| Progress on research of rice population was summarized on the basis of reviewing of internal and external papers of 257 in open publish in recent ten year( 1990 - 1999), which included yield production,grain filling,physiology and physiological chemistry,farmland microclimatic characteristics, source- sink characteristics and optimizing control. Taking the progress as research background,a series of field experiments were designed and put into effect in 1995 - 2001, the source - sink characteristks and their influencing factors of rice population were studied and the main conclusions were reached as follows:1 The source, sink and source - sink relation of rice population were measured by the adjusted photosynthetic potential (APP), total spikelets per 667m2 (TSM) and ratio of APP to sink(P/S)or grade of filled grain(GFG) .respectively. According to APP,TSM,P/S,GFG and the yield,rice population may be divided into four types as follows: the population with source limiting yield(PSO) , the population with sink limiting yield(PSI),the population with source-sink limiting yield(PSL) and the population with source - sink advantaging yield (PSA). Among them, PSA is high - yielding population. In order to achieve the population with high yield of 650 - 700kg/667m2 in rice, 30million spikelets with the GFG of 0.7-0.8 must be needed, the ratio of APP to sink must be up to 16- 18m2 · d/104 - grain, i. e. 30days after heading, the leaf area(index)of population is not below the maximum leaf area( index) of first three leaves from the top at heading stage.2 The experiment showed that characteristics of rice population were influenced by agronomic methods,such as planting density(PD) and fertilizing method(FM). The peak value of shoots shifted to an earlier date and the drop of shoots was bigger when PD was increased. The tillering capacity of variety(TCV), tillering capacity of population(TCP), TSM, GFG and P/S of all decreased with increase of PD.but LAI increased with the increase of PD. Aforementioned indexes of population assumed a regular change with change of FM.but significance level of index might vary with the variety. The characteristics of rice population were influenced by the ratio of row spacing to intrarow spacing (RS/ IS) under same PD.too. The relationship between population and RS/IS assumed a parabola change,so did the relationship between panicles/667m2,TSM,setting percentage,or 1000 - grain weight and RS/ IS,The equation between spikelets/panicle and RS/TS was a linear one ,so was the equation between RS/TS and rachis internode length,single leaf area(SLA) of the first leaf from the top,or SLA of the second leaf from the top. When RS/IS was on the increase, the intensity of illumination was increased and the light distribution tended to efficient inside rice population. A regular changes of population'scharacteristics were caused by the method of applying nitrogenous fertilizer,too.3 Field experiments proved that full heading time and population' s yield were influenced by seeding time and the yield was controlled by TSM and GFG in rice. Effects of seeding time on GFG were more significance than on TSM under same planting density. Most of partial correlation coeffi-cients( + r)between effective temperature( >10℃) summation (ETS) after full heading and GFG of population were up to significance or very significance, and partial correlation coefficient - r)between accumulated duration of sunshine (ADS) after full heading and GFG of population tended to significance. The reason for those was the displositon of temperature and illumination(MTI)broke out during ripening period frequently. The conditions that compel MTI to occur are as follows: the mean temperature of 5 - day(MTD) after MTI ought to be under 15.5℃ , the difference of MTD around MTI over 3℃ ,and the difference of mean illumination of 5 - day(MID) with delay of Id over 4h. Further analysis indicated that the relation between GFG and ETS was described by a formula as follows:GFG = (a + bETS)ETS-1. The formula can...
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