Effects Of Slow-release Urea Combined With Fulvic Acid On Photosynthetic Characteristics,Nitrogen Supply And Yield Of Longzi Black Barley

The soil nutrient content of Longzi black highland barley is in the middle or lower level in Tibet,and the cultivation measures are not perfect,which seriously restricts the development of local black highland barley industry.Therefore,the study on the influence of different nitrogen fertilizer combined with fulvic acid on black highland barley is conducive to promoting the development of local black highland barley industry.In order to understand the effects of nitrogen reduction(N),slow-release urea(CN)and combined application of fulvic acid(FA)on the physiological characteristics,nutrient absorption and yield of black highland barley,the relevant indexes of photosynthetic characteristics,nutrient utilization and grain filling of Longzi black highland barley under different nitrogen treatments were determined and analyzed,in order to provide reference for the fertilization technology of Tibetan black highland barley.The main results are as follows:(1)Compared with conventional urea and CK treatment,slow-release urea can improve the flag leaf chlorophyll(SPAD),leaf area,net photosynthetic rate,stomatal conductivities,intercellular CO2concentration and transpiration rate of black barley,and the photosynthetic performance of black barley can be further improved after applying xanthovic acid.Under the condition of 20%nitrogen reduction,the photosynthetic performance of black barley showed a decreasing trend.According to various photosynthetic physiological indexes of black highland barley,slow-release urea combined with fulvic acid is superior,which can promote the production and accumulation of photosynthetic products of black highland barley.(2)At flowering stage and maturity stage,the effects of slow-release urea and fulvic acid on the dry matter accumulation of black barley were relatively consistent,and both showed an increasing trend.Nitrogen reduction by 20%could reduce the dry matter accumulation of black barley.Slow-release urea and xanthovic acid can reduce the pre-flowering storage dry matter transport of vegetative organs of black barley,improve the distribution rate of leaves at flowering stage,and promote the increase of the accumulation and contribution rate of light compound in black barley after flowering.(3)The application of slow-release urea and fulvic acid can improve the nitrogen accumulation of black barley at flowering and maturity stages,and reducing nitrogen by 20%can reduce the nitrogen accumulation of black barley.Slow-release urea and fulvic acid can increase the nitrogen allocation rate of leaves at flowering stage,reduce the proportion of stem sheath and ear allocation,and increase the grain proportion of black barley at maturity stage.Slow-release urea and xanthovic acid can improve the pre-flowering storage nitrogen transfer of vegetative organs,reduce the pre-flowering storage nitrogen transfer rate and contribution rate of black barley,and then promote the increase of post-flowering black barley nitrogen accumulation and contribution rate.The synergistic effect of N+FA treatment on nitrogen of black barley was lower than that of CN+FA treatment.(4)The application of slow-release urea and fulvic acid can improve the grout rate and prolong the grout duration of black barley.CN+FA treatment has the best effect,and the grouting indexes of black barley with 20%nitrogen reduction show a downward trend.One-time application of slow-release nitrogen fertilizer has no significant advantage in reducing nitrogen and improving the grout duration.The grouting rate,the maximum grouting rate and the duration of grouting in the rapid increase stage were significantly positively correlated with the 1000-grain weight(P<0.01).Increasing the grouting rate and extending the duration of grouting were effective measures to increase the yield of black barley.(5)The application of slow-release urea and fulvic acid can increase the plant height,ear length,nitrogen utilization,yield and constituent factors of black barley,which showed a decreasing trend after nitrogen reduction by 20%.Applying slow-release urea can increase the biomass of black barley and reduce the ratio of root to shoot of black barley.The biomass and root-shoot ratio of black barley increased significantly after adding fulvic acid.Above-ground biomass decreased and root biomass to root-shoot ratio increased under 20%nitrogen reduction.The comprehensive analysis shows that 135kg/hm~2slow-release urea combined with 45kg/hm~2fulvic acid is the best fertilization scheme for black barley production.