| In this study,six foxtail millet cultivars,including Gonggu 88,Jingu 21,Changnong47,Changnong 35,Jigu 41 and Yugu 35 were employed to explore the effects of nitrogen application and delayed harvest on yield components,nutrient accumulation and utilization,grain exterior quality（size and colour）,nutrient quality（protein,starch,micronutrient and folate content）and cooking quality（pasting properties）of foxtail millet.There were four treatments:without N application combined with harvest at physiological maturity（N0T1）,without N application combined with harvest 14 after physiological maturity（N0T2）,150N kg·hm-2 combined with harvest at physiological maturity（N1T1）and 150 N kg·hm-2combined with harvest 14 after physiological maturity（N1T2）.The results of this study can provide a theoretical basis for high-quality and high-mechanized cultivation of foxtail millet.The major results are as follows:（1）N application and delayed harvest affected grain yield,1000-grain weight,grain number per ear and nutrient accumulation of foxtail millet,significantly.N application and delayed harvest increased the grain yield.Compared with the treatment in without N application,the grain yield of foxtail millet increased by 9.2～33.1%.Compared with the treatment in harvest at physiological maturity,the grain yield of foxtail millet in delayed harvest increased by 0.8～8.0%.The N,P,K accumulation in plant above-ground and N,K accumulation in grains with N application were significantly increased.Compared with the treatment in without N application,the N accumulation in plant above-ground increased by45.5～105.0%,the P accumulation in plant above-ground increased by 0.2～41.1%,the K accumulation in plant above-ground increased by 1.0～53.8%,the N accumulation in grains increased by 14.6～66.0%and the K accumulation in grains increased by 7.1～38.3%.The K accumulation in plant above-ground and N,K accumulation in grains were significantly decreased under the treatment of delayed harvest.Compared with the treatment in harvest at physiological maturity,the K accumulation in plant above-ground decreased by11.1～45.3%,the N accumulation in grains increased 1.5～15.2%and the K accumulation in grains increased 8.3～24.9%.The N,P,K harvest index of foxtail millet were not significantly affected under delayed harvest.Delayed harvest increased the N,K use efficiency in grains.The K use efficiency in grains of delayed harvest was about 1.2～2.0times that of harvest at physiological maturity.The N application decreased the N,P harvest index and N use efficiency in grains,significantly.Compared with the treatment in without N application,the N harvest index decreased by 0.9～27.5%,the P harvest index decreased by 1.6～33.0%and the N use efficiency in grains decreased by 18.3～42.8%.（2）N application and delayed harvest affected appearance quality of grain,significantly.The volume of grain was increased by N application.Compared with the volume when N was not supplied,the volume of grain increased by 0.3～6.4%by N;whereas it was not significantly affected by delayed harvest.Delayed harvest significant increased both the single weight and density of grain.Compared with the treatment in harvest at physiological maturity,the single weight of grain increased by 0.9～13.0%,and the density of grain increased by 1.3～6.5%.N application increased L*value,b*value and E*value of grain,but the a*value of grain was increased.The CCI value was not significantly affected under N application.The L*value,b*value and E*value of grain were not significantly affected under delayed harvest,but the a*value and CCI value of grain were significantly decreased.（3）N application increased the grain protein content by 14.6～65.2%compared with that when N was not applied.The grain protein content was not significantly affected by harvest time.N application decreased the amylose content of grain.Delayed harvest increased the ratio of amylose to amylopectin of grain,but the amylopectin and total starch content of grain were decreased.The Fe,Zn,Ga,Mg and Se content of grain were significantly increased under the treatment of N application.Compared with the treatment in without N application,the Fe content of grain increased by 0.1～71.1%,the Zn content of grain increased by 3.1～52.9%,the Ga content of grain increased by 2.0～30.3%,the Mg content of grain increased by 5.7～39.7%,and the Se content of grain increased by4.7～122.1%.The Fe,Zn,Ga,Mg and Se content of grain were significantly decreased under the treatment of delayed harvest.Compared with the treatment in harvest at physiological maturity,the Fe content of grain decreased by 6.0～39.6%,the Zn content of grain decreased by 8.9～22.3%,the Ga content of grain decreased by 6.4～16.0%,the Mg content of grain decreased by 8.7～18.1%,and the Se content of grain decreased by 20.6～46.8%.N application increased the total folate content of grain,significantly.Compared with the treatment in without N application,the total folate content of grain increased by27.4～115.2%.Delayed harvest decreased the total folate content of grain.Compared with the treatment in harvest at physiological maturity,the total folate content of grain decreased by 42.8～65.4%.Changes in the content of folate derivatives coincided with changes in total folate content.N application also alleviated the reduction of trace elements content and folate content caused by delayed harvest.（4）N application and delayed harvest affected the cooking quality of grain,significantly.N application decreased peak viscosity,trough viscosity,final viscosity and setback.For six cultivars,the highest values of PV,TV,and FV were obtained by N0T1 and the lowest values were induced by N1T2 for all treatments.Delayed harvest decreased setback,pasting temperature and setback.The pasting temperature was increased 1.0～2.7℃by N0T2 compared with the rest three treatments.The effect of N application on pasting temperature was not noticed. |
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