Effects Of Sowing Method And Nitrogen Application Rate On Growth Physiological Characteristics And Nitrogen Use Efficiency Of Drip Irrigation Winter Wheat

The plot control experiment was carried out in the network room of Agronomy experimental station of Tarim University from 2018 to 2019.The winter wheat Handan 5316 was used as the test variety,and the two factor split plot design was adopted.The main area consisted of three sowing methods,namely,row sowing?B1?,hole sowing?B2?and broadcast sowing?B3?;the sub area was treated with four nitrogen application rates,namely,no nitrogen fertilizer?N0?,138 kg·hm^-2?N1?,207 kg·hm^-2?N2?and 276kg·hm^-2?N3?.The population and individual growth dynamics,flag leaf photosynthetic characteristics and protective enzymes,SPAD value and NBI value,yield and nitrogen use efficiency were observed in the combined plots with different sowing methods and nitrogen application rates.The effects of different sowing methods and nitrogen application rates on the population quality and nitrogen use efficiency of winter wheat under drip irrigation were analyzed,and the sowing mode and nitrogen application rate under the condition of fertilizer saving and stable yield were screened.The results of this study will lay a foundation for further study on the production behavior of winter wheat under drip irrigation and the mechanism of efficient utilization of water and fertilizer,and provide a theoretical basis for the improvement of water-saving and fertilizer saving planting techniques of winter wheat in extremely arid irrigation areas.The results are as follows.1.The results showed that sowing wheat had the most tillers before winter and the largest total number of stems before winter,but the quality of wheat seedlings was poor;the tiller growth of drill sowing and hole sowing was relatively stable,and the spike rate was 22.38%and 27.31%higher than that of broadcast sowing.The growth peak of plant height of winter wheat under drip irrigation was from jointing stage to flowering stage,and the final plant height of hole sowing was 6.72%and 8.40%higher than that of row sowing and broadcast sowing respectively,and the appropriate amount of nitrogen fertilizer had a significant effect on the growth of plant height;the LAI of drill sowing increased rapidly before growth,while that of hole sowing reached 7.21 at booting stage,and decreased slowly in the later stage.The average LAI of N1,N2 and N3 treatments increased by 15.33%,33.74%and 23.78%compared with N0 treatment;the average leaf angle of hole sowing and N2 treatment was the largest,followed by drilling and N1 treatment.The dry matter accumulation of shoot was the highest in B2 and N2 treatments,reaching 18 377.67 kg·hm^-22 and 20 078.29 kg·hm^-22 at the end of grain filling stage;the grain to leaf ratio was B2>B1>B3,and nitrogen application significantly increased the grain leaf ratio;grain filling rate reached the peak at 15-20 days after anthesis,the highest in B2 treatment(2.33 g·D^-1),followed by B1.The size of nitrogen application was N3>N3>N1>N0;In conclusion,the population quality of B2N2was the best,with plant height of 83.94 cm,total stem number of 1479.81×10⁴ plants·hm^-22 before winter,the highest total number of stems at jointing stage of 1 847.18×10⁴ plants·hm^-2,721.35×10⁴ ears·hm^-22 at mature stage,39.05%ear formation rate.LAI was 3.66 at jointing stage,7.99 at booting stage and 4.32 at filling stage;average leaf inclination angle was 50.65 degrees;the maximum accumulation of dry matter was 20 119.05 kg·hm^-2,and the ratio of grain number to leaf and grain weight to leaf reached 3 311.86grain·m^-22 and 249.37 g·m^-2,respectively.2.The maximum photosynthetic characteristic value of winter wheat under drip irrigation was at flowering stage.The average CAP,Pn,Gs and Tr of hole sowing were the highest,reaching 4.71gCO₂·m^-2·h^-1,20.69?mol·m^-2·s^-1,0.41?mol·m^-2·S^-11 and 7.37 mmol·m^-2·s^-1,respectively.The Ci of hole sowing was the highest,which was 505.28?mol·mol^-1.Under N2 treatment,CAP,Pn,Gs,Ci and Tr were the highest,reaching 5.10 g CO₂·m^-2·h^-1,17.34?mol·m^-2·s^-1,0.34?mol·m^-2·s^-1,377.47?mol·mol^-1and 4.75 mmol·m^-2·s^-1,respectively.The average CAP,Pn,Gs and Tr of B2N2 were the largest,and the Ci of B3N2 was the largest.The activity of SOD in flag leaf was B2>B1>B3 in each stage,and the effect of nitrogen application was N2>N1>N3>N0;The content of MDA was B3>B1>B2,and the effect of nitrogen application was N0>N1>N3>N2.The enzyme activity was the highest and MDA was the lowest.The SPAD value of flag leaf was the highest at flowering stage.The average SPAD values of hole sowing and drilling sowing were 54.80 and 52.83,which were 5.96%and 2.15%higher than those of sowing.The highest average SPAD value of the whole period was N2,which was 47.63,higher than that of N0,N1 and N3 treatment by 4.36%,1.97%and 1.53%respectively.3.The panicle length and effective spikelet number of B2 and N2 were the largest,followed by B1and N3;the ear length of B3N2 was the highest,which was 14.8 cm,and the effective spikelet number of B2N2 was the highest,reaching 18.79.The average number of ears harvested,the average number of grains per spike and the average 1000 grain weight of all nitrogen treatments were the highest at N2 level,which were 707.44×10⁴·hm^-2,26.15 grains and 47.54 g,respectively;Among the different sowing methods,the number of harvest ears and grains per ear of hole sowing was the largest,which was 682.51×10⁴·hm^-22 and24.14 grains respectively,and the seed weight of broadcast sowing was the largest,which was 44.33 g.In the combination treatment,the number of grains per spike of B2N3 was the largest,which was 26.60,and that of B2N2 was 721.33×10⁴·hm^-2.Compared with N0,N1 and N3,N2 increased by 49.98%,24.14%and 14.92%respectively.Compared with drilling and sowing,hole sowing increased 9.63%and 16.17%respectively.The final yield of B2N2 treatment was the largest,reaching 9 144.75 kg·hm^-2,followed by B1N2,which was 8 715.89 kg·hm^-2.4.With the increase of nitrogen application rate,NBI increased,reaching the maximum at the flowering stage,and rapidly decreased after the filling stage.The decline rates of drill sowing,hole sowing and broadcast sowing were different,and the average decline rates were 47.56%,20.62%and 53.03%at milk ripening stage,respectively.The peak period of nitrogen accumulation was from jointing stage to flowering stage,which accounted for 61.45%-70.38%of total nitrogen accumulation.Nitrogen transport of various vegetative organs was shown as:leaf>stem sheath>glue husk+cob,the contribution rate of nitrogen operation of leaves,stem sheath and glume axis to the grain was:25.62%-30.40%,20.90%-24.51%And 4.13%-6.70%,agronomic utilization rate of nitrogen fertilizer:9.66%-21.71%,partial productivity of nitrogen fertilizer:24.28%-52.60%,nitrogen fertilizer utilization efficiency:9.34%-26.86%.When the nitrogen application rate was 207 kg·hm^-2,the drilling or hole sowing winter wheat could significantly improve the nitrogen use efficiency.Only the combination of suitable sowing method and high-efficiency nitrogen management measures was the key to improve the yield of winter wheat.