Development And Application Of Critical Nitrogen Dilution Curve For Potato And Sugar Beet

The critical nitrogen concentration dilution model is the basis of crop nitrogen nutrition diagnosis,its curve parameters may be affected by factors such as variety.The main purpose of this study is to construct a dilution curve model of critical nitrogen concentration for potatoes and sugar beets based on multi-year field trials.And use the corresponding nitrogen nutrition index for nitrogen nutrition diagnosis of potato and sugar beet,Thereby reducing the environmental risks and economic losses caused by excessive use of nitrogen fertilizer during the critical growth period.The main results are as follows:Relatively based on aboveground biomass and aboveground nitrogen concentration,a critical nitrogen concentration dilution model is established.It is more reasonable to establish a critical nitrogen concentration dilution model based on the whole plant biomass of tuber and tuber crops and the whole plant nitrogen concentration.Moreover,the model is less affected by the variety,to a certain extent,it overcomes the problem that the dilution curve of the critical nitrogen concentration caused by different varieties in the uniform climate cultivation area is not uniform.The dilution model of critical nitrogen concentration under potato drip irrigation in Inner Mongolia is Nc=4.57W-0.41,the verification results prove that the curve can be used for nitrogen nutrition diagnosis of potatoes.Based on the critical nitrogen concentration dilution model,the reasonable nitrogen application rates of three potato varieties Kexin 1,Xiapodi and Holland 14 under drip irrigation conditions in Inner Mongolia were about 170-180?190-200 and 215-225 kg N hm-2,respectively.The dilution model of Mongolian sugar beet critical nitrogen concentration is Nc=4.23W-0.49,according to this curve,the reasonable nitrogen application rate of main sugar beet varieties in Inner Mongolia is in the range of 160-180 kg N hm-2.Compared with different critical nitrogen concentration curves of sugar beet and potato published recently,the critical nitrogen concentration dilution curve parameters of tuber and root crops are affected by the variety and other factors.Climatic factors have a greater influence on the critical nitrogen concentration dilution curve parameters,and varieties have less influence on the critical nitrogen concentration dilution curve parameters.When the whole plant biomass is greater than 20 t hm-2 during potato harvest,the potato critical nitrogen concentration dilution model will no longer be affected by the variety and other factors,and a critical nitrogen concentration dilution model can be shared.