Prediction of plant water consumption in each growth stage plays an important role in soil and water resources management and proper irrigation scheduling. The aim of this study was to determine the amount of water requirement and crop coefficient of pepper in terms of soil coverage with different amounts of Zycosil. This paper used the Kc procedure of FAO No. 56 (Allen et al. 1998) to obtain single and dual crop coefficients of sweet pepper. The dual crop coefficient approach is more complicated and requires more numerical calculations than the single crop coefficient approach. The single crop coefficient is defined as the ratio of ET from crop to some reference ET as defined by weather data. The dual crop coefficient has two fractions, one for crop transpiration, i. e., the basal crop coefficient (Kcb), and one for soil evaporation (Ke). Basal crop coefficients, Kcb, represent primarily the transpiration component of ET and a small evaporation component from soil that is visibly dry at the surface.

Introduction: The chickpea (Cicer arietinum L.) especially Bivanij cultivar is one of the most important bean crops cultivated in the Kermanshah Province. The high value of protein in chickpea is the reason for its cultivation. For an efficient and optimum use of water resources in each area, the water requirement and crop coefficients of each plant is necessary. The crop evapotranspiration and irrigation water requirement can be estimated from meteorological data. Although, a precise values of mentioned parameters determination can be obtained by lysimeter in the field condition. Determination of crop coefficients is necessary for an accurate irrigation water requirement and irrigation scheduling. Also, crop water estimation at different crop stages makes it a precise determination of total water requirement. However, water requirement and the crop coefficients of chickpea (Bivanij cultivar) have not been determined in semiarid area in Kermanshah province for practical purposes and proper irrigation management use.Materials & Methods: In this study the water requirement, single and dual crop coefficients of chickpea (Bivanij) cultivar was determined by using water balance lysimeter during two years from 2013 to 2014. Five water balance drainable lysimeters in the lysimeteric station belong to Department of Irrigation and Water Resources Engineering in Campus of Agriculture and Natural Resource, Razi University were used. One lysimeter was used for grass evapotranspiration and one lysimeter was used for bare soil evapotranspiration estimation. Therefore, three Lysimeters were used for determination of chickpea evapotranspiration. Drainable lysimeters were used with an internal diameter of 1.20 m and a depth of 1.40 m. Both inside and outside of each lysimeter were painted with epoxy paint to prevent rusting. A Time Domain Reflectometer system (Trime -Fm with P2G probes) was used to measure soil moisture. TDR probes were 6 mm in diameter and 160 mm long. The probes were installed in all lysimeters at 6 different depths of 0.20, 0.40, 0.60, 0.80, 1.0 and 1.2 m. The irrigation was carried out in all lysimeters after 30% depletion of available soil moisture to avoid any water stresses during the growing period. The collected water from lysimeters was measured by a graded container. Silty clay soil consisting of 54% clay, 42.3% silt and 3.7% sand was used in lysimeters. In this study, the SIMDualKc model were calibrated and validated for chickpea crop to find its ability for proper and accurate water resources management. Regression coefficients (r), root mean square error (RMSE), mean bias error (MBE) and t-statistic test (t) were used for SIMDualKc model evaluation by comparing observed and simulated Dual Kc values over time, for the experimental area.Results & Discussion: Water requirement of chickpea (Bivanij cultivar) was determined as 379.05 and 480.45 mm for 2013 and 2014 respectively. In this study, the average length of the four stages of chickpeas during years 2013 and 2014 were determined as 16, 24, 39 and 25 days. The chickpea growing period in lysimeters was divided into four stages (initial, development, middle and end).The average single crop coefficients for different periods of growth were obtained as 0.54, 0.82, 1.11 and 0.69, respectively. Moreover, the basal crop coefficients of chickpeas values for different periods of growth in two years and the average values were obtained as 0.39, 0.71, 1.01 and 0.62, respectively. Also, by comparing the results of lysimeteric data with SIMDualKc model it was observed that the results of the model with calculation results were highly correlated as (R2= 0.85) in the year 2013 and (R2= 0.86) in year 2014.Conclusion: The seasonal ETc of chickpea (Bivanij cultivar) was determined in semiarid area of Kermanshah province. According to obtained results during of two years investigation, it can be suggest that the estimated water requirement and irrigation management of chickpea's plant in dry and semi-dry climate with acceptable accuracy was possible. The results of this research showed the ability of SIMDualKc model for estimating all irrigation management parameters with high accuracy conditions.

The main purpose of irrigation is to achieve an optimum amount of yield with an economical use of water according to the crop water requirement. An improved irrigation scheduling would lead to the reduction of the excess water use, and the enhancement of crop production. In order to develop a proper irrigation scheduling, actual crop water requirement must be determined.Accordingly, it was attempted to determine the water requirement of tuberose (Polianthes tuberose L.) irrigated by a drip irrigation system and grown in a glass greenhouse located in Varamin during 1392. In order to calculate the water requirement of the tuberose, a simple water balance method was applied.. Tensiometers were installed at two soil depths and were used to determine the time of irrigation events. Irrigation was applied at any time when the soil suction reached to 30 centibar. The Water requirement of Polianthes tuberose for a 144 day growing season (Jun. to Oct.) was found to be 350 mm. The average actual evapotranspiration of Polianthes tuberose was 2.5 mm/day. Based on the data collected from a Class A evaporation Pan located inside the greenhouse, the monthly crop coefficients for tuberose were between 0.5- 0.7.

An experiment was conducted in a commercial greenhouse to determine cucumber (Negin cultivar) evapotranspiration and crop coefficient in two seasons of winter and spring cultivation in Hamedan province,Irrigation was done to meet 100% of the water requirement based on reaching the suction tensiometer to the field capacity (40 to 50 cm),The soil water balance was used to estimate plant evapotranspiration in the greenhouse,Stanghellini and FAO Penman-Monteith evapotranspiration methods were 214,2 and 181,5 mm in winter and 222,3 and 227,6 mm in spring,respectively,The evapotranspiration ratio by the FAO Penman-Monteith method inside and outside the greenhouse in winter and spring cultivation was 0,8 and 0,81,respectively,The actual evapotranspiration from soil water balance in winter and spring cultivation were 148,2 and 210,4 mm,respectively,The results showed that the average crop coefficient in the initial,middle,and final stages of the growing season in winter planting was 0,69,1,43,and 1,05,and in spring planting were 0,63,1,15,and 0,9,respectively,The results of this study showed the necessary scientific basis for optimizing irrigation and saving water consumption,creating appropriate irrigation planning,and improving the crop water use efficiency in the greenhouse,Also,by reducing excessive water consumption,it can reduce energy consumption and provide a maximum increase in product production efficiency and economic efficiency,The investigation of evapotranspiration,crop canopy growth,and humidity changes during the growing season also showed that it is necessary to prevent the development of plant diseases,to use a higher ventilation level or forced ventilation in greenhouses,

In all methods in which the evapotranspiration of plants is counted as a reference, in order to generalize the results to the vegetation, it is necessary to multiply the acquired amount to the crop coefficient. An experiment was done to estimate the crop coefficient amount of evening primrose that was repeated four times in a time period of 70 days on March 2018. [D1], in a weather station located in the agriculture college of Ferdowsi University of Mashhad. In this experiment, the plants were cultivated in white plastic pots (micro-lysimeter) by 50 centimetre height and 30 centimeter width. The demanded amount of water to provide the plants' water needs is considered based on the field capacity. By controlling the water balance in pots, the evapotranspiration of plants was measure and by the use of evaporation pan A data, the crop coefficient was calculated. According to the results of this study the crop coefficient of evening primrose in the initial, middle and final steps are 0. 75, 1. 05 and 1. 00 respectfully. The average in whole the period evening primrose growth was 0. 92. The total amount of evapotranspiration of plants was estimated to be about 377 millimeters.

An important factor in determining water demand and optimum water management at different growth stages of sugar beet seed-bearing plants is crop coefficient (Kc). The crop coefficient (the ratio of sugar beet seed-bearing plant evapotranspiration (ETc) to grass evapotranspiration (ET0)) was calculated at different growth stages. The study was carried out by 6 lysimeters located in research station of Karaj Soil and Water Research Institute, Meshkinabad, Karaj in 2006. Two lysimeters where grass had been cultivated were used for determining ET0. To determine ETc of sugar beet seed-bearing plants, vernalized roots of sugar beet (200-250 g) were planted in four lysimeters. About 2000 and 1000 m2 were planted by the same crop around the lysimeters of sugar beet seed-bearing plants and grass, respectively. The moisture contents of all lysimeters were measured during the growth period and also after harvest at the depth of 0-60 cm. To compensate soil moisture deficit, the irrigation was carried out after depletion of 40% of available moisture. In addition, precipitation, daily temperature, relative humidity, wind speed, sunny hours and evaporation from Class A pan was measured in a meteorological station located around the grass lysimeters during the growing period. The measured crop factors included root number, total biomass weight, shoot dry weight, root dry weight, flowering stem weight, seed total weight, seed size, standard seed weight, 1000-seed weight, vigor, germination rate and seed viability. ET0 was calculated by evaporation pan and applying pan coefficient (Kp) of Karaj and also by Penman & Mantis method and was compared with the data of grass lysimeter. ETc, ET0 as well as Kc were estimated at different growth stages. The results showed that there was great conformity between two methods of ET0 calculation, i.e. by software CROPWAT and measurement. But at the beginning of the study, the ET0 calculated by grass lysimeters was lower than that calculated by meteorological data. However, over the time, the latter was affected by climatic parameters of temperature and sunny hours and increased with a stronger gradient than the former. This period was from the 50th day on. The results indicated that crop evapotranspiration decreased at the initial stage because of undeveloped shoots and at final stage and at the end of growth period because of shoot yellowing and loss of green area and the need for the decrease in seed moisture during maturation. At the second stage, the crop absorbed greater amount of water and as a result, its evapotranspiration increased because of the fast growth of sugar beet seed-bearing plants and the proliferation of aerial organs. At the third stage, since on one hand the leaf area of sugar beet seed-bearing plants was at its peak and on the other hand, the other organs were green, the evapotranspiration of the crop was in its peak. At initial stages of the growth, ET0 was greater than ETc of sugar beet seed-bearing plants; however, the gradient of these two curves became almost constant over the time and ETc started to sharply decrease from the beginning of the final stage (i.e. about 90th day). The Kc of sugar beet seed-bearing plants at initial, development, middle and final stages was 0.29, 0.89, 1.12 and 0.66, respectively. Sugar beet seed-bearing plants consumed 35.13, 141.93, 273.59 and 65.49 mm water at initial, development, middle and final stages, respectively. Their peak water consumption was at middle stage with a rate of 7.82 mm/day.

Water is one of the most important factors that limit agricultural development, especially in arid and semiarid regions around the world. One of the important data for water management is the amount of water requirement of different plants. In this regard, by measuring water input and output in lysimeters and using water balance equation, crop water use is determined. In this study, to determine crop coefficients of Milk thistle, as a valuable medicinal herb, a 1-year lysimetric experiment was conducted in Faculty of Agriculture, Birjand University, during the growing season of 2018. To conduct this project, six weighing lysimeters were used. To determine potential evapotranspiration as a reference crop, grass was grown in three lysimeters and, in three other lysimeters, Milk thistle (Silybum marianum L. ) was planted. Based on the results, the reference crop evapotranspiration and actual evapotranspiration of the plant were equal to, respectively, 1179. 5 and 920. 2 mm, during the growing period of 177 days. The length of different stages of plant growth, including the initial, development, middle, and end stages was 22, 35, 70, and 50 days, respectively. Finally, based on the FAO method, the crop coefficient (KC) curve was drawn and the average of crop coefficient at each of four stages of plant growth was determined as 0. 34, 0. 69, 0. 93, and 0. 77, respectively.

Optimal use of irrigation water requires to the precise irrigation planning and the accurate crop coefficient estimation is the prerequisite of that particularly in the global scale. The aim of research was the comparison of preprocessing approaches of artificial neural network: regression and data reduction (principle component analysis and rotation) for crop coefficient estimation using NDVI, RI, TVI, MSAVI, SAVI, mTVI, EVI, MNDVI and TVX for wheat crop coefficient of East Azarbaijan Province. The performance of regression and data reduction approaches indicated the error criteria decreasing of data reduction approach, for example RMSE increasing from rotation to regression and from principle component analysis to regression was 11. 8 and 22. 7%, respectively. The used approaches of crop coefficient estimation has overestimation as the average increase of crop coefficient in the validation period showed 7. 7, 6. 13 and 4. 6% increasing of crop coefficient from FAO to the regression, principle component and rotation approaches, respectively. Therefore, using the rotation in the data reduction analysis increased the accuracy of estimation. Decreasing of correlation coefficient-39. 13%-from MSAVI to NDVI indicated that the improved indices basis on the study area condition increased the performance of crop coefficient estimation using satellite images.