| Synchronously improving grain yield and quality is a key target in the production of specialty wheat. Elucidating the mechanism and regulation principles for grain quality formation in wheat is of important significance for developing quality formation physiology and guiding specialty wheat production in practice. The present study characterized C/N assimilation transfer, endogenous hormone change in flag leaves and photosynthesis after anthesis in relation to the formation of grain yield and quality in different wheat genotypes under different nitrogen regimes, and established a regulation mechanism on quality formation of different specialty wheat and nitrogen management system under different ecological regions. The results were showed as below.Field experiments were carried out under high yield conditions at Xuzhou and Nanjing to investigate the effects of nitrogen dressing time on nitrogen accumulation and transfer, grain yield and protein content in two types of specialty wheat, middle- and weak gluten wheat. The results showed that nitrogen dressing at jointing and booting increased grain yield and protein content and yield, but too late dressing at heading and flowering might be unfavorable for simultaneous increases in grain yield and protein content. Compared with control, dressing treatments significantly increased post-anthesis nitrogen assimilation in Xumai 26 of Xuzhou and Sumai 6 of Nanjing, reduced the transfer ratio of reserved nitrogen in vegetative organs to the grains, but increased that in Huaimai 18. Grain protein content of Xumai 26 and Sumai 6 was significantly correlated with post-anthesis nitrogen assimilation. However, grain protein content in Huaimai 18 was significantly correlated with the transfer amount of reserved nitrogen in vegetative organs. These results indicate that different cultural strategies should be adopted for regulating grain protein content in different specialty wheat cultivars.At different eco-sites of Xuzhou, Jiangyan and Jintan, effects of different nitrogen rates and dressing times on grain yield and quality characters of two different specialty wheat genotypes were investigated under the same management practices. The results showed that grain yields increased under medium (225kg/hm2) and high nitrogen rates (300kg/hm2) compared with low nitrogen rate (150kg/hm2). Grain yield decreased withdelayed dressing time at 225kg/hm . The content of protein, wet gluten and gluteinin and ratio of glutenin/gliadin in grains significantly increased at medium and high nitrogen rates compared low nitrogen rate. Post-anthesis DW transfer, N accumulation and transfer amount were also enhanced. The results indicate that increased protein content at medium and high N rate and late dressing time was associated with higher N transfer and assimilation after anthesis, increased grain yield was associated with more DW transfer amount, higher chlorophyll content at anthesis and net photosynthetic rate during grain filling. To synchronously improve grain yield and quality, different N regimes should be adopted for different specialty wheat. Reducing N rate with dressing at jointing will favor grain yield and quality formation for weak-gluten wheat genotypes, and increasing N rate with later dressing at booting and heading will be more desirable for medium- or strong-gluten wheat cultivars.Field experiments were conducted to investigate the effects of nitrogen rate and dressing ratio on grain quality formation and characteristics of post-anthesis carbon and nitrogen assimilation and transfer. Two wheat cultivars with different grain protein contents were used, i.e. Xuzhou 26 (high protein) and Huaimai 18 (low protein). The results showed that wheat yield was higher at nitrogen ratio of 34/66 under high nitrogen level and at 66/34 under low nitrogen level. High nitrogen rate and dressing ratio increased the contents of protein and gluten, sedimentation value and glutenin/gliadin ratio, reduced the ratio of N and DW transfer after anthesis, but increased N transfer a... |
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