Study Of Nitrogen Regulation On The Inferior-grain Plumpness Of Rice

Widely used as rice cultivar in the Yellow and Huai River and two line hybridize rice,yujing6 and liangyoupei9 had been made experiments.Three treatments of N0,N90 and N180 were designed for studying grain plumpness respectively from dry matter accumulation,the assimilation products transportation channels-transfusion tissue,the dynamic change of sap flow,grain sink and so on at the base of the same quantity of basal fertilizer and tiller fertilizer.By field and pot experiments,the study on mechanism of inferior grain plumpness under panicle nitrogen regulation was carried out on experiments farm of Henan Agricultural university from 2004 to 2006.The results were as follow:1.The effection of nitrogen fertilizer on the yield components was studied.The results showed that seeding setting percentage,1000-grain weight and inferior grain plumpness were rather significantly among treatments.For yujing6,1000-grain weight and inferior grain plumpness were increased by spike nitrogen fertilizer application decreasing in the later grain filling.The number of spike and spike grain of NO were decreased.But the differences of treatments were not significant.For liangyoupei9,the effection of nitrogen fertilizer on the yield components was little. 1000-grain and actual yield increased because of more spikes and spike grain per mu.Three spike nitrogen fertilizer levels had effection on inferior grain rice quality significantly.The differences of treatments were rather significantly.For yujing6, milled quality of superior grain among treatments was not significant.Appearance quality such as chalky percentage,chalkiness and chalky area were significant.Brown rice percentage and milled rice percentage of NO comparing to N90 and N180 respectively increased by 7.22%,9.36%,28.05%,31.29%,and the differences of which were significant or rather significantly.Imperfect rice percentage,chalky percentage and chalkiness of NO comparing to N90 and N180 respectively decreased by 72.26%,73.74%,47.96%,34.61%,44.77%,35.68%,and the differences of which were significant or rather significantly.For liangyoupei9,Imperfect rice percentage, chalky percentage,chalky area and chalkiness of NO were lower than that of N90 and N180,amonge which Imperfect rice percentage,chalky percentage and chalkiness of NO comparing to N90 and N180 respectively decreased by 25.2%,18.36%,32.76%. The effection of nitrogen fertilizer on eating quality was the same as appearance quality.That is to say rice quality will get worse with spike nitrogen fertilizer application rising.2.Photosynthesis of flag leaf and chlorophyll in two varieties were different under nitrogen regulation during grain filling.The chlorophyll SPAD and Photosynthesis of N180 were higher evidently than NO and N90.The difference of yujing6 was greater than liangyouopei9.The yield of N90 and N180 were greater than NO because of higher photosynthesis of flag leaf.The correlation analysis revealed that the relationship between photosynthesis of flag leaf and yield was positive.3.The output and accumulation of stem and sheath after anthesis under nitrogen regulation were studied.The results showed that the change trend of soluble sugar and starch in the stem and sheath was the same.The soluble sugar and starch contents of different nodes displayed basically that contents decreased with the node rising approximately.Among treatments,NO was higher than the others in the middle-later stage.The soluble sugar and starch contents of stem and sheath in the ripe stage all decreased over that of the early anthesis stage.That is to say sugar and starch of plant were output gradually during grain filling stage.The dynamic change of nitrogen content of plant was the same as sugar and starch.Export percentage of soluble sugar and starch of stem and sheath increased with nitrogen fertilizer application rising,which was positive relationship with yield.But the NSC/panicle is opposition with it.From surveying treatments,NSC/panicle or total NSC/panicle of leaf,stem and sheath of NO were higher than the others.The relationship between inferior grain plumpness and NSC/panicle in the heading was positive significantly.That is to say the more accumulation substance in the early grain filling,the higher inferior grain plumpness.The inferior grain plumpness of NO was high probably because NSC/panicle of NO was high and accumulation substance of per panicle was more and the grain filling startup potential was strong.On the contrary,grain plumpness was low.The nitrogen output percentage deceased with spike nitrogen fertilizer application rising,and was positive significantly relationship with inferior grain plumpness.The C/N of leaf,stem and sheath of treatments was different evidently,which decreased with spike nitrogen fertilizer application rising approximately.The relationship between C/N of plant and superior grain plumpness in the prior grain filling stage and inferior grain plumpness in the middle-later grain filling stage was significant or rather significant.So grain plumpness might be proved by raising C/N of plant.4.Vascular bundle area in the neck internode was changed during grain filling and decreased in the ripe stage.Yujing6 and liangyoupei9 decreased respectively by 4.94%,11.94%,comparing to the maximum.Vascular bundle area was increased basically with spike nitrogen fertilizer application rising.Spike grain number of N180 was more,but inferior grain plumpness of it was low.So the big vascular bundle of neck internode was the base of forming big spike probably.The area and load of vascular bundle tissue in the first branch were studied. Vascular bundle tissue characteristics areas of the top and bottom of the inferior first branch and small branch of per grain in the second branch were greater than that of superior first and second branch.However,the load of vascular bundle tissue was on the contrary.The number of grain unit vascular bundle area on the top branch was greater than that of the bottom.So surveying of rice spike vascular bundle tissue structure,vascular bundle tissue characteristics areas of the same position manifested that the bottom was greater than the top.However,the load of vascular bundle tissue of the same position manifested that the top was greater than the bottom.Whether area or load of vascular bundle tissue,the first branch in the bottom was superior to that of the top.Vascular bundle tissue of the bottom was more abundant,and distributing more channels to per grain. Superior grain plumpness was greater than inferior grain although vascular bundle channels of the top was inferior to the bottom and the load of vascular bundle of the top was greater than the bottom.Accordingly,it was indicated that the restrictive factor of the grain filling difference between superior and inferior grain was not the vascular bundle channels,but the assimilation products of flowing through unit vascular bundle tissue.Under source and sink adjustment,inferior grain plumpness varied remarkably compared to inferior grain plumpness under normal source and sink structure condition.Inferior grain plumpness of top three branches removed was improved on the large scale.Japonica rice was improved by 18.4%and indica rice was improved by 12.86%.Inferior grain plumpness of half leaf removed of stem descended on the small scale.Japonica rice was reduced by 2.06%and indica rice was reduced by 12.15%.5.The fluctuating of bleeding intensity of neck internode was greater than that of the basal internode.The change trend of bleeding intensity was descent.The bleeding intensity achieved the maximum 5 days after anthesis.The bleeding intensity of neck internode descended the low level 11 days after anthesis.After it reached the second peak,it decended again.That was to say the bleeding intensity of neck internode was still actively metabolic situation.Comparing to treatments,the bleeding intensity of two positions descended with spike nitrogen fertilizer application rising,of which the neck internode manifested distinctly.The change regularity of soluble sugar was the same as the bleeding.The correlation analysis revealed that the relationship between grain plumpness and the bleeding intensity of two positions was positive.The relationship between the bleeding intensity of the neck intemode during grain filling and inferior grain plumpness and relative plumpness was significant or rather significant level.The greater bleeding intensity of the neck intemode,the smaller difference between superior and inferior grain filling.But for liangyoupei9,the relationship was not distinct with yujingr.The relationship of soluble sugar in bleeding of neck internode and inferior grain plumpness was positive rather significant level.6.The daily change trend of sap flow of neck and basal intemode was parabolic and the intensity between day and night was different during grain filling.The sap flow of basal internode increased with spike nitrogen fertilizer application rising in the day.At night,the sap flow of basal internode of three treatments was almost zero, which was consistent with plant transpiration.The differences of sap flow of neck intemode at night among treatments was great.The sap flow of neck internode at night of NO was greater than N90 and N180,which indicated probably that the sap flow of neck internode at night might be close relationship with grain filling at night. The correlation analysis revealed that the relationship between sap flow of neck internode at night and inferior grain plumpness was positive rather significant level.7.During grain filling stage,grain plumpness of different positions was rising along with weight of grains.The difference between superior and inferior grain filling was evident.The super-grain filling rate were 137.6%and 137.35%more than that Of inferior-grain at early grain-filling stage(5-10 days after heading)respectively in Japonica and indica rice.Grain relative plumpness was being connected to yield components factor and was related to rice quality closely.It was positive relationship with rice milled quality and was being connected reversely to appearance quality.It indicated that improving the grain filling rate of inferior grain,reducing the difference between inferior grain and superior grain,improving grain relative plumpness can improve the appearance quality and milled quality of rice grain,especially inferior grain.8.The research about soluble sugar and amylum content in superior grain and inferior grain indicated that soluble sugar content descended quickly in the early of grain filling and varied slowly in the later of grain filling,which was steadily on the whole;amylum content varied reversely.Soluble sugar content in superior grain and inferior grain of NO was smaller than N180.But amylum content in superior grain and inferior grain of NO was larger than N180.It indicated that the difference of inferior grain in treatments was big along with spike nitrogen fertilization reduced and the faculty of composing amylum improved.