Effect Of Different Nitrogen Fertilizer Rate And Different Ratio Of Base And Topdressing On Carbon And Nitrogen Metabolism In Wheat With Super High Yield

In order to offer theoretical basis of application of nitrogen (N) fertilizer for super high-yield winter wheat, the experiment was conducted with high-yield medium-gluten winter wheat cultivar Jimai 22 in 2009²010 wheat growing season in Chenwang village, Yanzhou, Shangdong. The field experiment used the split-plot design with the nitrogen rate as the main plot and the nitrogen ratio of base and topdressing as the subplot, in order to verify the effects of different nitrogen fertilizer rate and different ratio of base and topdressing on carbon and nitrogen metabolism.Three nitrogen rates were conducted: N application rate of 210kg·hm^-2(N210), 270kg·hm^-2(N270), and 330kg·hm^-2(N330); and three nitrogen ratios of base and topdressing were conducted with 7:3(N1), 5:5(N2) and 3:7(N3); without applying N fertilizer(N0) was regarded as control. The time for nitrogen applying stage was at jointing. The results were as follows:1 The effects of different nitrogen rate and different ratio of base and topdressing on carbon metabolism in wheat1.1 The effects of different nitrogen rate and different ratio of base and topdressing on photosynthesis characteristics of flag leafUnder the nitrogen rate of N210 and N270, with increasing topdressing nitrogen amount appropriately, the stomatal conductance (GS), the actual photochemical efficiencies (ФPSâ…¡) and net photosynthesis rate (Pn) increased at 14, 28 and 35 d after anthesis. However, under the nitrogen rate of N330, there was no significant difference between N1, N2 and N3 at 14 and 28 d after anthesis, but it was significant lower at 35 d after anthesis.With increasing nitrogen rate, the stomatal conductance (GS), the actual photochemical efficiencies (ФPSâ…¡) and net photosynthesis rate (Pn) in treatment of N270 were significantly higher than those of N210 and N330 at 28 and 35 d after anthesis.1.2 The effects of different nitrogen rate and different ratio of base and topdressing on canopy apparent photosynthesis and canopy apparent respirationAt the same nitrogen fertilizer rate, the canopy apparent photosynthesis (CAP) and the canopy apparent respiration (CAR) in treatment N2 was significantly higher than N1 at the late filling stage. Compared with treatment N2, the canopy apparent photosynthesis of treatment N3 decreased, whereas both the canopy apparent respiration (CAR) and CAR/ (CAP+CAR) had significantly increased.At the same ratio of base fertilizer to topdressing, the canopy apparent photosynthesis (CAP) and the canopy apparent respiration (CAR) in treatment N270 was higher than N210. To further enhance the nitrogen amount, the canopy apparent photosynthesis in the late filling stage decreased, whereas both the canopy apparent respiration (CAR) and CAR/ (CAP+CAR) had significantly increased.1. 3 The effects of different nitrogen rate and different ratio of base and topdressing on dry matter accumulation and distributionAt the same nitrogen fertilizer rate, with increasing basal nitrogen rate, the dry matter accumulation before jointing had enhanced, with increasing topdressing nitrogen rate, the dry matter accumulation after jointing had enhanced. There was no significant difference in dry matter accumulation amount among the treatments at maturity.The dry matter distribution ratio in grain at maturity in treatment N2 was higher than that in N3, with no significant difference from N1. Whereas its dry matter distribution amount and ratio in vegetative organs were significantly lower than those in treatment N3. The dry matter accumulation amount after anthesis in treatment N2 was significantly higher than N1 and N3.At the same ratio of base fertilizer to topdressing, with increasing nitrogen rate, the dry matter accumulation increased, which were presented as N330>N270>N210 at each growth stage.Compared with N210, N270 had gained the higher dry matter accumulation in grain and its distribution. To further enhance the nitrogen rate, the dry matter amount and ratio in vegetative orgens was significantly increased, however, it was not benifical to enhance the dry matter accumulationin amount in grain and its distrubution.The dry matter accumulation amount after anthesis in treatment N270 was significant higher than that in treatment N210. There was no significant difference in the dry matter accumulation amount between N270 and N330 before and after anthesis.1. 4 The effects of different nitrogen rate and different ratio of base and topdressing on activity of sucrose phosphate synthase (SPS) and sucrose content in flag leafAt the same nitrogen fertilizer rate, the sucrose phosphate synthase activity of treatment N2 was significantly higher than N1 and N3; the sucrose content in flag leaf of N2 was significantly higher than N1 and N3 during 0²1d after anthesis, but after 21d, the N3 was significantly higher than N2. At the same ratio of base fertilizer to topdressing, the sucrose phosphate synthase activity of treatment N270 was significantly higher than N210 and N330, the sucrose content in flag leaf of N270 was significantly higher than N210 and N330 during 0²1d after anthesis, but after 21d, the N330 was significantly higher than N270.1. 5 The effects of different nitrogen rate and different ratio of base and topdressing on starch contentAt the same nitrogen fertilizer rate, with increasing topdressing nitrogen rate appropriately, the amylopectin content, amylose content and total starch content were all decreased, the ratio of amylopectin to amylose were presented as N2,N3>N1, and there was no significant difference between N2 and N3.At the same ratio of base fertilizer and topdressing, N270 had the highest amylopectin content, amylose content and total starch content among the treatments. The ratio of amylopectin to amylose was presented as N210>N270, N330,and there was no significant difference between N270 and N330.2 The effects of different nitrogen rate and different ratio of base and topdressing on nitrogen accumulation and translocation in wheatAt the same nitrogen rate, with increasing basal nitrogen rate, the nitrogen accumulation in wheat plant before jointing enhanced, with increasing topdressing nitrogen amount, the nitrogen accumulation after jointing enhanced. The nitrogen accumulation at maturity in treatment N2 and N3 was significantly higher than N1, and there was no significant difference between N2 and N3.The treatment N2 had significantly increased the amount of grain nitrogen accumulation than treatment N1. To further enhanced the topdressing nitrogen rate, it was not benifit to increase the amount and the efficiency of nitrogen translocation from vegetative organs to grain.The grain nitrogen amount and nitrogen translocation amount in treatment N2 were significantly higher than those in treatment N1. To further enhanced the topdressing nitrogen amount, it was not favorable to improve the grain nitrogen amount, nitrogen translocation amount and efficiency.At the same ratio of base fertilizer to topdressing, with increasing nitrogen amount, the nitrogen accumulation increased, which was presented as N330>N270>N210 at each growth stage. The nitrogen translocation amount increased. It was not benefical to increase nitrogen translocation efficiency. Under the level of N1,the treatment N270 significantly increasd the nitrogen amount of both the grain and vegetavative organs, Under the level of N2 and N3, with increasing nitrogen amount appropriately, both the grain and vegetavative organs nitrogen amount increased, however , there was no significant difference among the treatments in nitrogen distribution. The treatment N3 was not benifit to increase the grain nitrogen amount and its distribution.3 The effects of different nitrogen rate and different ratio of base and topdressing on grain yield and quality and nitrogen use efficiencyUnder the nitrogen rate of N210, the grain yield showed as N2, N3>N1; under the nitrogen rate of N210, the grain yield showed as N2>N3, N1. At the same ratio of base fertilizer and topdressing, the grain yield showed as N270, N330>N210.At the same nitrogen fertilizer rate, protein content, dough developing time and stability time, the N agronomic efficiency, N productive efficiency and N uptake efficiency in treatment N2 were significantly higher than those in treatment N1. No significant difference was found between N270 and N330, which indicated that excess nitrogen was not favorable to improve the dough developing time and stability time, the N agronomic efficiency, N productive efficiency, N uptake efficiency and N use efficiency.At the same nitrogen fertilizer rate, the grain yield, protein content, dough developing time and stability time in treatment N2 were significantly higher than the treatment N1. To further enhanced the topdressing nitrogen amount, the dough developing time and stability time had no significant differences. The N agronomic efficiency, N productive efficiency, N uptake efficiency and N use efficiency were all significantly lower than treatment N270.Under the condition of this experiment, as grain yield, quality and nitrogen use efficiency were concerned, the most appropriate nitrogen fertilizer applying regime recommended was the treatment which nitrogen fertilizer rate was 270 kg·hm^-2 and the ratio of base fertilizer and topdressing was 5:5.