Response of nitrogen redistribution to irrigation at jointing in winter wheat

Abstract

To explore the effect of irrigation at the jointing stage on nitrogen (N) redistribution after flowering and productivity effects of water and N in winter wheat (Triticum aestivum L.), a 2‐yr field experiment was conducted between 2015 and 2017. Three irrigation regimes were designed as follows: rain‐fed (W0), irrigation at jointing and 7 d after flowering (W1), and irrigation at 7 d after flowering (W2). Compared with W2, W1 increased spike number, kernels per spike, and N and dry matter (DM) accumulation at flowering; delayed the senescence of flag leaves after flowering; increased the flag leaf photosynthetic rate, redistribution of N and DM from vegetative organs to grains in the middle and late grain filling stages, and grain yield; and decreased N and DM redistribution and grain weight during early grain development. This may be the reason why the N uptake efficiency and N productive efficiency were higher, whereas the productivities of water and N had no significant difference, and even water productivity was lower under W1 than W2. Therefore, on the basis of suitable water supply from jointing to flowering, achieving a high N and DM accumulation at flowering and high kernels per spike, if the grain development can be accelerated earlier and the redistribution of N and DM can be promoted, it is expected to further improve the productivities of water and N.

The end-use quality of wheat can be enhanced by optimal water management without incurring yield loss

“…Moreover, there is a negative association between GPC and total irrigation amount ( Moradi et al., 2022 ). Wu et al. (2020) also found that the concentration of grain protein was significantly increased by a water deficit during the grain-filling stage.…”

“…In this regard, the findings of some studies (Beral et al, 2020;Sanchez-Bragado et al, 2020) have indicated that the TGW is negatively correlated with grain number. Wu et al (2020) also found that irrigation at the jointing stage increased spike number, kernels per spike, and grain yield, but reduced grain weight. Consistently, we detected a significant negative relationship between TGW and the NGB (r = -0.58, p< 0.05) in the present study.…”

“…Moreover, there is a negative association between GPC and total irrigation amount (Moradi et al, 2022). Wu et al (2020) also found that the concentration of grain protein was significantly increased by a water deficit during the grain-filling stage. However, the effects of drought at the grain-filling stage were found to differ according to stress intensity, with a slight water deficit significantly reducing GPC, whereas severe water deficit has been found to increase the concentration of grain proteins during the grain-filling stage (Meng et al, 2016).…”

Optimized Border Irrigation Improved Nitrogen Accumulation, Translocation of Winter Wheat and Reduce Soil Nitrate Nitrogen Residue

“…We found that, compared with irrigation of other border lengths, L40 treatment promoted significantly higher grain nitrogen accumulation by increasing the grain nitrogen accumulation rates (Vmax and Vmean; Figure 7, Table 3). The low rate of nitrogen accumulation in grains under L20 and L30 treatments may be due to low nitrogen transport in vegetative organs, and to water stress, resulting in premature leaf senescence and reduced nitrogen accumulation in plants after anthesis [12]. Compared with that under L40 treatment, the decrease in the grain nitrogen accumulation under L50 treatment was mainly due to excessive irrigation, which caused the plants to retain nitrogen in stems and leaves and mature late; high temperatures in the later growth stage led to their rapid maturity, and the nitrogen accumulation in the stems and leaves was not transferred to the grains [39].…”

“…However, water stress significantly reduces the absorption of nitrogen by plants, and insufficient nitrogen reduces the chlorophyll content in leaves and the accumulation of photosynthetic products [11]. In another study, the plant nitrogen accumulation at anthesis, net photosynthetic rate in flag leaves after anthesis, and grain yield under supplemental irrigation at jointing and anthesis were 45.8%, 24%, and 8.86% higher, respectively, than those under supplemental irrigation at anthesis only [12]. Many studies of the effect of soil moisture and irrigation period on plant nitrogen accumulation have been conducted; however, information on the characteristics of grain nitrogen accumulation and the activity of nitrogen metabolic enzymes in flag leaves, especially under irrigation with different border lengths, is limited.…”