Effects Of N Application At Later Growth Stages On Matter Translocation And Quality Of Rice In Cold Area Of China

A plot experiment with different percentages of N panicle fertilizer ratio under the same N application rate was conducted, the ratio of basal and tiller to panicle fertilizer is 6:4,6.5:3.5, 7:3, 8:2 and 10:5, respectively. The effects of application N at later growth stage on the carbon-nitrogen metabolism, matter translocation and distribution and the quality formation were studied.1. Experiment results showed that Compared with 10:0, application N at later growth stage increased the dry matter accumulation of after heading, and the dry matter accumulation of 6.5:3.5 was significantly raised 1.86 t/ha (cp<0.05). By the application N at later growth stage, the dry matter translocation ratio of stem was reduced from heading to filling stage, and there was a significant negative correlation (p﹤0.05) between the dry matter translocation ratio of stem from heading to filling stage and yield and milling rate. Experiment results showed that increasing of dry matter accumulation after heading and decreasing of dry matter translocation ratio from heading to filling stage may be foundations of high yield and high milling rate.2. Soluble sugar content of the leaf was higher, but the soluble sugar content of stem and panicle was lower in 10:0 treatment, so that the dry matter translocation was not smooth. application N at later growth stage increased the soluble sugar content of stem and panicle compared with 10:0, and improved the soluble sugar translocation ability. Source-sink relation was improved by applying N at later growth stage. the application N at later growth stage increased the sugar-spikelet ratio, and 6.5:3.5 treatment increased the sugar-spikelet ratio by 33.3% (p﹤0.05), Compared with 10:0. there was a significant negative correlation(p﹤0.01) between the sugar-spikelet ratio and chalkiness(r=0.645*,n=15). It showed that cooperation of source and sink, and increasing of the sugar-spikelet ratio were the foundations of reduce the chalkiness.3. Compared with 10:0, the N translocation rate was increased by 0.83~9.4kg/ha in application N at later growth stage treatment, and the application N at later growth stage increased the N uptake before heading stage by 0.84 ~12.74kg/ha. Before the blossom, N assimilation and N translocation of 7:3 treatments were highest among all the treatments. There was a significant positive correlation(p﹤0.01) between the rice protein content and N assimilation, N translocation before blossom.N content of leaves at grain forming stage was increased by the applying N at later growth stage, and the senility of function leaves was postponed. Compared with 10:0 treatment, the leave of application N at later growth stage reduced area declining ratio by 3.6%~24%. There was a significant positive correlation(p﹤0.01) between chalkiness and leave area decline ratio(r=0.858**,n=14). 4. the application N at later growth stage increased dry matter accumulation after heading, and dry matter translocation ratio of was reduced, compared with 10:0 treatment, so that milling rate was increased by 4.4%-9.9%. The N accumulation after heading was increased, but the N assimilation before heading and N translocation among all treatments were not obvious difference, so the protein content was not obviously increased. There are no obvious effects of application N at later growth stage on chalkiness, amylase and the quality of rice taste. In a word, the rice yield was increased by the application N at later growth stage, but the rice quality was not low.