THE EFFECT OF SOWING DATE AND NITROGEN APPLICATION UNDER DIFFERENT ECOSYSTEM ON THE YIELD AND QUALITY OF THE SUPERIOR WHEAT VARIETY

Under the different agro-ecosystem over the jiangsu-Anhuai provinces a randomized split-block field experiment was carried out to test 4 sowing date and 3 levels of N application with 3 replications. Another field experiment in randomized complete block design located in two sites in liangsu province to test the time of N application with 4 replications. The Protein components of wheat flour was analysed by the solubility method and the rheological properties were measured by the use of farinograph and extensography. The results were reported as follows. The highest yield of wheat occurred at northern part of Huaihe, but the yield gradually decreased down to the Changjian alluvium. On the contrary the protein contents and rheological properties were improved from north to south.The sowing date had no effect on wheat yield at north-west of Huaihe, while early sowing date increased yield significantly at eastern part of Huaihe as well as Changjian alluvium. The high rates of N application from 225 to 300 kg/ha did not increase wheat yield except at western part of Huaihe where 80% of N fertilizer was applied as basal dressing. There was a high correlation between protein content of wheat and the rate of N application. The results from the test of time of N application indicated that the yield from split-application of 236.25 kg N/ha with 55.6% as basal dressing, 22.2% at seedling stage and 22.2% at stem-elongation stage was the highest. As compared with the 0 N plot the yield increased 59.7% at north of Jiangsu and 39.4% at south of Jiangsu and the Protein content increased 32.2% and 40.2% respectively. The theological properties kept at optimum pattern under different treatments. The improvement in wheat quality with the increase in N fertilizer applied was slower in the northern part of Huaihe than in the south.Further increase in N (e. g. 26.25 kg N/ha) top-dressed at late stem-elongation decreased in both yield and quality. It is explained that postponing the last topdressing of N fertilizer may rsduce the rate of grain filling and hindered the formation of more insoluble high molecular weight proteins fraction.Why does the good quality wheat have high yield potential with lowered process quality? The explanation may be that due to the 'dilution effect' within the plant the N supply in both quantily and intensity would not be great enough to meet the requirement for the synthesis of storage-protein in wheat grain.