Effects Of Nitrogen Levels On Large Panicle Rice In Grain Filling And Its Mechanism

Level of nitrogen fertility have an important impact on matter accumulation and grain filling in the late growth stage of rice,clear the mechanism of the the effect on material production,grain filling and seed setting of large panicl rice by the nitrogen levels, and its relationship with nitrogen metabolism,has important significance. This study chooses IIyou7954(hybrid rice), Zheyou12(hybrid japonica rice) and Yongyou9(indica japonica hybrid rice) three different grains of rice varieties, using different level of nitrogen treatment, photosynthetic production,spike stem structure,nitrogen accumulation and transport and grain filling characteristics and mechanism of rice were investigated in the heading to maturity period.The results were as follows:1. Clear physiological effects of nitrogen levels on large-panicle type of rice yield formation. Photosynthesis of three rice cultivars decreased gradually after heading, with the increase of nitrogen, japonica Zheyou12chlorophyll SPAD values significantly higher than Indica Ilyou7954. The difference among the N treatments in indica and japonica hybrid rice is higher than japonica Zheyoul2and indica IIyou7954,20days after heading,Yongyou9,Zheyou12and IIyou7954the photosynthetic rate of the high nitrogen treatment (N4), respectively,7.3,6.4and6.2%higher than the contrast (NO). With the process of growth period, three varieties photosynthetic rate declined, but the decreasing speed different by the performance for the Zheyou12<IIyou7954<Yongyou9. High nitrogen and contrast with the differences between the growth period down more and more obvious; Yongyou9in full panicle hybrid indica infarction in different periods and nitrogen level after next, which will have a higher photosynthetic capacity; Production and output growth are performing for Ilyou7954>Yongyou9>Zheyou12, mature, heading to the accumulation of dry matter of Zheyou12> Yongyou9>IIyou7954;Three varieties of dry matter accumulation and output with nitrogen rose at first, then decreased and excessive nitrogen (N4) dry matter accumulation and yield decreased, appropriate nitrogen level (N3) promote the production increases.2. Clear the impact of nitrogen levels to large-panicle type of rice of substantial influence and grain filling. With nitrogen, the rise of the strong weak grain of significant difference between grain weight increases; Nitrogen promote grain grouting rate increase, it was with the increased amount of nitrogen filling rate to rise significantly, the weak grains in later period with the amount of nitrogen fertilizer increased significantly lower rate grouting; Different varieties have differences between grouting rate, Zheyou12grouting curve and japonica varieties of two other differences are significant. The difference of degree of weak enrichment, not nitrogen treatment difference between varieties most (gene determination); With nitrogen rising grain weight difference between different varieties, narrow. The strength of the regeneration of the most rapidly full process; The strength of the grain japonica grouting longest, and kernel weight down the most slow; Indica hybrid japonica something in between, and the regeneration similar. Nitrogen late too high against the grain full NO when fast start heading, strength between the forces of big differences, relatively low degree of full, and slow start strength difference between the N4interchange forces of small, show relatively full degree is high;10days after the nitrogen treatment N4strong grain filling rate gap increases, the relative performance of plumpness down, decline. Relatively full degree later, low nitrogen treatment more than high nitrogen treatment. Ilyou7954relatively full degrees higher than other two varieties, explain the regeneration process fast, weak grain full enrichment degree good, strong or weak at the difference between the small grain, grain filling the ear is average. The result showed that the greater the higher the grain number panicle type varieties, the asynchronous grouting is more obvious; Indica and japonica hybrid rice Yongyou9grouting rule in Indica Japonica between.3. Clear the impact of N rates on the large panicle rice stalk of vascular and panicle characteristics. Stem diameter with the amount of nitrogen fertilizer increased with the increase of the stem and wall thickness also varies with the amount of nitrogen fertilizer increased with the increase in the number of vascular bundle internode also will increase; The amount of nitrogen fertilizer increased, the vascular bundle area and the area of the sieve tube will increase, the vascular bundle density increases; Vascular bundle in the area and the total size of vascular area and panicle primary branches and grain number are into significant positive correlation between the relations; Grains per ear and stem diameter positive relation between, especially primary branch and stem characters are very significant positive correlation, that the stem diameter to a certain extent decided to primary branch number, can improve the level of nitrogen increased thick degree stem, and improve the internal Dave over proportion, in order to improve the grain Numbers per spike, achieve the goal of with high yield. In a certain range, appropriate nitrogen (15kg pure nitrogen/mu) may increase the number of stem vascular bundle and area, make panicle primary branch, secondary branch number infarction increased, the total grains per ear improved, so as to improve the yield. The experiment also showed that the load on unit area grain Numbers per spike and solid grain number linearly with the rise of level of nitrogen decreased; Rice seed rate and the relative plumpness with increased nitrogen levels decreased, while the grain filling rate increased with the increase of nitrogen levels.4. Clear of nitrogen levels on nitrogen accumulation and translocation of large panicle rice. Rice each organ nitrogen content of nitrogen with the rise and rise significantly. High nitrogen rice makes vegetative organs matter accumulation, the influence to the grain nitrogen nutrient transshipment. Heading and mature rice nitrogen accumulation linearly with the amount of nitrogen fertilizer increased and rising, heading to mature leaves turn nitrogen freight volume with nitrogen rise, high nitrogen treatment by more than the low nitrogen treatment. Leaf nitrogen transport rate varies with nitrogen rise, IIyou7954nitrogen transport rate and nitrogen is inversely related, and with the same, Zheyou12with nitrogen increased first after a trend to decrease that nitrogen transport japonica and the other two cultivars with a difference; Stem with nitrogen content of increasing nitrogen and drop, NO controls the greatest reduction, stem nitrogen transport rate varies with nitrogen level and decline, explain the greater the amount of nitrogen to stem the smaller grain transport rate. Grain nitrogen accumulation and nitrogen uptake rate increased with increasing amount of nitrogen.