Studies On Preparation For And Mechanism Of Japonica Rice Grain Quality Regulator "PR₁"

Widely used as rice cultivar in the Yellow and Huaihe Rive plains for many years, Yujing 6 had characteristics of high yield,stronger growing potential,but of low grain filling extent and poor quality (especislly appearance quality) of inferior grains in the lower part of the spike which were major influencing factor to high yield and high efficiency and high grain quality. By field and pot experiments, the studies on screening for chemical regulators for rice grain quality were carried out on experiment farm of Henan Agricultural University from 2002 to 2004. The results were as follow:1. T17 (PR1) were determined to be the best optimized recipe to improve rice quality.It had a good regulation function not only to the appearance quality andmilling quality of rice grains, but also to yield increasing.The results of this dissertation indicated that PR1 did good to the appearance quality and milling quality of superior-grain ,and especially to the grain appearance quality.Their chalkinessy,chalky area,chalky percentage and imperfect rice percentage were reduced separately compareing to CK by 45.83%530.51%,26.79%,35.68%. The function of improving the inferior-grain(Especially to inferior-grain appearance quality) qunality was rather significantly. The chalkinessy,chalky area,chalky percentage and imperfect rice percentage of inferior-grain after spaying PRj were reduced separately compareing to CK by 68.42%,37.47%,50%,69.30%. Their brown rice percentage, milled rice percentage head milled percentage are raised by 4.77%,5.09%, 12.04%.They also did good to yield and its component factors(1000-grain weight fruiting ratio),Compareing to CK ,PR1 could increase yield by 15.72% per hectare,magorly increasing 1000-grain weight and fruiting ratio, its 1000-inferior grain weight were raised by 13.52%.But no significantly function to grain number per spikle.2.The figure of daily changes of canopy apparent photosynthetic rate was parabola in the initial milky maturity and late milky maturity . After spraying PR1, the stage of CAP climax which is at 10:00 was ahead to two hours compareing to CK, .and the canopy apparent photosynthetic rates were raised obviously, its averagephotosynthetic rate were increased by 34%(compare to CK). The figure of dynamic changes of CAP at grain-filling stages was also parabola,but the CAP of CK descends quickly. The CAP of PRi are raised obviously at mid-late stage of grain filling ,its average photosynthetic rate were increased by 19.5%(compare to CK).3.The output and accumulation of stem and sheath which were dynamic occupy certain position in the whole matter productivity and distribution .The output of reserves in the third stem of top was most in every stem, its output of reserves before anthesis played important role on the initiation of grain filling at the primary period of anthesis, which occupied 81.65% on the maxium output of reserves.The second was the second stem of top,its outputs of reserves after anthesis were most used for grain filling in the mid-late periods,occupying 75.22% on the total output. The reserves in the middle stems were a most "temporal sink",which occupying 72.94% on the whole top three shems and sheaths.Contents of soluble sugar and sucrose in stems were higher than the ones in sheath at every period of grain filling stage.The difference was significant at the primary period of grain filling stage,but was reduced at the late period. With the grain filling, the contents of soluble sugar and sucrose in stems and sheaths showed a gradient changes.especially to the third stem.Sugar content gradienthas close relation to the output and accumulation of reserves in sheaths and stems. Sugar content gradient changes were propably motive of export and transform of temporal reserves. The output nature in sheath as the same as that in stem.In fact, the reserves of output and transform were soluble sugar ( sucrose was mainly export forms).In normal conditions(CK),the output of soluble sugars before anthesis came mainly from the third stem. With the conditions of higher yield and higher grain quality,PR1 could not only improve the output of reserves in the third stem before anthesis,but also obviously improve the outputs of reserves the first,second, stem and the second sheath of top before anthesis (more 127%,144%,317.7% than CK), playing important role in the primary grain filling start up.The output of reserves from the first, second shems and sheaths of top after anthesis (mainly from the second stem and the first sheath of top, raising 65.31%, 100% compare with CK) which are promoted by PR1 were used on grain filling at the late stages of grain filling. But the output fromsheaths after anthesis had a little function to grain filling.4. The dynamics between bleeding intensity of basal internodes and bleeding intensity of the last internodes were similar at grain filling stage. The bleeding intensity of basal internode were bigger than bleeding intensity of the last internode at...