Abstract:

The aim of this study was to investigate the effects of different nitrogen application levels and base-topdressing ratio on wheat leaf physiology,source-sink regulation of grain storage and yield in the middle and lower region of Yangtze River in Anhui Province.Using Baihumai 1 as the experimental material,three nitrogen application rates(180,210 and 240 kg/ha)with different nitrogen application levels and base ratios of 5∶1∶4,7∶1∶2 and 5∶4∶1 were set;through the determination of different source-sink indexes,in order to determine the appropriate wheat nitrogen fertilizer management model in the middle and lower region of the Yangtze River.The results indicated that with increasing nitrogen application rates(0 to 240 kg/ha),wheat leaf area index(LAI),post-flowering chlorophyll relative content(SPAD),and source organ biomass allocation showed an upward trend.The grain biomass allocation during maturity and the conversion rate of post-flowering source production capacity exhibited a trend of initially increasing and then decreasing,with the highest values observed at a nitrogen application rate of 210 kg/ha.At the same nitrogen application level,under the condition of a 7∶1∶2 base-to-topdressing ratio(base fertilizer∶tillering fertilizer∶jointing fertilizer),wheat plant had the highest leaf area index,while under a 5∶1∶4 ratio,chlorophyll content was highest.The grain biomass allocation during maturity and the economic coefficient were highest with the 7∶1∶2 base-to-topdressing ratio.Under the same base-to-topdressing ratio treatment,increasing nitrogen application improved the number of wheat spikelets and effective spikes,while the thousand-grain weight decreased with increasing nitrogen application.Grain yield showed an initial increase followed by a decrease with increasing nitrogen application,and at a nitrogen application rate of 210 kg/ha and a 7∶1∶2 base-to-topdressing ratio,wheat population potential storage capacity was large,grain-to-leaf ratio was high,and grain filling index was suitable.Wheat grain yield reached its maximum.Considering both high yield and efficiency,the optimum nitrogen fertilizer application rate of 210 kg/ha and the base-to-topdressing ratio of 7∶1∶2 were the best for the rice-stubble wheat Baihumai 1 in the middle and lower region of the Yangtze River in Anhui Province,allowing for maximum potential storage capacity and yield under these conditions.

Key words: Rice-stubble wheat, Nitrogen fertilizer management, Source-sink relationship, Grain-to-leaf ratio, Population storage capacity