Comparative Analysis Of Yield And Quality Traits In Different Japonica Rice

This paper has selected newly-bred japonica rice strains as testing materials, among which there were 6 hybrid combinations and 26 conventional strains. The Analysis of yields and qualitative characters of the testing materials has presented difference in them and that provided us with an opportunity. to study the yield and quality of high-yield varieties. Results of the experiment are as follows:(1)The hybrid combinations had generally higher yields than the conventional strains while the high-yield groups of conventional strains had higher average yields than the former. Although the amount of spikelets of hybrid combinations was sharply larger than the conventional varieties, their setting percentages were generally lower. We also found both of the conventional Shen 158 and the hybrid LDZ15-1 possessed higher contributing factors of yield. The following agronomic traits of high yield groups in the experiment are like: individual heights of 105-115cm,effective panicles of 15-20,spikelets of 130-160 per panicle, setting percentage of more than 90%, thousand-grain weight of 25g more, dense, heavy and erect panicles, thicker and erect leaves of shorter length.(2)Flag leaves in all stages had higher SPAD values than that of top-second leaves, and the value showed overall constant trend. About 10 days after blooming, the value came to its peak and then would decline until the lowest point at individual maturity. The high-yield strains had higher SPAD and longer green stay, which were the physiological factors of the high yield. The LAI(Leaf Area Index) range of high-yield strains were 5.5-7.0,signifying raising the LAI was conducive to its high yield, a but excessive LAI could give rise to serious shrouding within leaves that would lead inefficient photosynthesis and decrease of yield.(3)Since source-sink relationship positively correlates with yield, then to expand and strengthen the source and sink to some extent can help with heightening the yield. However, exceeding glumous flowers would make sharply increasing load for the whole group, lowering the setting percentage and decreasing the grain weight at last. Rice would accumulate the dry matter of stem leaf sheaths to the most in the stage of full heading and,15 days later after full heading, the whole aboveground accumulation also got to its peak, of which the function is of great value to raise rice yield and economy coefficient.(4)The hybrid combinations and conventional strains had little difference in coarse rice rate that excellently reached the standard. Huge discrepancy of white rice rate and head rice rate existed among strains and the average of conventional strains was higher than that of hybrid combinations. On the exterior qualities, the hybrid combinations had bigger rice grains with proper length and width, and the chalky grains had mediocre up-to-standard rate, exactly no strain had a first class chalky degree. Compared with conventional strains, hybrid combination groups presented higher chalky rate, but with lower chalky degree. Thus it is still an important challenge of improving the rice quality to reduce the chalky rate. Both of hybrid combination groups and conventional strains had up-to-standard amylose content, but the former contained more. Then gelatinous thickness showed low level in both sides, and conventional strains performed better. Finally strains differed from each other hugely in protein content and, the average of hybrid combination groups was higher than that of conventional strains.(5)The correlations of qualitative characters were as followings:significant and extremely positive correlation existed between amylose content and head rice rate, and amylose and gelatinous thickness respectively, which was possibly due to the hard quality for the high amylose content. Then gelatinous thickness correlated negatively with grain width, but positively with the length. Finally, we can conclude that since insignificant correlation existed between the yield and qualitative characters, it is achievable to combine high yield and high quality.