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چکیده
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In order to model the combination of nitrogen application and irrigation level on corn yield, a three-years experiment (2018, 2019, and 2020) was perfumed based on a split-plot design. Four levels of Nitrogen fertilizer (0, 75, 125, 175, and 225 kg ha1 ) and three levels of irrigation (100%, 80%, and 60% FC) were applied in all three years. Different methods and models were tested to simulate the relationship between yield and nitrogen along with irrigation and the final results indicated that interaction term between irrigation regimes and nitrogen fertilizer levels is the most influential source on kernel yield of sweet corn. This is the first time considering a model that includes this interaction term in modeling the kernel yield of sweet corn. In addition, our results showed that a complete polynomial model would complex the explanation of the model and it can be replaced with an adjusted model in which irrigation, the square of nitrogen levels, and their interaction are the only sources with no significant loss of goodness of fit. The negative coefficient of squared nitrogen treatment indicated that under a lower irrigation level (around 60% FC) higher nitrogen fertilizer level than about 180 might lead to slightly decrease in the kernel yield. Overall, providing water of about 90% to 100% FC and a nitrogen level of about 180 kg ha1 is recommended to reach a high kernel yield and higher economic efficiency.
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