Effects of nitrogen rate and ratio of base fertilizer and topdressing on uptake, translocation of nitrogen and yield in wheat

Abstract

Application of nitrogen (N) fertilizer is one of the most important measures to increase grain yield and protein content in winter wheat (Triticum aestivum L.) production. However, misuse of N fertilizer will not only affect grain yield and quality, but also cause the decline of economic benefits and related negative environmental effects. It is essential to study reasonable N application regimes for profitable yields, efficient N utilization and reduction in possible environmental pollution. The objective of this study was to determine the N uptake and translocation in wheat plants by using 15 N isotope tracers in PVC cylinders (2.05 m long, W 0.2 m, without bottom) in seven treatments: without N fertilizer application (N0); N application rate of 168 kg/hm 2 (0.527 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N1), 1:2 (N2) and 0:1 (N3); N application rate of 240 kg/hm 2 (0.753 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N4), 1:2 (N5) and 0:1 (N6). The 15 N tracer experiment showed that the main basal N absorbed by plant from sowing to jointing stage accounted for 78.04%-89.67%; fertilizer N use efficiency (FNUE, N fertilizer accumulation in plant/N supplied) of topdressing was significantly higher than that of basal N; reducing basal N amount and increasing topdressing N amount could appropriately promote the plant's absorption of more N fertilizer and enhance FNUE, of which treatment N2 had the highest values. Under the high-yield condition, when N fertilizer rate was increased from 168 to 240 kg/hm 2 , there were no significant differences in the amount of N accumulation in plants and in grains between treatments with the same ratio of base fertilizer to topdressing; by reducing basal N amount and increasing topdressing N amount accordingly, the translocation efficiency (TE, accumulation amount from vegetative organs to grain/N accumulation in vegetative organs during anthesis) increased, and the amount of N assimilation to grains after anthesis and its contribution proportion (the amount of N assimilation to grains after anthesis/N accumulation in grain) also increased. In other words, grain N accumulation amount increased with increasing amount of topdressing N at the same N fertilizer rate. There were no significant differences among treatments N2, N3, N5 and N6 in grain N accumulation. Appropriate N fertilizer rate with a reduction in basal N amount and an increase in topdressing N amount such as in N2, N5 and N6 increased grain yield and protein content. In conclusion, under conditions used in this experiment, as far as grain yield, protein content and FNUE are concerned, the recommended appropriate N fertilizer application regime is treatment N2, with a N fertilizer rate of 168 kg/hm 2 and a ratio of base fertilizer to topdressing of 1:2.Keywords nitrogen fertilizer rate, ratio of base and topdressing, 15 N, nitrogen uptake, translocation, yield Front.

Optimized seeding rate and nitrogen topdressing ratio for simultaneous improvement of grain yield and bread‐making quality in bread wheat sown on different dates

“…Higher seeding rate and N topdressing ratio increased GPC and N tot mainly by enhancing N uptake pre‐ and post‐anthesis and the amount of N remobilized into grains during grain filling. The enhanced N uptake due to increased seeding rate and N topdressing ratio is consistent with previous findings 29,30,39,55,56 . The newly absorbed N after anthesis is partitioned to the grain more efficiently for grain protein synthesis, 57–60 so it is reasonable to infer that increased or decreased PAN up will, in turn, increase or decrease the amount of N translocated to grains during grain filling.…”

“…Generally, topdressing fertilizer N increases GPC without decreasing the final GY, 38 whereas N accumulation in grains increases with higher ratios of topdressing N 39 . The application of half or one‐third of total fertilizer N at stem elongation improves GY and GPC compared with application at sowing alone or at both sowing and tillering 40 .…”

“…35,36 Increasing the seeding rate up to double the current recommendations with N application at the flag leaf stage can improve most end-use quality traits. 37 Generally, topdressing fertilizer N increases GPC without decreasing the final GY, 38 whereas N accumulation in grains increases with higher ratios of topdressing N. 39 The application of half or one-third of total fertilizer N at stem elongation improves GY and GPC compared with application at sowing alone or at both sowing and tillering. 40 The highest GY and GPC have been reported with application of 30 kg N ha −1 before seeding and a total N fertilizer application of 180 kg N ha −1 .…”

Low N Fertilizer Application and Intercropping Increases N Concentration in Pea (Pisum sativum L.) Grains

“…In this study, N transportation capacity was quantified as the quantity and rate of N translocation (Xu et al, 2006 ; Shi et al, 2007 ). The amount of N translocation from stems was greater than that from leaves, whereas N translocation rate from stems was less than that from leaves.…”

Crop production kept stable and sustainable with the decrease of nitrogen rate in North China Plain: An economic and environmental assessment over 8 years

“…29 and Shi et al . 30 . Nitrogen partial factor productivity (PFP N ) and nitrogen agronomic efficiency (AE N ) were calculated as following equation:where GY was grain yield with N fertilizer (kg ha −1 ), GY 0 was grain yield without N fertilizer (kg ha −1 ), and NR was N fertilizer rate (kg ha −1 ).…”