Effects Of Nitrogen Rates On Photosynthetic Characteristics And Nitrogen Utilization Of Wheat With Micro-Sprinkling Irrigation

The experiment was carried out from 2015 to 2017 under field conditions at the experimental farm of the Shandong Agricultural University.The wheat cultivar was used jimai22.The experiment included field experiment and micro-zone experiment of ¹⁵N.Field experiment set six levels of nitrogen application,which were applied to nitrogen 0 kg?N0?,150 kg?N1?,180 kg?N2?,210 kg?N3?,240 kg?N4?,and 270 kg?N5?per hectare.The micro-zone experiment was carried out in the field,and N1,N3 and N5 were selected to set up marker test of ¹⁵N.The experiment was conducted to study the effects of nitrogen application rates on photosynthetic characteristics,water use efficiency and nitrogen use efficiency of wheat with micro-sprinkling irrigation.The main results are as follows:1 Effect of nitrogen application on water consumption characteristics of wheatIn 2015²016,the soil water consumption in the 40¹20cm soil layer of N3 was significantly higher than that of other treatments.The soil water consumption in the 0²00cm soil layer during the whole growth period in N3 and N4 were significantly higher than that of other treatments.From anthesis to maturity,the soil water consumption and the water consumption of N3 and N4 were significantly higher than that of other treatments.In 2016²017,the soil water consumption in the 60⁸0 and 100¹40cm soil layer during the whole wheat growth period of N3 was significantly higher than that of other treatments.Soil water consumption in the 0 to 200 cm soil layer in N3 was the highest,N4,N5,and N2were followed,and N0 was the lowest.The total water consumption of N3,N4,and N5 were significantly higher than that of N2 and N1.From anthesis to maturity,the soil water consumption,the water consumption and daily water consumption in N3 were significantly higher than that in other treatments.2 Effects of nitrogen application on photosynthetic characteristics and dry matter accumulation and distribution of wheatIn the two growing seasons,the net photosynthetic rate,transpiration rate,stomatal conductance and instantaneous water use efficiency of flag leaves in N3 were significantly higher than that in other treatments at 21,28 and 35 days after anthesis.The relative content of chlorophyll at 28 and 35 d after anthesis in N3 was significantly higher than that in other treatments.The actual photohemical efficiency at 21,28 and 35 d after anthesis of N3 was significantly higher than that of N4 and N5,and the non-photochemical quenching coefficientat at 28 and 35 d after anthesis in N3 was significantly higher than that in other treatments.In the middle and late filling stage,the sucrose content and the sucrose phosphate synthase activity of N3 treatment were significantly higher than that of N5 and N2.During the two growing seasons,the dry matter accumulation of N3,N4,and N5 at each growth stage were significantly higher than that of other treatments.Dry matter accumulation amounts in grains of N3,N4,and N5 were significantly higher than that of other treatments.The translocation of assimilates from vegetative organs to grain before anthesis in N3 and N4were significantly higher than that of other treatments.3 Effects of nitrogen application on the absorption and utilization of nitrogen from different sourcesAt the whole growth stage,the absorption and absorption ratio of nitrogen by wheat plants from basal nitrogen and topdressing nitrogen in N3 were the highest,N5 were followed,and N1 were the lowest.The uptake of nitrogen from soil by plants of N3 and N5 were significantly higher than that of N1.At anthesis,the nitrogen content from basal nitrogen and top dressing nitrogen in stem and sheath of N3 was significantly higher than that of N5 and N1.At maturity stage,the distribution of fertilizer nitrogen in grain of N3 was significantly higher than that of N5 and N1.After anthesis,the amount of nitrogen absorbed from the topdressing fertilizer transferred from the stem and sheath to grain of N3 was significantly higher than that of N5 and N1;and the amount of nitrogen absorbed from basal fertilizer and soil by the glume and spike axist transferred to grain of N3 and N5 were significantly higher than that of N1.The amount of nitrogen residue in 0 to 60 cm soil layer of topdressing fertilizer was higher than that of basal nitrogen application.In 120 to 160 cm soil layer,topdressing nitrogen was significantly lower than the base nitrogen.The amount of nitrogen fertilizer residue in 0 to 60 cm soil layer in N3 was significantly lower than that in N5.Comparing N3with N5 treatment,the amount of fertilizer N absorbed by wheat increased significantly,and the amount of N-fertilizer residues and losses decreased.4 Effects of nitrogen application on senescence characteristics of flag leaf and root of WheatIn the two growing season,during the middle and late filling stage,the superoxide dismutase?SOD?activity and soluble protein content in the flag leaf of N3 treatment were significantly higher than that of other treatments.The content of malondialdehyde?MDA?in N3 was significantly lower than that in N4,N5 and N2.The root activity in 0 to 40 cm soil layer of N3 was significantly higher than other treatments in the middle and later stages of grain filling.In the middle and late filling stage,the activity of SOD in the root of 0 to 40 cm soil layer of N3 was significantly higher than that of N4 and N5.5 Effects of nitrogen application on yield components,grain yield,water use efficiency and nitrogen use efficiency of wheatIn the period from 2015 to 2016,the spike numbers of N3,N4 and N5 were significantly higher than other treatments.The thousand kernel of weight of N3 was significantly higher than that of other treatments.There was no significant change in the number of grains per spike between treatments.There was no significant difference in grain yield between N3 and N4,but all of them were significantly higher than that of other treatments.The water use efficiency of N3 was significantly higher than that of N1 and N0 treatments.N3 treatment had the highest nitrogen agronomic efficiency.And nitrogen use efficiency and nitrogen absorption efficiency of N3 were significantly higher than those of N4 and N5.In the period from 2016 to 2017,the spike numbers of N3 was significantly higher than other treatments.The number of grains per spike of N1 and N0 were significantly lower than other treatments.There was no significant change in the thousand kernel of weight between treatments.The grain yield of N3 was significantly higher than that of N2.And there was no significant difference in grain yield of N3,N4 and N5.The water use efficiency of N3treatment was significantly higher than that of N1 and N0.The nitrogen agronomic efficiency of N3 was significantly higher than other treatments.The nitrogen use efficiency and nitrogen absorption efficiency of N3 were significantly higher than that of N4 and N5.In conclusion,the grain yield,water use efficiency and nitrogen use efficiency of N3were high during the two growing seasons,which was the best treatment to take account of high yield and high efficiency in this experiment.