National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
An experiment was carried out to develop crop coefficient model for estimation of crop evapotranspiration as a function of cumulative growing degree days of wheat (Triticum aestivum L.) and Maize (Zea mays L.). Crop coefficient values were calculated as ratio of crop evapotranspiration and reference evapotranspiration in which crop evapotranspiration for different periods of the growing season were determined using root zone water balance technique whereas reference evapotranspiration was estimated as the product of pan evaporation and appropriate values of pan coefficient for the period concerned. Daily maximum and minimum temperature data were used to calculate growing degree days (GDD) using base temperature of 5°C and 10oC with an upper threshold temperature of 25oC and 30°C, respectively for wheat and maize and cumulative GDD were calculated for different periods of crop season. Total GDD to attain maturity of wheat and maize were found as 1906.6oC-day and 1868.0oC-day, respectively. Polynomial function was fitted to the crop coefficient values plotted against cumulative growing degree days (CGDD) of wheat and maize in which fourth order polynomial equation was found to be best fit with high value of coefficient of determination. Using these equations, crop coefficient values for any cumulative growing degree days after crop sowing can be computed for estimation of crop evapotranspiration of these crops for better irrigation water management in climate change perspective. The agro-meteorological index like heat use efficiency (HTU) and photo thermal index (PTI) were also calculated as weather based parameters for assessing crop phenology.
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