Yield and Water Use Efficiency of Maize under Deficit ...

PHILIPP AGRIC SCIENTIST Vol. 96 No. 1, 32–41 March 2013

ISSN 0031-7454

Yield and Water Use Efficiency of Maize under Deficit Irrigation Regimes in a Sub-humid Climate Hayrettin Kuscu1,* and Ali Osman Demir2 Portion of the Ph.D. dissertation of H. Kuscu, under the supervision of A. O. Demir 1 Department of Plant Production, Mustafakemalpasa Vocational School, University of Uludag, 16500 Bursa, Turkey 2 Department of Biosystems Engineering, Faculty of Agriculture, University of Uludag, 16059 Bursa, Turkey * Author for correspondence; e-mail: [email protected]; Fax: +90 224 613 21 14; Tel.: +90 224 613 31 02 (61557) The responses of maize grain and dry matter yields to timing and severity of water deficit in a subhumid environment were studied in the field for two seasons. Seventeen irrigation treatments were applied to maize grown on clay-loam soil, at three critical development stages: vegetative, flowering and grain-filling. The grain and dry matter yields increased with the amount of irrigation water. In both seasons, the highest grain yields were obtained from full irrigation at each stage. Yields were reduced in all the other treatments in which water was limited in all or in part of the development stages. Yield response factor (ky) was separately calculated for the individual growth stages and for the total growing season, and was found to be 0.90, 1.12 (the highest value) and 0.87 (the lowest value) for the total growing season, flowering, and flowering and grain-filling combination stages, respectively. Maximum values of both water use efficiency and irrigation water use efficiency for grain yield under irrigation conditions were obtained as 2.05 kg m-3 and 1.62 kg m-3 from treatments of full irrigation at the flowering and grain-filling stages, and from full irrigation at the vegetative and flowering stages, respectively. Full irrigation during the total growing season was found to be the most appropriate choice for maximum grain yield under the local conditions, but these irrigation programs must be reconsidered in areas where water resources are more limited. Our data suggest that water stress should be scheduled on the grainfilling stage in the case of limited water or water scarcity. Withdrawal of irrigation water during the flowering stage was not a good strategy under the conditions of this study.

Key Words: deficit irrigation, evapotranspiration, irrigation water use efficiency, maize, yield response factor, Zea mays L. Abbreviations: DAP – days after planting, DI – deficit irrigation, ET – evapotranspiration, FC – field capacity, IWUE – irrigation water use efficiency, ky – yield response factor, PWP – permanent wilt point, WHC – water-holding capacity, WUE – water use efficiency

INTRODUCTION Maize is one of the most important crops in the world (Panda et al. 2004). Its grain is used as feed, food and a resource for many unique industrial and commercial products (Motto et al. 2003). It is grown in almost all areas of Turkey under various soil and climatic conditions. Maize grain yields of 18 ton ha-1 can be obtained under irrigated conditions in the Marmara region in west Turkey, while yields of 5 ton ha-1 are considered good in rainfed agriculture. Despite its location in a sub-humid climatic zone, the region experiences extremely low amounts of rainfall in summer, the main growing season of maize. Maize has been reported in the literature to have high irrigation requirements (Karam et al. 2003). In the region, therefore, irrigation is necessary during periods of 32

insufficient precipitation during the growth period of the crop. The limited water resources in the area and the cost of pumping irrigation water are the most important factors that force many farmers to reduce irrigation in the region. Major decreases in maize grain yields have been experienced in some water shortage years in Marmara Region. Deficit irrigation (DI) is a watering strategy that can be applied by different types of irrigation application methods. The appropriate application of DI requires a thorough understanding of the yield response to water (crop sensitivity to drought stress) and of the economic impact of reductions in harvest (English 1990). In the regions where water resources are restrictive, it can be more profitable for a farmer to maximize crop water productivity instead of maximizing the harvest per unit land (Fereres and Soriano 2007). The Philippine Agricultural Scientist Vol. 96 No. 1 (March 2013)

Maize Yield Response to Water Stress

DI creates water stress that can affect the growth and development of maize plants (Payero et al. 2006). Water stress effects on growth and yield are species- and variety-dependent (Çakir 2004). Moreover, sensitivity to drought varies by development stage (Doorenbos and Kassam 1979). The degree of yield depends on timing, severity and duration of water deficit (Hsiao 1990). Some researchers have evaluated the effect of stress timing on maize yield (NeSmith and Ritchie 1992; Çakir 2004; Igbadun et al. 2008). Most of these studies show that maize yield is most affected by DI when it occurs during the reproductive stages (tasselling, silking, pollination, or grain filling). NeSmith and Ritchie (1992) reported yield reductions exceeding 90% caused by water deficit during flowering in maize. Pandey et al. (2000) stated that grain yield reduction was nearly proportional to duration of DI imposed during growing season. In a semi-arid environment of Turkey, Çakir (2004) reported that even a single irrigation omission during one of the sensitive growth stages may cause a 30% and 40% grain yield loss during dry years and much higher grain yield losses of 66–93% should be expected as a result of prolonged water stress, due to irrigation omission during both tasseling and ear formation stages. Igbadun et al. (2008) found that DI at any maize crop growth stage led to decrease in dry matter and grain yields, seasonal evapotranspiration, and deep percolation. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) were strongly influenced by the number of growth stages in which DIs were applied and how critical the growth stages were to moisture stress rather than the amount of irrigation water applied. Istanbulluoglu et al. (2002) reported possible irrigation water saving of 26.3% by applying DI at the vegetative stage of maize, although with only a 2.7% yield reduction. Pandey et al. (2000) reported that yield reduction (22.6–26.4%) caused by DI was associated with a decrease in kernel number and weight. However, Lamm et al. (1995) stated that it is difficult to plan DI for maize without causing a reduction in yield. Variations in the reports of the effect of DI on crops only imply that the effects of DI for the same crop may vary with location. The climate of the location, which dictates the evaporative demand on the crop, and the soil type, which dictates the available water for plant uptake, play vital roles in dictating the influence of DI (Igbadun et al. 2008). Few studies, however, have been reported about the effect of variable irrigation regimes on maize water use, yield and quality under drip irrigation in a subhumid environment. Therefore, yield response to water of maize under different climate, soil and irrigation scheduling conditions should be investigated. The objective of this study was to determine the effects of different levels of irrigation water applied at different growth stages on the yield response and water use efficiency of maize (Zea mays L.) grown on clay-loam soil in a sub-humid environment. The Philippine Agricultural Scientist Vol. 96 No. 1 (March 2013)

Hayrettin Kuscu and Ali Osman Demir

MATERIALS AND METHODS Experimental Site The study was conducted during the 2008 and 2009 growing period (May–October) of corn in the BursaMustafakemalpasa plain of the Marmara region in the western part of Turkey. The plain lies between latitudes 39° 44′ and 40° 10′ North and longitudes 28° 12′ and 28° 49′ East. The local climate is temperate; summers are hot and dry, and winters are mild and rainy. Based on longterm meteorological data (1975–2007), annual mean rainfall, temperature and relative humidity are 679 mm, 14°C, and 68%, respectively (Anonymous 2008). The climate of the region is sub-humid, but rainfall amounts are extremely low in the summer. Seasonal rainfall amount is 52.2 mm, which coincides with 7.7% of the total annual rainfall, for the summer period (June, July and August) (Table 1). Meteorological data were taken from the Mustafakemalpasa weather station, which is located about 1 km east of the field experimental site. The soils of the experimental field are clay-loam (23.6% sand, 43.6% silt and 32.8% clay) located on top of the Entisol ordo (Soil Survey Staff 1999). The volumetric moisture content at field capacity (FC) (0.03 MPa) and the permanent wilting point (PWP) (1.5 MPa) in each 0.30-m layer to 0.90-m depth were measured using pressure plate apparatus (Richards 1949; Gee et al. 2002). The average values of FC and PWP in three measured layers in the 0–0.90 m soil profile were determined as 36% and 21%, respectively. The waterholding capacity (WHC) of the experimental site was determined as 184 mm in a 0.90 m soil profile. WHC was determined by the difference between the water content at FC and PWP. The features of the soil are as follows: 0.16% N content (Kjeldahl method), 59 kg ha-1 P (Olsen method, P2O5), 1086 kg ha-1 exchangeable K (ammonium acetate method, K2O), 2.15% total organic matter (WalkleyBlack method), 0.02% total salt, pH of 7.8. Soil bulk density at 0–0.9 m depth ranged from 1.36 to 1.44 g cm-3. Irrigation water applied during the experimental years was also analyzed (electrical conductivity: 1.4 dS m-1, pH: 7.3, Na adsorption ratio: 0.7) and classified as C3S1 according to graphical method of the United States Salinity Laboratory (US Salinity Laboratory 1954; Ayers and Westcot 1994). Experimental Design The field experiments were conducted in the experimental field of the Mustafakemalpasa Vocational School of Uludag University in Bursa, Turkey. The crops were sown on 14 May 2008 and 8 May 2009, and harvested on 7 October 2008 and 4 October 2009. The hybrid cultivar 31P41 variety (Pioneer Seed Company) was planted in the two seasons. Tolerance to moisture 33



Table 1. Meteorological parameters between 1975–2007 and 2008–2009. Meteorological Parameters Month January February March April May June July August September October November December Annual Total

Temperature (°C) Mean of 2008 2009 1975–2007 5.3 5.8 8.4 12.9 17.2 21.6 23.6 23.3 19.6 15.2 10.2 7.0 14.2

2.5 5.5 12.5 15.9 18.1 23.1 24.3 24.1 20.2 16.0 11.9 7.3 15.1

6.4 7.4 8.9 12.1 18.4 23.2 25.2 23.4 19.7 17.3 10.7 9.6 15.2

Humidity (%) Mean of 2008 1975–2007 75.2 71.8 69.4 65.7 66.3 61.2 61.1 61.7 64.8 70.2 72.8 74.8 67.9

stress and maize leaf disease are two characteristics of the maize variety which make it preferable under irrigation in the study area. It matures at 115–125 d after planting (DAP). The experiments for both seasons were conducted using a completely randomized block design in three replications. Each experimental plot was designed as 5.0 m long by 4.2 m wide (21.0 m2). A buffer zone spacing of 2.0 m was provided between the plots. Row spacing and plant-to-plant spacing was 0.7 and 0.2 m, respectively. The treatment variation was based on deficit or full irrigation in the critical crop growth stages. The crop growing period was divided into three stages which were considered to be the most relevant from the point of view of their response to irrigation, i.e., vegetative (V), flowering (F), and grain-filling (G), to determine irrigation scheduling (Doorenbos and Kassam 1979; Igbadun et al. 2008). Irrigation was applied at each of these stages as full and deficit according to the treatments listed in Table 2. Under full irrigation condition, irrigation water was applied to 900 mm of the soil profile to achieve FC. There is no irrigation applied under nonirrigated or rainfed condition, and irrigation was applied in as much as 25%, 50% and 75% of soil moisture deficit at three growth stages. Additionally, full irrigation was only applied at one and two growth stages. The total irrigation water applied over the season for each treatment to achieve FC was recorded. Agronomic Applications Standard cultural practices were adopted during the cropgrowing season. Fertilizer applications were based on soil analysis recommendations. Maize plots were fertilized with 70 kg ha-1 P2O5 as triple super phosphate (43–44% P2O5) and 100 kg ha-1 N in the form of ammonium sulphate.

42 34

88.2 82.4 71.0 68.6 66.7 63.2 60.9 62.0 76.1 82.8 89.2 89.8 75.1

2009 86.5 86.6 80.2 80.4 69.5 62.2 64.0 68.1 78.5 83.3 90.7 88.1 78.2

Precipitation (mm) Mean of 2008 2009 1975–2007 87.1 79.1 64.9 57.9 42.9 23.4 13.9 14.9 31.2 69.7 92.2 101.7

32.8 41.4 106.4 31.2 24.8 10.8 0 0 87.2 48.8 73.4 77.2

106.6 136.6 111.1 36.9 37.8 6.4 0 0 67.4 80.0 70.6 109.1

678.9

534.0

762.5

Water Application Drip irrigation method was used to deliver water to the plots. The drip irrigation laterals were installed on each row (0.7 m apart) at a distance of 0.1 m from the plants. The laterals had an outer diameter of 1.6 cm and pressure -compensating emitters and were spaced at a distance of 20 cm. Each emitter had a nominal flow rate of 2 L h-1 at a pressure of 100 kPa. The water pumped from the Mustafakemalpasa Aquifer was filtered using a 15-cm diameter screen filter with a 150-mesh screen. Water flowed through a manifold instrumented with flow meters, manual valves, pressure regulators and air vents on each supply line. Water was allowed into the plot for the calculated time and volume. The system was installed before planting in both seasons. First, irrigation water was applied to all treatments using the drip irrigation system during the experiments in 2008 and 2009 to replenish the soil water content at 0–0.90 cm soil depth up to FC level. Irrigation management in the full irrigation treatment was based on the common practice in the area, which consists of irrigation at 7 d intervals. All irrigation treatments were applied on the same day. Soil Moisture and Evapotranspiration Measurements Soil moisture contents were monitored at 0.3 m depth increments to 1.2 m prior to and after irrigation weekly from the plots throughout the growing season. Soil samples were taken at positions immediately under the drippers. Soil water moisture was determined by the gravimetric method (oven dry basis). Actual crop evapotranspiration under the different irrigation treatments was estimated using the following form of the water balance equation (Garrity et al. 1982): ET = I + P ± ∆S – R – D where ET is evapotranspiration (mm), I is the irrigation water (mm), P is the precipitation (mm), ∆S is the change The Philippine Agricultural Scientist Vol. 96 No. 1 (March 2013)


Table 2. Irrigation treatments and their description. Treatment

Description

C

Rainfed (non-irrigated) treatment Weekly irrigation applied only at vegetative stage Weekly irrigation applied only at flowering stage Weekly irrigation applied only at grain-filling stage Weekly irrigation applied at vegetative and flowering stages Weekly irrigation applied at vegetative and grain-filling stages Weekly irrigation applied at flowering and grain-filling stages Weekly irrigation applied at all the stages (fullirrigated) As VFG, but a 75% water deficit was applied at vegetative stage As VFG, but a 50% water deficit was applied at vegetative stage As VFG, but a 25% water deficit was applied at vegetative stage As VFG, but a 75% water deficit was applied at flowering stage As VFG, but a 50% water deficit was applied at flowering stage As VFG, but a 25% water deficit was applied at flowering stage As VFG, but a 75% water deficit was applied at grain-filling stage As VFG, but a 50% water deficit was applied at grain-filling stage As VFG, but a 25% water deficit was applied at grain-filling stage

V F G VF VG FG VFG V25FG V50FG V75FG VF25G VF50G VF75G VFG25 VFG50 VFG75


23%. Grain yields were adjusted to a constant moisture basis of 150 g kg-1 water. Data Analyses Data were subjected to analysis of variance for grain and dry matter yield using MSTAT-C (version 2.1-Michigan State University 1991) and MINITAB (University of Texas at Austin) software. The significance of irrigation treatments and treatment × year interactions were determined at the 0.05 and 0.01 probability levels, by the F test. The F-protected least significant difference (LSD) was calculated at the 0.05 probability level according to Steel and Torrie (1980). Regression analysis was used to evaluate water use-yield relationships using seasonal evapotranspiration and yield data obtained from the experiment. In our study, the model of Stewart et al. (1977) was used to estimate grain yield response to water deficit at the different crop growth stages. Irrigation water use efficiency (IWUE, kg m-3) and water use efficiency based on ET (WUE, kg m-3) were estimated based on the following equations (Zhang et al. 1999):

IWUE =

Yi − Y0 Ii

WUE =

Y ET

in soil water storage (mm), R is the runoff, and D is the drainage below the effective root zone. In the equation, I was measured by water meters, P was observed at the meteorological station nearby the experimental area, ∆S was obtained from gravimetric moisture observations in the soil profile to a depth of 0.9 m. In this study, surface runoff was assumed to be negligible because the amount of irrigation water was controlled through drip irrigation.

where Y is yield (kg ha-1), ET is seasonal crop evapotranspiration (mm), Yi is yield for irrigation treatment i (kg ha-1), Y0 is yield for equivalent dry land (non-irrigated control) and Ii is amount of irrigation water applied for treatment i (mm).

Yield Determination All the experimental treatments were harvested at the same time as the treatment of the weekly irrigation applied at all the stages (VFG), on 7 October 2008 and 4 October 2009. Ten plants were selected randomly from rows 2–5 of each plot at harvest. All sampled plants were divided into stover and ear fractions, and then weighed. The fresh samples from each plot were dried at 70 °C for 48 h for dry matter percentage. Then, dry matter yield of the plots was subsequently calculated. The corn ears of four middle rows in each plot (constituting an area of 2.8 m × 3.8 m) were harvested by hand. The four middle rows were harvested in order to minimize border effect on the yield results. The samples were shelled by a maize sheller. The grain samples were then weighed to obtain the grain weight. The grain moisture content at shelling was determined to be 15–

Irrigation Water Applied and ET The amounts of water applied to each experimental treatment are shown in Table 3. The crop was irrigated a total of eight times (thrice in the vegetative period, thrice in the flowering period and twice in the grain-filling period) for the VFG treatment with no water stress and for the treatments (V25FG, VF50G, VFG75, etc.) with water stress during any of the stages. The largest amount of irrigation water was applied to the VFG treatment in both years (1018 mm for 2008 and 995 mm for 2009). Table 4 shows the cumulative ET for the four crop growth stages and the seasonal ET of the maize. The highest ET values for the irrigated treatments occurred in the vegetative and flowering periods. The seasonal ET varied between 277 and 1164 mm. As expected, the highest seasonal ET was recorded in the reference treatment (VFG) obviously owing to an adequate soil

The Philippine Agricultural Scientist Vol. 96 No. 1 (March 2013)

RESULTS AND DISCUSSION

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Table 3. Amounts of irrigation water applied for the irrigation treatments. Irrigation Water Applied for the Growth Stages (mm) Treatment C V F G VF VG FG VFG V25FG V50FG V75FG VF25G VF50G VF75G VFG25 VFG50 VFG75

Establishment

Vegetative

Flowering

Grain-filling

Seasonal Total (mm)

2008

2009

2008

2009

2008

2009

2008

2009

2008

2009

76 76 76 76 76 76 76 76 76 76 76 76 76 76 76 76 76

66 66 66 66 66 66 66 66 66 66 66 66 66 66 66 66 66

0 383 0 0 388 388 0 387 120 208 309 385 381 383 384 387 383

0 305 0 0 311 311 0 309 101 185 256 310 309 307 311 315 307

0 0 428 0 348 0 435 341 421 388 360 97 172 259 352 345 339

0 0 457 0 397 0 456 397 427 412 406 123 226 304 397 395 397

0 0 0 334 0 270 210 214 227 219 215 262 215 209 63 110 157

0 0 0 367 0 306 247 223 223 224 221 269 251 238 64 122 175

76 459 504 410 812 734 721 1018 844 891 960 820 844 927 875 918 955

66 371 523 433 774 683 769 995 817 887 949 768 852 915 838 898 945

Table 4. Evapotranspiration for the irrigation treatments. Treatment

Evapotranspiration for the Growth Stages (mm) Establishment

C V F G VF VG FG VFG V25FG V50FG V75FG VF25G VF50G VF75G VFG25 VFG50 VFG75

Vegetative

Grain-filling

2008

2009

2008

2009

2008

2009

2008

2009

2008

2009

162 154 161 158 160 153 158 158 159 151 156 160 161 151 162 159 156

172 172 172 172 175 178 172 175 176 176 175 178 174 175 178 182 179

44 349 47 49 357 355 52 356 152 218 287 360 351 359 360 356 355

85 330 85 85 333 330 86 332 154 223 287 329 333 330 331 328 330

39 66 336 40 335 69 378 334 352 342 340 118 179 258 335 333 328

39 43 355 41 360 43 378 358 356 356 359 124 211 275 357 358 357

32 47 100 236 97 237 251 254 265 265 262 269 239 256 143 174 208

36 64 127 288 127 285 291 299 300 301 298 309 305 304 181 219 261

277 616 644 483 949 814 839 1102 928 976 1045 907 930 1024 1000 1022 1047

332 609 739 586 995 836 927 1164 986 1056 1119 940 1023 1084 1047 1087 1127

water supply during the growing period while the least seasonal ET was recorded in the continuous stress treatment (C). In similar studies, seasonal ET for maize was calculated as 701–1040 mm in Sanliurfa, Turkey by Oktem et al. (2003), 410–1026 mm in the Cukurova region in Turkey by Gencoglan and Yazar (1999) and 920–952 mm in the Bekaa Valley of Lebanon by Karam et al. (2003). Grain Yield and Dry Matter Yield Table 5 shows a wide range of grain and above-ground dry matter yields of maize under DI. Data obtained from the 2-yr study showed that grain yield was significantly (P