Effects Of Different Nitrogen Rates On Physiological Characteristics,nutrient Absorption And Yield Of Black Highland Barley

In order to study the effects of different amounts of basal application of nitrogen fertilizer before sowing on the physiological characteristics and yield of black highland barley,a field randomized block design was used to study the effects of different amounts of basal application of nitrogen fertilizer on the photosynthetic physiological characteristics,dry matter and nitrogen accumulation and translocation of black Highland barley in Longzi,Tibet It can provide technical support for the development of black highland barley industrialization and local rational application of nitrogen fertilizer.The main results are as follows(1)The results showed that the nitrogen application rates of N1(96kg/hm~2),N2(120 kg/hm~2),N3(144 kg/hm~2),N4(168 kg/hm~2),N5(196kg/hm~2)and N6(216 kg/hm~2)were higher than that of the control N0,The SPAD value,leaf area,net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of flag leaf of black highland barley after anthesis were better than those of control N0.Secondly,each index of different nitrogen application treatments was better in N3treatment.According to the Photosynthetic Physiological Indexes of Longzi highland barley,N3 treatment showed some advantages.(2)Compared with N0,nitrogen application could increase the accumulation of dry matter and nitrogen in leaves,stem sheath,rachis+glume and grain at flowering and maturity,but had little effect on the distribution ratio of dry matter and nitrogen accumulation in each part;secondly,nitrogen application could reduce the transfer rate of dry matter and nitrogen stored in vegetative organs before anthesis The accumulation of assimilate and nitrogen after anthesis was increased,and the contribution rate of assimilate and nitrogen to grain was increased.It was found that N3 treatment had more significant effects on dry matter and nitrogen accumulation after anthesis than other treatments.(3)Compared with the control treatment N0,nitrogen application could increase the 1000 grain weight of Longzi black highland barley,and increase the grain filling rate and maximum grain filling rate at progressive stage(R1),rapid growth stage(R2),slow growth stage(R3).The effect of Nitrogen Application on the duration of progressive stage(Ta),rapid growth stage(Tb)and slow growth stage(Tc)was not obvious.Among different nitrogen application treatments,N3 treatment performed better in filling indexes of Longzi black highland barley at all levels.(4)Under different nitrogen application rates,with the increase of nitrogen application rate,the partial productivity of nitrogen fertilizer and partial productivity of nitrogen fertilizer decreased,the nitrogen absorption efficiency and contribution efficiency of nitrogen fertilizer increased first and then decreased,and reached the peak in N3 treatment.Compared with N0,the effective panicle number,grain number per panicle,1000 grain weight and yield of different nitrogen application treatments were increased in varying degrees;among all nitrogen application treatments,the increase of yield components of N3 was more advantageous than other nitrogen application treatments,and the yield of N3 was increased by more than 70%in two years,that is 144 The nitrogen application rate of kg/hm~2 was more suitable for the production of black highland barley in Longzi,Tibet.