J. Agr. Sci. Tech. (2021) Vol. 23(5): 1179-1191
Changes in Climatic Variables and Their Effect on Wheat Water Requirement in Urmia Lake Basin
H. Faghih1, J. Behmanesh1*, H. Rezaie1, and K. Khalili1
ABSTRACT
Climate change and low water use efficiency are the main reasons for reducing the water entering the Urmia Lake. Therefore, water use management via irrigation scheduling can be an effective strategy to restore this lake. This research was conducted to investigate the effect of climatic variables on water requirements, identify water-sensitive growth stages, and prepare irrigation scheduling guidelines for wheat, which is one of the main crops in the studied region. For this purpose, crop Evapotranspiration (ETc) and Net Irrigation Requirement (NIR) of wheat growth stages were estimated by computing the daily soil water balance of the root zone for a period of 32 years (1985-1986 to 2016- 2017). Dividing wheat growth period into nine phenological stages was performed using Growing Degree Days (GDDs) and Zadoks scale. These stages included intervals of [Sowing-Emergence (StE)], [Emergence-Trifoliate (EtT)], [Trifoliate-Double ridge (TtD)], [Double ridge-Jointing (DtJ)], [Jointing-Booting (JtB)], [Booting-Heading (BtH)], [Heading-Anthesis (HtA)], [Anthesis-Maturity (AtM)] and [Maturity-Harvesting (MtHa)], whose mean ETc was estimated to be 2.30, 1.33, 1.03, 3.63, 4.69, 5.13, 6.53, 7.09 -1 and 1.35 mm d , respectively. The mean ETc, Effective Precipitation (Eff. P) and NIR of wheat during its growth period were estimated to be 774, 349, and 425 mm, respectively. Results showed that wheat sensitivity to water stress is high from booting to maturity, is low from sowing to double ridge and from maturity to harvesting, and is moderate in other stages. Therefore, increasing the irrigation interval in the first three stages of growth and eliminating the end-stage irrigation are recommended for water saving.
Keywords: Dual Kc, FAO Penman-Monteith, GDD, Mann-Kendall test, Zadoks scale. INTRODUCTION undesirable water use in this sector are the most important reasons for over-harvesting Urmia Lake, in north-western Iran, is the of the renewable water resources in the largest saltwater lake in the Middle East Urmia Lake Basin (Khazaei et al., 2019). (Zoljoodi and Didevarasl, 2014). Over a period Irrigation scheduling is one of the most Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 of 20 years (1995-2015), the lake water level has important practices to manage water use in decreased more than 8 m (Khazaei et al., 2019). agriculture. In numerous studies, the This decline in the lake water level has caused a effectiveness of different irrigation significant decrease in lake surface area and its scheduling methods in reducing water use water volume. Continuation of the drying up of and increasing water productivity has been Urmia Lake will cause serious damages to evaluated (Rosa et al., 2012; Zhao et al., health, hygiene, livelihood, and destruction of its 2013; Gao et al., 2014; Incrocci et al., 2014; basin ecosystem. Goosheh et al., 2018; Zhang et al., 2018; The drying process of this lake is the Ewaid et al., 2019; Jha et al., 2019; consequence of negative impacts of human Mehmood et al., 2019; Zhou et al., 2019; activities and natural factors. Unbalanced Taromi Aliabadi et al., 2019; Erken and and unsustainable development of Yildirim 2019; Dindarlou et al., 2019; Singh agricultural activities and excessive and et al., 2019).
1 Department of Water Engineering, Urmia University, Urmia, Islamic Republic of Iran. * Corresponding author; e-mail: [email protected]
1179 ______Faghih et al.
Irrigation scheduling involves methods method for irrigation scheduling. The that are based on plant stress indices, soil vastness of the area is an obstacle to moisture budget, crop water use (ET), or a generalize the results of field experiments to combination of these approaches (Hill, the whole region. This research was 2002). Applying these methods requires conducted to prepare irrigation scheduling field measurements and experiments, or the guidelines for wheat using FAO P-M model use of simulation models. Field experiments and dual Kc approach, as well as investigate have some limitations (including cost and the effect of climatic variables on water time consuming, unable to perform multiple requirements and identifying water-sensitive and complex irrigation management options, growth stages of wheat. and generalization of test findings to other conditions and regions (external validity)). MATERIALS AND METHODS Simulation models are used to overcome these limitations. Among the most used ones are FAO Penman-Monteith (P-M), CERES, Study Area and AquaCrop models. The effectiveness of these models has been studied and approved The study area is Saqqez County in for irrigation scheduling of different crops, Kurdistan province, located in the southern reducing water use and increasing water part of the Urmia Lake basin of Iran (Figure productivity in different parts of the world 1). Saqqez has a cold semi-humid climate. (Rosa et al., 2012; Zhao et al., 2013; Gao et The climate of Saqqez was determined using al., 2014; Incrocci et al., 2014; Goosheh et Emberger method (Arkian et al., 2018). al., 2018; Zhang et al., 2018; Ewaid et al., Daily minimum and maximum temperatures 2019; Zhou et al., 2019). of Saqqez in the coldest and warmest In Saqqez County, located in the Urmia months of the year are -36 and 43°C, Lake basin, farmers do not use the scientific respectively. Mean annual precipitation of Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021
Figure 1. Location of Urmia Lake basin and Saqqez County and the textural classes of 94 soil samples of the study area in the USDA soil texture triangle.
1180 Climate Change and Wheat Water Requirements ______
Saqqez is about 450 mm. In this county, pressures (kPa), G is soil heat flux density -2 -1 approximately 118,000 ha of the land is (MJ m d ), and Rn is net Radiation at the cultivated. On average, wheat is planted in crop surface (MJ m-2 d-1). 83000 ha (70%) of these cultivated lands. Therefore, wheat is one of the main crops of Crop Growth Stages this county. The textural classes of 94 soil samples of the study area are presented in Figure 1. Every plant needs a certain amount of heat According to this figure, Saqqez soils to pass a growth stage, which is referred to include clay loam (41.5%), clay (21.3%), as the heat requirement and is expressed in loam (14.9%), sandy clay loam (9.6%), terms of Growing Degree Days (GDDs). sandy loam (5.3%), silty clay (3.2%), silty Table (1) presents the GDDs required for clay loam (2.1%) and silty loam (2.1%). some wheat growth stages (Bowden et al., These data were obtained from Kurdistan 2008). In this study, the GDDs were Agricultural and Natural Resources calculated using Equation (2). Research and Education Center. nm1 GDD= (( Tib ) T ) (2) j=1m i=1
FAO P-M Equation Where, Ti is hourly air Temperature (°C), m is number of daily air temperature
In this method, reference ET (ET0) is records, n is number of days after sowing, estimated by Equation (1). The required and Tb is the base Temperature. The base climate variables to calculate daily ET0 by temperature, or physiological zero, is the this method were obtained from the Saqqez minimum temperature at which the plant Synoptic Station. This station has a grows, and its value varies for each plant. longitude of 46° 16′ E, a latitude of 36° 15′ For wheat, Tb was set to zero degrees N, and an altitude of 1,522.8 m above mean Celsius (Bowden et al., 2008). sea level. Based on the Kc approach, the plant 900 growth period is divided into four stages 0.408 (Rn G) u(e 2 s e) a ET T 273 including initial (Lini), development (Ldev), 0 (1 0.34 u ) 2 (1) mid (Lmid) and late (Lend) season. The GDDs -1 Where, ET0 is reference ET (mm d ), is required for wheat to pass through the initial slope of the saturation vapor pressure curve (trifoliate), crop development (heading), (kPa °C-1), is psychrometric constant (kPa mid-season (maturity), and late-season -1 -1 Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 °C ), u2 and T are wind speed (m s ) and (harvesting) stages were considered 300, mean air temperature (°C) at 2 m height, ea 1400, 2,200, and 2,500°C, respectively and es are actual and saturation vapor (Allen et al., 1998; Bowden et al., 2008). Table 1. Generic GDDs required for wheat growth stages (Bowden et al., 2008). GDDs GDDs Row growth stage (Codea) Row growth stage (Codea) (°C) (°C) 1 Seeding (00) to emergence (09) 100 7 Flag leaf to heading (59) 140 Emergence to 3 leaves unfolded (Trifoliate) 2 200 8 Heading to anthesis (69) 75 (13) 3 Trifoliate to double ridge (29) 305 9 Anthesis to maturity (89) 800 Maturity to harvested product 4 Double ridge to terminal spikelet (30) 150 10 300 (99) 5 Terminal spikelet to jointing (36) 105 Total 2475 6 Jointing to flag leaf (49) 300 a The decimal code is based on the well-known cereal code developed by Zadoks et al., (1974).
1181 ______Faghih et al.
Dual Kc Method (Kr) is constant (Kr= 1). In the second step, topsoil is apparently dry, and evaporation decreases in proportion Kc is a coefficient that is multiplied by the reference crop ET (ET ) to get the ET . The to the amount of water remaining in the 0 c topsoil. During stage 2 of drying, the Kc is used in the form of single (Equation 3) or dual (Equation 4) approaches. In real-time evaporation rate decreases and Kr is smaller than one (Equation (9)) (Allen et al., 1998). irrigation scheduling, dual Kc is more accurate than single Kc (Allen et al., 1998). Ke K r (K c max K cb ) f ew K c max Therefore, in this study, dual Kc method was (7) used to calculate daily ET of wheat (ETc-w): D TEW 1000( 0.5 ) Z ET K ET e,j 1 FC WP e c c 0 (3) (8) ET (K K ) ET always (K K ) K TEW D c cb e 0 cb e c max Ke,j 1 D REW (4) rTEW REW e,j 1 In Equations (3) and (4), ETc is crop ET (9) -1 (mm d ) and ET0 is reference crop (grass or IE D D (P RO ) jj T DP alfalfa) ET (mm/d), Kc, Kcb, and Ke are e,j e,j1 j j ew,j e,j ffw ew single Kc, basal Kc, and soil evaporation (10) coefficient, respectively. The dual K is c E K ET always smaller than the maximum value of j e 0 (11) Kc (Kc-max). The Kc-max can be obtained using I j Equation (5). The Kcb of mid and late season DP (P RO ) D 0 e,j j jf e,j 1 stages (Kcb-mid and Kcb-end) must be modified w (12) by using Equation (6) for local weather f min(1 f ,f ) conditions (Allen et al., 1998). ew c w (5) Where, u2 is mean wind speed at 2 m KKcb c min (1 0.5 h) -1 fc ( ) height (m s ), RHmin is mean minimum KK Relative Humidity (%), K is modified c max c min cb-adj (6) K , max ( ) is maximum amount of the cb In Equations (7) to (14), K is minimum parameters in the braces { }, separated by c-min K for dry bare soil, f is mean fraction of the comma. c w topsoil wetted by irrigation or rainfall, f is K describes the evaporation component of ew e fraction of the soil wetted and exposed to air ET . To estimate K , it is necessary to c e or soil fraction having maximum calculate daily water balance for the surface Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 evaporation, f is the effective fraction of soil layer using Equations (7) to (14). For c topsoil covered by vegetation, θ and θ this purpose, the process of evaporation FC WP are soil water content at Field Capacity (FC) from bare soil exposed to air is divided into and wilting point (m3 m-3), Z is depth of the two steps. In the first step, topsoil is moist e topsoil layer that is subject to drying by after rainfall or irrigation. Soil evaporation evaporation [0.1-0.15m], TEW (Total has maximum rate, which is limited only by Evaporable Water) is cumulative depth of energy availability. During step 1 of soil evaporable water during a complete cycle of drying, the evaporation reduction coefficient topsoil drying (mm), REW (Readily
h 0.3 Kc max max({1.2 [0.04 (u 2 2) 0.004 (RH min 45)] ( ) },{K cb 0.05}) 3 (5)
h 0.3 Kcb adj K cb [0.04 (u 2 2) 0.004 (RH min 45)] ( ) 3 (6)
1182 Climate Change and Wheat Water Requirements ______
D D (P RO) I CR ET DP , 0 D TAW r,j r,j1 jj j c,j j r,j (15)
Evaporable Water) is cumulative depth of RAW p (TAW) (18) evaporation at the first stage of drying soil Where, the j subscript represents day j, Dr (mm), and h is average plant height (m). Also, is root zone Depletion at the end of the day in these equations, the j subscript represents (mm), P is Precipitation (mm), RO is Runoff day j, De is cumulative evaporation at the end (mm), I is net Irrigation (mm), CR is of the day (mm), P is Precipitation (mm), RO Capillary Rise from the groundwater table is Runoff (mm), I is Irrigation (mm), E is (mm), ETc is crop ET (mm), DP is water Evaporation (mm), Tew is transpiration from loss out of the root zone by Deep the fraction of the topsoil exposed to air and Percolation (mm), Zr is root Zone depth, θFC moisture (mm), and DPe is Deep Percolation is soil water content at FC (m3 m-3), θ is (mm) when the soil moisture content is above 3 -3 average soil water content for Zr (m m ), FC. TAW is Total Available soil Water in Zr As long as the soil moisture content in the (mm), RAW is Readily Available soil Water evaporation layer is less than FC (i.e., De,j> 0), in Zr (mm), and p is average fraction of DPe,j is zero. The amount of Transpiration TAW that can be depleted from Zr before from evaporating soil layer (Tew) is not very moisture stress occurs [0-1]. effective in calculating daily moisture balance After heavy rainfall or irrigation, it can be and can be ignored. The Kc-min coefficient is assumed that θj-1 is about FC and Dr,j-1 is usually the same as the Kcb-ini used for annual zero. Also, in the region where water table is crops (0.15 for wheat) in bare soil conditions more than about 1 m below the bottom of (Allen et al., 1998). root zone (such as in Saqqez), CR can be Time and depth of subsequent irrigation are assumed to be zero (Allen et al., 1998). In determined by computing daily soil water this study, RO was estimated using the balance of the root zone using Equations (15) Curve Number method (Schmit and Scott, to (18). To avoid water stress, irrigation should 2019). be done before or at the moment when Readily Available Water (RAW) is depleted (i.e. Dr,j≤ RAW). Also, to avoid deep percolation, which Mann-Kendall Trend Test leads to leaching of soil nutrients, the net irrigation depth should be smaller than or The M-K statistical test is applied to Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 equal to the amount of water depleted (Ij≤ Dr,j) evaluate the significance of trend in the data (Allen et al., 1998). time series. The M-K statistic, S, is D 1000 ( ) Z calculated using Equation (19). The mean of r,j 1 FC j 1 r (16) S is zero and its variance is calculated by TAW 1000 ( ) Z FC WP r (17) Equation (20). Using the Z-transformation [i.e. Equation (21)], distribution of the S
1 if (Xji X ) 0 n 1 n S sgn(Xj X) i , sgn(X j X) i 0if(X j X) i 0 i 1 j i 1 1 if (X X ) 0 ji (19) 1 m Var(S) [n (n 1) (2n 5) ti (t i 1) (2t i 5)] 18 i1 (20)
1183 ______Faghih et al.
statistic will be an approximately normal (sprinkler) and soil texture fw, REW, TEW, distribution. and TAW were considered 1, 8 (mm), 20 S1 (mm), and 170 (mm), respectively (Allen et if S 0 al., 1998). Maximum crop height (h) and Var(S) root development depth (Zr) were 0.8 and Z 0 if S 0 1.2 m, respectively, according to the experts S1 from Kurdistan Agricultural and Natural if S 0 Resources Research and Education Center. Var(S) (7) Where, Xj is data value, n is number of RESULTS AND DISCUSSION data points, m is number of tied groups (a tied group is a set of sample data having the Trends in ET0 and Climatic Variables same value), and ti is number of data points in the ith tied group. If calculated |Z| value is greater than Z1-α/2, obtained from the The monthly means and M-K statistics of standard normal distribution table with the climatic data and ET0 in Saqqez County significance level of α, the data follow a during 1985-1986 to 2016-2017 are monotonic trend (Yue and Wang 2004; presented in Table 2. It is observed that ET0 Pohlert 2020). has an upward trend at significant levels of In this study, ETc, Eff.P, and NIR were less than 1% in all months of the year, calculated by programming in the Excel except for November. The significant spreadsheet. The calculation process increase trend in ET0 for northwestern Iran, included determining Lini, Ldev, Lmid, Lend, where Urmia Lake basin is located, is also Kcb, Ke, ET0, ETc, Eff.P, and NIR. To use found in the studies of Dinpashoh et al. Equations (7) to (18), it was necessary to (2011) and Kousari and Ahani (2012). determine Kcb-ini, Kcb-mid, Kc-end, Kc-min, p, fw, Precipitation declined significantly in REW, TEW, TAW, Zr, and h. The Kcb-ini, February, March, and April. The average air Kcb-mid, Kc-end, Kc-min and p for winter wheat Temperature (Tmean) has significantly were set as 0.15, 1.10, 0.15, 0.15, and 0.55, increased in all months of the year, except respectively. Based on the irrigation type
Table 2. Monthly means and M-K statistics of climatic data and ET0 in Saqqez County during 1985-1986 to 2016-2017.
-1 -1 -1 ET0 (mm d ) P (mm d ) S (h d ) Tmean (°C) RHmean (%)
Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 Month Mean Z Mean Z Mean Z Mean Z Mean Z Jan. 0.8 6.66*** 1.8 -1.25 ns 4.5 9.90*** -2.2 2.65** 73.8 0.58ns Feb. 1.2 7.72*** 2.0 -4.73*** 5.5 5.28*** -0.3 5.44*** 70.5 -6.41*** Mar. 2.3 4.24*** 2.3 -4.26*** 6.4 4.90*** 4.9 5.65*** 63.9 -2.35* Apr. 3.5 4.21*** 2.2 -4.50*** 7.6 3.13** 10.3 2.58** 59.7 0.49ns May 4.7 2.62** 1.1 -0.08ns 9.5 -0.33ns 14.3 3.32*** 55.5 1.06ns Jun. 6.1 5.01*** 0.2 -1.67ns 11.9 1.44ns 19.1 3.25** 43.6 -0.66ns Jul. 6.6 4.09*** 0.2 1.31ns 11.7 0.74ns 23.6 2.35* 36.1 -2.17* Aug. 6.1 2.82** 0.1 2.77** 11.3 1.08ns 23.4 6.43*** 31.6 -1.15ns Sep. 4.6 3.68*** 0.1 1.06ns 10.5 1.45ns 18.7 5.73*** 32.7 1.81ns Oct. 2.8 2.94** 1.0 0.78ns 8.1 1.77ns 13.0 2.49* 47.1 -1.46ns Nov. 1.3 0.95ns 2.1 0.54ns 6.0 -0.31ns 6.2 -0.11ns 62.8 2.63** Dec. 0.8 3.10** 1.9 -0.03ns 4.5 5.26*** 0.6 -0.46ns 70.7 0.38ns Annual 3.4 3.72*** 1.2 -4.00*** 8.1 3.92*** 11.0 5.11*** 53.9 -0.63ns
*, ** and ***: Indicate a trend at the significance level of 5% (ZC= 1.96), 1% (ZC= 2.576), and 0.1% (ZC= 3.291), respectively.
1184 Climate Change and Wheat Water Requirements ______
for November and December. The Sunshine obtained as 31, 195, 39 and 12 days, (S) had a significant increase in 5 months of respectively. Allen et al. (1998) reported 30, the year (December to April). At the annual 140, 40, and 30 days for Lini, Ldev, Lmid, and scale, ET0, S, and Tmean variables had a Lend for winter wheat, respectively. significant incremental trend. The trend of Therefore, the length of wheat growth period annual precipitation and relative humidity determined in this study is longer than that was decreasing. However, the decreasing suggested by Allen et al. (1998). trend of relative humidity was not significant. Changes in Kc and Ke
Changes in the Length of the Growth Figure 3 shows the daily variations of K Stages cb- adj, Ke, (Kc-adj+Ke), and Kc-max in 2015-2016. Due to low vegetation cover at the beginning Date of planting was set to October 12 by of the growing season (initial stage), Ke will reviewing the literature and according to the be very high if the soil gets wet by irrigation experts from Kurdistan Agricultural-Jahad or rain. As the crop grows and vegetation Organization (Bazgeer et al., 2008). Also, cover is completed, Ke decreases. According using Table 1 and Eq. (2), Lini, Ldev, Lmid, and to Figure 3, it can be said that Ke has a Lend of winter wheat in Saqqez County for 32 decreasing trend during the growth period years (1985-1986 to 2016-2017) were and its fluctuations are related to the wetting estimated. Results are presented in Figure of the soil surface. This result is consistent (2). Coefficient of Variation (CV) for Lini, with field experiments by Zhao et al. (2013). Ldev, Lmid, and Lend was 35.0%, 6.74%, Figure 4 shows the mean Kcb-adj, Ke, (Kc- 6.52% and 7.52%, respectively. The higher adj+Ke), and Kc-max at nine growth stages of value of CV for Lini was due to higher the winter wheat for 2015-2016. Due to the fluctuations in air temperature in the initial low vegetation cover in the initial growth stage than in other stages. Mean Lini, Ldev, stage (planting to trifoliate), Ke is high and Lmid, and Lend for winter wheat were Kcb-adj is low. Thus, in the initial growth
1986 2017 80 1987 1986 2016 1988 2017 1987 2015 70 1989 2016 300 1988 275 2014 60 1990 2015 1989 50 2014 250 1990 2013 1991 Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 225 40 2013 1991 200 2012 30 1992 2012 175 1992 20 2011 1993 150 10 2011 1993 125 2010 0 1994 2010 100 1994 2009 1995 2009 1995 2008 1996 2008 1996 2007 1997 2007 1997 2006 1998 2006 1998 2005 1999 2005 1999 2004 2000 2003 2001 2004 2000 2002 2003 2001 2002 LIni. LMid Lend LDev. Total
Figure 2. Length of the wheat growth stages in Saqqez (1985-1986 to 2016-2017).
1185 ______Faghih et al.
1.4 140
1.2 120
max
- c 1.0 100
), andK ), 0.8 80 e
+K 0.6 60
add -
cb 0.4 40
, (K , e
0.2 20 (mm) and Precipitation NIR
, K ,
add -
cb 0.0 0
K S T D J B HA M H Day after Sowing P Net Irr. Kcb-adj Ke Kcb-adj+Ke Kc-max
Figure 3. Daily Kcb-adj, Ke, Kcb-adj+Ke, Kc-max, and NIR for winter wheat, and precipitation in 2015-2016.
1.4 400
max - c 1.2 350 300
1.0 , K and e 250
0.8 +K
adj 200 - b 0.6
150 , Kc e 0.4
, K 100
adj
- NIR NIR and Precipitation(mm)
cb 0.2 50 K 0.0 0 StE EtT TtD DtJ JtB BtH HtA AtM MTH Stage P Net Irr. Kcb-adj Ke Kcb-adj+Ke Kc-max
Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 Figure 4. Mean Kcb-adj, Ke, (Kcb-adj +Kc), and Kc-max, NIR, and P in nine wheat growth stages in 2015-2016.
Table 3. ETc, NIR, and length of different growth stages of winter wheat in Saqqez region. ET (mm) Net irrigation (mm) Duration c Stage Confidence level Confidence level Nu Of Irr (Day) Distribution Distribution 50 75 90 50 75 90 StE 10 Wakeby 23.0 25.1 27.6 Wakeby 23.0 25.1 27.6 1 EtT 21 Johnson SB 27.9 37.3 47.5 Gumbel Max 5.00 13.5 23.3 TtD 128 Wakeby 132 173 227 Gumbel Max 1.30 7.20 13.9 DtJ 30 Wakeby 109 121 140 Gumbel Min 14.5 42.3 74.1 1 JtB 23 Johnson SB 108 119 128 Normal 59.1 99.0 135 1 BtH 9 Gen Extreme 46.2 51.1 55.6 Gumbel Max 29.7 67.0 109 1 HtA 4 Wakeby 26.1 29.1 32.7 Gumbel Max 26.1 29.1 32.7 1 AtM 40 Wakeby 284 298 313 Wakeby 266 322 358 3 MtHa 13 Wakeby 17.6 24.0 30.9 Gumbel Max 0.20 13.9 29.4 Total 278 774 878 1002 425 619 803 8
1186
Climate Change and Wheat Water Requirements ______
stage, the E portion in ETC is on the calculations are presented in Table 3. It can average more than 80%. With the onset of be seen from this table that the ETc of wheat tillering, due to the increasing trend of green at 50% probability level is 774 mm. The vegetation, the descending trend of Ke mean NIR of wheat was estimated to be 425 begins and continues until the end of the mm. The number of irrigations per growth physiological maturity stage. From the stages include StE (once; 27 mm), DtJ (1 physiological maturity to harvesting, due to time; 16 mm), JtB (1 time; 60 mm), BtH (1 the partial reduction of vegetation cover, Ke time; 30 mm), HtA (1 time; 26 mm), and shows a slightly increasing trend. AtM (3 times; 266 mm). Figure 5 presents the results of calculating According to Equation (14), the mean daily (Kcb-adj+Ke) for initial, mid, and evapotranspiration of wheat (ETc) in Saqqez late-season stages of winter wheat growth is supplied by precipitation and irrigation. during the 32-year period (1985-1986 to Therefore, the difference between ETc (774 2016-2017). The mean daily (Kcb-adj+Ke)ini, mm) and NIR (425 mm) indicates the (Kcb-adj+Ke)mid and (Kcb-adj+Ke)end were 0.79, amount of effective precipitation (i.e. 349 1.18, and 0.23, respectively. These mm). Total evaporation from soil during the coefficients include the effect of both crop wheat growth period (E) was 157 mm, transpiration and soil evaporation; therefore, which was 20% of Evapotranspiration (ETc). they can be used instead of the single Kc. Reference documents for estimating water According to Allen et al. (1998), the single requirement of main crops in Iran (Farshi et Kc of initial, mid and late-season growth al., 1997; Alizadeh, 2003) cite ETc and NIR stages of winter wheat are 0.4, 1.15 and for wheat in Saqqez as (531 and 366 mm) 0.25, respectively. It can be seen from this and (375 and 220 mm), respectively. These figure that (Kcb-adj+Ke)ini and (Kcb-adj+Ke)end reported ETc and NIR values are much less vary for each year. But the (Kcb-adj+Ke)mid than those estimated in this study (774 and was almost constant. The (Kcb-adj+Ke)ini and 425 mm). These researchers considered the (Kcb-adj+Ke)end are dependent on the topsoil length of growth stages to be constant each moisture balance, which is strongly affected year and did not modify the crop coefficients by the weather conditions. Different weather based on weather conditions. These were the conditions in each year caused changes in main reasons for the large differences in soil moisture balance and, as a result, their results compared to the present study. changes in the (Kcb-adj+Ke)ini and (Kcb- Other reasons for the discrepancy can be adj+Ke)end. attributed to the differences in the statistical length of the data and the increasing or
Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 decreasing trend of some climatic data. This ET and NIR c discrepancy in results confirms the necessity of revising and updating the mentioned Daily ETc of wheat (ETc-w) was calculated references. using Equation (4). The time and depth of Mean daily net irrigation requirements, irrigation were determined by Equation (15). evaporation, transpiration, and evaporation The calculations were repeated for 32 years portion of ET (E/ETc) at wheat growth (1985-1986 to 2016-2017). The ETc and stages are presented for 32 years in Figure 6. NIR of the growth stage were obtained from Based on the mean daily ETc and E/ETc, the sum of the daily data. EasyFit5.5 each of the nine wheat growth stages can be software was used to select the statistical classified into three groups with low, distribution of the ETc and NIR data of the moderate, and high sensitivity to water wheat growth stages. The ETc and NIR of stress. wheat were calculated at different Mean soil evaporation and wheat probability levels using the selected transpiration in the four stages of Sowing to appropriate distribution. Results of the Emergence (StE), Emergence to Trifoliate
1187 ______Faghih et al.
) ) 1.40 e
+K 1.20
adj
- cb 1.00
0.80
0.60 ) ) andmean of (K
e 0.40
+K 0.20
adj
- cb
K 0.00 (
Year (Kcb-adj+Ke)ini (Kcb-adj+Ke)Mid (Kcb-adj+Ke)Late mean of (Kcb-adj+Ke)ini mean of (Kcb-adj+Ke)Mid mean of (Kcb-adj+Ke)Late
Figure 5. Mean daily (Kcb-adj+Ke)ini, (Kcb-adj+Ke)mid and (Kcb-adj+Ke)end of winter wheat during the 32-year period (1985-1986 to 2016-2017).
8.0 100 7.0 90 80 6.0 70 5.0 60
4.0 50
)*100 c 3.0 40 30 2.0 (E/ET 20
1.0 10 and Net Irr.,E(mm/day) and T c c 0.0 0
ET StE EtT TtD DtJ JtB BtH HtA AtM MtHa Stage Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 Net Irr. ETc E T (E/ETc)*100
Figure 6. Average daily NIR, T, E, and E/ETc at wheat growth stages in 32 years (1985-1986 to 2016-2017).
(EtT), Trifoliate to Double ridge (TtD), and Mean E and wheat T in three stages of Maturity to Harvesting were (1.84, 0.46), Booting to Heading (BtH), Heading to (1.02, 0.31), (0.58, 0.45), and (0.34, 1.01) Anthesis (HtA), and Anthesis to Maturity mm d-1, respectively. In these four stages, (AtM) were (0.15, 4.98), (0.13, 6.40), and -1 E/ETc was high, and ETc and wheat (0.14, 6.95) mm d , respectively. In these sensitivity to water stress were low. three stages, E/ETc was low, and ETc and Therefore, increasing the irrigation interval wheat sensitivity to water stress were high. in the first three stages of growth and In these three wheat growth stages in the eliminating the end-stage irrigation are Saqqez region, precipitation probability is recommended for saving water and very low and ETc must be supplied through increasing WUE. accurate and timely irrigation.
1188 Climate Change and Wheat Water Requirements ______
Mean E and wheat T in two stages of in ET0 data, which is a compelling reason Double ridge to Jointing (DtJ) and Jointing for updating former documents. to Booting (JtB) were (0.73, 2.90) and (0.42, 4.27) mm d-1, respectively. In these two
stages, wheat sensitivity to water stress was moderate. REFERENCES CONCLUSION 1. Alizadeh, A. 2003. Net Irrigation Requirement of Field Crops and Orchards Proper identification of wheat water- in Iran. Iran Meteorological Organization sensitive growth stages will help planners and Ministry of Agriculture-Jahad, Tehran. and farmers in timely irrigation and optimal (in Persian). management of water use. Also, scientific 2. Allen, R. G., Pereira, L. S. and Smith, D. R. use of deficit irrigation (reducing or 1998. Crop Evapotranspiration (Guidelines eliminating irrigation in growth stages non- for Computing Crop Water Requirements). sensitive to water stress) and supplemental FAO Irrigation and Drainage, Rome, Italy. 3. Arkian, F., Nicholson, S. E. and Ziaie, B. irrigation methods would be possible. In 2018. Meteorological Factors Affecting the addition, water use efficiency can also be Sudden Decline in Lake Urmia’s Water increased. Results showed that wheat Level. Theor. Appl. Climatol., 131: 641– sensitivity to water stress was high from 651. doi:10.1007/s00704-016-1992-6 booting to maturity, low from sowing to 4. Bazgeer, S., Kamali, G., Sedaghatkerdar, double ridge and from maturity to A. and Moradi, A. 2008. Pre-harvest Wheat harvesting, and moderate in other stages. Yield Prediction Using Agrometeorological Agricultural operations are done based on Indices for Different Regions of Kurdistan plant growth stages, which are known to the Province, Iran. Res. J. Environ. Sci., 2(4): farmer. However, previous relevant 275-280. 5. Bowden, P., Edwards, J., Ferguson, N., reference documents of Iran have reported McNee, T., Manning, B., Roberts, K., crop ETc and NIR for ten-day periods. Schipp, A., Schulze, K. and Wilkins, J. Therefore, it is difficult to use the results of 2008. Wheat Growth and Development. these documents in practice. In this study, to NSW Department of Primary Industries, solve this problem, wheat irrigation Sydney. scheduling guideline was developed based 6. Dindarlou, A., Ghaemi, A. A., Shekafandeh on nine principal growth stages of the Nobandegani, A., Bahrami, M. and
Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 Zadoks scale, and the sensitivity of each Dastourani, M. 2019. Interaction of Water stage to water stress was determined. Salinity and Different Irrigation Levels on Duration and crop coefficients of winter Physiological Growth of Olive (Olea europaea L.). J. Agr. Sci. Tech., 21(6): wheat growth stages (i.e. L , L , L , ini. dev. mid 1623-1637. Lend, Kc-ini and Kc-end) varied each year. 7. Dinpashoh, Y., Jhajharia, D., Fakheri-Fard, Therefore, using a constant value for them in A., Singh, V. P. and Kahya, E. 2011. different years will be the main source of Trends in Reference Crop error in calculating the water requirement Evapotranspiration Over Iran. J. Hydrol., based on the Kc method. This subject has not 399: 422-433. been addressed in the national water 8. Erken, O. and Yildirim, M. 2019. Yield and documents of Iran. This result confirms the Quality Compounds of White Cabbage necessity of revising the reference (Brassica oleracea L. cv. Capitata) under documents for estimating water requirement Different Irrigation Levels. J. Agr. Sci. Tech., 21(5): 1341-1352. of the main plants in Iran. In addition, this 9. Ewaid, S. H., Al-Hamzawi, S. A. A. and study showed a significant increasing trend Al-Ansari, N. 2019. Crop Water Requirements and Irrigation Schedules for
1189 ______Faghih et al.
Some Major Crops in Southern Iraq. Water, 18. Mehmood, F., Wang, G., Gao, Y., Liang, 11(4): 1-12. Y., Chen, J., Si, Z., Ramatshaba, T. S., 10. Farshi, A. A., Shariati, M. R., Jarollahi, R., Zain, M., Rahman, S. U. and Duan, A. Ghaemi, M. R., Shahabifar, M. and 2019. Nitrous Oxide Emission from Winter Tavallaei, M. M. 1997. An Estimate of Wheat Field as Responded to Irrigation Water Requirement of Main Field Crops Scheduling and Irrigation Methods in the and Orchards in Iran. Vol. 1, Agricultural North China Plain. Agric. Water Manag., Research, Education and Extension 222: 367-374. Organization, Tehran. (in Persian). 19. Pohlert, T. 2020. Non-Parametric Trend 11. Gao, Y., Yang, L., Shen, X., Li, X., Sun, J., Tests and Change-Point Detection. Duan, A. and Wu, L. 2014. Winter Wheat Available at: https://cran.r- with Subsurface Drip Irrigation (SDI): project.org/web/packages/trend/vignettes/tr Crop Coefficients, Water Use Estimates, end.pdf. Accessed 25 November 2020 and Effects of SDI on Grain Yield and 20. Rosa, R. D., Paredes, P., Rodrigues, G. C., Water Use Efficiency. Agric. Water Fernando, R. M., Alves, I., Pereira, L. S. Manag., 146: 1-10. and Allen, R. G. 2012. Implementing the 12. Goosheh, M., Pazira, E., Gholami, A., Dual Crop Coefficient Approach in Andarzian, B. and Panahpour, E. 2018. Interactive Software: 2. Model testing. Improving Irrigation Scheduling of Wheat Agric. Water Manag., 103: 62-77. to Increase Water Productivity in Shallow 21. Schmit, E. J. and Scott, W. 2019. Design Groundwater Conditions Using Aquacrop. Hydrographs. In “National Engineering Irrig. Drain., 67(5): 738-754. Handbook Natural Resources Conservation 13. Hill, R. W. 2002. Sprinklers, Crop Water Service”, (Eds.): Woodward, D. E. and Use and Irrigation Time Rich County. Utah Hoeft, C. C. Washington DC, 51 PP. State University, Logan. Available at: 22. Singh, M. C., Singh, K. G. and Singh, J. P. https://digitalcommons.usu.edu/cgi/viewco 2019. Nutrient and Water Use Efficiency of ntent.cgi?article=1175&context=extension_ Cucumbers Grown in Soilless Media under histall. Accessed 25 November 2020 a Naturally Ventilated Greenhouse. J. Agr. 14. Incrocci, L., Marzialetti, P., Incrocci, G., Sci. Tech., 21: 193-207. Vita, A. D., Balendonck, J., Bibbiani, C., 23. Taromi Aliabadi, B., Hassandokht, M. R., Spagnol, S. and Pardossi, A. 2014. Etesami, H. Alikhani, H. A. and Substrate Water Status and Dehghanisanij, H. 2019. Effect of Evapotranspiration Irrigation Scheduling in Mulching on Some Characteristics of Heterogenous Container Nursery Crops. Tomato (Lycopersicon esculentum Mill.) Agric. Water Manag., 131: 30-40. under Deficit Irrigation. J. Agr. Sci. Tech., 15. Jha, S. K., Ramatshaba, T. S., Wang, G., 21(4): 927-941. Liang, Y., Liu, H., Gao, Y. and Duan, A. 24. Yue, S. and Wang, C. 2004. The Mann- 2019. Response of Growth, Yield and Kendall Test Modified by Effective Sample Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 Water Use Efficiency of Winter Wheat to Size to Detect Trend in Serially Correlated Different Irrigation Methods and Hydrological Series. Agric. Water Manag., Scheduling in North China Plain. Agric. 18: 201–218. Water Manag., 217: 292–302. 25. Zadoks, J. C., Chang, T. T., Konzak, C. F. 16. Khazaei, B., Khatami, S., Alemohammad, 1974. A Decimal Code for the Growth S., Rashidi, L., Wu, C., Madani, K., Stages of Cereals. Weed Res., 14(6): 415- Kalantari, Z., Destouni, G. and 421. Aghakouchak, A. 2019. Climatic or 26. Zhang, D., Ruiqi, L., Batchelor, W. D., Ju, Regionally Induced by Humans? Tracing H. and Li, Y. 2018. Evaluation of Limited Hydro-Climatic and Landuse Changes to Irrigation Strategies to Improve Water Use Better Understand the Lake Urmia Efficiency and Wheat Yield in the North Tragedy. J. Hydrol., 569: 203–217. China Plain. PLoS One, 13(1): e0189989. 17. Kousari, M. R. and Ahani, H. 2012. An 27. Zhao, N., Liu, Y., Cai, J., Paredes, P., Rosa, Investigation on Reference Crop R. D. and Pereira, L. S. 2013. Dual Crop Evapotranspiration Trend from 1975 to Coefficient Modelling Applied to the 2005 in Iran. Int. J. Climatol., 32: 2387– Winter Wheat–Summer Maize Crop 2402. Sequence in North China Plain: Basal Crop
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Coefficients and Soil Evaporation the North China Plain. Irrig. Drain., 68(4): Component. Agric. Water Manag., 117: 93- 753-764. doi:10.1002/ird.2355 105. 29. Zoljoodi, M. and Didevarasl, A. 2014. 28. Zhou, L., Liao, S., Wang, Z., Wang, P., Water-Level Fluctuations of Urmia Lake: Yan, H., Zhang, Y., Zhang, L., Zhao, X., Relationship with the Long-Term Changes Lin, S. and Zhou, S. 2019. Simulation of of Meteorological Variables (Solutions for Soil Water Content for Irrigation Water-Crisis Management in Urmia Lake Management Based on on-Field and Ceres- Basin). Atmos. Clim. Sci., 4(3): 358-368. Wheat Simulated Data in Winter Wheat in
تغییر در متغیرهای آب و هوایی و تأثیر آنها بر نیاز آبی گندم در حوضه دریاچه ارومیه
ه. فقیه، ج. بهمنش، ح. رضایی و ک. خلیلی
چکیده
تغییر آب و هوا و کارآیی پایین مصرف آب در بخش کشاورزی، دو عامل اصلی کاهش آب ورودی به دریاچه ارومیه میباشند. بنابراین، مدیریت مصرف آب از طریق برنامهریزی آبیاری میتواند راهکاری موثر برای احیای این دریاچه باشد. این تحقیق با هدف بررسی اثر متغیرهای آب و هوایی بر نیاز آبی، شناسایی مراحل رشد حساس به آب و تهیه دستورالعمل برنامهریزی آبیاری برای گندم، که یکی از گیاهان زراعی اصلی در حوضه دریاچه ارومیه است، انجام شد. برای این منظور، تبخیر-تعرق )ETC( و نیاز آبیاری خالص )NIR( مراحل رشد گندم با محاسبه بیالن روزانه رطوبت خاک منطقه ریشه برای دوره 23 ساله )1265-1264 تا 1236-1235( برآورد شد. جداسازی دوره رشد به نه مرحله فنولوژی با استفاده از درجه روزهای رشد و مقیاس Zadoks انجام شد. این مراحل شامل فواصل ]کاشت تا سبز شدن[، ]سبز شدن تا سه برگی[، ]سه برگی تا برجستگی دوگانه[، ]برجستگی دوگانه تا Downloaded from jast.modares.ac.ir at 20:14 IRST on Wednesday September 29th 2021 تشکیل ساقه[، ]تشکیل ساقه تا چکمهپوش[ ، ]چکمهپوش تا تشکیل خوشه[، ]تشکیل خوشه تا گلدهی[، ]گلدهی تا رسیدگی[ و ]رسیدگی تا برداشت[ بودند، که میانگین ETC آنها بهترتیب برابر با 3322، 1322، 1322، 2362، 4363، 5312، 6352، 9323 و 1325 میلیمتر در روز برآورد شد. میانگین تبخیر-تعرق، بارش مؤثر و نیاز آبیاری خالص گندم در طول دوره رشد آن به ترتیب 994 ، 243 و 435 میلیمتر برآورد شد. نتایج نشان داد حساسیت گندم نسبت به تنش آبی از چکمهپوش تا رسیدگی زیاد، از کاشت تا برجستگی دوگانه و از رسیدگی تا برداشت کم و در سایر مراحل متوسط است. بنابراین افزایش فاصله آبیاری در سه مرحله اول رشد و حذف آبیاری مرحله آخر رشد برای صرفه جویی در مصرف آب توصیه میشود.
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