Determination of Crop Water Stress Index for Irrigation Scheduling of Turfgrass (Cynodon dactylon L. Pers.) under Drought Conditions

Document Type : Research Paper


The crop water stress index (CWSI) is a valuable tool for monitoring and quantifying water stress as well as for irrigation scheduling. A field experiment was conducted during spring and summer 2012 at Research Station of College of Agriculture and Natural Resources of Darab, Shiraz University, Iran, to determine CWSI of  turfgrass for irrigation scheduling. Four levels of water regimes including well watered [Irrigation according to 100% field capacity (FC)], mild drought stress (75% FC), severe drought (50% FC), and most severe drought (25% FC) stress were arranged in a randomized complete block design with four replicateions. The highest monthly average value of CWSI for all treatments was reached in August and decreased in September slightly. In all treatments the CWSI values showed an increasing trend from June (0.097 in well watered treatment) to August (0.684 under most severe drought) as a result of higher vapor pressure deficit values and negatively increase in Tc-Ta differential. Also, significant differences were observed between mean CWSI values of well watered and mild drought, with severe drought and most severe drought treatments. The color grading number for mild drought treatment in turfgrass decreased sharply from 8 to 4 at the start of the experiment in July, and remained constant (3) for August and September. The amounts of irrigation water more than 75% FC did not affect visual quality of turfgrass, which appeared to be sufficient to fulfill an acceptable turfgrass quality. A negative relationship was found between CWSI with water applied and color quality under different irrigation regimes. It appeared that under arid and semi-arid conditions, such as southern Iran, where the amount of water is a major limiting factor, the amount of applied water could be lowered to 75% FC without any loss in visual quality of turfgrass with the seasonal CWSI being kept about 0.15.


Article Title [فارسی]

تعیین شاخص تنش خشکی گیاه برای برنامه ریزی آبیاری چمن (Cynodon dactylon L. Pers.) در شرایط تنش خشکی

Abstract [فارسی]

شاخص تنش خشکی گیاه ابزاری سودمند برای پایش و به کمیت در آوردن تنش خشکی در برنامه ریزی آبیاری است. آزمایشی مزرعه­ای در بهار و تابستان 1392 در ایستگاه تحقیقاتی دانشکده کشاورزی و منابع طبیعی داراب، دانشگاه شیراز برای تعیین شاخص تنش خشکی گیاه در برنامه ریزی آبیاری به اجرا در آمد. چهار سطح رژیم رطوبتی شامل آبیاری مطلوب (آبیاری بر اساس 100% ظرفیت مزرعه)، تنش ملایم (75% ظرفیت مزرعه)، تنش شدید (50% ظرفیت مزرعه) و تنش خیلی شدید (25% ظرفیت مزرعه) در قالب طرح کاملا تصادفی با چهار تکرار به اجرا در آمد. بیشترین میزان شاخص تنش خشکی گیاه در همه تیمارها در مرداد ماه مشاهده شد و در شهریور ماه این شاخص به صورت جزئی کاهش یافت. در همه تیمارها شاخص تنش خشکی روندی افزایشی از خرداد ماه (097/0 در آبیاری مطلوب) تا مرداد ماه (684/0 در تنش شدید) داشت که تابعی از میزان کمبود فشار بخار محیط بود و رابطه منفی با تفاوت دمای سایه انداز و دمای هوا داشت. همچنین تفاوت میانگین مقدار شاخص تنش خشکی در شرایط آبیاری مطلوب و تنش خشکی ملایم با تنش خشکی شدید و بسیار شدید معنی­دار به دست آمد. در خرداد ماه در شروع آزمایش بر اساس شاخص درجه بندی رنگ در تنش ملایم این شاخص از 8 به 4 کاهش یافت و تا مرداد و شهریور در حد 3 ثابت باقی ماند. مقدار آبیاری بیشتر از 75% ظرفیت مزرعه تاثیری روی کیفیت رنگ چمن نداشت. به نظر می­رسد که تنش ملایم برای رسیدن به کیفیت مطلوب چمن کافی باشد. شاخص تنش خشکی گیاه رابطه منفی با میزان آب آبیاری و کیفیت رنگ چمن در شرایط مختلف رژیم آبیاری داشت. به نظر می­رسد که در شرایط خشک و نیمه خشک مانند جنوب ایران که میزان آب عامل مهمی در آبیاری است مقدار آب آبیاری می تواند به 75% ظرفیت مزرعه کاهش یابد بدون این که در کیفیت ظاهری رنگ چمن تغییری حاصل شود به طوری که در این شرایط شاخص تنش خشکی فصلی گیاه در حد 15/0 باقی بماند.

Keywords [فارسی]

  • تنش خشکی
  • چمن
  • شرایط نیمه خشک
  • کیفیت ظاهری
Alderfasi AA and Nielsen DC, 2001. Use of crop water stress index for monitoring water status and scheduling irrigation in wheat. Agriculture Water Management 47: 69–75.
Al-Faraj A, Meyer GE and Horst GL, 2001. A crop water stress index for tall fescue (Festuca arundinacea Schreb.) irrigation decision-making: a traditional method. Commercial Agriculture 31: 107–124.
Allen RG, Pereira LS, Raes D and Smith M, 1998. Crop evapotranspiration. FAO Irrigation and Drainage Paper 56. FAO, Rome.  
Alves I and Pereira LS, 2000. Non-water-stressed baselines for irrigation scheduling with infrared thermometers: a new approach. Irrigation Science 19: 101–106.
Bastug R and Buyuktas D, 2003. The effects of different irrigation levels applied in golf courses on some quality characteristics of turfgrass. Irrigation Science 22: 87–93.   
Bijanzadeh E and Emam Y, 2012.  Evaluation of crop water stress index, canopy temperature and grain yield of five Iranian wheat cultivars under late season drought stress. Journal of Plant Physiology and Breeding 2: 23-33.    
Bonos SA and Murphy JA, 1999. Growth responses and performance of Kentucky bluegrass under summer stress. Crop Science 39: 770–774.
Braunworth WS, 1989. The possible use of the crop water stress index as an indicator of evapotranspiration deficits and yield reductions in sweet corn. Journal of American Society of Horticulture Science 114: 542-546.    
Emam Y and Bijanzadeh E, 2012. Water uptake and hydraulic conductivity of seminal and adventitious roots of five wheat cultivars at early growth stage .Journal of Agriculture Science and Technology 14: 1605-1616.    
Emekli Y, Bastug R, Buyuktas D and Emekli NY, 2007. Evaluation of a crop water stress index for irrigation scheduling of bermudagrass. Agricultural Water Management 90: 205- 212.    
Garrot DJ and Mancino, CF, 1994. Consumptive water use of three intensively managed bermudagrasses growing under arid conditions. Crop Science 34: 215–221.
Grimes DW, Yamada H and Hughes SW, 1987. Climate normalized cotton leaf water potentials for irrigation scheduling. Agricultural Water Management 12: 293–304.
Idso SB, Jackson, RD, Pinter, JR, Reginato RJ and Hatfield JL, 1981. Normalizing the stress-degree-day parameter for environmental variability. Agriculture Meteorology 24: 45–55.
Idso SB and Reginato RJ, 1982. Soil and atmosphere-induced plant water stress in cotton as inferred from foliage temperatures. Water Resource Research 18:  1143-1148.
Irmak S, Haman DZ and Bastug R, 2000. Determination of crop water stress index for irrigation timing and yield estimation of corn. Agronomy Journal 92: 1221–1227.
Jackson RD, 1982. Canopy Temperature and Crop Water Stress Index. Advances in Irrigation, vol. 1. Academic Press, New York, pp. 43–85.
Jackson RD, Idso, RB, Reginato, RJ and Pinter PJ, 1981. Canopy temperature as a crop water stress indicator. Water Resource Research 17: 1133–1138.
Jalali-Farahani HR, Slack DC, Kopec DM and Matthias AD, 1993. Crop water-stress index models for Bermuda grass turf-a comparison. Agronomy Journal 85: 1210–1217.
Karcher DE and Richardson MD, 2003. Quantifying turfgrass color using digital image analysis. Crop Science 43: 943–951.
Kneebone WR, Kopec DM and Mancino CF, 1992. Water requirement and irrigation. In: Waddington DV, Carrow RN and Shearman RC (Eds.), Turfgrass. Agronomy Monograph No. 32, ASA-CSSA-SSSA, Madison, Wisconsin, USA, 441–473 pp.
Monteith JL and Unsworth MH, 1990. Principles of Environmental Physics. Edward Arnold, London, 243 pp.    
     Orta AH, Erdem Y and Erdem T, 2003. Crop water stress index for watermelon. Scientica Horticulture 98: 121–130.
Ritchie WE, Green RL, Klein GJ and Hartin JS, 2002. Tall fescue performance influenced by irrigation scheduling, cultivar and moving height. Crop Science 42: 2011–2017.
Stokcle CO and Dugas WA, 1992. Evaluating canopy temperature-based indices for irrigation scheduling. Irrigation Science13: 31-37.
Wilde SA and Voigt GK, 1977. Munsell Color Chart for Plant Tissues. Munsel Color, Gretagmacbeth, New Windsor, New York.
Table captions:
Table 2. Soil physicochemical characteristics of  the experimental site
Table3. Page numbers of Munsell Color Chart, color numbers and visual quality values (Wilde and Voigt, 1977)
Table 4. Monthly and mean CWSI values for turfgrass as affected by drought treatments  
Table 5. Visual color quality values of turfgrass during the experiment as affected by drought treatments
Figure captions:
Figure 1. Stressed and non-stressed baselines for calculation of CWSI in turfgrass.
VPD = vapor pressure deficit.
Figure 2. Relationship between CWSI and water applied in turfgrass.
Figure 3. Relationship between CWSI and visual color quality values in turfgrass.