7
reza saeidi
Abstract
For an accurate irrigation schedule, should be estimated the daily soil water depletion amount during the crop growth period. Soil water depletion is dependent to daily evapotranspiration amount. In this research, daily evapotranspiration of S.C 704 maize was measured in mini-lysimeter. Estimation of ...
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For an accurate irrigation schedule, should be estimated the daily soil water depletion amount during the crop growth period. Soil water depletion is dependent to daily evapotranspiration amount. In this research, daily evapotranspiration of S.C 704 maize was measured in mini-lysimeter. Estimation of daily evapotranspiration was done by continuous measurement of soil moisture. Leaves stomatal resistance was measured as daily, and by AP4 Porometer device. Soil water allowable depletion limit in four growth stages of initial(C1), development(C2), mid(C3) and late(C4), was determined based on the leaves stomatal resistance response. The time of leaves stomatal resistance increasing (at each growth stage) relative to control crops, was the time of readily available water ending and doing of new irrigation. Main factor was included of growth stage effect on crop evapotranspiration and water depletion coefficient amounts, which was investigated in a completely randomized basic design, with three replications. Regression functions (models) were used for simulation of soil water allowable depletion coefficient (P) based on the daily evapotranspiration (ETc). The models were calibrated by daily data in initial and development stages, and they were evaluated by daily data in mid and late stages. The FAO-56 linear model was compared with introduced models in this research. The results showed that maize ETc (S.C 704) rate in initial, development, mid, and late stages was in the range of 1.5-4.5, 3.9-7.1, 1.4-7.5, and 0.2-2.1 mm.d-1, respectively. The allowable soil water depletion limit in mentioned stages was calculated as 0.45, 0.66, 0.61 and 0.7, respectively. Different sensitivity in crop growth stages was caused that, readily available water limit not be constant in growth period. The ETc increasing was caused a decreasing in P coefficient, and ETc decreasing was caused an increasing in P coefficient, in growth stages. Linear, exponential, logarithmic, polynomial, power, and FAO-56 linear functions, were investigated. Polynomial function with statistical indices of RMSE=0.00035, NRMSE=0.054, ME=0.0008, CRM=-000005, R2=0.999 and EF=0.999, was the optimal model in estimation of P coefficient. The reason of weak performance in FAO-56 model, was considering the constant limit for readily available water and mean ETc rate in growing season. Therefore, the FAO-56 model was modified. The research result was to estimate the soil water allowable depletion coefficient (by using ETc), without daily measurement of soil moisture. This method will be useful in irrigation scheduling with short rounds, especially. So that, the suitable time and volume of irrigation are determined for water loss prevention.
7
Reza Saeidi; Mohamad Mahdi Zarrabi; Davood Babaei
Abstract
In this research, the effect of irrigation water salinity and salicylic acid spraying were investigated on the yield of shallot (Qazvin local variety). Water salinity treatments at four levels of 2(S1), 4(S2), 6(S3), and 8(S4) dS.m-1 and salicylic acid at four concentrations of 0(A1), 0.5(A2), 1(A3) ...
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In this research, the effect of irrigation water salinity and salicylic acid spraying were investigated on the yield of shallot (Qazvin local variety). Water salinity treatments at four levels of 2(S1), 4(S2), 6(S3), and 8(S4) dS.m-1 and salicylic acid at four concentrations of 0(A1), 0.5(A2), 1(A3) and 2(A4) mM were applied in the greenhouse. The experiment was performed as factorial and in a completely randomized design, with three replications. Soil moisture was measured daily, and irrigation scheduling was done based on it. Results showed that salinity stress reduced crop water uptake and shallot tuber weight. Salicylic acid application improved crop water status and increased tubers weight under salinity stress. A4 treatment was the ideal concentration for maximum yield. Application of 2 mM salicylic acid at salinity levels of S1, S2, S3, and S4 increased tubers yield by 11.6%, 32%, 40% and 91%, respectively, compared to the control (A1). The response of dry yield to evapotranspiration showed that by increasing salinity stress, percentage of yield decreased more than the percentage of evapotranspiration. Use of salicylic acid decreased dry yield sensitivity to salinity stress, such that from treatment S1 to S4 yield response coefficients (Ky) were between 1.01- 1.62 (in A1 treatment), 0.93- 1.3 (A2), 0.48- 1.09 (A3) and 0.31- 0.97 (A4). The effect of salicylic acid on water productivity were calculated between 2.13- 1.14 (in A1), 2.15- 1.68 (A2), 2.26- 2 (A3), and 2.38- 2.19 kg.m-3 (A4). In conditions of using saline water for crop irrigation, application of salicylic acid will increase water productivity. Based on the experiment results and in conditions of lack of high-quality water for irrigation, salicylic acid spraying on crops will be a suitable method to reduce the harmful effects of salinity stress.
1
reza saeidi; AbdolMajid Liaghat
Abstract
This research aimed to simulate the yield of maize cv. S. C 704 under conditions of separate application of salinity stress at different growth stages in mini-lysimeter, in Qazvin area, Iran. The experiment was performed as factorial and in a completely randomized design. Soil salinity treatments, as ...
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This research aimed to simulate the yield of maize cv. S. C 704 under conditions of separate application of salinity stress at different growth stages in mini-lysimeter, in Qazvin area, Iran. The experiment was performed as factorial and in a completely randomized design. Soil salinity treatments, as the main factor, included four levels of 1.7(S1), 3(S2), 5(S3) and 7(S4) dS.m-1. The sub-factors included different growth stages as follows: one-stage at 6-leaves (C1), flowering (C2), and milk stage (C3); and two-stages of C1C2, C1C3 and C2C3. By combining saline water (from a salt marsh) with a well fresh water (0.5 dS.m-1), saline water was prepared according to the treatments. Irrigation was done in a way that the salinity of input and output water from the mini-lysimeters was equal. The control treatment was irrigated with fresh water. By combining the water uptake reduction functions, the derived models were presented and evaluated for simulating yield reduction coefficient (α). The stress application data in one and two-growth stages were used for models calibration and validation, respectively. Applying the highest salinity level led to decrease in dry matter yield from 157.2 g. plant-1 (in S1 treatment) to 115.9, 53.2, 77.7, 86.1, 97 and 46.5 g. plant-1 in the C1, C2, C3, C1C2, C1C3 and C2C3 treatments, respectively. The results showed that crop sensitivity was different in one-stage and two-stage stress application. Salinity stress at flowering (C2) and milk stage (C3) had a more negative effect relative to C1C2 and C1C3. In this research, Van Genuchten's additive model and Dirksen-Maas-Hoffman's multipliable model could be recommended as the optimal models for crop yield simulation. Also, application of two-stage salinity stress (up to level of 7 dS.m-1) in C1C2 and C1C3, had higher yield relative to application of one-stage stress in C2 and C3 growth stages.
7
reza saeidi
Abstract
For irrigation planning, parameters such as actual crop water needs (transpiration) and water losses (evaporation) are considered. In this research, for management of deficit irrigation, the amounts of maize evapotranspiration components were simulated under water stress conditions. Water stress was ...
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For irrigation planning, parameters such as actual crop water needs (transpiration) and water losses (evaporation) are considered. In this research, for management of deficit irrigation, the amounts of maize evapotranspiration components were simulated under water stress conditions. Water stress was applied by reducing the soil water, relative to the readily available water. Four treatments were defined as depletion of the available soil water by 40% (I0), 55% (I1), 70% (I2), and 85% (I3). The amounts of maize evapotranspiration and its components (transpiration and evaporation rates separately) were measured in a mini-lysimeter. The seasonal total values of evapotranspiration and components of transpiration and evaporation were equal to 443, 319 and 124 mm (I0), 401, 282 and 119 mm (I1), 303, 211 and 92 mm (I2), and 201, 127 and 74 mm (I3), respectively. Soil water deficiency reduced the evapotranspiration and its components relative to the normal conditions (treatment I0). Reduction of evaporation losses was favorable point in this deficit irrigation method (long irrigation interval). Transpiration and evaporation values were simulated based on the evapotranspiration data (in I0), evapotranspiration stress coefficient (Ks), and crop growth stage sensitivity (Kpi). For this purpose, we used the linear, exponential, logarithmic, polynomial, and power functions as the regression models. By using the actual data, unknown coefficients in the functions were estimated by SPSS software and regression models were generated. Statistical analyses showed that the linear function (R2= 0.91) and polynomial function (R2= 0.874) were the optimal models for estimation of transpiration and evaporation components (under water stress conditions), respectively. The actual water requirement of crop and evaporation losses can be estimated more accurately by separate estimation of evapotranspiration components. This would provide a suitable criterion for irrigation planning and calculation of water use efficiency.
7
reza saeidi
Abstract
In this research, the effect of salinity stress on the amount of evapotranspiration components of maize were investigated in mini-lysimeters (in the initial, development, mid, and late growth stages). Salinity treatments were applied by water with EC of 0.5(S0), 2.1(S1), 3.5(S2), and 5.7(S3) dS.m-1. ...
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In this research, the effect of salinity stress on the amount of evapotranspiration components of maize were investigated in mini-lysimeters (in the initial, development, mid, and late growth stages). Salinity treatments were applied by water with EC of 0.5(S0), 2.1(S1), 3.5(S2), and 5.7(S3) dS.m-1. The experiment was performed as factorial and in a completely randomized design. For the whole growth period and for S0 to S3 treatments, the values of evapotranspiration, transpiration, and evaporation were measured in the range of 420-320, 285-124, and 135-196 mm, respectively. The share of crop transpiration (T/ETc) decreased by 29% while the share of evaporation (E/ETc) increased by the same value. From S0 to S3 treatment, the values of evapotranspiration, transpiration and evaporation were measured in the range of 420-320, 1 / 285-3 / 124 and 134-7 / 195.9 mm (in the whole growth period), respectively.From S0 to S3 treatments, the values of evapotranspiration, transpiration and evaporation were measured in the range of 79-72, 19-10 and 61-62 mm (initial stage), 202-150, 150-71, and 51-79 mm (development stage), 124-84, 110-39, and 14-45 mm (mid stage), and 15-14, 6-4, and 9-10 mm (the late stage). The shares of crop transpiration decreased in the order of the developmental, mid, initial, and the late stages, while the decreasing order for the shares of evaporation was related to the initial, developmental, mid, and late stages, respectively. The dry biomass yield decreased by salinity stress, and its amount in treatments S0, S1, S2, and S3 was as 12942, 12168, 10872, and 8928 kg.ha-1, respectively. Stress coefficients of evapotranspiration (KS), transpiration (KS-T), and evaporation (KS-E) were calculated in the range of 1-0.76, 1-0.43, and 1-1.45, respectively. The results showed that for 1 dS.m-1 increase in water salinity, the amounts of relative evapotranspiration and relative transpiration decreased by 4.7% and 11.1%, respectively, and the amount of relative evaporation increased by 9%. The results showed that the transpiration component decreased with a greater slope, relative to the evapotranspiration.
7
reza saeidi
Abstract
Determining the intra-seasonal sensitivity of maize evapotranspiration to environmental stresses has an important effect on modeling of yield. In this research, the effect of drought and salinity stresses were investigated on the relative evapotranspiration (during initial, development, mid, and late ...
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Determining the intra-seasonal sensitivity of maize evapotranspiration to environmental stresses has an important effect on modeling of yield. In this research, the effect of drought and salinity stresses were investigated on the relative evapotranspiration (during initial, development, mid, and late stages) and relative yield of maize, in a field with sandy loam soil texture. Salinity treatments were applied by water with EC of 0.5(S0), 2.1(S1), 3.5(S2), and 5.7(S3) dS.m-1. Drought treatments included four irrigation levels of 100% (I0), 80% (I1), 60% (I2), and 40% (I3) of the crop water requirement. The experiment was performed as factorial in a randomized complete block design, with three replications. The relative evapotranspiration of maize in the initial, development, middle and final stages was estimated between 63.5-100%, 62.6-100%, 55.2-100%, and 66.4-100%, respectively. The relative yield of maize in the I0S0 to I3S3 treatments was calculated between 42.6-100%. The results showed that salinity and drought stresses reduced both the evapotranspiration and maize yield. Also, evapotranspiration decreased with a steeper slope in sensitive growth stages compared to yield. Effect of the mentioned stresses at sensitive growth stages caused disruption in the flowering and fruiting of maize. In this study, the relative yield of maize was modeled by additive models of Blank, Stuart, Singh and multipliable models of Jensen, Rao, and Minhas. According to the results, Stewart model with sensitivity coefficients (in four growth stages) of 0.227, 0.416, 0.604, 0.14 and Jensen model with sensitivity coefficients of 0.301, 0.41, 0.608, and 0.147 were selected as the optimal models. However, Rao, Blank, Singh, and Minhas models were chosen as the next priorities. Therefore, under salinity and drought stress, the relative yield of maize was modeled based on the amount of evapotranspiration in the growth stages.
reza saeidi; Hadi Ramezani Etedali; Abbas Sotoodehnia; abbas kaviani; Bijan Nazari
Abstract
In this study, yield and evapotranspiration of maize (cv. SC 704) were investigated under salinity stress and nitrogen deficiency. The experiment was carried out in a randomized complete block design. Electrical conductivities of saline water treatments were 0.5( 15S0"> ), 2.1( 15S1)"> , 3.5( 15S2) ...
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In this study, yield and evapotranspiration of maize (cv. SC 704) were investigated under salinity stress and nitrogen deficiency. The experiment was carried out in a randomized complete block design. Electrical conductivities of saline water treatments were 0.5( 15S0"> ), 2.1( 15S1)"> , 3.5( 15S2) "> , and 5.7( 15S3) "> dS. 15m-1"> . Nitrogen deficiency treatments were 100% ( 15F0"> ), 75% ( 15F1"> ), 50% ( 15F2"> ), and 25% ( 15F3"> ) of nitrogen fertilizer requirement based on soil testing. The treatments were carried out in three replications and in plots with area of 9 m2. In different treatments, evapotranspiration of maize was between 220 to 349 mm and dry matter yield between 9.4 to 15.2 ton.ha-1. With increase in the salinity levels in , , , and treatments, the slopes of yield function were estimated as 0.2, 0.207, 0.218, and 0.231, respectively. Also, with reduction of nitrogen at salinity levels of , , and , the slopes were estimated as 0.175, 0.182, 0.194 and 0.221, respectively. The results showed that, with increasing stresses, yield of maize decreased more than evapotranspiration. The coefficient of was calculated using the Doorenbos-Kassam relationship. With reduction of nitrogen at salinity levels of , , and , values of coefficient were estimated as 1.01, 1.048, 1.119, and 1.272, respectively. Also, with increase in the salinity at nitrogen levels of , , and , Ky values were estimated as 1.15, 1.19, 1.258, and 1.328, respectively. On the average, Ky was calculated as 1.27. Under the highest stress 15 S3F3"> , water and nitrogen use efficiency decreased by: 38% and 34.5%, respectively, compared to the control treatment (S0F0). The results showed that the water requirement and yield of maize under the mentioned stresses were less than the region’s potential. Under these conditions, by supplying soil nitrogen and reducing water use, water resources will be used optimally and yield will increase.