Effects Of Nitrogen Phosphorus And Potassium On Yield Traits And Physicochemical Characters Of Tartary Buckwheat Starch

Tartary buckwheat is a kind of crop with high nutritional,medicinal and health value.With the improvement of living standards and the pursuing of the health for people,the application of Tartary buckwheat in the food and non-food industries has attracted more and more attention.However,Tartary buckwheat grows in the mountainous areas where the soil is poor,and its yield is low and unstable.Tartary buckwheat starch accounts for about 70%of Tartary buckwheat grains.Its structure and physical and chemical properties are closely related to the nutritional and functional properties of Tartary buckwheat,and it is important for promoting the application of Tartary buckwheat and its starch in food and non-food industries.The yield of Tartary buckwheat and its starch physicochemical properties depend not only on the genetic background,but also on the cultivation factors during growth and development,such as soil conditions,climatic conditions and agricultural treatments.Nitrogen,phosphorus and potassium are important mineral elements,and proper fertilization amount is of great significance for crop growth,development and quality formation.In this study,we measured and analyzed the agronomic traits,yield and yield components,quality and physicochemical properties of starch of Tartary buckwheat of Xinong 9940,in order to reveal the differences in the traits of different levels of NPK fertilizer and explore the trends of the effects of different treatments on the agronomic traits,yield and yield components,quality and physicochemical properties of starch of Tartary buckwheat.Main conclusions are as follows:(1)Under different levels of NPK fertilizer,there were some differences in agronomic traits,yield and quality of Tartary buckwheat.The yields of Tartary buckwheat were highest under N2 treatment(180 kg/hm~2),P3 treatment(135 kg/hm~2)and K3 treatment(135 kg/hm~2),which were 1490.1 kg/hm~2,1225.1 kg/hm~2 and 1145.1 kg/hm~2,respectively.(2)Under different nitrogen levels,the amylose content of Tartary buckwheat starch ranged from 25.26%to 28.61%.The morphology of starch granules did not change at different nitrogen fertilizers,but the particle size was significantly different.Nitrogen application did not change the number of subgroups,but it does change the proportion of each subgroup.With the increase of nitrogen application rate,the peak viscosity,trough viscosity,breakdown viscosity,setback viscosity and final viscosity of Tartary buckwheat starch decreased,while pasting temperature,enthalpy of gelatinization and relative crystallinity increased significantly.Compared with no application of nitrogen fertilizer,the retrogradation rate of Tartary starch paste under nitrogen application reduced,and the transparency and solubility improved.The results of variance analysis showed that the nitrogen application level and the year significantly affected the physical and chemical properties of Tartary buckwheat starch.(3)Under different levels of phosphate fertilizer,Tartary buckwheat starch granules showed spherical and polygonal shapes with smooth edges,and the particle morphology did not change.With the increase of phosphate fertilizer level,the proportion of large-sized starch granules and small-sized starch granules decreased,the proportion of medium-sized starch granules increased,and the median diameter and amylose content of Tartary buckwheat starch granules decreased first and then increased.Under different phosphorus application levels,the pasting properties of Tartary buckwheat starch were significantly different,but showed an inconspicuous pattern.Compared with no application of phosphate fertilizer,the enthalpy of gelatinization and relative crystallinity of Tartary buckwheat starch at the application of phosphate fertilizer increased significantly.The starch paste under P2(75 kg/hm~2)level had the lowest retrogradation rate and the highest solubility and transparency.(4)The application rate of different potassium fertilizers did not change the morphology of Tartary buckwheat starch,but changed the particle size.With the increase of potassium application rate,the amylose content in Tartary buckwheat starch increased first and then decreased.There were significant differences in pasting properties and thermal properties under different potassium application rates.The peak viscosity,trough viscosity,breakdown viscosity,final viscosity and setback viscosity under K1 treatment(15 kg/hm~2)were the highest,which were 7941 cP and 4799 cP,3142 cP,3142 cP,7900 cP,3101 cP,respectively,compared with those under the control,increased by 27.83%,15.36%,53.12%,13.25%,10.12%.The enthalpy of gelatinization of 10.59 J/g under K3 treatment was the highest and increased by 21.31%than that under the control.With the increase of potassium application rate,the transparency of Tartary buckwheat starch paste decreased first and then increased.The transparency of Tartary buckwheat starch paste under K3 treatment was the highest value of 38.4%,which increased by 25.91%than that under the control.