Effects Of Sulfur On Rice Quality Of Japonica Rice And Its Mechanism

It has great significance in studying effect and mechanism of sulfur on rice quality for japonica rice. Wujing15 and wuyujing3 were the two cultivars. In solution culture and field experiment, the studies were conducted to investigate effect of sulfur on quality, carbon-nitrogen metabolism in Japonica rice grains and nitrogen metabolism in flag leaf. The research elucidated effect of sulfur on quality, carbon-nitrogen metabolism in Japonica rice grains and nitrogen metabolism in flag leaf. The main results were as follows:1. Effect of sulfur on milling and appearance qualities for japonica rice.Solution culture showed that Wujingl5 and Wuyujing3 rice quality were improved significantly, with rational sulfur concentration. Milling quality and appearance quality were improved remarkably, under 200μmol S.L-1 treatment for wujing15 and 260μmol S.L’1 for wuyujing3, in comparison with 80μmol S.L-1treatment. Under 200μmolS.L-1 treatment for wujingl5 and 260μmol S.L-1for wuyujing3, grain quality physiochemical properties of the two cultivars had substantial improvement. In 0-20cm soil horizon, with effective sulfur 19.3mg.kg-1, field experiment with random block experiment showed that application sulfur 45kg.hm-2 could increase the two cultivar’s Head rice rate, and could inpromve rice milling quality; In comparison with CK, the two cultivar’s Chalkiness rate were decreased by applying sulfur, but kernel shape were not affected remarkably.2. Effect of sulfur on nutrient, cooking qualities and starch structure for japonica rice.Solution culture found out protein contents and total amino acid contents increased with S concentration increasing for both cultivars, in comparison with 80μmol S.L-1 treatment. The two rice cultivars’ four protein fractions content had positive relationship with sulfur concentrations, on the whole. In field experiment, protein contents and total amino acid contents increased with S application increasing for the both cultivars, in comparison with CK treatment, when S application increased to 135kg.hm-2, the both did not increased remarkedly. S application did not affect Albumin and Globulin significantly. The both cultivar’s Prolamin and Glutelin increased with S application increasing. It found out increasing sulfur dosage could make amylose content decrease, so as to make Setback reduce and Relative crystallinity enhance. The crystallinity patterns of the two cultivars showed as typical A type. The arrangement and shape were different between the dorsum and abdomen of amyloplast in riceendosperm.Increasing sulfur dosage rationally bring in that Amyloplast in rice endosperm arranged fitly and closely.Condering the quality and economic comprehensive factors, suggest 45kg.hm-2.3.Effect of sulfur on carbon-nitrogen metabolism in Japonica rice grains.This text studied the effect of applying sulfur on material accumulation in endosperm in Grain-Filling Periods, with two cultivars, wujingl5 and wuyujing3. The results showed trend of material accumulation in endosperm under applying sulfur treatments accorded to that of control,which during Grain-Filling Periods, the weight of dry matter accumulated gradually, about 25d after heading,this accumulation stabilized; the effect of applying sulfur on starch accumulation were similar to that of dry matter, which before 20d after heading, all treatments’ weight of total starch increased sharply, after 20d after heading, speed of all treatments’ total starch decended; besides 25d after heading, treatments applied sulfur’s weight accumulation amylose of wujingl5 was lower than that of control; in whole of Grain-Filling Periods, treatments applied sulfur’s weight accumulation amylose of wuyujing3 was lower than that of control; from 20d after heading, weight accumulation of protein for treatments applied sulfur were higher than that of control of the two cultivars, but between accumulation of protein for treatments applied sulfur did not.4. Effect of sulfur on japonica rice nitrogen metabolism in flag leaf.Solution culture and Field experiment showed that increasing S dosage would result in increasing of NR active in flag leaf; it also made total free amino acids content and soluble protein content in flag leaf increases, which were propitious to protein synthesis. Increasing S concentration also enhanced SPAD value in flag leaf. When S dosage get to 320μmol.L-1 or 135kg.hm-2, NR active in flag leaf did not change remarkably, and total free amino acids content and soluble protein content in flag leaf did not, SPAD value in flag leaf did not increase remarkably.