Study On Diagnosis Of Nitrogen And Fertilizer Recommendation Of Drip-irrigated Spring Wheat

[Object] Nitrogen is one of the most important nutrient elements, which plays an important role in dry matter accumulation and yield of drip-irrigated spring wheat. However,unreasonable application of nitrogen in wheat production process is widespread. In order to explore the appropriate nitrogen diagnosis methods on drip-irrigated spring wheat,the three methods of nitrate reflectometer, Greenseeker handheld spectrometer and SPAD-502 chlorophyll meter were compared, and the model of fertilizer recommendation for different stage based on rapid nitrogen nutrition diagnosis for wheat was established.This article is to provide scientific reference for judging the abundance or shortage of nitrogen situation and nitrogen management.[Method] The field experiment was conducted by cultivars XC 6 and XC 35.There was 6 N treatments were 0,75,150,225,300,375 kg · hm-2, respectively corresponding N0, N1, N2, N3, N4, N5. Logistic regression equation was used to analysis dry matter accumulation under different nitrogen levels; three nitrogen nutrition diagnosis RQflex 2 nitrate reflectometer, SPAD chlorophyll meter and Greenseeker handheld remote sensing spectrometer was compared, to obtain the optimum diagnosis method of drip-irrigated spring wheat methods;Nitrogenous fertilizer recommendation model was established based on NDVI.[Result](1) The results showed that within a certain range, nitrogen application increased the accumulation of dry matter and the transfer of dry matter to grain. The maximum dry matter accumulation rate, the maximum dry matter accumulation, the length of the growing period and the demand for nitrogen were greater in Xinchun 35 than in Xinchun 6. Grain yield initially increased and then decreased as the amount of nitrogen applied to both cultivars increased.(2) The yield was a maximum when the nitrogen application rate was 288 kg·hm-2 for Xinchun 6 and335 kg·hm-2 for Xinchun 35. The thousand-grain weight of Xinchun 6 was greater than that of Xinchun 35.In contrast, the number of grains per panicle was less in Xinchun 6 than in Xinchun 35. In conclusion,different varieties of spring wheat needs different of nitrogen, the growth characteristics of different cultivars should be taken into account when making fertilizer recommendations for drip-irrigated spring wheat.(3)Jointing, booting, heading and flowering, milk stage, SPAD chlorophyll meter reading value and canopy NDVI values and nitrogen levels, leaf nitrogen content was highly significant linear correlation with yield was significantly related to the secondary.(4) The three indicators can be used for diagnostic fertilization for drip-irrigated spring wheat.The fit of the three indicators and N application, yield was NDVI> SPAD> NO3- concentrations. The result of Nitrate lacked reliability and stability, experimental operation is relatively cumbersome.The diagnosis results of Greekseeker handheld spectrometer which is the best for N diagnosis of the three methods are stable, easy to operate, suitable for use in the diagnosis of fertilizer drip-irrigated spring wheat.In addition,SPAD-502 can be also used as a N diagnostic method.(5)The critical NDVI at jointing stage,booting stage,heating stage and filling stage were XC 6(0.7154,0.7916,0.8868,0.9112);XC 35(0.6914, 0.7643, 0.8913, 0.9132).The nitrogenous fertilizer recommendation model was evaluated according the relationship between NDVI and Nfer at different growth stages.N fertilizer recommendation form was built by the model.[Conclusion] The three indicators can be used for diagnostic fertilization for drip-irrigated spring wheat.The fit of the three indicators and N application, yield was NDVI> SPAD> NO3- concentrations.The result of Nitrate lacked reliability and stability,experimental operation is relatively cumbersome.The diagnosis results of Greekseeker handheld spectrometer which is the best for N diagnosis of the three methods are stable, easy to operate, suitable for use in the diagnosis of fertilizer drip-irrigated spring wheat,especially on Xinchun 35.In addition, SPAD-502 can be also used as a N diagnostic method.