Research Article
Determining the Crop Water Stress Index for Scheduling Sesame Irrigation with Subsurface Drip Systems under Mediterranean Conditions
Abstract
Investigating how plants respond to water stress is extremely important for effective irrigation management under changing climatic conditions and diminishing water resources. This study aimed to determine the plant water stress index (CWSI) values of sesame grown in semiarid climate conditions in Antalya province. In the study, the leaf crown temperature of the plant was determined by infrared thermometer (IRT) measurements. In addition, the relationships between yield, irrigation time and CWSI were determined using these index values. In this study, four different irrigation rates (I100, I70, I40 and I0) were created with subsurface drip irrigation method established at 40 cm lateral depths. Thus, full irrigation (I100), irrigation at two different stress levels (I70 and I40) and no irrigation (I0) were included. In the research, a total of 266 mm and 248 mm of irrigation water were given in the first and subsequent years, respectively, under I100 (control) irrigation. Plant water consumption values of control subjects were determined as 288 mm in the first year and 273 mm in the second year. In the mentioned irrigation, the yield per hectare was determined as 1840 kg in the first year and 1800 kg in the second year of the research. By combining the data from the first and second years of the study, the lower limit (LL) values for the case without water stress were calculated with the equation Tc-Ta= 4.67-2.43VPD (r2=0.86, P<0.01). The upper limit (UL) value at which the plant is completely under water stress is 5.9 °C. The threshold CWSI value at which sesame yield begins to decrease was calculated as 0.27 from infrared thermometer measurements taken at irrigation time. Additionally, a negative linear relationship was found between yield and CWSI values.
Ethical Statement
Data availability The manuscripts' data is contained in the text. Funding This study is based on data obtained from project number TAGEM/TSKAD/A/19/A9/P3/1068, carried out at the Western Mediterranean Agricultural Research Institute (BATEM) and supported by the General Directorate of Agricultural Research and Policies (TAGEM). Ethics declarations Conflict of interests The authors state that they have no other financial or personal affiliations or interests that would have affected the research presented in this paper. Code availability Not applicable. Ethics approval Not Applicable. Consent to participate Not applicable. Content for publication Not applicable.
Supporting Institution
Tarımsal Araştırmalar ve Politikalar Genel Müdürlüğü
Project Number
TAGEM/TSKAD/A/19/A9/P3/1068
References
- Akın F., & Cemek, B., (2021). Determination of Yield and Quality Characteristics of Sesame Irrigated with Subsurface Drip Irrigation under Different Water Shortage Conditions and Evaluation of Suitable Lateral Depth with Hydrus Model. General Directorate of Agricultural Research and Policies, Final Report, TAGEM/TSKAD/A/19/A9/P3/1068.
- Allen, R.G., Pereria, L.S., Raes, D., & Smith, M. (1998). Crop Evapotranspiration FAO56. Rome. Ballester, C., Jimenez Bello, M., Castel, J., & ntrigliolo, D. (2013). Usefulness of thermography for plant water stress detection in citrus and persimmon trees. Agricultural and Forest Meteorology 168, 120-129.
- Bellvert, J., Marsal, J., Girona, J., & Zarco-Tejada, P. J. (2015). Seasonal evolution of crop water stress index in grapevine varieties determined with high-resolution remote sensing thermal imagery. Irrigation Science, 33, 81-93.
- Çamoğlu, G., Genç, L., & Aşık, Ş. (2011). The effects of water stress on physiological and morphological parameters of sweet corn (Zeamays saccharata Sturt.). Ege University Faculty of Agriculture Journal, 48 (2), 141-149.
- Candoğan, B.N., Sincik, M., Büyükcangaz, H., Demirtaş, C., Göksoy, A.T. & Yazgan, S. (2013). Yield, quality, and crop water stress index relationships for deficit-irrigated soybean (Glycine max (L.) Merr.) in sub-humid climatic conditions. Agricultural Water Management, 118, 113– 121.
- Clawson, K.L., & Blad, B.L. (1982). Infrared thermometry for scheduling irrigation of corn. Agronomy Journal, 74, 311-316.
- Çolak, Y.B., Yazar, A., Sezen S.M., Tangolar, S., Gökçel, F., & Eker, S. (2012). Monitoring of plant water stress in alphonse lavallee table grape variety using infrared thermometer in the Mediterranean Region. II. National Irrigation and Agricultural Structures Symposium, 1, 101-108.
- De Jonge, K.C., Taghvaeian, S., Trout, T.J., & Comas, L.H. (2015). Comparison of canopy temperature-based water stress indices for maize. Agricultural Water Management, 156, 51-62.
- Der. G., & Everitt, B.S. (2002). A Handbook of Statistical Analyses Using SAS. Second Edition. CRC Press LLC. 2000 N.W. Corporate Blvd., Boca Raton. Florida 3431. USA.
- Erdem, T., Erdem, Y., Okursoy, H., & Göçmen, E. (2012). Variations of non-water stressed baselines for dwarf cherry trees under different irrigation regimes. Journal of Tekirdağ Agricultural Faculty, 9(2), 41-49.
- Erdem, T., Halim Orta, A., Erdem, Y., & Okursoy, H. (2005). Crop water stress index for potato under furrow and drip irrigation systems. Potato Research, 48, 49-58.
- Gardner, B.R., & Shock, C.C. (1989). Interpreting the Crop Water Stress Index. ASAE Paper 89-2642. ASAE, St. Joseph, MI.
- Gençel, B. (2009). Estimation of irrigation water amount to be applied in second crop maize plants using plant water stress index (CWSI). Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Gençoğlan, C. (1996). Water-Yield Relationships of Maize Plant, Determination of Root Distribution and Plant Water Stress Index and Investigation of Adaptability of CERES Maize Plant Growth Model to the Region. Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Gu, S., Liao, Q., Gao, S., Kang, S., Du, T., & Ding, R. (2021). Crop water stress index as a proxy of phenotyping maize performance under combined water and salt stress. Remote Sensing, 13(22), 4710.
- Idso, S.B. (1982). Non-water-stressed baselines: a key to measuring and interpreting plant water stress. Agricultural Meteorology, 27, 59-70.
- Idso, S.B., Jackson, R.D., Pinter, P.J., Reginato, R.J., & Hatfield, J.L. (1981). Normalizing the stress-degree-day parameter for environmental variability. Agricultural Meteorology, 24, 45-55.
- Idso, S.B., Pinter, P.J., & Reginato, R.J. (1990). Non-water stressed baselines: the importance of site selection for air temperature and air vapor pressure deficit measurements. Agricultural and Forest Meteorology, 53, 73-80.
- Jackson, R.D. (1982). Canopy Temperature and Crop Water Stress. Advances in Irrigation. Academic Press 1, 43-85.
- Jackson, R.D., Hatfield, J.L., Reginato, R.J., Idso, S.B., & Pinter, P.J. (1983). Estimation of daily evapotranspiration from one time-of-day measurements. Agricultural Water Management, 7, 351-362.
- Jackson, R.D., Idso, S.B., Regina, R.J., & Pinter, P.J. (1981). Canopy Temperature as a Crop Water Stress Indicator. Water Resources Research, 4 (17), 1133-1138.
- Jones, H.G. (1999). Use of infrared thermometry for estimating of stoma conductance as a possible aid to irrigation scheduling. Agricultural and Forest Meteorology, 95, 139-149.
- Jones, H.G., Stoll, M., Santos, T., Sousa, C., Chaves, M., & Grant, O.M. (2002). Use of infrared thermography for monitoring stomatal closure in the field: application to grapevine. Journal of Experimental Botany, 378 (53), 2249-2260.
- Khorsand, A., Rezaverdinejad, V., Asgarzadeh, H., Majnooni Heris A., Rahimi, A., & Besharat, S. (2019). Irrigation scheduling of maize based on plant and soil indices with surface drip irrigation subjected to different irrigation regimes. Agricultural Water Management, 224, 105740.
- Khorsandi, A., Hemmat, A., Mireei, S.A., & Amirfattahi, R. (2018). Plant temperature-based indices using infrared thermography for detecting water status in sesame under greenhouse conditions. Agricultural Water Management, 204, 222-233.
- Kırnak, H., & Gençoğlan, C. (2001). Use of crop water stress index for scheduling irrigation in second crop corn. Harran University Faculty of Agriculture Journal, 5(3-4), 67-75.
- Köksal, H. (1995). Determination of the suitability of second crop corn plant+water production functions and different growth models to the region in Çukurova conditions. Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Leinonen, I., & Jones, H.G. (2004). Combining thermal and visible imagery for estimating canopy temperature and identifying plant stress. Journal of Experimental Botany, 401 (55), 1423–1431.
- Moroni, I.F., Fraysse, M., Presotto, A., & Cantamutto, M. (2012). Evaluation of Argentine wild sunflower biotypes for drought stress during reproductive stage. Proc. 18th International Sunflower Conference, Mar del Plata, Argentina, 420-425.
- Nielsen, D.C. (1990). Scheduling irrigations for soybeans with the crop water stress index (CWSI). Field Crops Research, 23,103–116.
- Nielsen, D.C., Clawson, K.L., & Blad, B.L. (1983). Effect of solar azimuth and Infrared thermometer view direction on measured soybean canopy temperature. Agronomy Journal, 76, 607-610.
- Nielsen, D.C., Gardner, B.R. (1987). Scheduling Irrigations for Corn with the Crop Water Stress Index (CWSI). Applied Agricultural Research, 5 (2), 295-300.
- Ödemiş, B., & Baştuğ, R. (1999). Infrared Termometre Tekniği Kullanılarak Pamukta Bitki Su Stresinin Değerlendirilmesi ve Sulamaların Programlanması. Turkish Journal of Agriculture and Forestry, 23, 31-37.
- Qin, A., Ning, D., Liu, Z., Li, S., Zhao, B., & Duan, A. (2021). Determining Threshold Values for a Crop Water Stress Index-Based Center Pivot Irrigation with Optimum Grain Yield. Agriculture, 11(10), 958. https://doi.org/10.3390/agriculture11100958
- Ramirez Cuesta, J., Kilic, A., Allen, R., Santos, C., & Lorite, I. (2017). Evaluating the impact of adjusting surface temperature derived from Landsat 7 ETM+ in crop evapotranspiration assessment using high resolution airborne data. International journal of remote sensing 38, 4177-4205.
- Reginato, R.J. (1983). Field qualification of crop water stress. Transactions of the American Society of Agricultural Engineers 26(3), 772 – 781.
- Ru, C., Hu, X., Wang, W., Ran, H., Song, T., & Guo, Y. (2020). Evaluation of the crop water stress index as an indicator for the diagnosis of grapevine water deficiency in greenhouses. Horticulturae, 6(4), 86.
- Smith, W.K. (1978). Temperatures of desert plants: another perspective on the adaptability of leaf size. Science, 201, 614-616.
- Taghvaeian, S., Cha´vez, J.L., Bausch, W.C., DeJonge, K.C., & Trout, T.J. (2013). Minimizing instrumentation requirement for estimating crop water stress index and transpiration of maize. Irrigation Science, 32(1), 53-65.
- Uçak, A.B, Arslan, H., Özçınar, A.B., & Arslan, D. (2022). Determination of Irrigation Time by Utilizing Plant Water Stress Index (CWSI) Values of II. Crop Sesame Genotype in Siirt Conditions. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:2454-1850, Vol-8, Issue-1, January.
- Ward, A.D., & Elliot, W.J. (1995). Environmental Hydorolgy. CRC Press., 462. USA.
- Yazar, A., Howell, T.A., Dusek, D.A., & Copeland, K.S. (1999). Evaluation of crop water stress index for LEPA irrigated corn. Irrigation Science, 18, 171-180.Wanjura, D.-F., Upchurch, D.R., & Mahan, J.R. (1992). Automated irrigation based on threshold canopy temperature. Transaction of the ASAE, 35(1), 153-159.
Yüzeyaltı Damla Sulama Yöntemi ile Sulanan Susamın Akdeniz İklim Koşullarında Bitki Su Stres İndeksinin Belirlenmesi
Abstract
Değişen iklim koşulları ve azalan su kaynakları altında etkili sulama yönetimi için bitkilerin su stresine nasıl yanıt verdiklerinin araştırılması son derece önemlidir. Bu çalışmada, Antalya ilinde yarı kurak iklim koşullarında yetiştirilen susamın bitki su stres indeksi (CWSI) değerlerinin belirlenmesi amaçlanmıştır. Çalışmada, bitkinin yaprak taç sıcaklığı kızılötesi termometre (IRT) ölçümleri ile belirlenmiştir. Ayrıca bu indeks değerleri kullanılarak verim, sulama zamanı ve CWSI arasındaki ilişkiler belirlenmiştir. Bu çalışmada, 40 cm lateral derinliğinde kurulan yüzey altı damla sulama yöntemi ile dört farklı sulama oranı (I100, I70, I40 ve I0) oluşturulmuştur. Böylece tam sulama (I100), iki farklı stres seviyesinde sulama (I70 ve I40) ve hiç sulama yapılmaması (I0) uygulamasına yer verilmiştir. Araştırmada, I100 (kontrol) sulaması altında ilk ve sonraki yıllarda sırasıyla toplam 266 mm ve 248 mm sulama suyu verilmiştir. Kontrol deneklerinin bitki su tüketim değerleri birinci yıl 288 mm, ikinci yıl 273 mm olarak belirlenmiştir. Söz konusu sulamada hektara düşen verim araştırmanın birinci yılında 1840 kg, ikinci yılında ise 1800 kg olarak belirlenmiştir. Araştırmanın birinci ve ikinci yılına ait veriler birleştirilerek su stresi olmayan durum için alt sınır (LL) değerleri Tc-Ta= 4.67-2.43VPD (r2=0.86, P<0.01) denklemiyle hesaplanmıştır. Bitkinin tamamen su stresi altında kaldığı üst sınır (UL) değeri ise 5.9 °C’dir. Susam veriminin azalmaya başladığı eşik CWSI değeri sulama zamanında alınan kızılötesi termometre ölçümlerinden 0.27 olarak hesaplanmıştır. Ayrıca verim ile CWSI değerleri arasında negatif doğrusal bir ilişki bulunmuştur.
Project Number
TAGEM/TSKAD/A/19/A9/P3/1068
References
- Akın F., & Cemek, B., (2021). Determination of Yield and Quality Characteristics of Sesame Irrigated with Subsurface Drip Irrigation under Different Water Shortage Conditions and Evaluation of Suitable Lateral Depth with Hydrus Model. General Directorate of Agricultural Research and Policies, Final Report, TAGEM/TSKAD/A/19/A9/P3/1068.
- Allen, R.G., Pereria, L.S., Raes, D., & Smith, M. (1998). Crop Evapotranspiration FAO56. Rome. Ballester, C., Jimenez Bello, M., Castel, J., & ntrigliolo, D. (2013). Usefulness of thermography for plant water stress detection in citrus and persimmon trees. Agricultural and Forest Meteorology 168, 120-129.
- Bellvert, J., Marsal, J., Girona, J., & Zarco-Tejada, P. J. (2015). Seasonal evolution of crop water stress index in grapevine varieties determined with high-resolution remote sensing thermal imagery. Irrigation Science, 33, 81-93.
- Çamoğlu, G., Genç, L., & Aşık, Ş. (2011). The effects of water stress on physiological and morphological parameters of sweet corn (Zeamays saccharata Sturt.). Ege University Faculty of Agriculture Journal, 48 (2), 141-149.
- Candoğan, B.N., Sincik, M., Büyükcangaz, H., Demirtaş, C., Göksoy, A.T. & Yazgan, S. (2013). Yield, quality, and crop water stress index relationships for deficit-irrigated soybean (Glycine max (L.) Merr.) in sub-humid climatic conditions. Agricultural Water Management, 118, 113– 121.
- Clawson, K.L., & Blad, B.L. (1982). Infrared thermometry for scheduling irrigation of corn. Agronomy Journal, 74, 311-316.
- Çolak, Y.B., Yazar, A., Sezen S.M., Tangolar, S., Gökçel, F., & Eker, S. (2012). Monitoring of plant water stress in alphonse lavallee table grape variety using infrared thermometer in the Mediterranean Region. II. National Irrigation and Agricultural Structures Symposium, 1, 101-108.
- De Jonge, K.C., Taghvaeian, S., Trout, T.J., & Comas, L.H. (2015). Comparison of canopy temperature-based water stress indices for maize. Agricultural Water Management, 156, 51-62.
- Der. G., & Everitt, B.S. (2002). A Handbook of Statistical Analyses Using SAS. Second Edition. CRC Press LLC. 2000 N.W. Corporate Blvd., Boca Raton. Florida 3431. USA.
- Erdem, T., Erdem, Y., Okursoy, H., & Göçmen, E. (2012). Variations of non-water stressed baselines for dwarf cherry trees under different irrigation regimes. Journal of Tekirdağ Agricultural Faculty, 9(2), 41-49.
- Erdem, T., Halim Orta, A., Erdem, Y., & Okursoy, H. (2005). Crop water stress index for potato under furrow and drip irrigation systems. Potato Research, 48, 49-58.
- Gardner, B.R., & Shock, C.C. (1989). Interpreting the Crop Water Stress Index. ASAE Paper 89-2642. ASAE, St. Joseph, MI.
- Gençel, B. (2009). Estimation of irrigation water amount to be applied in second crop maize plants using plant water stress index (CWSI). Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Gençoğlan, C. (1996). Water-Yield Relationships of Maize Plant, Determination of Root Distribution and Plant Water Stress Index and Investigation of Adaptability of CERES Maize Plant Growth Model to the Region. Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Gu, S., Liao, Q., Gao, S., Kang, S., Du, T., & Ding, R. (2021). Crop water stress index as a proxy of phenotyping maize performance under combined water and salt stress. Remote Sensing, 13(22), 4710.
- Idso, S.B. (1982). Non-water-stressed baselines: a key to measuring and interpreting plant water stress. Agricultural Meteorology, 27, 59-70.
- Idso, S.B., Jackson, R.D., Pinter, P.J., Reginato, R.J., & Hatfield, J.L. (1981). Normalizing the stress-degree-day parameter for environmental variability. Agricultural Meteorology, 24, 45-55.
- Idso, S.B., Pinter, P.J., & Reginato, R.J. (1990). Non-water stressed baselines: the importance of site selection for air temperature and air vapor pressure deficit measurements. Agricultural and Forest Meteorology, 53, 73-80.
- Jackson, R.D. (1982). Canopy Temperature and Crop Water Stress. Advances in Irrigation. Academic Press 1, 43-85.
- Jackson, R.D., Hatfield, J.L., Reginato, R.J., Idso, S.B., & Pinter, P.J. (1983). Estimation of daily evapotranspiration from one time-of-day measurements. Agricultural Water Management, 7, 351-362.
- Jackson, R.D., Idso, S.B., Regina, R.J., & Pinter, P.J. (1981). Canopy Temperature as a Crop Water Stress Indicator. Water Resources Research, 4 (17), 1133-1138.
- Jones, H.G. (1999). Use of infrared thermometry for estimating of stoma conductance as a possible aid to irrigation scheduling. Agricultural and Forest Meteorology, 95, 139-149.
- Jones, H.G., Stoll, M., Santos, T., Sousa, C., Chaves, M., & Grant, O.M. (2002). Use of infrared thermography for monitoring stomatal closure in the field: application to grapevine. Journal of Experimental Botany, 378 (53), 2249-2260.
- Khorsand, A., Rezaverdinejad, V., Asgarzadeh, H., Majnooni Heris A., Rahimi, A., & Besharat, S. (2019). Irrigation scheduling of maize based on plant and soil indices with surface drip irrigation subjected to different irrigation regimes. Agricultural Water Management, 224, 105740.
- Khorsandi, A., Hemmat, A., Mireei, S.A., & Amirfattahi, R. (2018). Plant temperature-based indices using infrared thermography for detecting water status in sesame under greenhouse conditions. Agricultural Water Management, 204, 222-233.
- Kırnak, H., & Gençoğlan, C. (2001). Use of crop water stress index for scheduling irrigation in second crop corn. Harran University Faculty of Agriculture Journal, 5(3-4), 67-75.
- Köksal, H. (1995). Determination of the suitability of second crop corn plant+water production functions and different growth models to the region in Çukurova conditions. Çukurova University, Institute of Science, Department of Agricultural Structures and Irrigation, PhD Thesis.
- Leinonen, I., & Jones, H.G. (2004). Combining thermal and visible imagery for estimating canopy temperature and identifying plant stress. Journal of Experimental Botany, 401 (55), 1423–1431.
- Moroni, I.F., Fraysse, M., Presotto, A., & Cantamutto, M. (2012). Evaluation of Argentine wild sunflower biotypes for drought stress during reproductive stage. Proc. 18th International Sunflower Conference, Mar del Plata, Argentina, 420-425.
- Nielsen, D.C. (1990). Scheduling irrigations for soybeans with the crop water stress index (CWSI). Field Crops Research, 23,103–116.
- Nielsen, D.C., Clawson, K.L., & Blad, B.L. (1983). Effect of solar azimuth and Infrared thermometer view direction on measured soybean canopy temperature. Agronomy Journal, 76, 607-610.
- Nielsen, D.C., Gardner, B.R. (1987). Scheduling Irrigations for Corn with the Crop Water Stress Index (CWSI). Applied Agricultural Research, 5 (2), 295-300.
- Ödemiş, B., & Baştuğ, R. (1999). Infrared Termometre Tekniği Kullanılarak Pamukta Bitki Su Stresinin Değerlendirilmesi ve Sulamaların Programlanması. Turkish Journal of Agriculture and Forestry, 23, 31-37.
- Qin, A., Ning, D., Liu, Z., Li, S., Zhao, B., & Duan, A. (2021). Determining Threshold Values for a Crop Water Stress Index-Based Center Pivot Irrigation with Optimum Grain Yield. Agriculture, 11(10), 958. https://doi.org/10.3390/agriculture11100958
- Ramirez Cuesta, J., Kilic, A., Allen, R., Santos, C., & Lorite, I. (2017). Evaluating the impact of adjusting surface temperature derived from Landsat 7 ETM+ in crop evapotranspiration assessment using high resolution airborne data. International journal of remote sensing 38, 4177-4205.
- Reginato, R.J. (1983). Field qualification of crop water stress. Transactions of the American Society of Agricultural Engineers 26(3), 772 – 781.
- Ru, C., Hu, X., Wang, W., Ran, H., Song, T., & Guo, Y. (2020). Evaluation of the crop water stress index as an indicator for the diagnosis of grapevine water deficiency in greenhouses. Horticulturae, 6(4), 86.
- Smith, W.K. (1978). Temperatures of desert plants: another perspective on the adaptability of leaf size. Science, 201, 614-616.
- Taghvaeian, S., Cha´vez, J.L., Bausch, W.C., DeJonge, K.C., & Trout, T.J. (2013). Minimizing instrumentation requirement for estimating crop water stress index and transpiration of maize. Irrigation Science, 32(1), 53-65.
- Uçak, A.B, Arslan, H., Özçınar, A.B., & Arslan, D. (2022). Determination of Irrigation Time by Utilizing Plant Water Stress Index (CWSI) Values of II. Crop Sesame Genotype in Siirt Conditions. International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:2454-1850, Vol-8, Issue-1, January.
- Ward, A.D., & Elliot, W.J. (1995). Environmental Hydorolgy. CRC Press., 462. USA.
- Yazar, A., Howell, T.A., Dusek, D.A., & Copeland, K.S. (1999). Evaluation of crop water stress index for LEPA irrigated corn. Irrigation Science, 18, 171-180.Wanjura, D.-F., Upchurch, D.R., & Mahan, J.R. (1992). Automated irrigation based on threshold canopy temperature. Transaction of the ASAE, 35(1), 153-159.
There are 42 citations in total.
Details
| Primary Language | English |
|---|---|
| Subjects | Biosystem, Agronomy |
| Journal Section | Araştırma Makaleleri |
| Authors | |
| Project Number | TAGEM/TSKAD/A/19/A9/P3/1068 |
| Early Pub Date | June 28, 2025 |
| Publication Date | June 30, 2025 |
| Submission Date | May 15, 2025 |
| Acceptance Date | June 16, 2025 |
| Published in Issue | Year 2025 Issue: 381 |
Bu eser Creative Commons Alıntı-GayriTicari-Türetilemez 4.0 Uluslararası Lisansı ile lisanslanmıştır.