I treatment led to greater grain yield and water-use efficiency when compared to the C treatment. In treatment IM, the soil temperature and soil water content in the seedling stage were increased by film mulching and pre-sowing irrigation, respectively. The greatest shoot biomass accumulation, grain yield and water-use efficiency were obtained consistently in IM treatment in both years. This indicates that combining pre-sowing irrigation with plastic film mulching works well to facilitate plant growth and yield of spring wheat.
Acknowledgements The authors thank Drs. S.Q. Li and Q.H. Song for their partial contribution to the field experiment, and Drs. Xinyuan Ben Wu and Huilian Xu for editing the manuscript. National Important Basic Research Pre-arrangement Special Project, NSFC (39970148), and Talent Training Program of China Education Ministry supported this research.
References Boatwright, G.O., Ferguson, H., Sims, J.R., 1976. Soil temperature around the crown node influences early growth, nutrient uptake, and nutrient translocation of spring wheat. Agron. J. 68, 227–281. Chaudhary, T.N., Chopra, U.K., 1983. Effect of soil covers on growth and yield of irrigated wheat planted at two dated. Field Crops Res. 6, 293–304. Chen, P.Y., Li, Y., Jiang, Y.L., 1992. Study of fertility pattern on winter wheat responsive type in loess dryland. In: CAS Bureau of Resources and Environment (Ed.), The Integrated Father and Development of Small Watershed in Loess Plateau. China Science and Technology Press, Beijing, pp. 503–520. Cumbus, I.P., Nye, P.H., 1985. Root zone temperature effects on growth and phosphate absorption in Rape Brassica napus CV. Emerald. J. Exp. Bot. 36, 219–227. Gao, Z.Q., Yin, J., Miao, G.Y., Gao, F.W., 1999. Effects of tillage and mulch methods on soil moisture in wheat fields of Loess Plateau, China. Pedosphere 9 (2), 161–168. Hui, D.-F., Jiang, C.-J., 1996. Application Guide for SAS. Beihang University Press, Beijing. Li, F.M., 1999. On agricultural productivity and ecosystem’s sustainability in semiarid areas of China. Resour. Sci. 21 (5), 25–30. Li, F.M., Guo, A.H., Wei, H., 1999a. Effects of plastic film mulch on yield of spring wheat. Field Crops Res. 63, 79–86. Li, F.M., Wang, J., Zhao, S.L., 1999b. The rainwater harvesting technology approach for dryland agriculture in semi-arid Loess plateau of China. Acta Ecol. Sin. 19 (2), 259–264. Li, F.M., Liu, X.L., Guo, A.H., 2001a. Effects of early soil moisture distribution on the dry matter partition between root and shoot of winter wheat. Agric. Water Manage. 49, 163–171. Li, F.M., Song, Q.H., Liu, X.L., Li, F.R., Liu, H.S., 2001b. Effects of pre-sowing irrigation and phosphorus application on water use and yield of spring wheat under semi-arid conditions. Agric. Water Manage. 49, 173–183. Li, F.M., Yan, X., Li, F.R., Guo, A.H., 2001c. Effects of different water supply regimes on water use and yield performance of spring wheat in a simulated semiarid environment. Agric. Water Manage. 47, 27–37. Mo, X.M., Chen, G.L., Zhao, K.X., 1991. The water ecology character of spring wheat farmland and its improving approach in dry land of loess area. Mem. ISWC 11, 56–63.
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Niu, J.Y., Gan, J.W., Zhang, J.W., Yang, Q.F., 1998. Post-anthesis dry matter accumulation and redistribution in spring wheat mulched with plastic film. Crop Sci. 38, 1562–1568. Rawson, H.M., Bagga, A.K., 1979. Influence of temperature between floral initiation and flag-leaf emergence on grain number in wheat. Aust. J. Plant Physiol. 6, 391–400. Shan, L., Chen, G.L., 1993. The Theory and Practices of Dryland Agriculture in Loess Plateau. Science Press, Beijing. Shi, G.A., Wei, L.Y., Chen, M.C., 2000. A path analysis of relative yield characters of winter wheat in dryland under simulated rainfall conditions. China J. Agric. Res. Arid Area 18 (3), 64–69. Wang, X.Q., Li, S.X., Gao, Y.J., 1998. Effects of film mulch on physi-ecology and yield of spring corn. Acta Agron. Sin. 24 (3), 348–353. Zhao, S.L., 1996. Introduction to Rainwater Harvesting Agriculture. Shaanxi Science and Technology Press, Xi’an.