Meysam Abedinpour; hadi dehghan; mahdi mokari; hadi Memarian
Abstract
This study was conducted to simulate water balance components at field scale, predict soil moisture profile, and grain yield in irrigated wheat fields in Neyshabur plain. In this regard, three farms were selected in different parts of the plain. AquaCrop input data including air, soil, and crop parameters ...
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This study was conducted to simulate water balance components at field scale, predict soil moisture profile, and grain yield in irrigated wheat fields in Neyshabur plain. In this regard, three farms were selected in different parts of the plain. AquaCrop input data including air, soil, and crop parameters were collected at each farm separately, then, the required model parameters and wheat crop data were calibrated. Root mean square error (RMSE), model efficiency (EF) and prediction error (Pe) were used to evaluate the model performance. The results of moisture simulation in soil profile showed that the model correctly simulated moisture content at different depths and times. The statistical parameters used for evaluating efficiency of the model at the calibration stage for simulating soil moisture in all farms were 0.027<RMSE<0.032, 0.80<EF<0.91, and 3.5<Pe<14%. These values at model validation stage were 0.025<RMSE<0.031, 0.82<EF<0.94, and 2.7<Pe<12%. The minimum and maximum percentages of model simulation error for grain yield and water productivity in all farms managed by the farmers were 4-8.8% and 4.6 to 9%, respectively. According to the results of the research, AquaCrop model can simulate soil moisture content, grain yield, and water productivity with acceptable accuracy under similar field conditions.
Sina Fallah; razieh kakolvand; ali abbasi
Abstract
Increasing water use efficiency (WUE) is one of the most important strategies for mitigating water deficiency crisis. The aim of this study was to investigate the effect of plant competition on water use efficiency of intercropping under different moisture regimes. The experiment was a ...
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Increasing water use efficiency (WUE) is one of the most important strategies for mitigating water deficiency crisis. The aim of this study was to investigate the effect of plant competition on water use efficiency of intercropping under different moisture regimes. The experiment was a split–split-plot design with three replications. The main plot consisted of three levels of soil moisture including W1: full irrigation, W2: mild stress (irrigation on the basis of 75% W1), W3: severe stress (irrigation on the basis of 75 % W1). The subplot contained five planting patterns: fenugreek sole crop, nigella sole crop and three mixed ratios (2:1, 1:1, 1:2 of fenugreek and nigella). Results showed that the greatest WUE for seed production (WUEs) was obtained in fenugreek: nigella (1:2) treatment under drought stress conditions. Under mild stress conditions, the WUEs in fenugreek: nigella (1:2) treatment was even higher than nigella sole crop under no stress conditions, under which the highest WUE for biomass was observed in fenugreek: nigella (1:2) and (2:1) treatments and the lowest level was in nigella sole crop. The water equivalent ratio (WER) of intercropping treatments was superior to each of the sole crops of fenugreek and nigella. Under mild stress conditions, the maximum level of WER in fenugreek: nigella (1:2) and (2:1) treatments was 1.44 and 1.47, respectively. It can be concluded that interspecies competition is one of important strategies to increase the WUE and production under drought stress conditions.
z s; m d; mehdi panahi; E A
Abstract
Effects of six irrigation treatments on vegetative characteristics, yield, and sugar content of sugar beet and water use efficiency were investigated. The experiment was conducted at Aleshtar in Lorestan province during growing seasons of 2014 and 2015, using a randomized complete block design. Irrigation ...
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Effects of six irrigation treatments on vegetative characteristics, yield, and sugar content of sugar beet and water use efficiency were investigated. The experiment was conducted at Aleshtar in Lorestan province during growing seasons of 2014 and 2015, using a randomized complete block design. Irrigation treatments consisted of full irrigation (T1) as the control, T1 +cutting off the last irrigation (T2), 10% higher than the control (T3), 10% less than the control (T4), 20% (T5) and 30% less than the control (T6). The results of combined analysis of variance showed that the effects of different irrigation treatments on leaf area index, tuber dry weight, root yield, biomass, sugar content, sugar yield and water use efficiency on the basis of sugar yield was significant at 1% level. However, their effects on leaf dry weight and water use efficiency on the root yield basis was significant at 5% level. Although there were no significant differences between T2, T3, and T4 treatments in terms of crop vegetative characteristics, root yield, biomass and sugar yield, they increased these characteristics significantly compared to T5 and T6 treatments. Also, the highest water use efficiency on the basis of both root and sugar yield was obtained in T2 and T4 treatments. Therefore, to conserve water in sugar beet production in Lorestan province, decreasing the amount of water up to 10 % at each irrigation during the growing season or cutting off the last irrigation is recommended.
p sh; e a; s r; m a
Abstract
Today, even in humid areas, the water crisis is a major problem for agriculture and increasing the efficiency of water use is also one of the requirements for sustainable development. Regarding this, the use of plant growth simulation models as a tool for managing water crisis seems useful. In this study, ...
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Today, even in humid areas, the water crisis is a major problem for agriculture and increasing the efficiency of water use is also one of the requirements for sustainable development. Regarding this, the use of plant growth simulation models as a tool for managing water crisis seems useful. In this study, WOFOST model to simulate the performance of two soybean cultivars (DPX and SEPIDEH) under deficit irrigation was used in the Gorgan region. Using the measured plant yield and simulated water balance components from the model, the average productivity of evapotranspiration (Wp < sub>ET), based on seed yield, was obtained as 0.72 kg m-3. With increasing water stress, water use efficiency based on irrigation and precipitation series (Wp < sub>I+R) and water use efficiency based on irrigation (Wp < sub>I) increased in both cultivars, but the DPX water use efficiency under drought stress was higher than the SEPIDEH cultivar. According to the results and accuracy of WOFOST model, index of relative root mean square errors of seed yield and total biomass in both cultivars was less than 10%, the index of the coefficient of residual mass (CRM) was close to zero, the performance factor (EF) was 0.89, the coefficient of determination (R2) equaled 0.93, and the index of Willmott agreement (IOA) was about 0.89. Overall, based on the findings of this study, favorable performance of the model to simulate the growth process and water impact on soybean seed yield and water efficiency is confirmed and cultivar DPX is recommended for cultivation in the Golestan province.
m m; k d; b gh; h a; a h
Abstract
Crop growth simulation models have been developed for predicting the effects of water and salinity on grain and biomass yields and water productivity of different crops. These models are calibrated and validated for different regions using the data generated from field. This study was carried in Mashhad ...
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Crop growth simulation models have been developed for predicting the effects of water and salinity on grain and biomass yields and water productivity of different crops. These models are calibrated and validated for different regions using the data generated from field. This study was carried in Mashhad for two years (2010 and 2011) in order to evaluate the AquaCrop model under simultaneous salinity and water stress. Calibration was done using the data of 2009-2010 and validation with the data of 2010-2011.Results indicated that AquaCrop successfully simulated yield, biomass, water productivity, harvest index, soil moisture and salinity profiles for spring wheat under salinity and water-limiting treatments with high accuracy, although simulation of harvest index and soil salinity profiles were less accurate. Average value of normalized root mean square error (NRMSE), maximum error (ME), index of agreement (d), coefficient of the residual mass (CRM) and coefficient of determination (R2) in both the calibration and verification were 13.3 %, 36.1 %, 0.95, -0.072, and 0.87, respectively, for grain yield, while these measures were 12.59%, 34.46%, 0.92, 0.057, and 0.77, respectively, for biomass. Also, value of NRMSE, ME, d and CRM were 11.84 %, 25.72 %, 0.93, and 0.032, respectively, for soil moisture, while these measures were 26.25%, 58.5%, 0.91 and -0.12, respectively, for soil salinity. Sensitivity analysis revealed that crop transpiration coefficient (KC-Tr), normalized crop water productivity (WP*), reference harvest index (HIO), volumetric water content at field capacity, soil water content at saturation[S1] , and air temperature were the most sensitive parameters. Although the accuracy of the model simulation decreased with increasing salinity and water stress, AquaCrop can be a valuable model for simulating spring wheat yield and soil water content and salinity in Mashhad region, because the model requires few input data which can be readily available or easily collected. [S1]This is probably”initial conditions” and not saturation.
Mostafa Ghasemi; Kazem Arzani; Abbas Yadolahi; Hossin Hokmabadi
Abstract
Chlorophyll fluorescence is a non-destructive tool for estimation of the efficiency of photochemistry and photosynthesis status in plants and has extensively been used in assessing plants response to environmental stresses. The aim of this study was to evaluate the effect of drought stress on chlorophyll ...
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Chlorophyll fluorescence is a non-destructive tool for estimation of the efficiency of photochemistry and photosynthesis status in plants and has extensively been used in assessing plants response to environmental stresses. The aim of this study was to evaluate the effect of drought stress on chlorophyll fluorescence, chlorophyll content, chlorophyll index, and biomass in four pistachio seedling rootstocks grown under greenhouse conditions. The rootstocks were Pistacia vera cv. Badami-e-Zarand, P. vera cv Ghazvini, P. vera cv. Sarakhs, and P. mutica. The results showed that water stress reduced FV/Fm ratio (which is an indicator for the maximum efficiency of photosystem II), chlorophyll contents, and biomass in plants. Highest amount of FV/Fm ratio was observed in the control treatment (full irrigation) and had significant difference with the severe stress treatment. In most cases, there was no significant difference among studied rootstocks, except P. mutica that showed the highest quantum yield of PSII. The maximum and minimum chlorophyll concentrations in irrigation treatments were also obtained in the control and severe stress treatments, respectively. The effects of genotypes on the chlorophyll contents (a, b, total and CCI) were significant and the highest and the lowest of these parameters belonged to P. mutica and P. vera cv. Sarakhs, respectively. In the case of shoot, root, and leaf dry weight, the rootstocks P. mutica and P. vera cv. Badami showed lower reduction under water stress. Based on the results, water stress had negative effects on pistachio seedling rootstocks and P. mutica showed more resistance than the other genotypes.