The translocation of pre-anthesis nitrogen to the grain is an important source for winter wheat. The relation between the nitrogen translocation and irrigation regime was studied in the field under a rain-proof trough shelter. Nitrogen (N) translocation amount, N translocation efficiency decreased with a decline in irrigation amount or by excessive irrigation. Compared with different organs, the leaf and stem had higher N translocation amounts, and contributions to grain for both cultivars -Jinan 17 and Lumai 21, indicating that stem also is a major N source for grain development. The contribution of pre-anthesis total above ground N to grain N ranged from 57 to 76 %, indicating the importance of pre-anthesis storage of N for achieving high grain N concentrations. Grain nitrogen and yield (kg ha )1 ) were positively and significantly correlated with the N translocation amounts and contributions, respectively, suggesting that the sink strength may be involved in the translocation of N from a vegetative organ to the grain. N harvest index (NHI) was significantly correlated with N translocation efficiency, suggesting that the latter is a prerequisite for increasing grain N and improving grain quality. The experiment showed that N translocation status is enhanced by better irrigation practices, but limited by severely deficient or excessive irrigation.

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Accumulation and translocation of nitrogen (N) in the vegetative organs and grains of winter wheat (Triticum aestivum L.) are important processes in determining yield and quality. The present study was conducted to compare the effects of water deficit and cultivars (cv. Lumai 21 and Jinan 17) on N translocation from vegetative organs to grains in a mobile rain-shelter using 15 N-labeled ammonium sulfate fertilizer. The N translocation amounts (defined as the difference between the N amount at anthesis and the N amount at maturity for a vegetative organ) in leaves were greatest for the two cultivars, followed by glumes, stems, and sheaths, respectively. The N translocation ratio (defined as the ratio of the translocation amount to N amount at anthesis) in total above-ground parts were greater for Lumai 21 (0.65 g g )1 DW) than for Jinan 17 (0.60 g g )1 DW), and Lumai 21 plants had a higher N translocation ratio for the N derived from fertilizers. The N contribution (defined as the ratio of the translocation amount to grain N amount) of total vegetative parts aboveground to grain N ranged from 0.50 to 0.77 g g )1 DW, and that of the leaf was the greatest. The results showed that water deficit remarkably increased the N translocation ratio derived from soil and the contributions of N in various vegetative organs to grain N. It is suggested that water deficit would weaken the availability of fertilizer N but enhance the remobilization of prestored N to the grains.

The area of dryland wheat is large in Huang-Huai-Hai Rivers region, where grain yield of wheat was low and unstable because of deficient and variable precipitation. Conservation tillage is an important cultivation mode to stimulate crop production and has been a hotspot in cultivation research of winter wheat. Minimum tillage and no-tillage are believed to significantly increase grain yield and water use efficiency of dryland wheat. A field experiment was conducted to study the effects of tillage modes on water consumption and dry matter accumulation of wheat in hill area of Shandong Province in 2009-2010 and 2010-2011 growing seasons. Compared to strip rotary tillage (SR), rotary tillage after subsoiling (RS), and rotary tillage (R) treatments, strip rotary tillage after subsoiling (SRS) treatment was beneficial to reduce water consumption amount from sowing to pre-winter stage, increase water consumption amount from anthesis to maturity stage, and promote the ratio of water consumption after anthesis to the total water consumption. The water reduction amount in 0-20 cm soil layer was lower in SRS treatment than in RS and R treatments from sowing to jointing, while that in 40-160 cm soil layer was higher in SRS treatment than in SR and R treatments from jointing to maturity. In the whole growing period of 2009-2010 and seedling, anthesis, and filling stages of 2010-2011, the evaporation of SRS was lower than that of RS or R treatment, which was equivalent to that of SR with no significant difference. SRS treatment had the highest dry matter accumulation amount from anthesis to maturity stage. Compared to SR and R treatments, SRS treatment had higher water consumption amount and water use efficiency. There was no significant difference between SRS and SR treatments in water consumption and water use efficiency, but the grain yield was the highest in SRS treatment. Therefore, SRS treatment is considered as the best tillage treatment under the experimental condition.

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Our results suggested that N fertilization at 150 kg N ha 1 was optimal for grain production via promoting above-ground biomass and soil water consumption in deep soil layers. These results should help provide guidance for N fertilization management for optimal and sustainable wheat production in the said region.

Clarifying factors that underpinning the variation in wheat yield components between high and middle soil fertility fields is critical to increase grain production and narrow yield gap for smallholder farming systems in the Huang–Huai–Hai Plain (3HP), which characterized by a large variation in soil fertility. Two-year field experiments were conducted to investigate wheat tillering, leaf photosynthesis, and grain filling characteristics in different soil fertility fields: high soil fertility field (HF) and middle soil fertility field (MF). Results showed that the spike formation rate in HF was 12.7%–13.0% higher than that in MF, leading to an 18.0%–19.8% increase in spike number. In addition, HF improved canopy light interception and leaf photosynthesis characteristics after anthesis and delayed leaf senescence, contributing to the increase in both the active grain filling period and grain filling rate. This resulted in a higher 1,000 grain weight in HF, which was 8.2%–8.3% higher than that in MF. Compared to MF, HF obtained higher yields at 9,840 kg ha−1 in 2017/18 and 11,462 kg ha−1 in 2018/19, respectively. In summary, higher spike number and 1,000-grain weight, which were mediated by spike-formation rate, maximization of light interception and improved leaf photosynthesis. These results would have important implications for narrowing yield gap between MF and HF in the 3HP.

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