The Role of Climatic Factors in Determining the Start Date of Planting and Growing Period of Colza with Application of CropSyst Model, Case Study: Coastal Provinces of Caspean Sea in Iran

Document Type : Full length article


1 Ph.D. in Climatology Associate Prof., Dept. of Geography, Razi Univ., Kermanshah, Iran

2 Ph.D. in Irrigation and Drainage Assistant Prof., Dept. of Water Engineering, Razi Univ., Kermanshah, Iran

3 M. Sc. in Climatology, Dept. of Geography Razi Univ., Kermanshah, Iran


The use of climatic and natural variables in the regulation of agricultural activities has a particular importance. Of the important characteristics of climate are the onset and retreat dates of main rainy season which have a determining role in the agricultural activities such as seeding time, cultivation period and other agricultural programs and strategies like irrigation. Iran residing in the arid and semiarid region has a variety of climates and consequently experiences high irregularities of spatial and temporal distribution of precipitation and other climatic elements. Southern coasts of Caspian Sea in Iran as a region with the highest precipitation in the country, has good potentials for agricultural activities. Among the most important crops for the development of cultivation in this plain is colza (canola). Since colza can be cultivated under rainfed conditions in high precipitation areas, therefore the analysis of precipitation characteristics in the region on the one hand, and onset and retreat dates of main rainy season in that plain on the other hand, can play an important role in the development of cultivation area.

Materials and Methods
Average onset and retreat dates of main rainy season were calculated at selected stations of the region using an index called “cumulative percentage of mean daily rainfall during the year in 5-day periods (pentads)” with Instat software, and the relevant graphs were plotted. Average onset and retreat dates of main rainy season are the dates of year when 10% and 90% cumulative mean annual rainfall during pentads are obtained respectively. The length of the main rainy season is taken as the time interval between the rainfall onset and retreat. The cumulative rainfall based on pentads is used to decrease the daily rainfall fluctuations during the year, so that the detection of onset and retreat dates of main rainy season is much more convenient. Based on the dates obtained from the software and using the daily data of climatic elements including rainfall, minimum temperature, maximum temperature, minimum relative humidity, maximum relative humidity, solar radiation and wind speed in a 26-year period (1984-2009), and also with the aid of soil properties at the stations, the cultivation period and potential yield values of colza were estimated by CropSyst model. Finally, based on the highest yield obtained from the dates entered to the model, the most suitable planting date and duration of cultivation were determined.

Results and Discussion
The results of this study showed that the onset dates of main rainy season in the stations vary between 30 Aug to 1 Nov, and these dates have had less fluctuations in comparison with the retreat dates; since the retreat dates have had differences about 50 days, i.e. from 17 Mar in Bandar Anzali in the west to 6 May in Gorgan in the east of the region. The low differences among onset dates of main rainy season in the stations prove the regularity of rainfalls which result from the regularity of rainfall-producing mechanisms in the region. This occurs especially in September as the onset of rainy season in the region and the onset of advection rainfalls originating from Siberian high pressure, particularly around the Rasht and Bandar Anzali. It seems that determining the onset and retreat dates of main rainy season using rainfall amounts leads to more reasonable results than the use of number of the rainy days. Also the length of the main rainy season in the stations varies from 185 days in Manjil to 234 days in Ghaemshahr, which represents a few weeks difference in comparison with the graph illustrated by Sedaghat (2007: 36) regarding the cumulative mean monthly rainfall in Iran. The most appropriate planting dates for colza in the selected stations of the region were suggested from 5 Oct in Manjil to 20 Nov in Bandar Anzali. Relevant cultivation durations in the stations vary from 173 to 209 days. Potential yield of the product in the region shows significant direct correlation with amount of rainfall, and significant inverse correlation with distance from shore.

Recognition of characteristics of main rainy season and its onset and retreat dates has a determining role in the various activities especially agricultural activities. In this research average onset and retreat dates of main rainy season were calculated at selected stations of coastal provinces of Caspean Sea in Iran using an index called “cumulative percentage of mean daily rainfalls during the year in 5-day periods”. The results showed that the onset dates are more regular than the retreat dates due to regularity of rainfall-producing mechanisms in September. Differences in suggested planting dates in this study and the report of the Ministry of Agriculture can be related to different varieties of colza used in the studies, and different calibrations of models based on the climatic and natural circumstances at the various parts of the country; Hence our special offer for respected researchers in the future studies is to calibrate the CropSyst model with regard to the climatic and natural circumstances of the study area.


پاسبان اسلام، ب. ) 1388 (. اار زمان کارت روی یملکرد و اجزای یملکرد کلزای پاییزه. مجلة دان کشراورزی، جلرد 19 ، شرماره ی 2 ،
صص. 162 - 149 .
جعفرنژادی، ع.؛ راهنما، ع. ا. ) 1390 (. بررسی اار تأخیر در کارت بر یملکرد کلزا و کارآیی کاربرد نیتروژن. مجلة پرژوه هرای خرات
)علوم خات و آب(، الف، جلد 25 ، شمارة 3 ، 225 - 233 .
خیاط، م.؛ گوهری، م. ) 1388 (. اار تاریخ کارت بر یملکرد، اجزای یملکرد، راخص های ررد و صفات فنولوژی ژنوتیپ های کلزا در
اهواز. یافته های نوین کشاورزی، سال سوم، شمارة 3 ، ص233 - 248 .
خیاط، م.؛ لک، ش.؛ گوهری، م.؛ مطیعی، م. م. ) 1388 (. اار تاریخ کارت بر منحنی ررد و یملکرد ژنوتیپ های کلازا . فصرلنامة علمری -
تخصصی فیزیولوژی گیاهان زراعی، سال اول، شمارة اول،ص 1 - 11 .
ربیعی، م.؛ علی نیا، ف.؛ طوسی کهل، پ. ) 1390 (. اار تاریخ نشاکاری بر یملکرد و اجزای یملکرد داناة چقاار رقام کلازا ( Brassica napus L. ( به ینوان کشت دوم در منطقة ررت. مجلة به زراعی نهال و بذر، جلد 2 - 27 ، شمارة 3 ، ص251 - 267 .
شیرانی راد، ا. ح.؛ احمدی، م. ر. ) 1376 (. اار تاریخ کارت و تراکم بوته بر روند ررد و یملکرد داناة دو رقام کلازای روغنای پااییزه
( Brasica napus L. ( در منطقة کرج. مجلة علوم کشاورزی ایران، جلد 28 ، شمارة 2 ،ص 27 -
صداقت، م. ) 1386 (. منابع و مسائل آب ایران. چاپ ششم، انتشارات دانشگاه پیام نور، تهران.
مظفری، س.؛ پیردشتی، ه. ا.؛ اسماعیلی، م. ع.؛ رامئه، و. ا.؛ حیدرزاده، ا.؛ مصطفویان، ر. ) 1389 (. ااار تااریخ کارات و محادودیت منباع و
مخزن بر یملکرد دانه و اجزای یملکرد سه رقم کلزا ( Brassica napus L. (. مجلة علوم زراعی ایران، جلد دوازدهم، شمارة 4 ،
482 - 498 .
میرزائی، م. ر.؛ دشتی، ش؛ آبسالان، م.؛ سیادت، ع. ا.؛ فتحری، ق. ا. ) 1389 (. بررسی تأایر تاریخ کارت بر یملکارد، اجازای یملکارد و
محتوای روغن ارقام مختلف کلزا در منطقة دهلران، مجلة الکترونیکی تولید گیاهان زراعی، جلد سوم، شمارة دوم، 159 - 176 .
وزارت جهاد کشاورزی ) 89 - 1388 (. سازمان تحقیقات و آموزش کشاورزی، مؤسسة تحقیقات اصلاح و تهیة نهال و برذر، دساتورالعمل تولیاد
کلزا در اقلیم های چقارگانة کشور. 18 صفحه.
هنر، ت.؛ ثابت سرورستانی، ع.؛ کامگار حقیقی، ع. ا.؛ شمس، ش. ) 1390 (. واسنجی مدل گیااهی CropSyst جقات تخماین یملکارد و
ربیه سازی ررد گیاه کلزا. نشریة آب و خات )علوم و صنایع کشاورزی(، جلد 25 ، شمارة 3 ، 593 - 605 .
Aviad, Y., Kutiel, H. and Lavee, H. (2004), Analysis of Beginning, End, and Length of the Rainy Season Along A Mediterranean-Arid Climate Transect for Geomorphic Purposes, Journal of Arid Environments, No. 59, pp. 189-204.
Camberlin, P. and Okoola, R. E. (2003), The Onset and Cessation of the “Long Rains” in Eastern Africa and Their Interannual Variability, Theoretical and Applied Climatology, No. 74, pp. 43-54.
Camberlin, P., Moron., V., Okoola., R., Philippon, N. and Gitau, W. (2009), Components of Rainy Seasons’ Variability in Equatorial East Africa: Onset, Cessation, Rainfall Frequency and Intensity, Theoretical and Applied Climatology, No. 98, pp. 237-249.
Hachigonta, S., Reason, C.J.C. and Tadross, M. (2008), An Analysis of Onset Date and Rainy Season Duration Over Zambia, Theoretical and Applied Climatology, No. 91, pp. 229-243.
Honar, T., Sabet Sarvestani, A., Kamgar Haghighi, A.A. and Shams, Sh. (2011), Calibration of Crop System Model for Growth Simulation and Yield Estimation of Canola, Journal of Water and Soil, Vol. 25, No. 3, pp. 593-605.
Jafarnejadi, A. R. and Rahnema, A.A. (2011), Effects of Late Planting on Canola Yield and Nitrogen Use Efficiency, Iranian Journal of Soil Research (Soil and Water Sciences), Vol. 25, No. 3, pp. 225-233.
Khayyat, M. and Gouhari, M. (2009), Effect of Sowing Date on Yield, Yield Components, Growth Indices and Phonologic Properties of Canola Genotypes in Ahvaz, Journal of Agricultural Modern Findings, Vol. 3, No. 3, pp. 233-248.
Khayyat, M., Lak, Sh., Gouhari, M. and Motiei, M.M. (2009), Effect of Sowing Date on Growth Curve and Yield of Canola Genotypes, Journal of Agricultural Plants Physiology, Vol. 1, No. 1, pp. 1-11.
Ministry of Agriculture (2009-2010), Organization of Agricultural Research and Training, Research Institute of Improvement and Preparation of Seed and Plant, Guidelines for Canola Production in Four Climates of Iran, 18p.
Mirzaei, M., Dashti, Sh., Absalan, M., Siadat, A. and Fathi, Gh. (2010), Study the Effect of Planting Dates on the Yield, Yield Components and Oil Content of Canola Cultivars (Brassica Napus L.) in Dehloran Region, Electronic Journal of Crop Production, Vol. 3, No. 2, pp. 159-176.
Mozafari, S., Pirdashti, H., Esmaili, M. A., Ramea, V. and Heidarzade, A. (2010), Effect of Planting Date and Source - Sink Limitation on Grain Yield and Yield Components in Three Rapeseed (Brassica Napus L.) Cultivars, Iranian Journal of Crop Sciences, Vol. 12, No. 4, pp. 482-498.
Mugalavai, E.M., Kipkorir, E.C., Raes, D. and Rao, M.S. (2008), Analysis of Rainfall Onset, Cessation and Length of Growing Season for Western Kenya, Agricultural and Forest Meteorology, No. 148, pp. 1123-1135.
Odekunle, T.O. and Adejuwon, S.A. (2007), Assessing Changes in the Rainfall Regime in Nigeria Between 1961 and 2004, GeoJournal, No. 70, pp. 145–159.
Odekunle, T.O. (2006), Determination Rainy Season Onset and Retreat Over Nigeria from Precipitation
Amount and Number of Rainy Days, Theoretical and Applied Climatology, No. 83, pp. 193-201.36
Odekunle, T.O., Balogun, E. E. and Ogunkoya, O. O., (2005), On the Prediction of Rainfall Onset and Retreat Dates in Nigeria, Theoretical and Applied Climatology, No. 81, pp. 101-112.
Odekunle, T.O. (2004), Rainfall and the Length of the Growing Season in Nigeria, International Journal of Climatology, No. 24, pp. 467-479.
Pasban Eslam, B. (2009), Effects of Sowing Date on Yield and Yield Components in Winter Oilseed Rape, Journal of Agricultural Science, Vol. 19, No. 2, pp. 149-162.
Rabiee, M., Aliniya, F. and Tousi Kehal, P. (2011), Effect of Transplanting Date on Seed Yield and Its Components of Four Rapeseed (Brassica Napus L.) Cultivars as Second Crop in Rasht in Iran, Seed and Plant Production Journal, Vol. 27, No. 3, pp. 251-267.
Recha, C.W., Makokha, G.L., Traore, P.S., Shisanya, C., Lodoun T. and Sako, A. (2012), Determination of Seasonal Rainfall Variability, Onset and Cessation in Semi-Arid Tharaka District, Kenya, Theoretical and Applied Climatology, No. 108, pp. 479-494.
Sedaghat, M. (2007), Water Resources and Issues in Iran, 6th Edn., Payame Noor University Publications, Tehran.
Shirani-Rad, A.H. and Ahmadi, M.R. (1996), Effects of Sowing Date and Plant Density on Growth Analysis of Two Winter Rapeseed Varieties (Brassica Napus L.) in Karaj Region, Iranian Journal of Agricultural Sciences, Vol. 28, No. 2, pp. 27-36.
Sivakumar, M.V.K. (1988), Predicting Rainy Season Potential from the Onset of Rains in the Sahelian and Sudanian Climatic Zones of West Africa, Agricultural and Forest Meteorology, No. 42, pp. 295-305.