| During 1999-2000 under plot at yangzhou University Farm ,The relationship between indices of high yielding rice plant type and yield componets and increcement of grain after heading stage was studied systematically with mid-season rice Japenica,cv.wuyong8 and indica,cv.shanyou? as material,The results showed as follows:1.Plant type indicesGrain yield was positively correlated with the plant height and the ratio of the length of uppermost internode to stem , the ratio of the length of basal two internode to that of stem was positively negated with grain yield,the length of uppermost internode was positively correlated with that of ear. The plant height and the structure of uppermost and basal two internodes were reasonable ,The result show that 115cm and 107cm are appraprite length of hybrid rice andJapenica rice respectively, The length of basal two interriodes of hybrid rice were shorter ,The first basal internodes length was 4-5cm , the second internodes was 10-12cm, the uppermost internodes length was 29-32cm , the length of ears was about 27cm, The length of the firsE and second basal internodes of Japenica rice were respectively 4cm and 6.5cm, the uppermostinternodes length was 28-30cm the length of ears was about 20cm, the ratio of the length ofuppermost internodes and ears to plant height was greater, but it was correlated to the number of intemodes , the number of internodes was less the ratio was greater, for the five extendinternodes of hybrid rice ,the ratio was about 50%, for the six internodes of Japenica rice the ratio was about 45%, the sequence of length of high-yielding plant type was (wuyong8) thethird leaf from top , penultimate leaf, uppermost leaf ,the forth and the fifth leaf,(shanyou63) penultimate leaf from top, the third leaf, uppermost leaf ,the forth and the fifth leaf, Winding angels of upper three leaves of high-yielding population was third leaf from top>penultimateleaf>uppermost leaf ,the leaf layer showed æ·onverse ovun?or æ’pindle?,Ratio of highly effective leaf areas was greater, the mid and upper of plant had more leaf areas ,the base of the plant had also certain leaf areas, the upper leaves were rigid and erect ,light was suitably distributed within the population ,the base leaf was sloping, which was favourable to take in more sun-light ,and made the most of the light energy, advanced the photosynthic productivity of the population.2.Physiological traits of high yielding plant typeç”´igh-yielding plant type had appropriate leaf area at heading stage ,more leaves areas distributed in upper and mid of the plant ,the ratio of the leaf areas above 30cm of the plant was 85%, the specific leaf weight ,chlorophy II content and leaf areas index of upper three leaves of high-yielding rice decreased slowly during heading stage to maturing stage, leaf areas duration was prolonged, photo synthetic potential and net assimilation were increased. SOD and POD activity in uppermost leaf were greater, MDA content in uppermost leaves was lowerã•he high-yielding rice as a dynamic result of soure-sink correspond development, sink-capacity were decided at heading stage, so high or poor quality and development of source were the determinant to high or lower grain yield after heading stage. Photosynthetic potentials reflected the photosynthetic productive potential of source organs during heading stage to maturing stage. Moreover, total quantity of spikelets reflected the total sink-capacity of grain yield, consequently, ratio of photosynthetic potential versus the total quantity of pikelets (photosynthetic potential-grain ratio) described the relationship of different plant type between source and sink ,refleacted the developing relationship dynamically of source-sink during heading to maturing stage.Correlative analyses indicated, that the grain-yielding, seed seting percentage and 1000-grain weight were positively correlated with photosynthetic potential-grain ratio. The experimental result also show, if photosynthetic pote...
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