University of TehranIranian Journal of Soil and Water Research2008-479X511020201221Evaluation Of Production Functions In Estimating Two Varieties Of Corn Yield With Native Yield Response Factor In The IranEvaluation Of Production Functions In Estimating Two Varieties Of Corn Yield With Native Yield Response Factor In The Iran251925297731010.22059/ijswr.2020.304385.668646FAArashTaftehAssistant professor, Department of irrigation and soil physics, Soil and Water Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran0000-0002-1291-506XMohammad MehdiNakhjavani MoghadamAssistant professor of Irrigation and Drainage Engineering, Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organizationhttps://orcid.org/00AslanEgdernezhadAssistant Professor, Department of Water Sciences and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran.SaloomeSepehriAssistant Professor of Irrigation and Drainage Engineering, Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, IranJournal Article20200620Due to limited water resources and the problem of water distribution in irrigation and drainage networks and non-compliance of plant irrigation needs with existing irrigation periods, a water stress is introduced to the plants systematically. Therefore, in this study, two production functions of Raes (2004) and Tafteh <em>et al</em>. (2013) were evaluated for corn using the yield response factor suggested by Tafteh <em>et al</em>. (2014a). For this purpose, two varieties of corn 500 and 302 were harvested in two years of cultivation with irrigation treatments of 100, 75 and 50% of water requirement and their yield values were evaluated using the proposed functions. The results showed that both production functions in determining corn yield of 500 and 320 together with the amount of root mean square error is about 591 kg / ha, the normal root mean square error is about 8% and the mean bias error is about 25 kg / ha. The agreement index was about 0.94 and the efficiency factor index of the model was about 0.81. These statistical results showed that the proposed functions are highly effective in determining the yield of both varieties. A separate study of these two varieties also showed that the 302 cultivar has lower yield and in water shortage conditions, its sensitivity to the plant, especially in the middle period of growth, is higher than the 500 cultivar. Therefore, cultivar 500 has a higher yield than cultivar 302 and in water shortage conditions, its sensitivity coefficients are less and it shows more resistance to water stress. Yield response factor of cultivar 302 in the initial, middle and final stages of growth were determined to be 0.5, 1.4 and 0.8, respectively Which is different from the suggested values.. Therefore, it is necessary to evaluate the proposed cultivars in water stress conditions using production functions.Due to limited water resources and the problem of water distribution in irrigation and drainage networks and non-compliance of plant irrigation needs with existing irrigation periods, a water stress is introduced to the plants systematically. Therefore, in this study, two production functions of Raes (2004) and Tafteh <em>et al</em>. (2013) were evaluated for corn using the yield response factor suggested by Tafteh <em>et al</em>. (2014a). For this purpose, two varieties of corn 500 and 302 were harvested in two years of cultivation with irrigation treatments of 100, 75 and 50% of water requirement and their yield values were evaluated using the proposed functions. The results showed that both production functions in determining corn yield of 500 and 320 together with the amount of root mean square error is about 591 kg / ha, the normal root mean square error is about 8% and the mean bias error is about 25 kg / ha. The agreement index was about 0.94 and the efficiency factor index of the model was about 0.81. These statistical results showed that the proposed functions are highly effective in determining the yield of both varieties. A separate study of these two varieties also showed that the 302 cultivar has lower yield and in water shortage conditions, its sensitivity to the plant, especially in the middle period of growth, is higher than the 500 cultivar. Therefore, cultivar 500 has a higher yield than cultivar 302 and in water shortage conditions, its sensitivity coefficients are less and it shows more resistance to water stress. Yield response factor of cultivar 302 in the initial, middle and final stages of growth were determined to be 0.5, 1.4 and 0.8, respectively Which is different from the suggested values.. Therefore, it is necessary to evaluate the proposed cultivars in water stress conditions using production functions.https://ijswr.ut.ac.ir/article_77310_16d685c3e14a623af1685b9521dc255f.pdf