Effects Of Nitrogen And Phosphorus On Grain Starch Accumulation And Its Relationships To Grain Quality In Spring Wheat Differing In HMW-GS Composition

The studies were carried out in Wheat Lab of Northeast agricultural university in Harbin from 2001 to 2002. The formation and accumulation of the total grain starch and its compositions, and its relationships to grain quality, and the effects of the different types of nitrogen and the ratio of nitrogen to P2O5 on grain quality were studied by the different cultivars differing in HMW-GS composition and in quality. The results showed:The trend of dynamic accumulation of total grain starch was same mainly in the different cultivars differing in HMW-GS composition and in quality, and with the development of grain filling, the accumulation of total grain starch increased. The rate of accumulation of total grain starch was very low from 5th day to 10th post anthesis, after 10th day post anthesis, the accumulation rate was very high. The peak of accumulation appeared from 20th day and 25th post anthesis. The amount of total grain starch accumulation in maturity increased or decreased a little.The accumulation of grain amylose increased gradually during the period of grain filling. The initial accumulation of amylose was found about 10th day post anthesis. and the rate of accumulation was very high, until the later period of grain filling, the rate of accumulation decreased. The amylose content in maturity was highest or decreased a little.The high amount of grain amylopectin accumulation was found about 5 day post anthesis. The rate of amylopectin accumulation was very low during the period of grain filling, but the increasing or decreasing range was little when compared the final amount of amylopectin with the initial amount of amylopectin.The initial and final amount of accumulation and intensity of accumulation in the total grain starch and amylose and amylopectin were different in the all cultivars differing in HMW-GS composition. The accumulation of total grain starch and its compositions were different in the cultivars with the same HMW-GS composition. The final amount of amylose accumulation in NE7742 was the lowest among three cultivars with the HMW-GS 2+12, but the accumulation amount of total grain starch and amylopectin and the ratio ofIVamylopectin content to amylose content were very high. Therefore, the flour in NE7742 is suitable to make noodle.The regulation of types of N-fertilizer on the accumulation of grain starch and its compositions were different, and were related to the cultivars and the amount of nitrogen and phosphorus application, but the different types of N-fertilizer was no influence to the law of their accumulation. The accumulation of amylose and amylopectin and the ratio of amylopectin content to amylose content in the many cultivars can be improved by applying urea and NH4+-N.The ratio of nitrogen to P2O5 and applying amount of nitrogen and P2O5 can regulate the grain starch and its compositions content, but the regulation was related to the cultivars and the types of N-fertilizer. On the basis of low amount of nitrogen application, the total grain starch content and amylopectin content and the ratio of amylopectin content to amylose content in many cultivars can be improved by increasing amount of P-fertilizer, but the amylose content decreased. On the basis of high amount of N-fertilizer, it is not beneficial to improve the total grain starch content and amylopectin content and the ratio of amylopectin content to amylose content by increasing amount of P-fertilizer. Applying urea can increase the total grain starch and amylopectin content, and decrease the amylose content.The regulation of types of N-fertilizer on grain main quality characters was related to the cultivars and the amount of nitrogen and P2O5 . Overall, it is beneficial to improve the grain protein content and wet gluten content and SDS-sedimentation value by applying urea and NH-N-fertilizer.The correlation between the total grain starch and amylopectin and the ratio of amylopectin to amylose and grain main quality characters were negative, except gluten index, and the level of negative correlation was...